US3656904A - Graphitization process - Google Patents

Graphitization process Download PDF

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US3656904A
US3656904A US45160A US3656904DA US3656904A US 3656904 A US3656904 A US 3656904A US 45160 A US45160 A US 45160A US 3656904D A US3656904D A US 3656904DA US 3656904 A US3656904 A US 3656904A
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fibrous material
process according
heating zone
borate
continuous length
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Michael J Ram
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BASF SE
BASF Corp
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Celanese Corp
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    • 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
    • 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
    • D01F9/20—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products
    • D01F9/21—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D01F9/22—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyacrylonitriles
    • 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
    • D01F9/32—Apparatus therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D7/00—Forming, maintaining or circulating atmospheres in heating chambers
    • F27D7/06—Forming or maintaining special atmospheres or vacuum within heating chambers
    • F27D2007/063—Special atmospheres, e.g. high pressure atmospheres
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D99/0001—Heating elements or systems
    • F27D99/0006—Electric heating elements or system
    • F27D2099/0015—Induction heating
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • Graphite fibers are defined herein as fibers which consist es sentially of carbon and have a predominant X-ray diffraction pattern characteristic of graphite.
  • Amorphous carbon fibers or carbonized fibers are defined as fibers capable of undergoing graphitization in which the bulk of the fiber weight can be attributed to carbon and which exhibit an essentially amorphous X-ray diffraction pattern.
  • Graphite fibers generally have a much higher modulus and a higher tenacity than do amorphous carbon fibers and in addition are more highly electrically and thermally conductive.
  • graphite fibers theoretically have among the best properties of any fiber for use as high strength reinforcement.
  • these desirable properties are corrosion and high temperature resistance, low density, high tensile strength, and most important, high modulus.
  • Graphite is one of the very few known materials whose tensile strength increases with tem perature. Uses for such graphite fiber reinforced composites include aerospace structural components, rocket motor casings, deep-submergence vessels and ablative materials for heat shields on re-entry vehicles.
  • Amorphous carbon fibers have been; graphitized in the past by heating for extended periods of time, e.g., several hours, while present in a boron doped crucible.
  • a technique has heretofore been proposed in which the fibrous material undergoing graphitization is first soaked in an aqueous solution of boric acid, washed with water, and dried prior to graphitization. While such a technique has proven to be effective in catalyzing the graphitization of the fibrous material, it has proven to be unduly time consuming.
  • the precursor is a stabilized acrylic fibrous material and the heating zone is provided with a temperature gradient in which both carbonization and graphitization are carried out.
  • the fibrous material is a continuous multifilament yarn.
  • the fibrous material which is treated in the present process optionally may be provided with a twist which tends to improve the handling characteristics.
  • a twist of about 0.1 to 5 tpi, and preferably about 0.3 to 1.0 tpi may be imparted to a multifilament yarn.
  • a false twist may be used instead of or in addition to a real twist.
  • the fibrous material which is graphitized in accordance with the present process may be carbonaceous, contain at least about 90 per cent carbon by weight, and exhibit an essentially amorphous X-ray diffraction pattern.
  • amorphous carbon fibrous materials suitable for graphitization may be formed by a variety of techniques. For instance, organic polymeric fibrous materials which are capable of undergoing thermal stabilization may be initially stabilized by treatment in an appropriate atmosphere at a moderate temperature (e.g., 200 to 400 C.
  • Suitable organic polymeric fibrous materials from which the fibrous material capable of undergoing graphitization may be derived include an acrylic polymer, a cellulosic polymer, a polyamide, a polybenzimidazole, polyvinyl alcohol, etc.
  • acrylic polymeric materials are particularly suited for use in the formation of the fibrous material capable of undergoing graphitization which is employed in the present process.
  • suitable cellulosic materials include the natural and regenerated forms of cellulose, e.g., rayon.
  • suitable polyamide materials include the aromatic polyamides, such as nylon 6T, which is formed by the condensation of hexamethylenediamine and terephthalic acid.
