JPH07252481A - Production of isotropic pitch - Google Patents

Abstract

PURPOSE:To obtain an isotropic pitch for the production of general-purpose carbon fiber, etc., in high yield by continuously heating a coal-based heavy oil with a tubular heater under a specific condition, dissolving the product in a monocyclic aromatic hydrocarbon solvent, separating the soluble component and heat-treating the component. CONSTITUTION:This isotropic pitch suitable as a spinning pitch for the production of general-purpose carbon fiber can be produced in high yield from a coal- based heavy oil having a viscosity of <=1,000cSt at 100 deg.C and containing <=25wt.% of a fraction having a boiling point of <=250 deg.C and 5-40wt.% of a fraction having a boil-ing point of 250-350 deg.C by continuously heating the oil at 380-520 deg.C under 2-100kg/cm<2>G pressure at a residence time of 10-2,000sec with a tubular heater under a condition to increase the xylene-insoluble component by >=1wt.% and to suppress the increase of a quinoline-insoluble component to <1wt.%, dissolving the obtained heat-treated heavy oil in a monocyclic aromatic hydrocarbon solvent, separating the component insoluble in the solvent, removing the solvent from the obtained solution containing the soluble component to obtain a refined heat-treated heavy oil and heat-treating the obtained oil.

Description

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

【０００１】[0001]

【産業上の利用分野】本発明は、種々の炭素製品製造に
用い得る、特に汎用炭素繊維製造用紡糸ピッチとして適
した、メソフェーズを含まず、光学的に等方性である、
ピッチの製造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can be used for producing various carbon products, and is particularly suitable as a spinning pitch for producing general-purpose carbon fibers, is free of mesophase, and is optically isotropic.
The present invention relates to a pitch manufacturing method.

【０００２】[0002]

【従来の技術】炭素繊維は、一般にその機械的強度の面
から、高性能炭素繊維と汎用炭素繊維に大別されてい
る。すなわち、一般に、強度２００〜３５０Kg／mm² 、
弾性率１０〜４０ton ／mm² 程度のものが高性能炭素繊
維といわれ、例えばロケットや航空機等の特殊な材料、
ゴルフクラブ、テニスラケット、あるいは釣竿等の用途
に供されている。また、強度７０〜１４０Kg／mm² 、弾
性率３〜１０ton ／mm² 程度のものが汎用炭素繊維とい
われ、例えば土木建築分野、断熱材、摺動材、あるいは
パッキング類等の用途に供されている。2. Description of the Related Art Carbon fibers are generally classified into high-performance carbon fibers and general-purpose carbon fibers in terms of their mechanical strength. That is, generally, the strength is 200 to 350 Kg / mm ² ,
A high-performance carbon fiber having an elastic modulus of about 10 to 40 ton / mm ² is a special material such as rocket and aircraft,
It is used for golf clubs, tennis rackets, and fishing rods. Further, those having a strength of 70 to 140 kg / mm ² and an elastic modulus of about 3 to 10 ton / mm ² are said to be general-purpose carbon fibers, and are used, for example, in the fields of civil engineering and construction, heat insulating materials, sliding materials, or packings. There is.

【０００３】高性能炭素繊維は、その用途の拡大、ある
いはその用途面の技術の高度化に伴い、機械的強度の一
層の向上が望まれ、例えば強度３５０〜６００Kg／mm²
というような超高性能炭素繊維というものが望まれるよ
うになってきている。High-performance carbon fibers are desired to have further improved mechanical strength with the expansion of their applications or the sophistication of the technology of their applications. For example, the strength is 350 to 600 kg / mm ^2.
There is an increasing demand for such ultra-high performance carbon fibers.

【０００４】一方、汎用炭素繊維については、その性能
に応じた種々の用途、中でも土木建築分野の炭素繊維補
強コンクリート（ＣＦＲＣ）等で大量に使用される等、
近年その需要増に対して、より一層低廉に製造すること
が望まれている。On the other hand, general-purpose carbon fibers are used in various applications according to their performance, especially in large quantities in carbon fiber reinforced concrete (CFRC) in the field of civil engineering and construction.
In recent years, it has been desired to manufacture at a lower cost in response to the increase in demand.

【０００５】従来、炭素繊維は、ポリアクリロニトリル
（ＰＡＮ）を紡糸し、これを酸化雰囲気中で不融化し、
その後不活性雰囲気中で炭化もしくは黒鉛化することに
より製造されるＰＡＮ系炭素繊維が主流であった。しか
しながら、ＰＡＮ系炭素繊維は、原料が高価であり、炭
化収率が低く、毒性物質が発生する等の問題があり、近
年、原料として安価なピッチからもＰＡＮ系の炭素繊維
と同等もしくはそれ以上の性能を持ち、また、ＰＡＮ系
におけるような問題なしに炭素繊維を製造できることが
見出されている。Conventionally, carbon fibers are produced by spinning polyacrylonitrile (PAN), infusible in an oxidizing atmosphere,
The PAN-based carbon fiber produced by carbonizing or graphitizing in an inert atmosphere was the mainstream. However, PAN-based carbon fibers have problems that the raw materials are expensive, the carbonization yield is low, and toxic substances are generated. In recent years, PAN-based carbon fibers are equal to or more than PAN-based carbon fibers even from inexpensive pitches as raw materials. It has been found that carbon fibers can be manufactured with the same performance and without the problems as in the PAN system.

【０００６】このピッチ系炭素繊維製造用紡糸ピッチの
内、高性能炭素繊維製造用紡糸ピッチは、一般にメソフ
ェーズと言われる光学的異方性成分からなっている。こ
れは、コールタール等の石炭系重質油を加熱処理する際
に、熱分解や熱重合等の反応によって、芳香族分子があ
る程度の広がりを持った縮合芳香族環平面分子となり、
それが積層、配向して形成され、偏光顕微鏡下に観察し
たとき、光学的異方性を示す成分である。一方、汎用炭
素繊維製造用紡糸ピッチは、上記のようなメソフェーズ
を全く含まない光学的等方性成分からなるピッチであ
る。以下、この光学的に等方性成分からなるピッチを単
に「等方性ピッチ」という。Among the pitch-based spinning pitches for producing carbon fibers, the spinning pitch for producing high-performance carbon fibers is composed of an optically anisotropic component generally called mesophase. This is a fused aromatic ring planar molecule in which aromatic molecules have a certain extent by a reaction such as thermal decomposition or thermal polymerization when heat-treating coal-based heavy oil such as coal tar,
It is a component that is formed by stacking and orienting, and exhibits optical anisotropy when observed under a polarizing microscope. On the other hand, the spinning pitch for general-purpose carbon fiber production is a pitch composed of an optically isotropic component containing no mesophase as described above. Hereinafter, the pitch composed of this optically isotropic component is simply referred to as "isotropic pitch".

