EP0238787B1 - Process for producing a carbon fiber precursor - Google Patents

Process for producing a carbon fiber precursor Download PDF

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Publication number
EP0238787B1
EP0238787B1 EP87100271A EP87100271A EP0238787B1 EP 0238787 B1 EP0238787 B1 EP 0238787B1 EP 87100271 A EP87100271 A EP 87100271A EP 87100271 A EP87100271 A EP 87100271A EP 0238787 B1 EP0238787 B1 EP 0238787B1
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European Patent Office
Prior art keywords
pitch
carrier
process according
gas
mixture
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EP87100271A
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German (de)
French (fr)
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EP0238787A2 (en
EP0238787A3 (en
Inventor
Siegfried Prof. Dr. Peter
Herbert Dr. Beneke
Franz Oeste
Wolfgang Fexer
Wolfgang Jaumann
Manfred Meinbreckse
Joachim Kempfert
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Ruetgers Germany GmbH
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Ruetgerswerke AG
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10C—WORKING-UP PITCH, ASPHALT, BITUMEN, TAR; PYROLIGNEOUS ACID
    • C10C1/00—Working-up tar
    • C10C1/04—Working-up tar by distillation
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10C—WORKING-UP PITCH, ASPHALT, BITUMEN, TAR; PYROLIGNEOUS ACID
    • C10C3/00—Working-up pitch, asphalt, bitumen
    • C10C3/08—Working-up pitch, asphalt, bitumen by selective extraction
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
    • D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
    • D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
    • D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
    • D01F9/145—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from pitch or distillation residues
    • D01F9/15—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from pitch or distillation residues from coal pitch