  • An illustrative example of a suitable polybenzimidazole is poly- 2,2'-m-phenylene-5,5-bibenzimidazole.
  • a fibrous acrylic polymeric material prior to stabilization may be formed primarily of recurring acrylonitrile units.
  • the acrylic polymer should contain not less than about 85 mol per cent of recurring acrylonitrile units with not more than about 15 mol per cent of a monovinyl compound which is copolymerizable with acrylonitrile such as styrene, methyl acrylate, methyl methacrylate, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl pyridine, and the like, or a plurality of such monovinyl compounds.
  • multifilament bundles of an acrylic fibrous material may be initially stabilized in an oxygen-containing atmosphere (i.e., preoxidized) on a continuous basis in accordance with the teachings of U.S. Ser. No. 749,957, filed Aug. 5, 1968, of Dagobert E. Stuetz, which is assigned to the same assignee as the instant invention and is herein incorporated by reference.
  • the acrylic fibrous material should be either an acrylonitrile homopolymer or an acrylonitrile copolymer which contains no more than about 5 mol per cent of one or more monovinyl comonomers copolymerized with acrylonitrile.
  • the fibrous material is derived from an acrylonitrile homopolymer.
  • the stabilized acrylic fibrous material which is preoxidized in an oxygen-containing atmosphere is black in appearance, contains a bound oxygen content of at least 7 per cent by weight as determined by the Unterzaucher analysis, retains its original fibrous configuration essentially intact, and is nonburning when subjected to an ordinary match flame.
  • a continuous length of the fibrous material capable of undergoing graphitization is continuously passed through a heating zone having a maximum temperature of at least 2,000, e.g., a maximum temperature of 2,000 to 3,100 C. (preferably 2,400 to 3,100 C.), containing an inert gaseous atmosphere for a residence time sufficient to substantially convert the fibrous material to graphitic carbon while retaining its original fibrous configuration essentially intact.
  • Suitable inert gaseous atmospheres for the heating zone include nitrogen, argon, helium, etc.
  • a continuous length of an amorphous carbon fibrous material, e.g., a multifilament yarn may be passed through the heating zone while at a graphitization temperature of at least 2,000 C.
  • a continuous length of a stabilized acrylic fibrous material which is nonbuming when subjected to an ordinary match fiame and derived from an acrylic fibrous material selected from the group consisting of an acrylonitrile homopolymer and acrylonitrile copolymers which contain at least about mol per cent of acrylonitrile units and up to about 15 mol per cent of one or more monovinyl units copolymerized therewith is continuously passed through a heating zone containing an inert gaseous atmosphere and a temperature gradient in which said fibrous material is initially carbonized, and in which said carbonized fibrous material is heated to a maximum temperature of at least 2,000 C. until substantial graphitization occurs.
  • Representative inert gaseous atmospheres for the heating zone in which both carbonization and graphitization are accomplished include nitrogen, argon, helium, etc.
  • the fibrous material supplied to the heating zone is a stabilized acrylic fibrous material it may be carbonized and graphitized while passing through a temperature gradient in accordance with the procedures described in commonly assigned U.S. Ser. Nos. 777,275, filed Nov. 20, 1968 of Charles M. Clarke entitled Process for the Continuous Carbonization of a Stabilized Acrylic Fibrous Material; 17,780 filed Mar. 9, 1970 ofCharles M. Clarke, Michael .1. Ram, and John P. Riggs entitled Improved Process for the Carbonization of a Stabilized Acrylic Fibrous Material," and 17,832 filed Mar. 9, 1970 of Charles M. Clarke, Michael J. Ram, and Arnold .I. Rosenthal entitled Production of High Tenacity Graphitic Fibrous Materials.
  • Each of these disclosures is herein incorporated by reference.
