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
• • 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
  • C10C3/02—Working-up pitch, asphalt, bitumen by chemical means reaction
  • C10C3/04—Working-up pitch, asphalt, bitumen by chemical means reaction by blowing or oxidising, e.g. air, ozone
• • 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 the production of a highly anisotropic intermediate for carbon fibers from coal tar pitch.
• Such a pitch has liquid crystalline properties, in particular an orderly arrangement of large planar aromatic molecules while maintaining the fluidity.
• pitches are referred to as 'mesophase pitches', and in addition to the predominant anisotropic phase, an isotropic phase can also be present. The anisotropy is assessed by observing the ground pitch surface with a polarizing microscope.
• the treatment time is too short, a high isotropic content is present, which reduces the yield and affects the fiber strength.
• the high-molecular pitch components form infusible particles, which make spinning difficult and deteriorate the fiber quality.
• pitch hydrogenation Another way to produce spinnable mesophase pitch involves pitch hydrogenation.
• pitch with a hydrogenating agent for. B. tetrahydroquinoline, hydrogenated and after filtration and distillative removal of the solvent for mesophase generation thermally treated under vacuum.
• the disadvantage of the last two methods for producing spider pitch is the high technical outlay due to the high pressures and temperatures required for pitch hydrogenation.
• the last process with additional heat-pressure treatment, flashing and distillation is complex and can cancel out the cost advantage provided by the cheap raw material.
• the object was therefore to develop a simpler process for producing an anisotropic pitch without hydrogenation, from which fibers can be spun which, after carbonization, have a tensile strength of more than 2 GPa with an elongation at break of more than 1%.
• the object is achieved in that a coal tar pitch in a temperature range of 330 to 400 ° C for 8 to 12 hours with 1 to 10 ⁇ 10 ⁇ 3 kg / kg pitch ⁇ h of an oxygen-containing gas and then extracted with a pitch solvent, and the soluble pitch fraction after the distillative removal of the solvent at a heating rate of 1 to 50 K / min under a pressure of 0.5 to 50 mbar to a temperature between 400 and 480 ° C, the final temperature being maintained for up to 50 min .
• the blowing of coal tar pitch with air is known per se. It serves to increase the softening point and the coking residue.
• the pitch treated in this way is used, for example, as an insert for pitch coking in horizontal chamber furnaces. It has also been proposed to filter coal tar pitch, blow it with air, and then spin it (Fuel, 1981, Vol 60, pp. 848-850).
• the purpose of blowing is to increase the softening point so that the pitch fiber in the others Treatment does not stick.
• the pitch obtained is isotropic and therefore not suitable for producing high-strength fibers.
• Coal tar pitch is understood to mean the residue from the distillative processing of high-temperature coal tar, preferably a normal pitch coal pitch with a softening point (Kraemer-Sarnow) of approximately 70 ° C. All pitch solvents can be used as solvents which correspond to pyridine, quinoline or anthracene oil in their dissolving behavior.
• the bad luck blown off has the following material data: Floating point 160 ° C Toluene insoluble 52% by weight Quinoline insoluble 21% by weight Coking residue (Alcan) 68% by weight Ash (900 ° C) 0.2% by weight
• the blown pitch is ground and 1 part by weight of pitch is dissolved in 2 parts by weight of quinoline at 180 ° C. with stirring. After about 2 hours, the undissolved components of the pitch are separated from the soluble components by sedimentation. The liquid phase is suctioned off and filtered through a sintered metal filter (pore size: 1 ⁇ m) in order to separate even the finest solid particles.
• the quinoline is distilled off from the pitch solution under a pressure of 200 mbar up to a bottom temperature of 300 ° C.
• the remaining pitch fraction has the following material data: Floating point 170 ° C Toluene insoluble 46% by weight Quinoline insoluble less than 1% by weight Coking residue (Alcan) 65% by weight Ash (900 ° C) Rummage
• the pitch fraction is heated from 250 to 440 ° C. under a pressure of 5 mbar in 60 minutes and the final temperature is maintained for 20 minutes.
• the mesophase pitch produced in this way has the following properties: Floating point 320 ° C optical anisotropy more than 90 vol .-% Toluene insoluble 85% by weight Quinoline insoluble 18% by weight Coking residue (Alcan) 94% by weight Pressure filter test (1 ⁇ m) practically no infusible particles present
• the mesophase pitch can be spun at 380 ° C without thread breaks occurring.
• the pitch fibers are stabilized in air up to a temperature of 350 ° C and then carbonized up to 1200 ° C.
• the carbon fibers obtained in this way are characterized by the following data: diameter 9-10 ⁇ m
• the strength properties exceed those of the fibers obtained from double thermally treated pitch (EP 0 17 29 55 A1) and correspond approximately to those of the fibers produced from hydrogenated and thermally treated pitches.
• the same initial pitch as in the example is filtered after adding filter aids at 270 ° C.
• the filtrate has the following properties: Softening point (Kraemer-Sarnow) 70 ° C Toluene insoluble 22% by weight Quinoline insoluble less than 0.1% by weight ash traces
• the filtered pitch is treated thermally under the same conditions as in the example.
• the final temperature In order to obtain an optical anisotropy of at least 90% by volume, the final temperature must be increased to 465 ° C and the holding time to 30 minutes.
• the mesophase pitch produced in this way has the following properties: Floating point 340 ° C optical anisotropy 90 vol .-% Toluene insoluble 88% by weight Quinoline insoluble 51% by weight Coking residue (Alcan) 95% by weight Filter test (1 ⁇ m) 0.5% by weight infusible particles
• the mesophase pitch can only be spun at 405 ° C. Thread breaks often occur.
• the service life of the filter elements arranged in front of the spinnerets is short.
• the carbon fibers carbonized up to 1200 ° C can be characterized by the following typical properties: diameter 9-11 ⁇ m tensile strenght 1.6 GPa modulus of elasticity 230 GPa
• the tensile strength corresponds to that of double thermally treated pitches. However, the elongation at break is less than 1%.
• the comparison of the analysis data clearly shows that the mesophase formation is favorably influenced by blowing with air as pretreatment of the pitch.
• the mesophase pitch according to the invention surprisingly has a lower pour point and a lower quinoline-insoluble content with higher anisotropy. This simplifies spinning and significantly improves the strength properties of the carbonized fiber.

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

Applications Claiming Priority (2)

Publications (3)

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Cited By (1)

Citations (4)

• 1988
  • 1988-06-29 DE DE3821866A patent/DE3821866A1/de not_active Withdrawn
• 1989
  • 1989-01-10 CA CA000587816A patent/CA1309369C/fr not_active Expired - Fee Related
  • 1989-03-14 EP EP89104511A patent/EP0348599B1/fr not_active Expired - Lifetime
  • 1989-03-14 DE DE8989104511T patent/DE58900206D1/de not_active Expired - Fee Related
  • 1989-06-29 JP JP1165489A patent/JPH0247190A/ja active Pending

Patent Citations (4)

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