US3656903A - Direct production of graphite fibrous materials from preoxidized acrylic fibrous materials - Google Patents

Direct production of graphite fibrous materials from preoxidized acrylic fibrous materials Download PDF

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US3656903A
US3656903A US815200A US3656903DA US3656903A US 3656903 A US3656903 A US 3656903A US 815200 A US815200 A US 815200A US 3656903D A US3656903D A US 3656903DA US 3656903 A US3656903 A US 3656903A
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fibrous material
process according
halogenated
organic
preoxidized
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Dagobert E Stuetz
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BASF SE
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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
    • 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

Definitions

  • ABSTRACT A rapid process is provided for the direct conversion of a preoxidized acrylic fibrous material containing at least about 7 percent bound oxygen by weight to a fibrous material of predominantly graphitic carbon.
  • the preoxidized acrylic fibrous material is initially impregnated with an organic protective agent and subsequently is passed through a reducing flame which imparts a minimum fiber temperature of at least 1,900C. while the fibrous material is under tension at least sufficient to prevent visible sagging.
  • the reducing flame is generated by a fuel-oxidant mixture, e.g., an acetylene and oxygen mixture.
  • Graphite fibers are defined herein as fibers which consist essentially of carbon and which have a predominant x-ray diffraction pattern characteristic of graphite.
  • Amorphous carbon fibers are defined as fibers 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.
  • A'nother prior art approach to graphitizing amorphous car bon fiber, called conductive graphitization involves passing a yarn over electrically conductive contacts.
  • an amorphous carbon fiber is advanced over a pair of spaced electrically conductive rollers while passing an electric current through the advancing fiber to raise it to graphitization temperature.
  • a controlled atmosphere of nitrogen, argon, carbon dioxide, or mixtures thereof, generally must be provided around the fiber while undergoing direct resistance heating.
  • an. absence of structural integrity when heated for two seconds at a fiber temperature of 1,900 C. comprises: impregnating the preoxidized acrylic fibrous material with a quantity of an organic protective agent capable of rendering the material resistant to loss of structural integrity when heated for at least two seconds at a fiber temperature of l,900 C., and passing the impregnated fibrous material through a reducing flame imparting to the material a minimum temperature of at least l,900 C. at a speed sufficient to avoid breaking while the material is under a tension at least sufficient to prevent visible sagging.
  • the resulting graphite fibers are suitable for use as a reinforcing medium in composite articles which find particular utility in applications where a strong, lightweight, structural element is required.
  • the preoxidized acrylic fibrous material which is graphitized in accordance with the present process has l) a carbon content of up to about 65 per cent by weight, (2) a relatively amorphous x-ray diffraction pattern, (3) a bound oxygen content of at least 7 per cent by weight, and (4) an absence of structural integrity when heated for two seconds at a fiber temperature of 1,900 C.
  • the carbon content of the preoxidized acrylic fibrous material will vary with the extent of the preoxidation treatment referred to hereafter, and will commonly range from about 50 to 65 per cent by weight. As the extent of preoxidation increases, the carbon content of the preoxidized fiber commonly tends to decrease. Since the preoxidation treatment is conducted at a moderate temperature, the preoxidized acrylic fibrous material will exhibit a relatively amorphous xray diffraction pattern and an absence of an x-ray diffraction pattern characteristic of graphitic carbon.
  • the bound oxygen content of the preoxidized acrylic fibrous material is at least about 7 per cent by weight as determinable by routine analytical techniques, such as the Unterzaucher analysis.
  • a preoxidized acrylic fibrous material suitable for use in the process commonly has a bound oxygen content of about 7 to per cent by weight.
  • Preoxidized acrylic fibrous materials having higher bound oxygen contents tend to require more extended residence times for their production and tend to yield no commensurate advantage in the instant graphitization process.
  • the preoxidized acrylic fibrous materials utilized in the process lose their structural integrity when heated for two seconds at afiber temperature of l,900 C. produced by a reducing flame as described hereafter. Such failure of structural integrity is commonly exhibited by breakage of the fibrous material and partial or complete disintegration.
  • the preoxidized acrylic fibrous materials are commonly non-burning when subjected to an ordinary match flame even in the absence of the impregnation treatment.