  • a continuous length of stabilized acrylic fibrous material which is non-buming when subjected to an ordinary match flame and derived from an acrylic fibrous material selected from the group consisting of an acrylonitrile homopolymer and acrylonitrile copolymers which contain at least about 85 mol per cent of acrylonitrile units and up to about 15 mol per cent of one or more monovinyl units copolymerized therewith is converted to a graphitic fibrous material while preserving the original fibrous configuration essentially intact while passing through a carbonization/graphitization heating zone containing an inert gaseous atmosphere and a temperature gradient in which said fibrous material is raised within a period of about 20 to about 300 seconds from about 800 C.
  • the equipment utilized to produce the heating zone used to produce graphitization or carbonization and graphitization in the process of the present invention may be varied as will be apparent to those skilled in the art. It is essential that the apparatus selected be capable of producing the required temperature while excluding the presence of an oxidizing atmosphere.
  • the continuous length of fibrous material undergoing graphitization or carbonization and graphitization is heated by use of an induction furnace.
  • the fibrous material may be passed in the direction of its length through a hollow graphite tube or other susceptor which is situated within the windings of the induction coil.
  • relatively long tubes or susceptors be used so that the fibrous material may be passed through the same at a more rapid rate while being graphitized or carbonized and graphitized.
  • the temperature gradient of a given apparatus may be detemiined by conventional optical pyrometer measurements as will be apparent to those skilled in the art.
  • the fibrous material because of its small mass and relatively large surface area instantaneously assumes essentially the same temperature as the inert gaseous atmosphere of the heating zone through which it is continuously passed.
  • a tensional force may be optionally applied to the bundles undergoing graphitization in order to provide efficient handling of the fibrous material and/or to modify the physical properties of the same.
  • the inert gaseous atmosphere is commonly caused to flow through the heating zone while preserving the requisite heating.
  • the inert gaseous atmosphere may be continuously introduced through one or more small apertures provided in the walls of a hollow graphite tube which is surrounded by an induction coil.
  • the inert gaseous atmosphere accordingly exits from the graphite tube through the ends thereof.
  • the flow of the inert gaseous atmosphere out of each end of the graphite tube accordingly substantially excludes the introduction of air or an oxidizing atmosphere within the heating zone.
  • At least one gaseous stream containing a catalytic quantity of a volatile alkyl borate in vapor form capable of catalyzing the graphitization of the fibrous material is preferably introduced into the heating zone so that the vapor stream directly impinges upon the continuous length of fibrous material, or at least is provided in the inert gaseous atmosphere of the heating zone immediately adjacent the fibrous material.
  • the point of introduction of the stream containing the volatile alkyl borate in gaseous form is identical to that location where the fibrous material enters the heating zone or is in relatively close proximity thereto.
  • the gas stream is introduced into the heating zone in close proximity to the fibrous material prior to raising the temperature of the fibrous material above about 500 C.
  • the heating zone is preferably provided with a temperature gradient in which the fibrous material is progressively elevated to a maximum temperature of at least 2,000 C. where substantial graphitization is accomplished.
  • an auxiliary graphite tube or susceptor may be provided in series with the main graphite tube of the induction furnace to extend the length of the entrance portion of the heating zone, and the stream of boron compound as well as the starting fibrous material introduced into such extended portion.
  • the continuous length of fibrous material is supplied to the heating zone in an essentially anhydrous form which is absorbent with respect to the volatile alkyl borate which contacts the same within the heating zone.
  • the stream of volatile alkyl borate in vapor form may be at least partially diluted with an inert gas, such as nitrogen, argon, or helium, which is preferably identical to the inert gaseous atmosphere otherwise supplied to the heating zone.
  • the volatile alkyl borate capable of catalyzing the graphitization reaction is preferably introduced into the inert gaseous atmosphere surrounding the continuous length of fibrous material in at least a portion of the heating zone in a concentration of about 200 to 20,000 parts per million by volume.
  • the volatile alkyl borate is introduced into the gaseous atmosphere surrounding the continuous length of fibrous material in at least a portion of the heating zone in a concentration of about 200 to 2,000 parts per million by volume.