【０００７】これらの炭素繊維製造用紡糸ピッチの出発
原料である石炭系重質油、例えばコールタールは、石炭
を高温で乾留する際に副生する重質油であるため、０．
１〜０．３μm のフリーカーボンや遊離炭素と呼ばれる
非常に微細なすす状物や、また高温で乾留するときに生
成する著しく高分子量化した成分や、加熱処理時に容易
にメソフェーズ化する熱反応性の高い成分等を含有して
おり、これらは石炭系重質油から汎用炭素繊維製造用の
等方性ピッチを製造する際、紡糸時に悪影響をおよぼす
不良成分である。すなわち、等方性ピッチを紡糸し、汎
用炭素繊維を製造する際、これらの不良成分の内、フリ
ーカーボンや遊離炭素および著しく高分子量化した成分
は、等方性ピッチを加熱溶融して紡糸する際に固体状態
であるため、紡糸時の糸切れや得られる炭素繊維の繊維
強度の低下をもたらす。また、熱反応性の高い成分は、
等方性ピッチを製造する際の加熱処理時にメソフェーズ
化するため、得られる等方性ピッチがメソフェーズを含
有する原因となるものであって、かかるメソフェーズを
含有する等方性ピッチを加熱溶融して紡糸しようとする
と、等方性ピッチ成分が紡糸に適した粘度となっても、
メソフェーズの粘度はまだ紡糸に適さない高い粘度を有
しているため、安定した紡糸が困難である。The heavy oil of coal type, which is a starting material for the spinning pitch for producing carbon fiber, such as coal tar, is a heavy oil produced as a by-product when carbon is carbonized at high temperature.
Very fine soot-like substances called free carbon and free carbon of 1 to 0.3 μm, and extremely high molecular weight components generated during carbonization at high temperature, thermal reactivity that easily forms mesophase during heat treatment , Etc. are contained, and these are bad components that adversely affect spinning during the production of isotropic pitch for general-purpose carbon fiber production from heavy coal-based oil. That is, when spinning an isotropic pitch to produce a general-purpose carbon fiber, among these defective components, free carbon and free carbon and components having a remarkably high molecular weight are melted by heating the isotropic pitch and then spun. At that time, since it is in a solid state, it causes yarn breakage during spinning and a decrease in fiber strength of the resulting carbon fiber. In addition, the components with high thermal reactivity are
Since the mesophase is formed during the heat treatment for producing the isotropic pitch, the resulting isotropic pitch causes the mesophase to be contained, and the isotropic pitch containing the mesophase is heated and melted. When trying to spin, even if the isotropic pitch component has a viscosity suitable for spinning,
Since the viscosity of the mesophase has a high viscosity that is not suitable for spinning, stable spinning is difficult.

【０００８】したがって、石炭系重質油を原料として汎
用炭素繊維製造用の等方性ピッチを製造しようとする場
合、原料である石炭系重質油からフリーカーボン等の固
形分、石炭を高温で乾留したときに生成する著しく高分
子量化した成分、そして加熱処理により容易にメソフェ
ーズ化する熱反応性の高い成分をいかに効率良く除去す
るかということ、およびその製造工程中においてメソフ
ェーズをいかに生成させないようにするかということが
重要な問題となる。Therefore, when an isotropic pitch for general-purpose carbon fiber production is to be produced from coal-based heavy oil as a raw material, solid contents such as free carbon and coal at a high temperature are produced from the raw material coal-based heavy oil at high temperature. How to effectively remove components with extremely high molecular weight that are produced during dry distillation and highly thermally reactive components that easily form mesophases by heat treatment, and how to prevent mesophases from being produced during the production process. The question is whether or not to choose.

【０００９】このような問題を解決するための方法とし
て、例えば特公昭６１−２１５８９号公報には、原料コ
ールタール軟ピッチを３５０〜５００℃に加熱してメソ
フェーズを生成させ、原料中のフリーカーボンを、生成
したメソフェーズ球体の周囲に付着させて、芳香族系炭
化水素溶剤の不溶分として除去する方法が示されてお
り、その実施例では、コールタール軟ピッチを４３０〜
４５０℃、６０分間加熱処理し、メソフェーズを１０〜
２５重量％発生させ、メソフェーズにフリーカーボンを
付着させて、それらをタール油不溶分として同時に除去
している。また、特公昭６１−２７１２号公報にも、上
記と同様の方法が示されており、その実施例には、コー
ルタール軟ピッチを４００〜４９０℃、１０〜１３０分
間加熱処理しメソフェーズを１５〜２８重量％発生さ
せ、メソフェーズにフリーカーボンを付着させて、それ
らをタール油不溶分として除去している。すなわち、こ
れらの方法は、いずれも、前記不良成分の内、芳香族系
炭化水素溶剤に可溶な成分である熱反応性の高い不良成
分を、加熱処理によりメソフェーズ化し、芳香族系炭化
水素溶剤に不溶な成分とし、元来芳香族系炭化水素溶剤
に不溶な成分であるフリーカーボン等の固形分および著
しく高分子量化した成分と同時に除去するものである。As a method for solving such a problem, for example, in Japanese Patent Publication No. 61-21589, a raw material coal tar soft pitch is heated to 350 to 500 ° C. to form a mesophase, and free carbon in the raw material is produced. Is attached to the periphery of the generated mesophase spheres to remove it as an insoluble content of the aromatic hydrocarbon solvent. In that example, coal tar soft pitch is 430 to 430.
Heat treatment at 450 ° C for 60 minutes to give mesophase 10
25% by weight is generated, free carbon is attached to the mesophase, and they are simultaneously removed as tar oil insoluble matter. In addition, Japanese Patent Publication No. 61-2712 discloses a method similar to the above, and in its example, coal tar soft pitch is heat-treated at 400 to 490 ° C. for 10 to 130 minutes, and mesophase is heated to 15 to 30 minutes. 28 wt% is generated and free carbon is attached to the mesophase to remove them as tar oil insoluble matter. That is, in any of these methods, among the above-mentioned defective components, a defective component having a high thermal reactivity, which is a component soluble in an aromatic hydrocarbon solvent, is mesophased by a heat treatment to obtain an aromatic hydrocarbon solvent. It is a component insoluble in water and is removed at the same time as the solid component such as free carbon which is originally a component insoluble in the aromatic hydrocarbon solvent and the component having a remarkably high molecular weight.

【００１０】しかし、上記方法のようにメソフェーズを
１０〜２８重量％も発生させるような加熱処理の条件で
は、元来芳香族系炭化水素溶剤に可溶であって、また、
汎用炭素繊維製造用紡糸ピッチとして好適な等方性ピッ
チとなり得る有用な成分の一部までも、熱反応性の高い
成分と共にメソフェーズ化もしくはメソフェーズ化しな
いまでも芳香族系炭化水素溶剤に不溶な成分となり、該
溶剤不溶分として除去されるため、得られる等方性ピッ
チの収率が低くなるから、上記のような方法は経済的と
は言いにくい。また、上記のようにメソフェーズを生成
させる苛酷な加熱条件では、加熱処理に当たり、管式加
熱炉のような連続加熱処理法を採用すると、メソフェー
ズ等による管の閉塞の問題が発生するから、効率が悪く
かつ品質の安定性に欠けるバッチ式の加熱処理法を採用
せざるを得ないという問題もある。However, under the conditions of heat treatment such that 10 to 28% by weight of mesophase is generated as in the above method, it is originally soluble in an aromatic hydrocarbon solvent, and
Even some useful components that can be suitable as an isotropic pitch suitable for spinning pitch for general-purpose carbon fiber production, components that are insoluble in aromatic hydrocarbon solvent even if they are mesophased or not mesophased together with highly heat-reactive components Since it is removed as the solvent insoluble matter, the yield of the isotropic pitch obtained is low, and the above method is not economical. Further, under the severe heating conditions for producing the mesophase as described above, if a continuous heating method such as a tube heating furnace is adopted for the heat treatment, the problem of blockage of the tube due to the mesophase or the like occurs, so that the efficiency is improved. There is also a problem that a batch-type heat treatment method, which is bad and lacks in quality stability, has to be adopted.

【００１１】また、例えば、特開昭５２−７８２０１号
公報には、芳香族系炭化水素溶剤と脂肪族系炭化水素溶
剤をある特定の比率で混合した溶剤を用いて、これに不
溶なフリーカーボンや高分子量成分を濾過により除去す
る方法が示されている。Further, for example, in Japanese Unexamined Patent Publication No. 52-78201, there is used a solvent in which an aromatic hydrocarbon solvent and an aliphatic hydrocarbon solvent are mixed in a specific ratio, and free carbon insoluble in the solvent is used. A method of removing the high molecular weight component by filtration is shown.