Definitions

  • the invention relates to a method for producing a carbon fiber intermediate product from coal tar pitch.
  • the spinning temperatures are about 60 to 130 ° C above the softening point of the pitch used.
  • the pitch already decomposes, the pitch at least partially passing into the semi-coke stage and considerable amounts of gas being generated. This disrupts the spinning process. There are frequent thread breaks that make continuous spinning impossible.
  • pitches with the lowest possible softening point are required. Such pitches have a low content of components insoluble in quinoline or pyridine. Their average molecular weight is relatively low with a broad molecular weight distribution. This makes the process step to make the pitch fiber infusible before carbonization becomes more difficult.
  • DE-OS 35 09 861 describes a process for producing suitable carbon fiber precursors from aromatic, mineral oil-derived residual oils.
  • the residue is subjected to a two-stage heat treatment under pressures from 0.13 to 65 mbar in a falling film evaporator.
  • the temperatures, in particular in the second treatment stage are so high at 450 to 500 ° C. that the partial formation of coke structures cannot be prevented.
  • the known methods are very complex and often can only be carried out under laboratory conditions.
  • the object of the invention is therefore to produce a pitch material for carbon fiber production which has excellent spinnability, which can be made infusible in a short time, and from which carbon fibers of high strength with high modulus of elasticity can be produced, the disadvantages and Problems in the manufacture of the pitch material do not occur.
  • a coal tar pitch is solved by extraction at elevated temperature and pressure in a supercritical gas in the presence of an entrainer, with the exception of the components insoluble in quinoline, by lowering the pressure and / or increasing the temperature, the quinoline-soluble fraction or / and the toluene-soluble fraction is separated, one of these fractions or a mixture of both fractions is thermally treated at 380 to 450 ° C.
  • the following compounds or their mixtures can be used as supercritical gas: an aliphatic hydrocarbon, preferably having 2 to 5 carbon atoms and a halogen-containing hydrocarbon having 1 to 4 carbon atoms.
  • Suitable entraining agents are mono- or polynuclear hydrocarbons, which are optionally substituted with alkyl groups, in particular with 1 to 2 carbon atoms or an amino group, and can be both aromatic and fully or partially hydrogenated, mono- or di-core heterocyclic compounds, alkyl esters of aromatic acids with 1 up to 6 carbon atoms in the alcohol component or a mixture thereof.
  • the extraction stages are carried out at temperatures between 80 and 300 ° C, preferably between 120 and 250 ° C, at pressures from 80 to 300 bar, preferably from 150 to 250 bar.
  • the temperatures for the thermal treatment are high enough on the one hand to ensure a sufficient reaction rate, but on the other hand so low that no bulk mesophase tends to solidify.
  • the subsequent extraction stage for the removal of a predominant part of the isotropic pitch material also takes place at such low temperatures at which the pitch mesophase does not change. Since the mesophases consist only of plastically easily deformable spherules, which only flow together due to the shear forces in the extruder, the difference between the melting temperature and the spinning temperature can be reduced to 10 to 50 K without the withdrawal speed having to be reduced.
  • the extractant loaded with pitch is transferred to two successive regeneration autoclaves and gradually expanded to a pressure of 50 bar.
  • the temperature during regeneration is 150 ° C.
  • the cooling that occurs during relaxation due to the Joule-Thomson effect is compensated for by the addition of heat.
  • the regenerated mixture of extractant and entrainer is recycled.
  • the following pitch fractions are obtained in the regeneration autoclave after an extraction time of 5 h:
  • Fraction 2 is thermally treated at 400 ° C. under nitrogen at atmospheric pressure for 1.5 hours with stirring. This creates 50 vol .-% mesophase spherules. After cooling to 150 ° C. at a pressure of 130 bar, the mesophase pitch is extracted with a mixture of 30% by weight of propane and 70% by weight of toluene. A pitch with a mesophase content of 80% by volume, a content of pyridine-insoluble (PI) of 32% by weight, a melting point of 342 ° C. and an average molecular weight of about 1000 remains as the residue.
  • PI pyridine-insoluble
  • This pitch is at 370 ° C spun using an extruder with a spinneret plate with a hole diameter of 0.3 mm at a take-off speed of 1000 m / min.
  • the pitch fiber is heated in air at a heating rate of 20 K / min from 250 to 350 ° C. The final temperature is held for 5 minutes to make the fiber infusible.
  • the fiber is then carbonized at 1500 ° C. in an inert gas stream for 15 minutes.
  • the carbon fiber with a diameter of 9 ⁇ m has a strength of 2.47 kN / mm 2 , an elastic modulus of 158 kN / mm 2 and an elongation at break of 1.2%.
  • Fraction 3 is thermally treated at 430 ° C. under nitrogen at atmospheric pressure for one hour with stirring. This creates 60 vol .-% mesophase spherules. After cooling to 190 ° C extracted the mesophase pitch at a pressure of 130 bar with the same mixture as in the first extraction stage. This leaves a pitch with a mesophase content of 87% by volume, a pyridine-insoluble content of 44% by weight, a melting point of 357 ° C. and an average molecular weight of about 1100. This pitch is as described in Example 1 , spun at 380 ° C, made infusible and carbonized. The carbon fiber with a diameter of 7 gm has a strength of 2.58 kN / mm 2 , an elastic modulus of 153 kN / mm 2 and an elongation at break of 1.0%.

Description

Die Erfindung betrifft ein Verfahren zur Herstellung eines Kohlenstoffaser-Vorprodukts aus Steinkohlenteerpech.The invention relates to a method for producing a carbon fiber intermediate product from coal tar pitch.

Nach dem Stand der Technik werden die meisten Kohlenstoffasem durch Carbonisieren und Graphitieren von Fasern aus Polyacrylnitril hergestellt. Diese Kohlenstoffasem haben eine hohe Festigkeit und einen hohen Elastizitätsmodul. Ein Nachteil ist jedoch, daß das Ausgangsprodukt teuer ist und die Carbonisierungsausbeute gering ist. Es hat daher nicht an Versuchen gefehlt, andere Einsatzprodukte mit hohem Verkokungsrückstand auf ihre Verwendbarkeit für die Herstellung von Kohlenstoffasem zu untersuchen. Es wurden vor allem kohle- und mineralölstämmige Peche vorgeschlagen, die für die Herstellung hochanisotroper Kokse bekannt sind.According to the prior art, most carbon fibers are produced by carbonizing and graphitizing fibers made of polyacrylonitrile. These carbon fibers have a high strength and a high modulus of elasticity. A disadvantage, however, is that the starting product is expensive and the carbonization yield is low. There has been no shortage of attempts to examine other feedstocks with a high coking residue for their usability for the production of carbon fibers. In particular, pitches derived from coal and mineral oil, which are known for producing highly anisotropic coke, have been proposed.