  • the quantity of the volatile alkyl borate introduced into the heating zone is preferably about 0.01 to 4 per cent by weight based upon the weight of fibrous material introduced into the heating zone.
  • the quantity of volatile alkyl borate introduced into the heating zone is about 0.04 to 0.4 per cent by weight based upon the weight of the fibrous material introduced into the heating zone.
  • the alkyl borate possess substantial volatility at 500 C. or below and is conveyed to the heating zone while at a temperature not in excess of 500 C.
  • the alkyl borate possesses substantial volatility at about room temperature (i.e., about 25 C.) thereby facilitating convenient handling and introduction of the same without resorting to elevated temperatures.
  • alkyl borate which is capable of being introduced into the heating zone in vapor form may be selected for use in the process.
  • the preferred volatile alkyl borates for use in the process are the alkyl borates of the formula B(OR) where R is an alkyl group having 1 to 5 carbon atoms.
  • the particularly preferred alkyl borate for use in the process is trimethyl borate.
  • alkyl borates possessing sufficient volatility for use in the present process include higher molecular weight boric acid esters such as tricyclohexyl borate, tridodecyl borate, B(OC H- I and tri hexylene glycolbiborate, B tO C H l
  • boric acid esters such as tricyclohexyl borate, tridodecyl borate, B(OC H- I and tri hexylene glycolbiborate, B tO C H l
  • the ability for one to operate at a lower maximum graphitization temperature offers a substantial cost reduction since less power is required and the usable life of the apparatus utilized in the process is extended.
  • the graphite tube or susceptor of an induction furnace may have its life extended many times (e.g., five to 10 times) by simply lowering the maximum graphitization temperature from about 2,900 C. to 2,700 C. Not only is one spared the cost of a replacement graphite tube, but down time is eliminated which would otherwise be consumed while replacing the graphite tube, starting up the furnace, and allowing it to again come to equilibrium conditions.
  • EXAMPLE I A continuous length of 1,600 fil unwashed dry spun acrylonitrile homopolymer continuous filament yarn having a total denier of 2,000 was selected as the starting material.
  • the yarn was oriented and drawn to a single filament tenacity of about 3.2 grams per denier.
  • the yarn was subjected to a healing treatment in which residual N,N-dimethyl formamide spinning solvent was evolved by passage for 6 minutes through a muffle furnace provided with air at 185 C. during which time the yarn shrank 10 per cent in length.
  • the yarn was continuously stabilized in accordance with the teachings of U.S. Ser. No. 749,957, filed Aug. 5, I968, of Dagobert E.
  • Stuetz which is assigned to the same assignee as the present invention and is herein incorporated by reference.
  • the yarn was continuously passed in the direction of its length in the absence of shrinkage through a multi-wrap skewed roll oven provided with an air atmosphere at 270 C. for a residence time of I47 minutes.
  • the resulting stabilized yarn was black in appearance,contained a bound oxygen content of 10.85 per cent by weight as determined by the Unterzaucher analysis, and was non-burning when subjected to an ordinary match flame.
  • the preoxidized yarn was stored in a forced air oven at 1 l C. while wound upon a bobbin following stabilization.
  • the yarn was next unwound from the bobbin and passed through a drying zone (not shown) wherein volatiles were substantially removed prior to introduction into the heating zone wherein carbonization and graphitization were accomplished.
  • the drying zone consisted of one 12 inch muffle furnace provided with circulating air at 200 C.
  • the dried stabilized yarn l was next continuously passed at a rate of about 1.5 inches/minute in the direction of its length through a Lepel 450 KC induction furnace 2 utilizing a 20 KW power source wherein both carbonization and graphitization were accomplished.
  • the induction furnace comprised a 10 turn water cooled copper coil 4 having an inner diameter of three-fourths and a length of 2 inches and a hollow graphite tube or susceptor 6 suspended within the coil having a length of 8 /2 inches, an outer diameter of one-half inch and an inner diameter of one-eighth inch through which the yarn was continuously passed.