【００１２】しかし、上記のような混合溶剤を用いる方
法においては、フリーカーボンや著しく高分子量化した
成分は除去できても、加熱処理により容易にメソフェー
ズ化する熱反応性の高い成分は、混合溶剤に可溶である
ため、該混合溶剤による処理では除去されず、次の溶剤
不溶分の除去されたコールタール軟ピッチを、紡糸に適
したピッチとするための加熱処理工程においてメソフェ
ーズが発生し易く、全くメソフェーズを含まない紡糸用
等方性ピッチの製造法としては不十分である。また、特
定の混合溶剤を用いるため、溶剤の回収、混合比率の調
整等、操作上の煩雑さもある。However, in the method using the mixed solvent as described above, even if the free carbon and the component having a remarkably high molecular weight can be removed, the component having a high thermal reactivity which easily forms the mesophase by the heat treatment is the mixed solvent. Since it is soluble in the mixed solvent, it is not removed by the treatment with the mixed solvent, and the coal tar soft pitch from which the solvent-insoluble component is removed is likely to cause a mesophase in the heat treatment step for obtaining a pitch suitable for spinning. However, it is insufficient as a method for producing an isotropic pitch for spinning that does not contain any mesophase. In addition, since a specific mixed solvent is used, there are also operational complications such as recovery of the solvent and adjustment of the mixing ratio.

【００１３】[0013]

【発明が解決しようとする課題】上記のように、石炭系
重質油を原料として汎用炭素繊維製造用紡糸ピッチとし
て好適な等方性ピッチを製造するに当たり、原料である
石炭系重質油から、フリーカーボン等の固形分、著しく
高分子量化した成分、そして加熱処理により容易にメソ
フェーズ化する熱反応性の高い成分等の不良成分の除去
方法は、該等方性ピッチの工業的製造の経済性に大きく
影響することが明白であるが、今のところ、これらの不
良成分を効率良く経済的に除去できる方法は確立されて
おらず、結局、固形分、著しく高分子量化した成分およ
びメソフェーズを含まず、紡糸性、不融化性に優れた等
方性ピッチを高収率でかつ経済的に製造できる方法は確
立されていない。As described above, in producing an isotropic pitch suitable as a spinning pitch for general-purpose carbon fiber production from a coal-based heavy oil as a raw material, a coal-based heavy oil as a raw material is used. The method for removing defective components such as solid components such as free carbon, remarkably high molecular weight components, and highly heat-reactive components that are easily mesophased by heat treatment is economical in industrial production of the isotropic pitch. However, at present, there is no established method that can efficiently and economically remove these bad components, and, as a result, the solid content, the components having a significantly high molecular weight and the mesophase are eliminated. No method has been established for producing an isotropic pitch, which does not contain sponge and is excellent in spinnability and infusibilizability, in high yield and economically.

【００１４】したがって、本発明の目的は、石炭系重質
油から上記不良成分を効率良く経済的に除去し得る方法
を与え、石炭系重質油から高収率で経済的に汎用炭素繊
維製造用紡糸ピッチとして好適な等方性ピッチを製造で
きる方法を提供することにある。Therefore, an object of the present invention is to provide a method capable of efficiently and economically removing the above-mentioned defective components from a coal-based heavy oil, and to produce a general-purpose carbon fiber economically from a coal-based heavy oil in a high yield. An object of the present invention is to provide a method capable of producing an isotropic pitch suitable as a spinning pitch for use.

【００１５】[0015]

【課題を解決するための手段】本発明者らは、上記本発
明の目的を達成すべく鋭意研究を重ねた結果、次のこと
を見出して本発明を完成した。As a result of intensive studies to achieve the above-mentioned object of the present invention, the present inventors have found the following and completed the present invention.

【００１６】 一定の性状を有する石炭系重質油を原
料として用い、該石炭系重質油をキシレン不溶分が１重
量％以上増加し、かつキノリン不溶分が１重量％以上増
加しないように加熱処理すれば、単環の芳香族系炭化水
素溶剤に可溶性であって等方性ピッチになり得る有用な
成分が、従来方法のように単環の芳香族系炭化水素溶剤
に不溶な成分に転化されることが抑制されて、主として
単環の芳香族系炭化水素溶剤に可溶で加熱により容易に
メソフェーズ化する熱反応性の高い成分のみが単環の芳
香族系炭化水素溶剤に不溶な成分に転化され、斯く加熱
処理した石炭系重質油を単環の芳香族系炭化水素溶剤で
処理すれば、加熱により容易にメソフェーズ化する熱反
応性の高い成分を等方性ピッチになり得る有用な成分の
損失を抑制して、フリーカーボン等の固形分および高分
子量化した成分と共に、効率良く除去することができ、
従来方法によるよりも高収率で経済的に等方性ピッチを
製造できること。A coal-based heavy oil having a certain property is used as a raw material, and the coal-based heavy oil is heated so that the xylene-insoluble content does not increase by 1% by weight or more and the quinoline-insoluble content does not increase by 1% by weight or more. If treated, useful components that are soluble in monocyclic aromatic hydrocarbon solvents and can be isotropic pitch are converted into components that are insoluble in monocyclic aromatic hydrocarbon solvents as in the conventional method. The component that is soluble in the monocyclic aromatic hydrocarbon solvent and is easily mesophased by heating and has high thermal reactivity is the only component that is insoluble in the monocyclic aromatic hydrocarbon solvent. If the heat-treated coal-based heavy oil is treated with a monocyclic aromatic hydrocarbon solvent, it is possible to convert the highly heat-reactive component that is easily mesophased by heating into an isotropic pitch. To reduce the loss of -Can be efficiently removed together with solid components such as carbon and high molecular weight components,
Being able to produce isotropic pitch economically with higher yield than by conventional methods.

【００１７】 上記のキシレン不溶分が１重量％以上
増加し、かつキノリン不溶分が１重量％以上増加しない
ように加熱処理するための加熱処理手段としては、例え
ばオートクレーブを用いるバッチ式手段は適当でなく、
管式加熱炉を用いる連続式手段が適当であること。As a heat treatment means for heat treatment so that the xylene-insoluble matter increases by 1% by weight or more and the quinoline-insoluble matter does not increase by 1% by weight or more, for example, a batch-type means using an autoclave is suitable. Without
Appropriate continuous means using a tube heating furnace.

【００１８】 一定の性状を有する石炭系重質油か
ら、上記のような加熱処理とそれに次ぐ単環の芳香族系
炭化水素溶剤処理により、等方性ピッチになり得る有用
な成分の損失を抑制して高収率で得られた等方性ピッチ
が、従来方法で得られた等方性ピッチと比べて、同等な
いしそれ以上に優れた紡糸性を有し、汎用炭素繊維製造
用紡糸ピッチとして好適であること。By suppressing the loss of a useful component that may be an isotropic pitch from the above-mentioned heat treatment and subsequent monocyclic aromatic hydrocarbon solvent treatment from the coal-based heavy oil having a certain property Isotropic pitch obtained in a high yield by, as compared with the isotropic pitch obtained by the conventional method has a spinnability equal to or better than it, as a spinning pitch for general-purpose carbon fiber production Be suitable.

【００１９】したがって、本発明の要旨は、１００℃で
の粘度が１，０００cSt 以下であり、沸点が２５０℃以
下の成分が２５重量％以下、沸点が２５０〜３５０℃の
成分が５〜４０重量％の範囲にある石炭系重質油を、キ
シレン不溶分が１重量％以上増加し、かつキノリン不溶
分が１重量％以上増加しないように管式加熱炉を用い連
続的に加熱処理し、得られた加熱処理重質油を単環の芳
香族系炭化水素溶剤に溶解させ、該溶剤に不溶な成分を
分離除去し、得られた可溶成分を含む溶液から溶剤を除
去して精製加熱処理重質油を得、該精製加熱処理重質油
を加熱処理することを特徴とする等方性ピッチの製造方
法に存する。Therefore, the gist of the present invention is that the viscosity at 100 ° C. is 1,000 cSt or less, the component having a boiling point of 250 ° C. or less is 25% by weight or less, and the component having a boiling point of 250 to 350 ° C. is 5 to 40% by weight. % Of the coal-based heavy oil is continuously heat-treated using a tubular heating furnace so that the xylene-insoluble matter increases by 1% by weight or more and the quinoline-insoluble matter does not increase by 1% by weight or more. The heat-treated heavy oil is dissolved in a monocyclic aromatic hydrocarbon solvent, the components insoluble in the solvent are separated and removed, and the solvent is removed from the solution containing the obtained soluble components for purification and heat treatment. A method for producing isotropic pitch is characterized in that a heavy oil is obtained and the refined heat-treated heavy oil is heat-treated.