Die Spinntemperaturen liegen etwa 60 bis 130 °C über dem Erweichungspunkt des verwendeten Pechs. Bei hohen Spinntemperaturen tritt bereits eine Zersetzung des Pechs auf, wobei das Pech zumindest teilweise in die Halbkoksstufe übergeht und erhebliche Gasmengen entstehen. Dies stört den Spinnprozeß. Es entstehen häufige Fadenbrüche, die ein kontinuierliches Verspinnen unmöglich machen. Um dies zu vermeiden sind Peche mit möglichst niedrigem Erweichungspunkt erforderlich. Solche Peche haben einen geringen Gehalt an in Chinolin oder Pyridin unlöslichen Bestandteilen. Ihr mittleres Molekulargewicht ist verhältnismäßig gering bei einer breiten Molekulargewichtsverteilung. Dadurch wird der Verfahrensschritt, um die Pechfaser vor der Carbonisierung unschmelzbar zu machen, schwieriger.
In der DE-OS 35 09 861 wird ein Verfahren zur Herstellung geeigneter Kohlenstoffaser-Vorprodukte aus aromatischen, mineralölstämmigen Rückstandsölen beschrieben. Nach dem Abdestillieren der Leichtöle wird der Rückstand einer zweistufigen Wärmebehandlung unter Drücken von 0,13 bis 65 mbar in einem Fallfilmverdampfer unterworfen. Die Temperaturen, insbesondere bei der zweiten Behandlungsstufe, liegen mit 450 bis 500 °C so hoch, daß die partielle Ausbildung von Koksstrukturen nicht verhindert werden kann. Dies gilt insbesondere bei der Verwendung von Dünnschichtverdampfern mit rotierenden Einbauten, die von den Pechen benetzt werden, so daß die Verweilzeiten eines Teiles des Einsatzpechs unkontrollierbar werden. Wegen der unterschiedlichen Reaktivität der Peche und der Notwendigkeit, die nicht in anisotropes Pech umgewandelten Pechbestandteile aus dem Kohlenstoffaser-Vorprodukt entfernen zu müssen, sind die bekannten Verfahren sehr aufwendig und oft nur unter Laborbedingungen durchführbar.The spinning temperatures are about 60 to 130 ° C above the softening point of the pitch used. At high spinning temperatures, the pitch already decomposes, the pitch at least partially passing into the semi-coke stage and considerable amounts of gas being generated. This disrupts the spinning process. There are frequent thread breaks that make continuous spinning impossible. To avoid this, pitches with the lowest possible softening point are required. Such pitches have a low content of components insoluble in quinoline or pyridine. Their average molecular weight is relatively low with a broad molecular weight distribution. This makes the process step to make the pitch fiber infusible before carbonization becomes more difficult.
DE-OS 35 09 861 describes a process for producing suitable carbon fiber precursors from aromatic, mineral oil-derived residual oils. After the light oils have been distilled off, the residue is subjected to a two-stage heat treatment under pressures from 0.13 to 65 mbar in a falling film evaporator. The temperatures, in particular in the second treatment stage, are so high at 450 to 500 ° C. that the partial formation of coke structures cannot be prevented. This applies in particular to the use of thin-film evaporators with rotating internals which are wetted by the pitch, so that the dwell times of part of the pitch are uncontrollable. Because of the different reactivities of the pitches and the need not to have to remove the pitch constituents not converted into anisotropic pitch from the carbon fiber precursor, the known methods are very complex and often can only be carried out under laboratory conditions.