  • the acrylic fibrous precursor from which the preoxidized acrylic fibrous material utilized in the process is derived consists primarily of recurring acrylonitrile units.
  • the acrylic fibrous precursor should generally 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, such as styrene, methyl acrylate, methyl methacrylate, vinyl acetate, vinyl chloride, vinylidine chloride, vinyl pyridine, and the like.
  • the preoxidized acrylic fibrous material is derived from an acrylonitrile homopolymer.
  • the preoxidized acrylic fibrous material is formed by the thermal treatment of the fibrous precursor at a relatively moderate temperature in an oxygen-containing atmosphere.
  • the preoxidation treatment may be conducted on either a batch or a continuous basis in accordance with procedures known in the art.
  • Ram and Richard N. Rulison disclose preferred preoxidation procedures.
  • Each of the above-identified applications is assigned to the same assignee as the instant invention and is herein incorporated by reference.
  • Other preoxidation procedures capable of producing the requisite starting material for use in the instant process may be chosen as will be apparent to those skilled in the art.
  • the preoxidized acrylic fibrous materials which are graphitized in accordance with the present invention are preferably in yarn form. Appreciable lengths of a continuous multifilament yarn are graphitized in a particularly preferred embodiment of the invention. Staple yarns may also be selected, however, these generally give correspondingly lower tensile properties than do the continuous filament yarns. Other fibrous assemblages, such as fabrics, may likewise be treated in accordance with the present invention as will be apparent to those skilled in the art.
  • a yarn When a yarn is selected as the starting material, it may optionally be provided with a twist which improves its handling characteristics. For example, a twist of about 0.1 to l tpi, and preferably about 0.1 to 0.7 tpi may be conveniently utilized.
  • the preoxidized acrylic fibrous material is impregnated prior to subjection to the reducing flame with an organic protective agent which is capable of rendering the fibrous material resistant to loss of structural integrity when heated in a reducing flame for at least two seconds at a fiber temperature of 1,900 C.
  • an organic protective agent which is capable of rendering the fibrous material resistant to loss of structural integrity when heated in a reducing flame for at least two seconds at a fiber temperature of 1,900 C.
  • the impregnation step of the process may be conducted on either a batch basis or on a continuous basis.
  • the organic protective agent may be selected from the group consisting of organic phosphorus compounds, organic antimony compounds, organic tin compounds, halogenated alcohols, halogenated esters, halogenated organic acids, halogenated organic anhydrides, halogenated phenolic compounds, halogenated aliphatic hydrocarbons, halogenated aromatic hydrocarbons, halogenated aromatic ethers, silicon oils, and mixtures of the foregoing.
  • organic phosphorus compounds may be selected for use in the process.
  • organophosphorus compounds such as phosphates, phosphoramides, phosphites, phosphonates, etc. may be utilized.
  • organic phosphates which may be used are tris[2,3-dibromopropyl] phosphate available commercially under the designation Firemaster T23? from the Michigan Chemical Corporation, tris[beta-chloroethyl] phosphate, and tricresyl phosphate.
  • phosphoramides which may be used are cyanoethyl bis[dimethyl amino] phosphate and aziridinyl phosphine oxide.
  • Examples of particular phosphites which may be used are triphenylphosphite, and condensation products of triphenylphosphite with bisphenol A (para, para'-isopropylidenediphenol) and pentaerythritol.
  • Examples of particular phosphonates which may be used are monochloromethylphosphonate, and dimethyl[trichloro alpha-hydroxyethyl] phosphonate. Phosphite-phosphonates sold under the designation of Phosgard by the Monsanto Company may be selected.
  • Diphosphonium halides such as ethylene bis[tricyanoethyl] phosphonium bromide, tetrakis[hydroxymethyl] phosphonium chloride, and tetrakis[hydroxymethyl] phosphonium hydroxide are also representative of organophosphorus compounds which are suitable for use.
  • organic antimony compounds which may be used are triphenylantimony (triphenylstibine), diphenylantimony, trichloroantimony, tribromoantimony, and antimony salts of carboxylic acids, such as antimony tricaproate.
  • Suitable organic tin compounds include tin salts of carboxylic acids, e.g. tin octoate, tin oleate, and the various tin acrylates.