【００２０】本発明で原料として用いられる石炭系重質
油としては、１００℃における粘度が１，０００cSt 以
下、好ましくは３００cSt 以下、沸点２５０℃以下の成
分が２５重量％以下、好ましくは２０重量％以下、沸点
２５０〜３５０℃の成分が５〜４０重量％、好ましくは
１０〜４０重量％の範囲にあるものであれば、コールタ
ール、コールタールピッチあるいは石炭液化油等、種々
のものを用い得る。The heavy coal-based oil used as a raw material in the present invention has a viscosity at 100 ° C. of 1,000 cSt or less, preferably 300 cSt or less and a boiling point of 250 ° C. or less 25% by weight or less, preferably 20% by weight. Various components such as coal tar, coal tar pitch or coal liquefied oil may be used as long as the components having a boiling point of 250 to 350 ° C. are in the range of 5 to 40% by weight, preferably 10 to 40% by weight. .

【００２１】原料の石炭系重質油の加熱処理の条件は、
目的物である汎用炭素繊維製造用紡糸ピッチとして適し
た等方性ピッチの特性、収率、ひいては該等方性ピッチ
から誘導される炭素繊維の特性にまで影響を及ぼすため
重要である。本発明の実施に当たっては、原料の石炭系
重質油を、該石炭系重質油中のキシレン不溶分が１重量
％以上、好ましくは３重量％以上増加し、かつキノリン
不溶分が１重量％以上増加しない条件で加熱処理するこ
とが必要であり、かかる加熱処理条件は、一般に、温度
３８０〜５２０℃、圧力２〜１００Kg／cm²G、滞留時間
１０〜２，０００秒、好ましくは、温度４００〜５２０
℃、圧力５〜５０Kg／cm²G、滞留時間３０〜１，０００
秒の範囲から選ばれる。The conditions for heat treatment of the raw material coal-based heavy oil are as follows:
This is important because it affects the properties and yield of isotropic pitch suitable as a target spinning pitch for producing general-purpose carbon fibers, and eventually the properties of carbon fiber derived from the isotropic pitch. In carrying out the present invention, the xylene-insoluble content in the coal-based heavy oil is increased by 1% by weight or more, preferably 3% by weight or more, and the quinoline-insoluble content is increased by 1% by weight. It is necessary to perform heat treatment under the condition that the temperature does not increase above, and such heat treatment conditions are generally a temperature of 380 to 520 ° C., a pressure of ^{2 to} 100 Kg / cm ² G, a residence time of 10 to 2,000 seconds, and preferably a temperature. 400-520
C, pressure 5 to 50 kg / cm ² G, residence time 30 to 1,000
Selected from the range of seconds.

【００２２】本発明で採用する上記原料の石炭系重質油
の加熱処理条件、特に温度および滞留時間の条件は、単
環の芳香族系炭化水素溶剤に可溶で容易にメソフェーズ
化する熱反応性の高い成分が、単環の芳香族系炭化水素
溶剤に不溶な成分に転化されるが、メソフェーズまでに
は転化されない程度の加熱処理条件である。原料の石炭
系重質油の加熱処理が、温度が低すぎたり、滞留時間が
短すぎて、原料の石炭系重質油中のキシレン不溶分の増
加が１重量％以下であるような加熱処理では、単環の芳
香族系炭化水素溶剤に可溶で加熱により容易にメソフェ
ーズ化する熱反応性の高い成分が単環の芳香族系炭化水
素溶剤に不溶な成分に転化される反応が不十分となり、
芳香族系炭化水素溶剤による上記熱反応性の高い成分の
除去が不十分となる。また、かかる加熱処理では、当該
加熱処理における単環の芳香族系炭化水素溶剤に可溶な
成分の重質化が不十分であって、加熱処理後の単環の芳
香族系炭化水素溶剤に可溶な成分の分子量が低すぎるた
め、本発明方法の最終工程である精製加熱処理重質油を
目的物の等方性ピッチとするための加熱処理において、
成分の熱重合反応による重質化を一層促進させる必要が
生じ、その処理条件を厳しくする必要が生じる。この加
熱処理の条件をあまり厳しくすると、当該加熱処理にお
いてメソフェーズが生成し、得られる等方性ピッチが汎
用炭素繊維製造用紡糸ピッチに適さなくなる。一方、原
料の石炭系重質油の加熱処理が、温度が高すぎたり、滞
留時間が長すぎて、キノリン不溶分の増加が１重量％以
上であるような加熱処理では、成分の過度の熱重合が起
こり、汎用炭素繊維製造用紡糸ピッチに適した等方性ピ
ッチとなり得る成分までが、多量に単環の芳香族系炭化
水素溶剤に不溶な成分に転化されて、得られる等方性ピ
ッチの収率が低下し、また加熱手段として管式加熱炉を
採用する場合、コークスの生成による管式加熱炉の管の
閉塞をまねく。The heat treatment conditions of the above-mentioned raw material coal-based heavy oil employed in the present invention, particularly the conditions of temperature and residence time, are such that they are soluble in a monocyclic aromatic hydrocarbon solvent and easily undergo a mesophase thermal reaction. The heat treatment conditions are such that the highly reactive component is converted into a component insoluble in the monocyclic aromatic hydrocarbon solvent, but is not converted by the mesophase. The heat treatment of the raw material coal-based heavy oil is such that the temperature is too low or the residence time is too short, and the increase in the xylene-insoluble matter in the raw material coal-based heavy oil is 1% by weight or less. Is insufficient for the reaction in which a highly heat-reactive component that is soluble in a monocyclic aromatic hydrocarbon solvent and easily forms a mesophase by heating is converted to a component insoluble in a monocyclic aromatic hydrocarbon solvent. Next to
The removal of the above-mentioned components having high thermal reactivity by the aromatic hydrocarbon solvent becomes insufficient. In addition, in such heat treatment, since the heavy component of the component soluble in the monocyclic aromatic hydrocarbon solvent in the heat treatment is insufficient, the monocyclic aromatic hydrocarbon solvent after the heat treatment becomes Since the molecular weight of the soluble component is too low, in the heat treatment for making the refined heat treatment heavy oil which is the final step of the method of the present invention into the isotropic pitch of the target substance,
It is necessary to further accelerate the heaviness of the components due to the thermal polymerization reaction, and it is necessary to make the treatment conditions severe. If the conditions of this heat treatment are made too strict, a mesophase is generated in the heat treatment, and the resulting isotropic pitch becomes unsuitable for a spinning pitch for general-purpose carbon fiber production. On the other hand, in the heat treatment of the raw material coal-based heavy oil, if the temperature is too high or the residence time is too long and the increase in the quinoline insoluble content is 1% by weight or more, excessive heat of the components Isotropic pitch obtained by polymerization in which a large amount of components that can be an isotropic pitch suitable for spinning pitch for general-purpose carbon fiber production are converted into components insoluble in monocyclic aromatic hydrocarbon solvents. When the tube type heating furnace is used as the heating means, the tube of the tube type heating furnace is clogged due to generation of coke.

【００２３】また、圧力が低すぎる場合、原料重質油の
軽質分が気化し、気液の分離が起こり、液相部が著しく
重合し易くなりキノリン不溶分の生成と管の閉塞が起こ
り易くなる。一方、圧力が極端に高い場合は装置上不経
済である。必要とされる圧力は加熱処理される石炭系重
質油を実質的に液相に保つに足りる圧力であればよい。Further, if the pressure is too low, the light components of the heavy oil feedstock are vaporized, gas-liquid separation occurs, the liquid phase portion is apt to polymerize significantly, and the quinoline insoluble component is easily generated and the pipes are easily clogged. Become. On the other hand, if the pressure is extremely high, it is uneconomical on the device. The required pressure may be a pressure that is sufficient to keep the heat-treated coal-based heavy oil substantially in the liquid phase.