Aufgabe der Erfindung ist es daher, ein Pechmaterial für die Kohlenstoffaser-Herstellung zu erzeugen, das eine ausgezeichnete Verspinnbarkeit besitzt, das in kurzer Zeit unschmelzbar gemacht werden kann, und aus dem Kohlenstoffasern hoher Festigkeit bei hohem Elastizitätsmodul hergestellt werden können, wobei die geschilderten Nachteile und Probleme bei der Herstellung des Pechmaterials nicht auftreten.The object of the invention is therefore to produce a pitch material for carbon fiber production which has excellent spinnability, which can be made infusible in a short time, and from which carbon fibers of high strength with high modulus of elasticity can be produced, the disadvantages and Problems in the manufacture of the pitch material do not occur.

Die Aufgabe wird dadurch gelöst, daß ein Steinkohlenteerpech durch Extraktion bei erhöhter Temperatur und erhöhtem Druck in einem überkritischen Gas in Gegenwart eines Schleppmittels mit Ausnahme der in Chinolin unlöslichen Bestandteile gelöst wird, durch Absenken des Druckes oder/und Temperaturerhöhung die in Chinolin lösliche Fraktion oder/und die in Toluol lösliche Fraktion abgeschieden werden, eine dieser Fraktionen oder ein Gemisch aus beiden Fraktionen bei 380 bis 450 °C unter Inertgas oder einem nicht-oxidierenden Gas unter Atmosphärendruck thermisch behandelt wird, bis daß 40 bis 65 Vol.-% in Mesophasen umgewandelt sind, und daß das isotrope Pech durch Extrahieren des Mesophasen enthaltenden Pechs mit einem überkritischen Gas unter Verwendung eines Schleppmittels abgetrennt wird, um ein anisotropes Pech mit einem Mesophasengehalt von mindestens 75 Vol: %, einem Gehalt an Pyridinunlöslichem von 20 bis 50 Gew.-%, einem mittleren Molekulargewicht zwischen 900 und 1200 und einem Schmelzpunkt von 330 bis 360°C zu erhalten.The object is achieved in that a coal tar pitch is solved by extraction at elevated temperature and pressure in a supercritical gas in the presence of an entrainer, with the exception of the components insoluble in quinoline, by lowering the pressure and / or increasing the temperature, the quinoline-soluble fraction or / and the toluene-soluble fraction is separated, one of these fractions or a mixture of both fractions is thermally treated at 380 to 450 ° C. under inert gas or a non-oxidizing gas under atmospheric pressure until 40 to 65 vol.% is converted into mesophases and that the isotropic pitch is separated by extracting the mesophase-containing pitch with a supercritical gas using an entrainer to obtain an anisotropic pitch having a mesophase content of at least 75% by volume, a pyridine-insoluble content of 20 to 50% by weight. , an average molecular weight between 900 and 1200 and a Sc to get a melting point of 330 to 360 ° C.

Als überkritisches Gas können folgende Verbindungen oder ihre Gemische verwendet werden: ein aliphatischer Kohlenwasserstoff, vorzugsweise mit 2 bis 5 Kohlenstoffatomen und ein halogenhaltiger Kohlenwasserstoff mit 1 bis 4 Kohlenstoffatomen.The following compounds or their mixtures can be used as supercritical gas: an aliphatic hydrocarbon, preferably having 2 to 5 carbon atoms and a halogen-containing hydrocarbon having 1 to 4 carbon atoms.

Geeignete Schleppmittel sind ein- oder mehrkemige Kohlenwasserstoffe, die gegebenenfalls mit Alkylgruppen, insbesondere mit 1 bis 2 Kohlenstoffatomen oder einer Aminogruppe, substituiert sind und sowohl aromatisch als auch ganz oder teilweise hydriert sein können, ein- oder zweikemige heterocyclische Verbindungen, Alkylester aromatischer Säuren mit 1 bis 6 Kohlenstoffatomen in der Alkoholkomponente oder deren Gemisch.Suitable entraining agents are mono- or polynuclear hydrocarbons, which are optionally substituted with alkyl groups, in particular with 1 to 2 carbon atoms or an amino group, and can be both aromatic and fully or partially hydrogenated, mono- or di-core heterocyclic compounds, alkyl esters of aromatic acids with 1 up to 6 carbon atoms in the alcohol component or a mixture thereof.