  • Suitable halogenated alcohols include bis[2,3- dibromopropyl] pentaerythritol, the polychlorobutanediols, and 2,3-dibromopropanol.
  • halogenated esters which may be used are Diels-Alder adducts (essentially equimolar) of alphabeta unsaturated carboxylic acids (e.g. acrylic, methacrylic, and crotonic acid) with hexachlorocyclopentadiene.
  • Diels-Alder adducts essentially equimolar
  • alphabeta unsaturated carboxylic acids e.g. acrylic, methacrylic, and crotonic acid
  • hexachlorocyclopentadiene e.g. acrylic, methacrylic, and crotonic acid
  • halogenated organic acids are chlorendic acid (hexachloroendomethylenetetrahydrophthalic acid) which may be conveniently fonned by the hydrolysis of chlorendic anhydride, and tetrabromophthalic acid.
  • halogenated organic anhydrides which may be used are chlorendic anhydride (i.e. the Diels-Alder adduct of maleic anhydride with hexachlorocyclopentadiene), and tetrabromophthalic anhydride available commercially under the designation Firemaster PHT4 from the Michigan Chemical Corporation.
  • Suitable halogenated phenolic compounds include pentachlorophenol, pentabromophenol, and halogenated compounds of bisphenol A (i.e. para, para-isopropylidenediphenol), such as tetrabromobisphenol A (i.e. 4,4'-ispropylidenebis[2,6-dibromophenol]) available commercially under the designation Firemaster BP4A" from the Michigan Chemical Corporation.
  • bisphenol A i.e. para, para-isopropylidenediphenol
  • tetrabromobisphenol A i.e. 4,4'-ispropylidenebis[2,6-dibromophenol]
  • halogenated aliphatic hydrocarbons are the chlorinated higher paraffins, e.g. chlorinated paraffins having at least six carbon atoms per molecule.
  • chlorinated hydrocarbons commonly contain about 10 to 30 or more carbon atoms per molecule and are mainly saturated straight chain hydrocarbons which range from viscous liquids to solids at room temperature.
  • chlorinated paraffms are well known in the art and may contain various degrees of chlorination which generally range up to about 70 per cent chlorine by weight, e.g. about 40 to about 70 per cent chlorine by weight.
  • Chlorinated paraffins are available commercially under the designation Unichlor" (e.g.
  • halogenated aliphatic hydrocarbons may process a cyclic structure and include perchloropentacyclodecane, hexabromocyclododecane and hexabromododecatriene.
  • Suitable halogenated aromatic hydrocarbons include pentabromobenzene, pentabromotoluene, and pentachlorotoluene.
  • Exemplary halogenated aromatic ethers are pentabromodiphenylether, pentachlorodiphenylether, and dibromophenylether.
  • silicone oils contemplated for use in the process of the present invention are water-insoluble, substantially nonvolatile, liquid polysiloxanes, and any of the commonly known compositions of this type may be employed.
  • Polysiloxanes wherein the organic radical is a low molecular weight aliphatic group such as methyl or ethyl, or wherein a high percentage of low molecular weight aliphatic groups are present are the types most widely available and have the lowest cost, and are for this reason preferred.
  • silicone oils which may be used are the polymethyl s iloxanes having a viscosity of over 50 centistokes at 25 C.
  • organic protective agents may be utilized to impregnate the preoxidized acrylic fibrous material.
  • One may also optionally employ an additive in conjunction with the protective agent which enhances the operation of the protective agent.
  • bibenzyl l,2-diphenylethane
  • the mechanism whereby the organic protective agent renders the preoxidized acrylic fibrous material capable of withstanding the highly elevated temperature of the reducing flame (described in detail hereafter) is considered complex and incapable of simple explanation.
  • the result obtained is considered surprising in view of the fact that the organic compounds utilized are themselves not generally recognized to be capable of enduring the temperature of the reducing flame. For instance, it is difficult to envision how the organic protective agents perform their function since these agents are observed substantially to volatilize at the high temperature of the reducing flame. While some of the organic protective agents have been utilized as flame retardants in the past they have been generally considered to have no flame retardant activity above about 500 C. Conversely, well known inorganic flame retardants, such as boric acid, which have in the past been suggested' as high temperature flame retardants do not provide the protection required for successful graphitization of a preoxidized acrylic fibrous material in the reducing flame.