【００２４】また、一般に用いられているオートクレー
ブのようなバッチ式の加圧加熱処理装置では、１０〜
２，０００秒という短い滞留時間や、加熱処理される石
炭系重質油の装置内での均一な温度分布を調整するのは
困難であり、このような条件を調整するためには管式の
加熱炉を用いる必要がある。Further, in a batch type pressure heating apparatus such as an autoclave which is generally used,
It is difficult to adjust the residence time as short as 2,000 seconds and the uniform temperature distribution of the heat-treated coal-based heavy oil in the device. It is necessary to use a heating furnace.

【００２５】また、上記加熱処理で得られた加熱処理重
質油は沸点２５０℃以下の成分が２５重量％以下、好ま
しくは１０重量％以下、沸点２５０〜３５０℃の成分が
５〜４０重量％、好ましくは１０〜４０重量％、１００
℃における粘度が１，０００cSt 以下、好ましくは５０
０cSt 以下となるようにするのが望ましい。沸点２５０
℃以下の軽質分を多量に含んでいると、その後の単環の
芳香族系炭化水素溶剤に不溶な成分を除去する際、濾過
速度が著しく低下し、効率が悪くなるため、その前に、
蒸留等により軽質分を除去することが望ましい。The heat-treated heavy oil obtained by the above heat treatment contains 25% by weight or less of components having a boiling point of 250 ° C. or less, preferably 10% by weight or less, and 5-40% by weight of components having a boiling point of 250 to 350 ° C. , Preferably 10 to 40% by weight, 100
Viscosity at ℃ is less than 1,000cSt, preferably 50
It is desirable to set it to 0 cSt or less. Boiling point 250
If it contains a large amount of light components below ℃, when removing the components insoluble in the monocyclic aromatic hydrocarbon solvent thereafter, the filtration rate will be significantly reduced and the efficiency will deteriorate, so before that,
It is desirable to remove light components by distillation or the like.

【００２６】該軽質分を除去するための蒸留は、沸点２
５０℃以下の成分を２５重量％以下、好ましくは１０重
量％以下にするのに足りれば良く、減圧下もしくは常圧
下で、２５０℃以下の温度で行われる。Distillation for removing the light components has a boiling point of 2
It suffices that the content of the components at 50 ° C or less is 25% by weight or less, preferably 10% by weight or less, and it is carried out at a temperature of 250 ° C or less under reduced pressure or normal pressure.

【００２７】上記加熱処理で得られた加熱処理重質油
は、必要に応じ蒸留により、沸点２５０℃以下の軽質分
を除去した後、単環の芳香族系炭化水素溶剤に溶解さ
れ、その中の該溶剤に不溶な成分が除去される。The heat-treated heavy oil obtained by the above heat treatment is, if necessary, distilled to remove light components having a boiling point of 250 ° C. or lower, and then dissolved in a monocyclic aromatic hydrocarbon solvent. The insoluble components of the solvent are removed.

【００２８】この単環の芳香族系炭化水素溶剤として
は、ベンゼン、トルエン、キシレンあるいはエチルベン
ゼン等があげられ、これらは単独で用いても良いし、２
種類以上を混合して用いても良い。これらの溶剤は溶解
性が適度であるばかりでなく、その後の溶剤回収におい
ても、沸点が低く、しかも蒸留が容易であり経済的であ
る。Examples of the monocyclic aromatic hydrocarbon solvent include benzene, toluene, xylene and ethylbenzene, which may be used alone or 2
You may use it in mixture of 2 or more types. These solvents not only have a moderate solubility, but also have a low boiling point in the subsequent solvent recovery, and are easy to distill and economical.

【００２９】単環の芳香族系炭化水素溶剤の使用量は、
処理しようとする加熱処理重質油に対して１〜５重量倍
量、好ましくは１〜３重量倍量が適当である。溶剤量が
少ないと、混合液の粘度が高くなり不溶分の分離効率が
悪くなる。逆に、溶剤量を多くすると処理量の増大をま
ねき不経済である。The amount of the monocyclic aromatic hydrocarbon solvent used is
The amount is 1 to 5 times by weight, preferably 1 to 3 times by weight, with respect to the heat-treated heavy oil to be treated. When the amount of the solvent is small, the viscosity of the mixed solution becomes high and the separation efficiency of the insoluble matter becomes poor. On the contrary, if the amount of the solvent is increased, the amount of treatment increases, which is uneconomical.

【００３０】この溶液から溶剤に不溶な不良成分の分離
方法は、沈降分離、遠心分離、あるいは濾過等の任意の
方法が用いられるが、フリーカーボン等の微細な固形分
を含んでいるため、これらの固形分を完全に除去するた
めには、濾過の方法を採用することが好ましい。また、
必要に応じ、溶液を溶剤の沸点以下、好ましくは室温〜
６０℃に加温しておくことが望ましい。As a method for separating the solvent-insoluble defective component from this solution, any method such as sedimentation separation, centrifugation or filtration can be used, but since it contains fine solids such as free carbon, In order to completely remove the solid content of, it is preferable to employ a filtration method. Also,
If necessary, the solution is below the boiling point of the solvent, preferably at room temperature to
It is desirable to heat to 60 ° C.

【００３１】上記のようにして得られた、溶剤に不溶な
成分の除去された溶液から、溶剤を蒸留除去することに
より精製加熱処理重質油が得られ、該精製加熱処理重質
油は、最終加熱処理することにより重質化し、汎用炭素
繊維製造用紡糸ピッチに好適な、メソフェーズを含まな
い等方性ピッチとなる。From the solution obtained by removing the components insoluble in the solvent obtained as described above, the refined heat-treated heavy oil is obtained by removing the solvent by distillation. The refined heat-treated heavy oil is By the final heat treatment, it becomes heavy and becomes an isotropic pitch containing no mesophase, which is suitable for a spinning pitch for producing general-purpose carbon fibers.

【００３２】該最終加熱処理は、公知の方法を採用する
ことができ、一般に減圧下もしくは不活性ガス等の吹き
込み下に３５０〜５００℃の温度範囲で１０〜３００分
間、好ましくは、３８０〜４８０℃で１０〜１８０分間
で行われる。加熱処理の方法は、例えばオートクレーブ
等によるバッチ式でも良いが、減圧下あるいは常圧下に
不活性ガス等の流通下に、薄膜蒸留装置、流下膜式熱処
理装置等を用いて連続的に行っても良い。用いられる不
活性ガス等としては、窒素、ヘリウムあるいはアルゴン
等の不活性ガス、過熱水蒸気あるいは処理温度において
不活性な低沸点有機化合物、低沸点油等を加熱して高温
の過熱蒸気としたもの等があげられる。The final heat treatment may be carried out by a known method, generally under reduced pressure or blowing an inert gas or the like at a temperature range of 350 to 500 ° C. for 10 to 300 minutes, preferably 380 to 480. It is carried out at 10 ° C for 10 to 180 minutes. The method of heat treatment may be, for example, a batch method using an autoclave or the like, or may be continuously performed using a thin film distillation apparatus, a falling film type heat treatment apparatus, or the like under a reduced pressure or a normal pressure while flowing an inert gas or the like. good. Examples of the inert gas to be used include nitrogen, helium or argon, an inert gas, superheated steam or a low boiling point organic compound inert at the processing temperature, a low boiling point oil, etc. to be heated to a high temperature superheated steam, etc. Can be given.