Die Extraktionsstufen werden bei Temperaturen zwischen 80 und 300°C, vorzugsweise zwischen 120 und 250°C, bei Drücken von 80 bis 300 bar, vorzugsweise von 150 bis 250 bar, durchgeführt.The extraction stages are carried out at temperatures between 80 and 300 ° C, preferably between 120 and 250 ° C, at pressures from 80 to 300 bar, preferably from 150 to 250 bar.

Die Temperaturen für die thermische Behandlung sind einerseits hoch genug, um eine ausreichende Reaktionsgeschwindigkeit zu gewährleisten, andererseits aber so niedrig, daß sich keine zur Verfestigung neigende Bulkmesophase bildet. Die nachfolgende Extraktionsstufe zur Abtrennung eines überwiegenden Teils des isotropen Pechmaterials findet ebenfalls bei so niedrigen Temperaturen statt, bei denen sich die Pechmesophase nicht verändert. Da die Mesophasen nur aus plastisch leicht verformbaren Sphärulen bestehen, die erst durch die Scherkräfte im Extruder zusammenfließen, kann die Differenz zwischen Schmelztemperatur und Spinntemperatur auf 10 bis 50 K gesenkt werden, ohne daß dabei die Abzugsgeschwindigkeit vermindert werden muß.The temperatures for the thermal treatment are high enough on the one hand to ensure a sufficient reaction rate, but on the other hand so low that no bulk mesophase tends to solidify. The subsequent extraction stage for the removal of a predominant part of the isotropic pitch material also takes place at such low temperatures at which the pitch mesophase does not change. Since the mesophases consist only of plastically easily deformable spherules, which only flow together due to the shear forces in the extruder, the difference between the melting temperature and the spinning temperature can be reduced to 10 to 50 K without the withdrawal speed having to be reduced.

Die Erfindung wird anhand der nachfolgenden Beispiele näher erläutert, ohne darauf beschränkt zu sein.The invention is explained in more detail with reference to the following examples, without being restricted thereto.

Beispiel 1example 1

100 Gew.-Teile Normalpech mit einem Gehalt an Aschebildnern von 0,23 Gew.-%, einem Gehalt an Chinolinunlöslichem (Ql) von 5,8 Gew.-%, einem Gehalt an Toluolunlöslichem (TI) von 22,8 Gew.-% und einem Erweichungspunkt (EP) von 70 °C nach Kraemer-Samow (K.-S.) werden in einen Rührautoklaven gegeben, der auf 150 °C aufgeheizt ist. Sodann wird bei einem Druck von 180 bar ein Gemisch aus 30 Gew.-% Propan und 70 Gew.-% Toluol als Extraktions- bzw. Schleppmittel unter Rühren durch den Autoklaven geleitet. Das unter diesen Bedingungen überkritische Extraktionsmittel löst bis zu einer Konzentration von 13 Gew.-% Pech auf und transportiert es aus dem Autoklaven heraus. Das mit Pech beladenen Extraktionsmittel wird in zwei aufeinander folgende Regenerierautoklaven übergeführt und stufenweise bis auf einen Druck von 50 bar entspannt. Die Temperatur bei der Regenerierung beträgt 150 °C. Die bei der Entspannung wegen des Joule-Thomson-Effektes eintretende Abkühlung wird durch Wärmezufuhr ausgeglichen. Das regenerierte Gemisch aus Extraktions- und Schleppmittel wird im Kreislauf geführt. In dem Regenerierautoklaven werden nach einer Extraktionszeit von 5 h folgende Pechfraktionen gewonnen:

Figure imgb0001
100 parts by weight of normal pitch with an ash former content of 0.23% by weight, a quinoline-insoluble content (Ql) of 5.8% by weight and a toluene-insoluble content (TI) of 22.8% by weight. % and a softening point (EP) of 70 ° C according to Kraemer-Samow (K.-S.) are placed in a stirred autoclave which is heated to 150 ° C. A mixture of 30% by weight propane and 70% by weight toluene as extraction or entraining agent is then passed through the autoclave at a pressure of 180 bar with stirring. The extractant, which is supercritical under these conditions, dissolves up to a concentration of 13% by weight of pitch and transports it out of the autoclave. The extractant loaded with pitch is transferred to two successive regeneration autoclaves and gradually expanded to a pressure of 50 bar. The temperature during regeneration is 150 ° C. The cooling that occurs during relaxation due to the Joule-Thomson effect is compensated for by the addition of heat. The regenerated mixture of extractant and entrainer is recycled. The following pitch fractions are obtained in the regeneration autoclave after an extraction time of 5 h:
Figure imgb0001