  • the fibrous material may be simply contacted with the same.
  • the organic protective agent is a viscous liquid or solid.
  • the organic protective agent is a viscous liquid or solid.
  • it is dissolved in a suitable solvent or carrier in order to facilitate impregnation of the fibrous material.
  • the specific solvent selected is dictated by the solubility characteristics of the organic protective agent as will be apparent to those skilled in the art and is relatively volatile. For safety considerations it is recommended that solvents be employed which possess a relatively high self-ignition point, and which are accordingly not highly flammable.
  • the preoxidized acrylic fibrous material is impregnated by immersion in a liquid comprising the organic protective agent.
  • a liquid comprising the organic protective agent.
  • the fibrous material while present on a mandrel, bobbin, or other support may be placed in the liquid, or a continuous length of the material may be continuously passed through the liquid.
  • the liquid may be sprayed or padded upon the fibrous material; however, superior impregnation is generally achieved through immersion and is accordingly recommended.
  • the temperature of the liquid at the time of impregnation is not critical and may conveniently be room temperature.
  • a highly volatile non-viscous halogenated hydrocarbon solvent may be selected to dissolve many of the organic protective agents.
  • highly halogenated hydrocarbons such as carbon tetrachloride, perchloroethylene, tetrachloroethane, tetrabromoethane, dibromoethane, and trichloroethylene are preferred.
  • a particularly preferred solvent is trichloroethylene.
  • Organic protective agents such as tetrakis[ [hydroxymethyl] phosphonium chloride may be applied from water solutions. The concentration of the organic protective agent in a solvent required to achieve adequate loading of the fiber within a brief period of immersion (e.g. 5 seconds) is not highly critical.
  • concentrations of the organic protective agents in solvents generally may conveniently range from about 0.5 to 25 per cent by weight based upon the weight of the solvent (preferably about 1 to 10 per cent by weight based upon the weight of the solvent). Higher concentrations tend to yield no commensurate advantage.
  • the residence time during which the preoxidized acrylic fibrous material is immersed in a solution comprising the preoxidized acrylic fibrous material is somewhat dependent upon the form assumed by the material while immersed. If the fibrous material is present as a package, a longer residence time will be required for the material to be impregnated throughout. For instance, residence times in batch operations for the impregnation step may range as high as 5 minutes or more depending upon the thickness of the package. In a continuous operation in which a continuous length of the preoxidized acrylic fibrous material is continuously passed through the solution comprising the organic protective agent, the residence time conveniently may be from about 5 to 25 seconds, since adequate impregnation and coating of the fibrous material is not dependent upon extended soaking.
  • the preoxidized acrylic fibrous material be dried prior to its passage through the reducing flame.
  • the fibrous material is continuously passed through the impregnation zone and then directly to the reducing flame for graphitization.
  • a highly preferred reducing flame for use in the process is that resulting from an acetylene and oxygen mixture. With this reducing flame, the graphitizing step can be conducted in an open atmosphere.
  • a further advantage of the acetylene-oxygen reducing flame is that it has a fairly constant high temperature which is independent, within limits, of the fuel-oxidant ratio.
  • a carbon monoxide-oxygen flame also yields good results in an open atmosphere, although it is, of course, essential to provide adequate safety provisions for the operator under such conditions.
  • Hydrocarbon fuels such as propane and butane, may be selected but the process does not proceed as smoothly as with acetylene or with carbon monoxide. However, in the presence of an inert blanketing gas, e.g. nitrogen, or argon, comparable stability may be achieved with hydrocarbon fuels.
  • Molecular oxygen can be replaced in the fuel-oxidant mixture by a gaseous oxidant such as nitrous oxide although generally it is not advantageous to do so because of the convenience and ready availability of oxygen.
  • Fuel-oxidant combinations can also be employed to produce the reducing flame which do not contain a hydrocarbon fuel, such as a carbon monoxide-hydrogen mixture and a hydrogen-chlorine mixture.