【００３３】該最終加熱処理で注意しなければならない
ことは、メソフェーズもしくはコークスのような固形分
を生成しないような条件を選択することである。これら
を含んだピッチは、これを溶融紡糸して繊維化しようと
するときに、紡糸用ノズルの閉塞等の問題を生じる。一
方、これらの固形分を発生させないために、加熱処理の
条件を著しく温和にすることも考えられるが、この場
合、得られるピッチの軟化点が低く、またピッチ中の軽
質分が十分除去されていないものとなり、紡糸時に多量
のガスが発生するなどの問題が起こり、これを酸化雰囲
気中で加熱して不融化することが困難になる。One thing to be careful about in the final heat treatment is to select the conditions that do not produce solids such as mesophase or coke. The pitch containing these causes a problem such as clogging of a spinning nozzle when melt-spinning the same to form a fiber. On the other hand, in order to prevent these solids from being generated, it is possible to remarkably moderate the conditions of the heat treatment, but in this case, the softening point of the obtained pitch is low, and the light components in the pitch are sufficiently removed. However, there is a problem that a large amount of gas is generated during spinning, and it becomes difficult to heat this in an oxidizing atmosphere to make it infusible.

【００３４】本発明によって得られた等方性ピッチは、
光学的に等方性で、メソフェーズが実質的に存在せず、
一般に、キシレン不溶分が５０〜８０重量％でかつキノ
リン不溶分が１重量％以下、灰分が１００ppm 以下、軟
化点が２００〜２８０℃の範囲のものである。The isotropic pitch obtained by the present invention is
Optically isotropic, virtually free of mesophases,
Generally, the xylene insoluble content is 50 to 80% by weight, the quinoline insoluble content is 1% by weight or less, the ash content is 100 ppm or less, and the softening point is in the range of 200 to 280 ° C.

【００３５】なお、ここで言うメソフェーズを含まない
とは、ピッチを樹脂に埋め込み後ピッチ面を研磨し、偏
光顕微鏡５００倍率で１０視野中に１μm 以上のメソフ
ェーズが１個以下であるものを言う。The term "not include mesophase" as used herein means that the pitch surface is embedded in a resin and then the pitch surface is polished so that there is one or less mesophase having a size of 1 μm or more in 10 fields of view under a polarizing microscope of 500 magnification.

【００３６】[0036]

【実施例】以下実施例及び比較例によって本発明の方法
をさらに詳細に説明する。EXAMPLES The method of the present invention will be described in more detail with reference to the following examples and comparative examples.

【００３７】実施例１ １００℃の粘度が１０９cSt 、沸点が２５０℃以下の成
分が０重量％、２５０〜３５０℃の成分が１８重量％、
キシレン不溶分が８．３重量％、キノリン不溶分が０．
４重量％のコールタールを温度４４０℃、圧力２０Kg／
cm²G、滞留時間２３０秒で管式加熱炉を用い連続的に加
熱処理し、１００℃の粘度が６７cSt 、沸点が２５０℃
以下の成分が３重量％、２５０〜３５０℃の成分が２０
重量％、キシレン不溶分が１２重量％、キノリン不溶分
が０．４重量％の加熱処理重質油を得た。次にこの加熱
処理重質油を２倍量のキシレンに溶解し、濾過により溶
剤不溶分を除去し、濾液から蒸留によりキシレンを回収
し、精製加熱処理重質油を得た。この精製加熱処理重質
油を窒素ガスを吹き込みながら温度４５０℃、３０分間
最終加熱処理し、軟化点２４３℃、キシレン不溶分６
６．０重量％、キノリン不溶分０．１重量％以下、灰分
３０ppm で、偏光顕微鏡５００倍で１μm 以上のメソフ
ェーズが確認されない、全面光学的等方性のピッチを得
た。原料コールタールからの該等方性ピッチの収率は１
７％であった。Example 1 Viscosity at 100 ° C. is 109 cSt, component having boiling point of 250 ° C. or lower is 0% by weight, component at 250 to 350 ° C. is 18% by weight,
The xylene-insoluble matter is 8.3% by weight, and the quinoline-insoluble matter is 0.
4 wt% coal tar at a temperature of 440 ° C and a pressure of 20 kg /
cm ² G, residence time 230 seconds, continuous heat treatment using a tube heating furnace, viscosity at 100 ℃ 67 cSt, boiling point 250 ℃
3% by weight of the following components and 20 at 250 to 350 ° C
A heat-treated heavy oil containing 12% by weight of xylene-insoluble matter and 0.4% by weight of quinoline-insoluble matter was obtained. Next, this heat-treated heavy oil was dissolved in twice the amount of xylene, the solvent-insoluble matter was removed by filtration, and xylene was recovered from the filtrate by distillation to obtain a refined heat-treated heavy oil. This refined heat-treated heavy oil was finally heat-treated at a temperature of 450 ° C. for 30 minutes while blowing nitrogen gas, and had a softening point of 243 ° C. and a xylene-insoluble content of 6
With 6.0 wt%, quinoline insoluble content of 0.1 wt% or less, and ash content of 30 ppm, a mesophase of 1 μm or more was not observed under a polarizing microscope of 500 times, and a pitch of all-optically isotropic was obtained. The yield of isotropic pitch from raw coal tar is 1
It was 7%.

【００３８】得られた等方性ピッチを径０．２５mm、長
さ０．７５mmのノズル孔を持つ単孔紡糸機において、温
度２６３℃、捲取速度８００ m／min で紡糸し、空気中
１℃／min の昇温速度で３２０℃まで昇温し、この温度
で２０分間加熱することにより不融化し、続いて窒素雰
囲気中で１，０００℃にて炭化して炭素繊維とした。こ
の炭素繊維の物性は、引張強度１０６Kg／mm² 、引張弾
性率５．１ ton／mm²であった。The obtained isotropic pitch was spun in a single-hole spinning machine having a nozzle hole having a diameter of 0.25 mm and a length of 0.75 mm at a temperature of 263 ° C. and a winding speed of 800 m / min. The temperature was raised to 320 ° C. at a heating rate of ° C./min, and the mixture was infusibilized by heating at this temperature for 20 minutes, and subsequently carbonized at 1,000 ° C. in a nitrogen atmosphere to obtain carbon fibers. The physical properties of this carbon fiber were a tensile strength of 106 kg / mm ² and a tensile modulus of elasticity of 5.1 ton / mm ² .

【００３９】実施例２ 実施例１と同様のコールタールおよび管式加熱炉を用い
て、温度５２０℃、圧力２０Kg／cm²G、滞留時間２３０
秒で連続的に加熱処理し、粘度が２０８cSt 、沸点が２
５０℃以下の成分が３重量％、２５０〜３５０℃の成分
が１８重量％、キシレン不溶分が１９重量％、キノリン
不溶分が１．２重量％の加熱処理重質油を得た。この加
熱処理重質油から実施例１と同様に精製加熱処理重質油
を得、窒素ガスを吹き込みながら温度４５０℃、６０分
間最終加熱処理し、軟化点２５８℃、キシレン不溶分６
５．３重量％、キノリン不溶分０．１重量％以下、灰分
２８ppm で、偏光顕微鏡５００倍で１μm 以上のメソフ
ェーズが確認されない、全面光学的等方性のピッチを得
た。原料コールタールからの該等方性ピッチの収率は１
５％であった。図１に得られたピッチのＧＰＣプロファ
イルを示す。Example 2 Using the same coal tar and tube heating furnace as in Example 1, temperature 520 ° C., pressure 20 Kg / cm ² G, residence time 230
Heat treatment continuously for 2 seconds, viscosity is 208 cSt, boiling point is 2
A heat-treated heavy oil containing 3% by weight of components at 50 ° C. or lower, 18% by weight of components at 250 to 350 ° C., 19% by weight of xylene-insoluble matter and 1.2% by weight of quinoline-insoluble matter was obtained. A refined heat-treated heavy oil was obtained from this heat-treated heavy oil in the same manner as in Example 1, and was subjected to final heat treatment at a temperature of 450 ° C. for 60 minutes while blowing in nitrogen gas, and had a softening point of 258 ° C. and a xylene-insoluble content of 6
With 5.3% by weight, quinoline insoluble content of 0.1% by weight or less, and ash content of 28 ppm, a fully optically isotropic pitch in which a mesophase of 1 μm or more was not observed under a polarizing microscope of 500 times was obtained. The yield of isotropic pitch from raw coal tar is 1
It was 5%. FIG. 1 shows the GPC profile of the obtained pitch.