Die Fraktion 2 wird bei 400 °C unter Stickstoff bei Normaldruck 1,5 Stunden lang unter Rühren thermisch behandelt. Dabei entstehen 50 Vol.-% Mesophasensphärulen. Das Mesophasenpech wird nach Abkühlen auf 150 °C bei einem Druck von 130 bar mit einem Gemisch aus 30 Gew.-% Propan und 70 Gew.- % Toluol extrahiert. Dabei verbleibt als Rückstand ein Pech mit einem Mesophasengehalt von 80 Vol.-%, einem Gehalt von Pyridinunlöslichem (PI) von 32 Gew.-%, einem Schmelzpunkt von 342 °C und einem mittleren Molekulargewicht von etwa 1000. Dieses Pech wird bei 370 °C über einen Extruder mit einer Spinndüsenplatte mit einem Lochdurchmesser von 0,3 mm mit einer Abzugsgeschwindigkeit von 1000 m/min versponnen. Die Pechfaser wird in Luft mit einer Aufheizrate von 20 K/min von 250 auf 350 °C erhitzt. Die Endtemperatur wird 5 min gehalten, um die Faser unschmelzbar zu machen. Anschließend wird die Faser bei 1500 °C im Inertgasstrom 15 min carbonisiert. Die Kohlenstoffaser mit einem Durchmesser von 9 µm hat eine Festigkeit von 2,47 kN/mm2, einen Elastizitätsmodul von 158 kN/mm2 und eine Bruchdehnung von 1,2 %.Fraction 2 is thermally treated at 400 ° C. under nitrogen at atmospheric pressure for 1.5 hours with stirring. This creates 50 vol .-% mesophase spherules. After cooling to 150 ° C. at a pressure of 130 bar, the mesophase pitch is extracted with a mixture of 30% by weight of propane and 70% by weight of toluene. A pitch with a mesophase content of 80% by volume, a content of pyridine-insoluble (PI) of 32% by weight, a melting point of 342 ° C. and an average molecular weight of about 1000 remains as the residue. This pitch is at 370 ° C spun using an extruder with a spinneret plate with a hole diameter of 0.3 mm at a take-off speed of 1000 m / min. The pitch fiber is heated in air at a heating rate of 20 K / min from 250 to 350 ° C. The final temperature is held for 5 minutes to make the fiber infusible. The fiber is then carbonized at 1500 ° C. in an inert gas stream for 15 minutes. The carbon fiber with a diameter of 9 µm has a strength of 2.47 kN / mm 2 , an elastic modulus of 158 kN / mm 2 and an elongation at break of 1.2%.

Beispie) 2Bei p e) 2

100 Gew.-Teile Normalpech (EP (K.-S.) = 72 °C, Aschebildner = 0,23 Gew.-%, 01 = 5,8 Gew.-%, TI = 22,7 Gew.-%) werden in einen Rührautoklaven gegeben. Der Autoklav wird auf eine Temperatur von 190 °C aufgeheizt. Bei einem Druck von 200 bar wurde ein Gemisch aus 50 Gew.-% Waschbenzol und 50 Gew.-% Flüssiggas (LPG) als Extraktions- bzw. Schleppmittel unter Rühren durch den Autoklaven geleitet. Während der Extraktionszeit von etwa 70 min beträgt die mittlere Beladung des Extraktionsmittels etwa 15 Gew.-%. Das mit Pech beladene Extraktionsmittel wird in zwei aufeinander folgende Regenerierautoklaven überführt und stufenweise auf einen Druck von 50 bar entspannt. Die Temperatur im Regenerierautoklaven wird auf 190 °C gehalten. Das regenerierte Gemisch aus Waschbenzol und LPG wird in den Rührautoklaven zurückgeführt. Es werden folgende Pechfraktionen erhalten:

Figure imgb0002
100 parts by weight of normal pitch (EP (K.-S.) = 72 ° C, ash generator = 0.23% by weight, 01 = 5.8% by weight, TI = 22.7% by weight) are placed in a stirred autoclave. The autoclave is heated to a temperature of 190 ° C. At a pressure of 200 bar, a mixture of 50% by weight of washing benzene and 50% by weight of liquid gas (LPG) as the extraction or entrainer was passed through the autoclave with stirring. During the extraction time of about 70 minutes, the average loading of the extractant is about 15% by weight. The extraction agent loaded with pitch is transferred to two successive regeneration autoclaves and gradually expanded to a pressure of 50 bar. The temperature in the regeneration autoclave is kept at 190 ° C. The regenerated mixture of washing benzene and LPG is returned to the stirred autoclave. The following pitch fractions are obtained:
Figure imgb0002

Die Fraktion 3 wird bei 430 °C unter Stickstoff bei Normaldruck eine Stunde lang unter Rühren thermisch behandelt. Dabei entstehen 60 Vol.-% Mesophasensphärulen. Nach Abkühlen auf 190 °C wird das Mesophasenpech bei einem Druck von 130 bar mit dem gleichen Gemisch wie in der ersten Extraktionsstufe extrahiert. Dabei verbleibt als Rückstand ein Pech mit einem Mesophasengehalt von 87 Vol.- % mit einem Gehalt an Pyridinunlöslichem von 44 Gew.-%, einem Schmelzpunkt von 357 °C und einem mittleren Molekulargewicht von etwa 1100. Dieses Pech wird, wie im Beispiel 1 beschrieben, bei 380 °C versponnen, unschmelzbar gemacht und carbonisiert. Die Kohlenstoffaser mit einem Durchmesser von 7 gm hat eine Festigkeit von 2,58 kN/mm2, einen Elastizitätsmodul von 153 kN/mm2 und eine Bruchdehnung von 1,0 %.Fraction 3 is thermally treated at 430 ° C. under nitrogen at atmospheric pressure for one hour with stirring. This creates 60 vol .-% mesophase spherules. After cooling to 190 ° C extracted the mesophase pitch at a pressure of 130 bar with the same mixture as in the first extraction stage. This leaves a pitch with a mesophase content of 87% by volume, a pyridine-insoluble content of 44% by weight, a melting point of 357 ° C. and an average molecular weight of about 1100. This pitch is as described in Example 1 , spun at 380 ° C, made infusible and carbonized. The carbon fiber with a diameter of 7 gm has a strength of 2.58 kN / mm 2 , an elastic modulus of 153 kN / mm 2 and an elongation at break of 1.0%.

Claims (7)