  • Non-conventional flame sources such as augmented flames (cf. B. Karlovitz, International Science of Technology, June, 1962, pp. 36-41); recombination flames, such as the atomic hydrogen torch (cf. 1. Langmuir, Industrial and Engineering Chemistry, June, 1927, pp. 667-674); plasma torches; and the like; can also be employed to provide high temperatures. The temperature should not be so high, however, as to destroy the fibrous configuration.
  • the fuel to oxidant ratio generally is a significant parameter in the present process.
  • the graphitizing treatment is best carried out in a luminous flame obtained by keeping the amount of oxygen in the fuel mixture below the stoichiometric amount which is required to burn the fuel completely to carbon dioxide. Oxidation reactions within the flame are essentially limited to the combustible gas mixture, and the fibrous material traveling through the flame is exposed to an essentially reducing environment. The fibrous material can be destroyed by oxidation if the oxidant-fuel ratio is too high.
  • the luminosity of the flame is believed to be caused by ionized carbon fragments in the flame resulting from incomplete combustion of the fuel. More pyrolytic carbon will be deposited at higher oxygen to fuel ratios than at lower ratios.
  • a deposit of pyrolytic graphite is desirable since it increases the high temperature stability of the resulting graphitic product.
  • such a deposit is undesirable, e.g., where high adhesion to a matrix is desired.
  • a surface protective layer of pyrolytic graphite alternatively can be formed in a separate step in which the fibrous material is heated to a high temperature in a controlled environment containing hydrocarbon vapors.
  • temperatures in the flame zone refer to the temperature of the fibrous material as measured by an infra-red radiation thermometer and not to a theoretical reducing flame temperature under adiabatic conditions, i.e. without withdrawal of heat by immersing a body into the reducing flame.
  • the temperature of the fibrous material in the flame is generally significantly lower than the theoretical reducing flame temperature.
  • the theoretical flame temperature of an oxygen-acetylene reducing flame is about 3,lO C.
  • An upper limit of about 2,500 C. for the fiber temperature of a yarn undergoing treatment is generally sufficient and safe.
  • the impregnated fibrous material is passed through the reducing flame at a fast enough rate to avoid breaking.
  • the minimum rate at which breakage is avoided also increases. This minimum speed can be determined for any given combination of impregnated fibrous material and specific reducing flame.
  • the longer the residence time the greater the extent of graphitization. Thermal degradation with graphite formation occurs within the reducing flame to the substantial exclusion of oxidative degradation. Optimum conditions are reached at the point where the loss of the fiber mass is lowest and the conversion of the remainder of the fibrous material to graphitic carbon is the highest.
  • the two effects can be balanced favorably by adjusting the residence time and the fiber temperature.
  • residence times of about 2 to 24 seconds, and preferably about 6 to 17 seconds are generally suitable.
  • An exemplary set of optimum conditions is a yarn temperature of 2,300 C. with a residence time of about seconds.
  • the necessary apparatus for graphitization according to the present process is simple and should be so arranged that the fibrous material is exposed to a minimum of frictional contacts.
  • a convenient arrangement is to continuously feed an impregnated yarn from a rotating-reciprocating bobbin through the reducing flame to an identically functioning takeup mechanism. Starting at the correct reciprocating position on the bobbin, the yarn is unwound without traverse movement and analogously rewound at the take-up side. Hence, random yarn motions are minimized. Further positioning of the yarn in the reducing flame can be accomplished with minimal action by two cylindrically shaped guides located before and after the reducing flame source. Feed and take-up bobbins can be driven by, for example, solid-state controlled DC motors with r.p.m.
  • the yarn may be put under constant tension as, for example, by passing it over a rubber-capped electro-magnetic clutch and a skewed roll.
  • the geometry of the burner is also a factor in maximizing the effectiveness of the graphitization of the present invention.
  • Two impinging flames originating from two standard conical tips significantly raise the temperature of the fibrous material passing therethrough.
  • a particularly preferred embodiment of this technique is the impingement of the two reducing flames on the tips of their inner cones at an angle of 45.
  • the addition of more than two orifices does not have a beneficial effect.
  • a series of burners such as to form a continuous reducing flame zone of increased lateral dimension may permit increased processing speeds or the processing of larger fibrous assemblages. Since residence time in the reducing flame is a major parameter, processing speed is significantly related to the length of the flame zone.