  • Four Ma inch holes were provided in the wall of graphite tube 6.
  • the hollow graphite tube 6 was held in position by supports 7.
  • the copper coil 4 which encompassed a portion of the hollow graphite tube 6 was positioned at a location essentially equidistant from the respective ends of the graphite tube.
  • the copper coil 4 was connected to 20 KW power source 8.
  • An auxiliary graphite tube 10 through which the fibrous material passed was placed at the entrance end of graphite tube 6.
  • the auxiliary tube 10 had an overall length of 5 3/4 inches, one-half inch of which encompassed the end of graphite tube 6.
  • the outer diameter of the auxiliary tube 10 was 1 inch and the inner diameter of the auxiliary tube was one-fourth inch.
  • a stainless steel enclosure or housing 12 having a wall thickness of about one-fourth inch and an overall length of about 11 inches, a height of about 6 inches, and a width of about 6 inches surrounded the induction furnace 2.
  • the resulting graphite yarn 14 as it left graphite tube 6 passed through cylindrical orifice 16 formed of graphite having an outer diameter of one-half inch and an inner diameter of oneeighth inch.
  • Nitrogen was passed through line 18 to rotometer 20 which delivered the nitrogen at a rate of 25 standard cubic feet per hour through line 22.
  • Line 22 branched into line 24 which communicated with a centrally located orifice in the wall of housing 12, and line 26 which communicated with rotometer 28.
  • a stream of nitrogen from line 24 entered the interior of the housing 12 at a rate of 24.976 standard cubic feet per hour.
  • Nitrogen was delivered from rotometer 28 through line 30 at a flow rate of 0.024 standard cubic feet per hour.
  • the stream of nitrogen from line 30 was bubbled through liquid trimethyl borate 32 present in vessel 34. Nitrogen gas as well as trimethyl borate in vapor form was withdrawn from the space 36 above the liquid trimethyl borate 32 through line 38.
  • An ice bath 40 surrounded vessel 34 to insure a constant vapor pressure for the trimethyl borate. Approximately 10 per cent by volume of the gaseous stream in line 38 was trimethyl borate, and approximately per cent by volume of the gaseous stream in line 38 was nitrogen.
  • the gaseous stream containing the trimethyl borate in vapor form is introduced into the interior of auxiliary graphite tube 10 through an orifice in the wall thereof located 4% inches from the entrance end thereof.
  • the yarn While passing through the heating zone defined by the auxiliary graphite tube 10 and graphite tube 6, the yarn was raised from about 100 C. to a temperature of 800 C. in approximately 300 seconds, from 800 C. to l,600 C. in approximately 60 seconds to produce a carbonized yarn, and from 1,600 C. to a maximum temperature of approximately 2,700 C. in approximately 40 seconds where it was maintained 50 C. for approximately 40 seconds. While passing through the heating zone constant longitudinal tensions of 300, 400, and 500 grams were maintained upon portions of the yarn at various points in time. The resulting yarn 14 exhibited a graphitic carbon X-ray diffraction pattern and a specific gravity of about 2.0. The following single filament tensile properties were obtained for the various graphite yarn samples.
  • a stream of nitrogen gas from line 24 entered the interior of housing 12 at a rate of 24.76 standard cubic feet per hour. Nitrogen was delivered from rotometer 28 through line 30 at a rate of 0.24 standard cubic feet per hour.
  • 3.9 X 10 grams of trimethyl borate in vapor fonn entered graphite tube 10 via line 38 per minute and directly impinged upon the yarn.
  • Trimethyl borate in vapor form was supplied to the inert gaseous atmosphere of the heating zone in a quantity of about 0.45 per cent by weight based upon the weight of the yarn.
  • the quantity of trimethyl borate in the inert atmosphere surrounding the yarn in the immediate area of the heating zone wherein the boron compound was introduced was about 2,000 parts per million.