1. A process for producing a carbon-fibre precursor from coal tar pitch, characterized in that a coal tar pitch is dissolved by extraction at raised temperature and raised pressure in a supercritical gas in the presence of a carrier with the exception of the quinoline-insoluble components, the fraction soluble in quinoline or/and the fraction soluble in toluene being precipitated by reducing the pressure or/and increasing the temperature, one of these fractions or a mixture of both fractions is treated thermally at 380 to 450°C under inert gas or a non-oxidizing gas at atmospheric pressure, until 40 to 65% by volume is converted into mesophases, and the isotropic pitch is separated by extracting the pitch containing mesophases with a supercritical gas using a carrier in order to obtain an anisotropic pitch with a meso- phase content of at least 75% by volume, a content of pyridine-insolubles of 20 to 50% by weight, an average molecular weight of 900 to 1200 and a melting point of 330 to 360°C.
2. A process according to Claim 1, characterized in that the supercritical gas used is in the form of one of the following compounds or a mixture thereof above its critical temperature and its critical pressure: an aliphatic hydrocarbon, preferably with 2 to 5 carbon atoms, an olefinic hydrocarbon, preferably with 2 to 5 carbon atoms, a halogen-containing hydrocarbon, in particular with 1 to 4 carbon atoms.
3. A process according to Claim 1, characterized in that a liquid petroleum gas (LPG) is used as the supercritical gas.
4. A process according to Claims 1 to 3, characterized in that uni- or multinuclear hydrocarbons, which where appropriate are substituted with alkyl groups, in particular with 1 to 2 hydrocarbon atoms, or an amino group, and may be both aromatic and entirely or partially hydrogenated, or uni- or binuclear heterocyclic compounds, in particular nitrogen-containing heterocyclic compounds, in which one nucleus or both nuclei are heterocyclic, alkylesters of aromatic acids with preferably 1 to 6 carbon atoms in the alcohol component or mixtures thereof, may be used as the carrier.
5. A process according to Claims 1 to 3, characterized in that washing benzene is used as the carrier.
6. A process according to any one of Claims 1 to 5, characterized in that the pitch is treated at temperatures in the range of 80°C to 300°C, preferably 120 to 250°C, with a mixture of a supercritical gas and a subcrictical carrier.
7. A process according to any one of Claims 1 to 6, characterized in that the pitch is treated at pressures in the range of 80 to 300 bar, preferably 150 to 250 bar, with a mixture of a supercritical gas and a subcritical carrier.
EP87100271A 1986-03-27 1987-01-12 Process for producing a carbon fiber precursor Expired EP0238787B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19863610375 DE3610375A1 (en) 1986-03-27 1986-03-27 METHOD FOR PRODUCING A CARBON FIBER PRE-PRODUCT AND CARBON FIBERS MADE THEREOF
DE3610375 1986-03-27

Publications (3)

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EP0238787A2 EP0238787A2 (en) 1987-09-30
EP0238787A3 EP0238787A3 (en) 1987-12-16
EP0238787B1 true EP0238787B1 (en) 1989-07-19

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EP87100271A Expired EP0238787B1 (en) 1986-03-27 1987-01-12 Process for producing a carbon fiber precursor

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EP (1) EP0238787B1 (en)
JP (1) JPS62243830A (en)
DE (2) DE3610375A1 (en)
PL (1) PL151114B1 (en)

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AU651847B2 (en) * 1990-09-13 1994-08-04 Commonwealth Scientific And Industrial Research Organisation Process for refining pitch
WO1992005231A1 (en) * 1990-09-13 1992-04-02 Commonwealth Scientific And Industrial Research Organisation Process for refining pitch
CA2055092C (en) * 1990-12-14 2002-01-15 Conoco Inc. Organometallic containing mesophase pitches for spinning into pitch carbon fibers
JP5262119B2 (en) * 2008-01-10 2013-08-14 ソニー株式会社 Negative electrode and battery
RU2480509C1 (en) * 2012-03-16 2013-04-27 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Башкирский государственный университет" Method to produce anisotropic fibre-forming oil pitch by extraction of aromatic and heterocyclic compounds
JP6437355B2 (en) * 2015-03-17 2018-12-12 株式会社神戸製鋼所 Carbon fiber manufacturing method
JP6392701B2 (en) * 2015-05-12 2018-09-19 株式会社神戸製鋼所 Raw material pitch for carbon fiber production
US11434429B2 (en) * 2019-03-18 2022-09-06 Terrapower, Llc Mesophase pitch for carbon fiber production using supercritical carbon dioxide
CN113549466B (en) * 2021-08-05 2022-09-20 广州市浩立生物科技有限公司 Preparation method of high-quality mesophase pitch
CN116606669A (en) * 2023-05-31 2023-08-18 石河子大学 Solvent for deasphalting cycloalkyl vacuum residuum and solvent deasphalting method

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Also Published As

Publication number Publication date
DE3610375A1 (en) 1987-10-01
DE3760336D1 (en) 1989-08-24
EP0238787A2 (en) 1987-09-30
EP0238787A3 (en) 1987-12-16
JPS62243830A (en) 1987-10-24
PL264837A1 (en) 1988-05-12
US4756818A (en) 1988-07-12
PL151114B1 (en) 1990-08-31

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