  • Surrounding the conical tip with a cylindrical or globular reflector, constructed from polished stainless steel sheets, for example also significantly raises the yarn temperature.
  • the volume flow of the fuel and oxidant through the burner should be as high as possible, consistant with good reducing flame stability, in order to maximize the moduli of the fibers.
  • Tension during reducing flame treatment is recommended for the achievement of optimum properties as it prevents the tendency of the fibrous material to shrink.
  • Shrinkage usually leads to relaxation of ordered structures and, thereby, causes a lowering of physical properties.
  • Preservation of orientation and/or an increase in orientation, depending upon the magnitude of tension applied increases both the Youngs modulus and the tensile strength.
  • the tension applied should be at least sufficient to avoid visible sagging. Beyond the optimum tension the fibrous material may be damaged by still higher tensions.
  • Graphite fibers produced according to the present process may possess relatively uniform properties. Although i do not wish to be limited by the theory of this improvement, it appears to be due to two factors: (1) the flame healing of flaws by ionized carbon fragments in a luminous reducing flame, and (2) the reduced mechanical wear of the fibrous material in the reducing flame.
  • EXAMPLE 1 The data in Table I illustrate the results obtainable to an embodiment of the invention wherein a tris[2,3-dibromopropyl] phosphate organic protective agent is applied on a batch basis and an acetylene-oxygen reducing flame source is utilized to form a graphite yarn from a preoxidized acrylonitrile homopolymer yarn.
  • a 760 continuous filament acrylonitrile homopolymer yarn was preoxidized in air at about 270 C. in a Lindberg muffle fumace on a continuous basis in accordance with the teachings of US. Ser. No. 749,957, filed on Aug. 5, 1968 in my name, which is assigned to the same assignee as the instant invention, and is herein incorporated by reference.
  • the acrylonitrile homopolymer yarn had a twist of about 0.5 tpi.
  • the preoxidized yarn exhibited a bound oxygen content of about 8 per cent by weight as determined by the Unterzaucher analysis and a carbon content of about 62 per cent by weight.
  • the preoxidized yarn was non-buming when subjected to an ordinary match flame, but was incapable of withstanding a reducing flame when heated for two seconds at a fiber temperature of l,900 C.
  • the preoxidized yarn exhibited an amorphous X-ray diffraction pattern, and had a denier of 1.93, a single filament tenacity of 1.89 grams/denier, a single filament Youngs modulus of about grams/denier, and an elongation of 7.3 per cent.
  • a 10 per cent by weight solution of tris[2,3-dibromopropyl phosphate in trichloroethylene based upon the weight of the solvent was prepared and present at room temperature (i.e. about 23 C.).
  • the preoxidized acrylonitrile homopolymer yarn while wound on a bobbin was immersed in the solution for about 1 Va minutes in order to thoroughly impregnate the same with he organic protective agent.
  • the yarn was next continuously graphitized without drying the same.
  • the yarn was passed in the open atmosphere through an acetylene-oxygen reducing flame in which the volume ratio of the gases was 1:1.
  • the total flow rate was 1,500 mL/min. and a National Blow Torch", Tip A-3 was employed.
  • the acetylene-oxygen reducing flame imparted a fiber temperature of about 2,200 C. to the yarn.
  • the tension applied to the yarn was varied as indicated and no visible sagging of the yarn was apparent in any of the runs.
  • Table I summarizes the properties (single filament breaks) of the resulting graphite yarn as a function of the residence time of the yarn in the reducing flame.
  • Example l The preoxidized acrylic fibrous material identified in Example l was continuously passed through the solutions containing the organic protective agent for a residence time of about 8 seconds, and subsequently flame graphitized according to the procedure of Example 1 without first drying the same. In each instance the tension applied to the yarn while present in the reducing flame was sufficient to prevent visible sagging.
  • Table II summarizes the properties (single filament breaks) of the resulting graphite yarn as a function of the concentration of the protective agent in the trichloroethylene solvent in weight per cent based upon the weight of the solvent.
  • Example 4 Example 2 was repeated with the exception that the organic protective agent was solely the silicone oil described in Example 3 which was applied from a 10 per cent by weight solution in trichloroethylene based on the weight of the solvent.