【００４０】また、得られた等方性ピッチを実施例１と
同じ紡糸機を用い、温度２７８℃、捲取速度８００ m／
min で紡糸し、実施例１と同じ条件で不融化および炭化
を行い炭素繊維を得た。この炭素繊維の物性は、引張強
度１１２Kg／mm² 、引張弾性率５．８ ton／mm² であっ
た。Using the same spinning machine as in Example 1, the obtained isotropic pitch was heated at a temperature of 278 ° C. and a winding speed of 800 m / m.
Spinning was carried out for min, and infusibilization and carbonization were carried out under the same conditions as in Example 1 to obtain carbon fibers. The physical properties of this carbon fiber were a tensile strength of 112 kg / mm ² and a tensile elastic modulus of 5.8 ton / mm ² .

【００４１】比較例１ 実施例１と同様のコールタールを加熱処理を実施せずに
実施例１と同様にキシレン抽出し、得られた溶剤可溶成
分を実施例１と同様に、温度４５０℃、２５分間最終加
熱処理し、軟化点２４９℃、キシレン不溶分６５．７重
量％、キノリン不溶分０．１重量％、灰分５０ppm のピ
ッチを得た。メソフェーズは実施例１と同様の方法で観
察したところ、粒径１〜２μm のメソフェーズが確認さ
れた。原料コールタールからの該ピッチの収率は２０％
であった。図１に得られたピッチのＧＰＣプロファイル
を示す。Comparative Example 1 The same coal tar as in Example 1 was subjected to xylene extraction in the same manner as in Example 1 without heat treatment, and the solvent-soluble component obtained was heated at a temperature of 450 ° C. as in Example 1. Final heat treatment for 25 minutes gave a pitch having a softening point of 249 ° C., xylene insoluble content of 65.7% by weight, quinoline insoluble content of 0.1% by weight, and ash content of 50 ppm. When the mesophase was observed in the same manner as in Example 1, the mesophase having a particle size of 1 to 2 μm was confirmed. The yield of the pitch from the raw coal tar is 20%
Met. FIG. 1 shows the GPC profile of the obtained pitch.

【００４２】得られたピッチを実施例１と同じ紡糸機を
用い、温度２７０℃、捲取速度を２００〜８００ m／mi
n に変化させたが、糸切れが多く紡糸は困難であった。
得られた生糸を走査電子顕微鏡で観察したところ、生糸
表面に１〜２μm の異物（メソフェーズ）が多数観察さ
れた。Using the same spinning machine as in Example 1, the obtained pitch was used at a temperature of 270 ° C. and a winding speed of 200 to 800 m / mi.
Although the value was changed to n, many yarn breakages made spinning difficult.
When the obtained raw silk was observed with a scanning electron microscope, many foreign matters (mesophase) of 1 to 2 μm were observed on the raw silk surface.

【００４３】図１のＧＰＣプロファイルより、該比較例
で製造されたピッチは、熱反応性の高い成分が除去され
ていないため、高分子量成分が多量に含まれ分子量分布
が広いことがわかる。一方、実施例２で得られたピッチ
は、熱反応性の高い成分が十分除去され、分子量分布が
シャープであり、均質で紡糸性の優れたピッチであるこ
とがわかる。From the GPC profile of FIG. 1, it can be seen that the pitch produced in the comparative example contains a large amount of high molecular weight components and has a wide molecular weight distribution because the components having high thermal reactivity are not removed. On the other hand, it can be seen that the pitch obtained in Example 2 is a pitch in which components having high thermal reactivity are sufficiently removed, the molecular weight distribution is sharp, and the pitch is uniform and has excellent spinnability.

【００４４】比較例２ 実施例１と同様のコールタールおよび管式加熱炉を用い
て、温度５４０℃、圧力２０Kg／cm²G、滞留時間２３０
秒で連続的に加熱処理したところ、実験開始後約２時間
で管式加熱炉の管が閉塞した。管が閉塞するまでに得ら
れた加熱処理重質油は、キシレン不溶分２６重量％、キ
ノリン不溶分２．５重量％で、キノリン不溶分が非常に
多いものであった。Comparative Example 2 Using the same coal tar and tube heating furnace as in Example 1, temperature 540 ° C., pressure 20 kg / cm ² G, residence time 230
When the heat treatment was continuously performed for 2 seconds, the tube of the tubular heating furnace was closed about 2 hours after the start of the experiment. The heat-treated heavy oil obtained by the time the tube was blocked had a xylene-insoluble content of 26% by weight and a quinoline-insoluble content of 2.5% by weight, and the quinoline-insoluble content was very large.

【００４５】比較例３ 実施例１と同様のコールタールをオートクレーブ反応装
置を用い、温度４５０℃、圧力２０Kg／cm²G、反応時間
９０分で加熱処理した。オートクレーブ内部は、コーク
ス状物質が多量に付着し、得られた加熱処理重質物は不
均一であった。コークス状物質を含めた加熱処理物は、
沸点が２５０℃以下の成分が５重量％、２５０〜３５０
℃の成分が１３重量％、キシレン不溶分が５２．１重量
％、キノリン不溶分が２７．４重量％であった。粘度は
コークス状物質が混入しているため測定できなかった。
この加熱処理重質油をキシレンに溶解させ、不良成分で
ある溶剤不溶分を濾過により除去し、濾液から蒸留によ
り、溶剤および軽質分を除去し、精製加熱処理重質油を
得た。この精製加熱処理重質油を実施例１と同様に最終
加熱処理し、軟化点２５０℃、キシレン不溶分５８．５
重量％、キノリン不溶分０．１重量％以下、灰分２６pp
m で、偏光顕微鏡５００倍で１μm 以上のメソフェーズ
が確認されない、全面光学的等方性のピッチを得た。原
料コールタールからの該等方性ピッチの収率は６％であ
った。Comparative Example 3 The same coal tar as in Example 1 was heat-treated in an autoclave reactor at a temperature of 450 ° C., a pressure of 20 Kg / cm ² G and a reaction time of 90 minutes. A large amount of coke-like substance adhered to the inside of the autoclave, and the obtained heat-treated heavy product was non-uniform. Heat-treated products including coke-like substances
5% by weight of components having a boiling point of 250 ° C. or lower, 250 to 350
The component at 0 ° C. was 13% by weight, the xylene-insoluble matter was 52.1% by weight, and the quinoline-insoluble matter was 27.4% by weight. The viscosity could not be measured due to the inclusion of coke-like substances.
The heat-treated heavy oil was dissolved in xylene, the solvent-insoluble component, which was a poor component, was removed by filtration, and the solvent and light components were removed from the filtrate by distillation to obtain a refined heat-treated heavy oil. This refined heat-treated heavy oil was finally heat-treated in the same manner as in Example 1 to give a softening point of 250 ° C. and a xylene-insoluble matter of 58.5.
% By weight, quinoline insoluble matter 0.1% by weight or less, ash content 26 pp
At m 2, a fully optically isotropic pitch was obtained in which a mesophase of 1 μm or more was not observed under a polarizing microscope of 500 times. The yield of the isotropic pitch from the raw coal tar was 6%.

【００４６】[0046]

【発明の効果】本発明方法によれば、等方性ピッチを高
収率で製造することができる。しかも、連続的製造法で
あるから、一定の品質の等方性ピッチを大量に、安定し
て、低廉に製造することができる。また、本発明方法で
得られる等方性ピッチは、メソフェーズを実質的に含有
せず、優れた紡糸性を有しており、汎用炭素繊維製造用
紡糸ピッチとして好適なものである。また、紡糸ピッチ
として用いた場合、紡糸機のフィルターや紡糸ノズルの
閉塞の問題もなく、低温紡糸、高速捲取りが可能であ
り、また不融化性も優れている。According to the method of the present invention, isotropic pitch can be produced in high yield. Moreover, since it is a continuous manufacturing method, it is possible to manufacture a large amount of isotropic pitches of constant quality, stably, and at low cost. The isotropic pitch obtained by the method of the present invention has substantially no mesophase and has excellent spinnability, and is suitable as a spinning pitch for general-purpose carbon fiber production. Further, when used as a spinning pitch, there is no problem of clogging of a filter of a spinning machine or a spinning nozzle, low-temperature spinning and high-speed winding are possible, and infusibility is excellent.

