Classifications

• • 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 and the carbon fibers produced therefrom by methods known per se.
• 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. This is particularly true when using thin film evaporators with rotating internals that are wetted by the pitch, so that the Residence times of part of the bad luck become 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.
• 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 dinuclear 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 carbon fiber precursor obtained is by means of a twin-screw extruder with a spinneret plate, the hole diameter of which is 0.2 to 0.4 mm, at a temperature of 10 to 50 K above of the melting point, with a take-off speed between 500 and 1200 m / min, preferably 800 to 1000 m / min, spun.
• the pitch fibers are heated in an oxygen-containing gas such as air with a heating rate of 15 to 30 K / min from 250 to 350 ° C. and the final temperature is held for at least 3 minutes.
• the pitch fibers made infusible in this way are carbonized in an inert gas stream for 10 to 20 minutes at 1300 to 1700 ° C. and, if appropriate, subsequently graphitized at 2000 to 2500 ° C.
• 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 extraction agent 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 propane and 70% by weight toluene. This leaves a pitch with a mesophase content of 80 vol .-%, a pyridine insoluble content (PI) of 32 wt .-%, a melting point of 342 ° C and an average molecular weight of about 1000.
• PI pyridine insoluble content
• 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 / mm2, a modulus of elasticity of 158 kN / mm2 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., the mesophase pitch is extracted at a pressure of 130 bar with the same mixture as in the first extraction stage. 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 remains as the residue. This pitch is, as described in Example 1 , spun at 380 ° C, made infusible and carbonized. The carbon fiber with a diameter of 7 ⁇ m has a strength of 2.58 kN / mm2, a modulus of elasticity of 153 kN / mm2 and an elongation at break of 1.0%.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Textile Engineering (AREA)
• Inorganic Fibers (AREA)
• Working-Up Tar And Pitch (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Applications Claiming Priority (2)

Publications (3)

Family

ID=6297406

Family Applications (1)

Country Status (5)

Cited By (3)

Families Citing this family (11)

Family Cites Families (31)

• 1986
  • 1986-03-27 DE DE19863610375 patent/DE3610375A1/de not_active Withdrawn
• 1987
  • 1987-01-12 DE DE8787100271T patent/DE3760336D1/de not_active Expired
  • 1987-01-12 EP EP87100271A patent/EP0238787B1/fr not_active Expired
  • 1987-02-24 US US07/018,200 patent/US4756818A/en not_active Expired - Fee Related
  • 1987-03-26 PL PL1987264837A patent/PL151114B1/pl unknown
  • 1987-03-27 JP JP62071964A patent/JPS62243830A/ja active Pending

Also Published As

Similar Documents

Legal Events