  • Example 2 was repeated with the exception that the organic protective agent comprised a combination l per cent by weight of the silicone oil described in Example 3, and l per cent by weight of bibenzyl in trichloroethylene based upon the weight of the solvent.
  • the organic protective agent comprised a combination l per cent by weight of the silicone oil described in Example 3, and l per cent by weight of bibenzyl in trichloroethylene based upon the weight of the solvent.
  • the silicone oil was a polymethyl siloxane having a viscosity in excess of 50 centistokes at 25 C. and available commercially from Elbe) [30w Corning Corporation under the designation DC Summarized below are the graphitization conditions and the properties (single filament breaks) of the resulting graphite yarn.
  • EXAMPLE 7 and passage openings for the fiber.
  • a surface-mix propane-oxygen burner is mounted within the vessel.
  • Example 2 is repeated with the exception that the organic protective agent is present as a 7.5 per cent by weight solution based upon the weight of the solvent of triphenylantimony in trichloroethylene.
  • Example 9 Example 2 is repeated with the exception that the organic protective agent is present as a per cent by weight solution based upon the weight of the solvent of antimony tricaproate in trichloroethylene.
  • Example 2 is repeated with the exception that the organic protective agent is present as a 7.5 per cent by weight solution based upon the weight of the solvent of tin octoate in trichloroethylene.
  • Example 2 is repeated with the exception that the organic protective agent is present as a 10 per cent by weight solution based upon the weight of the solvent of bis[2,3- dibromopropyl] pentaerythritol in trichloroethylene.
  • Example 2 is repeated with the exception that the organic protective agent is present as a 10 per cent by weight solution based upon the weight of the solvent of an equimolar Diels- Alder adduct of methacrylic acid with hexachlorocyclopentadiene in which trichloroethylene serves as solvent.
  • Example 2 is repeated with the exception that the organic protective agent is present as a 5 per cent by weight solution based upon the weight of the solvent of chlorendic acid (hexachloroendomethylenetetrahydrophthalic acid) in trichloroethylene.
  • chlorendic acid hexachloroendomethylenetetrahydrophthalic acid
  • Example 14 Example 2 is repeated with the exception that the organic protective agent is a 7.5 per cent by weight solution based upon the weight of the solvent of tetrabromophthalic anhydride in trichloroethylene.
  • Example 15 Example 2 is repeated with the exception that the organic protective agent is a 10 per cent by weight solution based upon the weight of the solvent of pentachlorophenol in trichloroethylene.
  • EXAMPLE 16 EXAMPLE 17 Example 2 is repeated with the exception that the organic protective agent is a 5 per cent by weight solution based upon the weight of the solvent of hexabromocyclododecane in trichloroethylene.
  • Example 2 is repeated with the exception that the organic protective agent is a 5 per cent by weight solution based upon the weight of the solvent of pentabromotoluene in trichloroethylene.
  • preoxidized acrylic fibrous material is derived from an acrylonitrile homopolymer.
  • said preoxidized acrylic fibrous material is derived from an acrylonitrile copolymer which contains 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.
  • organic protective agent is selected from the group consisting of organic phosphorus compounds, organic antimony compounds, organic tin compounds, halogenated alcohols, halogenated esters, halogenated organic acids, halogenated organic anhydrides, halogenated phenolic compounds, halogenated aliphatic hydrocarbons, halogenated aromatic hydrocarbons, halogenated aromatic ethers, silicone oils, and mixtures of the foregoing.
  • a process according to claim 7 wherein the residence time of said impregnated fibrous material in said reducing flame is from about 2 to 24 seconds.
  • a process according to claim 9 wherein the residence time of said impregnated fibrous material in said reducing flame is from about 6 to 17 seconds.
  • a process according to claim 8 wherein the ratio of oxygen to fuel is such that the amount of oxygen is less than the stoichiometric amount required to completely oxidize said fuel.