【図面の簡単な説明】[Brief description of drawings]

【図１】実施例２および比較例１で得られたピッチのＧ
ＰＣプロファイルであり、横軸は分子量、縦軸は重量濃
度である。1 is the G of the pitch obtained in Example 2 and Comparative Example 1. FIG.
It is a PC profile, the horizontal axis is the molecular weight, and the vertical axis is the weight concentration.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 佐藤 智彦 千葉県市原市加茂439番地 丸善石油化学 国分寺台寮123号室 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomohiko Sato 439 Kamo, Ichihara, Chiba Maruzen Petrochemical Kokubunji Dairyo Room 123

Claims (8)

【特許請求の範囲】[Claims] 【請求項１】 １００℃での粘度が１，０００cSt 以下
であり、沸点が２５０℃以下の成分が２５重量％以下、
沸点が２５０〜３５０℃の成分が５〜４０重量％の範囲
にある石炭系重質油を、キシレン不溶分が１重量％以上
増加し、かつキノリン不溶分が１重量％以上増加しない
ように管式加熱炉を用い連続的に加熱処理し、得られた
加熱処理重質油を単環の芳香族系炭化水素溶剤に溶解さ
せ、該溶剤に不溶な成分を分離除去し、得られた可溶成
分を含む溶液から溶剤を除去して精製加熱処理重質油を
得、該精製加熱処理重質油を加熱処理することを特徴と
する等方性ピッチの製造方法。1. A component having a viscosity at 100 ° C. of 1,000 cSt or less and a boiling point of 250 ° C. or less of 25% by weight or less,
Pipe the heavy coal-based oil having a boiling point of 250 to 350 ° C. in the range of 5 to 40% by weight so that the xylene insoluble content is increased by 1% by weight or more and the quinoline insoluble content is not increased by 1% by weight or more. The resulting heat-treated heavy oil is dissolved in a monocyclic aromatic hydrocarbon solvent, and the insoluble components are separated and removed. A method for producing isotropic pitch, which comprises removing a solvent from a solution containing components to obtain a refined heat-treated heavy oil, and heat-treating the refined heat-treated heavy oil. 【請求項２】 石炭系重質油を加熱処理して得られた加
熱処理重質油を、蒸留により軽質分を除去した後、単環
の芳香族系炭化水素溶剤に溶解させる請求項１記載の等
方性ピッチの製造方法。2. The heat-treated heavy oil obtained by heat-treating a coal-based heavy oil, after removing light components by distillation, is dissolved in a monocyclic aromatic hydrocarbon solvent. Method for producing isotropic pitch of. 【請求項３】 石炭系重質油の加熱処理が、温度が３８
０〜５２０℃、圧力が２〜１００Kg／cm²G、滞留時間が
１０〜２，０００秒の範囲内の条件で行われる請求項１
または２記載の等方性ピッチの製造方法。3. The heat treatment of coal-based heavy oil is performed at a temperature of 38.
The method is carried out under the conditions of 0 to 520 ° C., a pressure of ² to 100 kg / cm ² G, and a residence time of 10 to 2,000 seconds.
Alternatively, the method for producing an isotropic pitch described in 2. 【請求項４】 単環の芳香族系炭化水素溶剤が、ベンゼ
ン、トルエン、キシレンおよびエチルベンゼンから選ば
れる少なくとも１種類からなり、加熱処理重質油に対し
１〜５重量倍加えられる請求項１ないし３のいずれかの
一つの請求項記載の等方性ピッチの製造方法。4. The monocyclic aromatic hydrocarbon solvent comprises at least one selected from benzene, toluene, xylene and ethylbenzene, and is added in an amount of 1 to 5 times by weight relative to the heat-treated heavy oil. 3. The method for producing an isotropic pitch according to claim 3. 【請求項５】 得られる等方性ピッチが、メソフェーズ
が実質的に存在せず、キシレン不溶分が５０〜８０重量
％でかつキノリン不溶分が１重量％以下、灰分が１００
ppm 以下、軟化点が２００〜２８０℃の範囲である請求
項１または２記載の等方性ピッチの製造方法。5. The resulting isotropic pitch is substantially free of mesophase, has a xylene insoluble content of 50 to 80% by weight, a quinoline insoluble content of 1% by weight or less, and an ash content of 100.
The method for producing an isotropic pitch according to claim 1 or 2, wherein the softening point is ppm or less and the softening point is in the range of 200 to 280 ° C. 【請求項６】 得られる等方性ピッチが、汎用炭素繊維
製造用紡糸ピッチである請求項１または２記載の等方性
ピッチの製造方法。6. The method for producing an isotropic pitch according to claim 1, wherein the obtained isotropic pitch is a spinning pitch for producing general-purpose carbon fibers. 【請求項７】 １００℃での粘度が１，０００cSt 以下
であり、沸点が２５０℃以下の成分が２５重量％以下、
２５０〜３５０℃の成分が５〜４０重量％の範囲にある
石炭系重質油を、キシレン不溶分が１重量％以上増加
し、かつキノリン不溶分が１重量％以上増加しないよう
に、温度３８０〜５２０℃、圧力２〜１００Kg／cm²G、
滞留時間１０〜２，０００秒の範囲で、管式加熱炉を用
い連続的に加熱処理し、得られた加熱処理重質油をベン
ゼン、トルエン、キシレンおよびエチルベンゼンから選
ばれる少なくとも１種類からなる単環の芳香族系炭化水
素溶剤の１〜５重量倍量に溶解させ、該溶剤に不溶な成
分を分離除去し、得られた可溶成分を含む溶液から溶剤
を除去して精製加熱処理重質油を得、該精製加熱処理重
質油を加熱処理することを特徴とする、メソフェーズが
実質的に存在せず、キシレン不溶分が５０〜８０重量％
でかつキノリン不溶分が１重量％以下、灰分が１００pp
m 以下、軟化点が２００〜２８０℃の範囲である等方性
ピッチの製造方法。7. A component having a viscosity at 100 ° C. of 1,000 cSt or less and a boiling point of 250 ° C. or less of 25% by weight or less,
In order to prevent the xylene-insoluble content from increasing by 1% by weight or more and the quinoline-insoluble content not increasing by 1% by weight or more, the coal-based heavy oil whose components at 250 to 350 ° C. are in the range of 5 to 40% by weight is used. ~ 520 ° C, pressure 2-100 kg / cm ² G,
The residence time is 10 to 2,000 seconds, and heat treatment is continuously performed using a tubular heating furnace, and the obtained heat-treated heavy oil is composed of at least one selected from benzene, toluene, xylene and ethylbenzene. It is dissolved in 1 to 5 times by weight of the aromatic hydrocarbon solvent of the ring, the component insoluble in the solvent is separated and removed, the solvent is removed from the solution containing the obtained soluble component, and the purified heat-treated heavy An oil is obtained, and the refined heat-treated heavy oil is heat-treated, wherein mesophase is substantially absent, and xylene-insoluble content is 50 to 80% by weight.
And less than 1% by weight of insoluble quinoline and 100 pp of ash
A method for producing an isotropic pitch having a softening point of m or less in the range of 200 to 280 ° C. 【請求項８】 石炭系重質油を加熱処理して得られた加
熱処理重質油を、蒸留により軽質分を除去した後、単環
の芳香族系炭化水素溶剤に溶解させる請求項７記載の等
方性ピッチの製造方法。8. The heat-treated heavy oil obtained by heat-treating a coal-based heavy oil, after removing light components by distillation, is dissolved in a monocyclic aromatic hydrocarbon solvent. Method for producing isotropic pitch of.