  • the yarn While passing through the heating zone defined by the auxiliary graphite tube 10 and graphite tube 6, the yarn was raised from about 100 C. to a temperature of 800 C. in approximately 300 seconds, from 800 C. to l,600 C. in approximately 60 seconds to produce a carbonized yarn, and from 1,600" C. to a maximum temperature of approximately 2,900 C. in approximately 40 seconds where it was maintained fl0 C. for approximately 40 seconds.
  • the following single filament tensile properties were determined for the various graphite yarn samples.
  • Example III In a comparative graphitization procedure Example III was repeated in an identical apparatus with the exception that no boron compound was introduced into the heating zone. A stream of nitrogen gas from line 24 entered the interior of housing 12 at a rate of 25 standard cubic feet per hour. The overall tensile properties of the resulting graphite yarn were generally lower than those obtained in Example III. The following single filament tensile properties were determined for the various graphite yarn samples.
  • the continuous length of continuous filament yarn which is introduced into the heating zone is a carbonaceous yarn derived from an acrylonitrile homopolymer containing about 99 per cent carbon by weight and exhibits an essentially amorphous X-ray diffraction pattern. Substantially similar results are achieved.
  • said continuous length of fibrous material capable of undergoing graphitization is a carbonaceous fibrous material containing at least about 90 per cent carbon by weight and having an essentially amorphous X-ray diffraction pattern.
  • a process according to claim 1 wherein said continuous length of fibrous material is a continuous multifilament yarn.
  • said inert gaseous atmosphere is selected from the group consisting of nitrogen, argon, and helium.
  • heating zone contains an inert gaseous atmosphere having a maximum temperature of about 2,400 to 3,l00 C.
  • said volatile alkyl borate is an alkyl borate of the formula B(OR) where R is an alkyl group having one to five carbon atoms.
  • a process according to claim 7 wherein said trimethyl borate in vapor form is introduced into said inert gaseous atmosphere surrounding said continuous length of fibrous material in a concentration of about 200 to 2,000 parts per million.
  • a process according to claim 10 wherein said stabilized acrylic fibrous material is derived from an acrylonitrile homopolymer.
  • a process according to claim 10 wherein said stabilized acrylic fibrous material is derived from an acrylonitrile copolymer which contains at least about 95 mol per cent of acrylonitrile units and up to about mol per cent of one or more monovinyl units copolymerized therewith.
  • a process according to claim wherein said continuous length of stabilized acrylic fibrous material is a continuous multifilament yarn.
  • said inert gaseous atmosphere is selected from the group consisting of nitrogen, argon, and helium.
  • said volatile alkyl borate is an alkyl borate of the formula B (OR) where R is an alkyl group having one to five carbon atoms.
  • said stabilized acrylic fibrous material is derived from an acrylonitrile copolymer which contains at least about mol per cent of acrylonitrile units and up to about 5 mol per cent of one or more monovinyl units copolymerized therewith.
  • a process according to claim 21 wherein said continuous length of stabilized acrylic fibrous material is a continuous multifilament yarn.
  • said inert gaseous atmosphere is selected from the group consisting of nitrogen, argon, and helium.
  • said volatile alkyl borate is an alkyl borate of formula B(OR) where R is an alkyl group having one to five carbon atoms.