  • an organic protective agent capable of rendering said material resistant to loss of structural integrity when heated for at least two seconds at a fiber temperature of l,900 C. selected from the group consisting of organic phosphorus compounds, organic antimony compounds, organic tin compounds, halogenated alcohols, halogenated esters, halogenated organic acids, halogenated organic anhydrides, halogenated phenolic compounds, halogenated aliphatic hydrocarbons, halogenated aromatic hydrocarbons, halogenated aromatic ethers, silicone oils, and mixtures of the foregoing, wherein said preoxidized acrylic fibrous material is impregnated with said organic protective agent, and
  • preoxidized acrylic fibrous material is derived from an acrylonitrile homopolymer.
  • preoxidized acrylic fibrous material is derived from an acrylonitrile copolymer which contains at least about mol per cent of acrylonitrile units and up to about l5 mol per cent of one or more monovinyl units copolymerized therewith.

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  • Textile Engineering (AREA)
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US815200A 1969-04-10 1969-04-10 Direct production of graphite fibrous materials from preoxidized acrylic fibrous materials Expired - Lifetime US3656903A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3975482A (en) * 1972-06-21 1976-08-17 Celanese Corporation Process for drawing acrylic fibrous materials to form a product which particularly is suited for thermal stabilization and carbonization
US4002426A (en) * 1971-01-25 1977-01-11 Celanese Corporation Production of stabilized non-burning acrylic fibers and films
FR2504560A1 (fr) * 1981-04-23 1982-10-29 Toho Beslon Co Procede de fabrication d'une fibre de carbone activee
US4452601A (en) * 1982-03-19 1984-06-05 Celanese Corporation Process for the thermal stabilization of acrylic fibers and films

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3281261A (en) * 1963-08-30 1966-10-25 Deering Milliken Res Corp Method of preparing refractory metal oxide coated carbonized acrylic textile fibers
US3285696A (en) * 1960-08-25 1966-11-15 Tokai Denkyoku Seizo Kabushiki Method for the preparation of flexible carbon fibre
US3294489A (en) * 1961-12-19 1966-12-27 Hitco Process for preparing carbon fibers
US3395970A (en) * 1963-10-30 1968-08-06 Deering Milliken Res Corp Method of carbonizing polyacrylonitrile impregnated cellulose, cyanoethylated cellulose and acrylonitrile graft copolymerized cellulose textiles
US3412062A (en) * 1964-04-24 1968-11-19 Nat Res Dev Production of carbon fibres and compositions containing said fibres
US3427120A (en) * 1962-12-21 1969-02-11 Agency Ind Science Techn Producing method of carbon or carbonaceous material
US3449077A (en) * 1967-02-13 1969-06-10 Celanese Corp Direct production of graphite fibers

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3285696A (en) * 1960-08-25 1966-11-15 Tokai Denkyoku Seizo Kabushiki Method for the preparation of flexible carbon fibre
US3294489A (en) * 1961-12-19 1966-12-27 Hitco Process for preparing carbon fibers
US3427120A (en) * 1962-12-21 1969-02-11 Agency Ind Science Techn Producing method of carbon or carbonaceous material
US3281261A (en) * 1963-08-30 1966-10-25 Deering Milliken Res Corp Method of preparing refractory metal oxide coated carbonized acrylic textile fibers
US3395970A (en) * 1963-10-30 1968-08-06 Deering Milliken Res Corp Method of carbonizing polyacrylonitrile impregnated cellulose, cyanoethylated cellulose and acrylonitrile graft copolymerized cellulose textiles
US3412062A (en) * 1964-04-24 1968-11-19 Nat Res Dev Production of carbon fibres and compositions containing said fibres
US3449077A (en) * 1967-02-13 1969-06-10 Celanese Corp Direct production of graphite fibers

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Vosburgh Textile Research Journal Vol. 30, 1960, pages 882 896 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4002426A (en) * 1971-01-25 1977-01-11 Celanese Corporation Production of stabilized non-burning acrylic fibers and films
US3975482A (en) * 1972-06-21 1976-08-17 Celanese Corporation Process for drawing acrylic fibrous materials to form a product which particularly is suited for thermal stabilization and carbonization
FR2504560A1 (fr) * 1981-04-23 1982-10-29 Toho Beslon Co Procede de fabrication d'une fibre de carbone activee
US4452601A (en) * 1982-03-19 1984-06-05 Celanese Corporation Process for the thermal stabilization of acrylic fibers and films

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