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Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3764662A (en) * 1971-04-21 1973-10-09 Gen Electric Process for making carbon fiber
US3923950A (en) * 1971-11-18 1975-12-02 Celanese Corp Production of stabilized acrylic fibers and films
US4073870A (en) * 1975-04-02 1978-02-14 Toho Beslon Co., Ltd. Process for producing carbon fibers
US4388227A (en) * 1979-03-02 1983-06-14 Celanese Corporation Intercalation of graphitic carbon fibers
US4431623A (en) * 1981-06-09 1984-02-14 The British Petroleum Company P.L.C. Process for the production of carbon fibres from petroleum pitch
US4526770A (en) * 1980-10-02 1985-07-02 Fiber Materials, Inc. Method of producing carbon fiber and product thereof
US4534919A (en) * 1983-08-30 1985-08-13 Celanese Corporation Production of a carbon fiber multifilamentary tow which is particularly suited for resin impregnation
US4714642A (en) * 1983-08-30 1987-12-22 Basf Aktiengesellschaft Carbon fiber multifilamentary tow which is particularly suited for weaving and/or resin impregnation
US4781223A (en) * 1985-06-27 1988-11-01 Basf Aktiengesellschaft Weaving process utilizing multifilamentary carbonaceous yarn bundles
US4876077A (en) * 1985-05-30 1989-10-24 Research Development Corp. Of Japan Process for producing graphite
US5004590A (en) * 1983-08-05 1991-04-02 Hercules Incorporated Carbon fibers
CN100491613C (zh) * 2005-10-12 2009-05-27 中国科学院山西媒炭化学研究所 一种生产石墨化纤维的方法及装置
WO2012164577A1 (en) 2011-06-03 2012-12-06 Council Of Scientific & Industrial Research A process for the preparation of kish graphitic lithium-insertion anode materials for lithium-ion batteries
US20160059444A1 (en) * 2014-08-29 2016-03-03 Yanbo Wang Production of highly conductive graphitic films from polymer films
US12060273B2 (en) 2020-04-21 2024-08-13 Global Graphene Group, Inc. Production of graphitic films from a mixture of graphene oxide and highly aromatic molecules

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Cited By (15)

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Publication number Priority date Publication date Assignee Title
US3764662A (en) * 1971-04-21 1973-10-09 Gen Electric Process for making carbon fiber
US3923950A (en) * 1971-11-18 1975-12-02 Celanese Corp Production of stabilized acrylic fibers and films
US4073870A (en) * 1975-04-02 1978-02-14 Toho Beslon Co., Ltd. Process for producing carbon fibers
US4388227A (en) * 1979-03-02 1983-06-14 Celanese Corporation Intercalation of graphitic carbon fibers
US4526770A (en) * 1980-10-02 1985-07-02 Fiber Materials, Inc. Method of producing carbon fiber and product thereof
US4431623A (en) * 1981-06-09 1984-02-14 The British Petroleum Company P.L.C. Process for the production of carbon fibres from petroleum pitch
US5004590A (en) * 1983-08-05 1991-04-02 Hercules Incorporated Carbon fibers
US4534919A (en) * 1983-08-30 1985-08-13 Celanese Corporation Production of a carbon fiber multifilamentary tow which is particularly suited for resin impregnation
US4714642A (en) * 1983-08-30 1987-12-22 Basf Aktiengesellschaft Carbon fiber multifilamentary tow which is particularly suited for weaving and/or resin impregnation
US4876077A (en) * 1985-05-30 1989-10-24 Research Development Corp. Of Japan Process for producing graphite
US4781223A (en) * 1985-06-27 1988-11-01 Basf Aktiengesellschaft Weaving process utilizing multifilamentary carbonaceous yarn bundles
CN100491613C (zh) * 2005-10-12 2009-05-27 中国科学院山西媒炭化学研究所 一种生产石墨化纤维的方法及装置
WO2012164577A1 (en) 2011-06-03 2012-12-06 Council Of Scientific & Industrial Research A process for the preparation of kish graphitic lithium-insertion anode materials for lithium-ion batteries
US20160059444A1 (en) * 2014-08-29 2016-03-03 Yanbo Wang Production of highly conductive graphitic films from polymer films
US12060273B2 (en) 2020-04-21 2024-08-13 Global Graphene Group, Inc. Production of graphitic films from a mixture of graphene oxide and highly aromatic molecules

Also Published As

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CA948816A (en) 1974-06-11
GB1315744A (en) 1973-05-02
DE2128907A1 (de) 1971-12-16
DE2128907C3 (de) 1979-09-20
DE2128907B2 (enrdf_load_stackoverflow) 1979-01-25
FR2096154A5 (enrdf_load_stackoverflow) 1972-02-11

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