US3615212A - Method of manufacturing carbon fibers - Google Patents

Method of manufacturing carbon fibers Download PDF

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Publication number
US3615212A
US3615212A US804639A US3615212DA US3615212A US 3615212 A US3615212 A US 3615212A US 804639 A US804639 A US 804639A US 3615212D A US3615212D A US 3615212DA US 3615212 A US3615212 A US 3615212A
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Prior art keywords
bed
fiber
heated
conducted
particles
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Expired - Lifetime
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US804639A
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English (en)
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Ian Whitney
John William Johnson
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Rolls Royce PLC
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Rolls Royce PLC
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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
    • D01F9/32—Apparatus therefor
    • 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

Definitions

  • This invention relates to a method of manufacturing carbon fibers.
  • fluidizing medium is to be understood to mean the gas or other medium used to fluidize the particles, spheres or other solid objects which comprise the bed.
  • a method of manufacturing carbon fibers by the pyrolysis of a polymeric fiber comprising at least one step in which the fibers is heat-treated in a fluidized bed.
  • the fluidizing medium of said bed preferably reacts with the fiber.
  • Heaters may be provided in the bed to achieve and maintain the desired temperature in the bed; these heaters preferably comprise electrical-resistance heaters.
  • the starting material preferably comprises a polyacrylonitrile fiber, although other fibers such as a polyamide may be used.
  • Said step may comprise a preoxidation step in which the polymeric fiber is preoxidized prior to pyrolysis.
  • the preoxidation may be carried out at a temperature in the region of 200-400 C., but preferably between 200 and 350 C.
  • said step comprises an etching treatment after pyrolysis of said fiber.
  • Said etching step may be carried out with the bed at a temperature of between 400 and 500 C.
  • F 1G. 1 is a diagrammatic view of apparatus for carrying out the method of the present invention.
  • FIG. 2 is a diagrammatic view of apparatus for carrying out a second embodiment of the method of the invention.
  • the starting fiber which in this case is 1% denier polyacrylonitrile fiber, is wound from a supply drum in the form of a sheet of fiber onto a drive unit 11 which comprises a plurality of rollers 12 some of which are driven and which are in frictional engagement with the fiber.
  • the drive unit 11 pulls the fiber from the supply drum l0 and transports it through an inlet duct 30 into a fluidized bed 13 for preoxidation treatment.
  • the fluidized bed 13 comprises an insulated container 14 having a perforated bottom 15, the lower surface of which is supplied with compressed air from the duct 16.
  • the space above the perforated bottom 15 is filled with ballotini which may be glass or hollow alumina, the latter being less demanding of fluidizing medium, up to a level shown at 17.
  • ballotini which may be glass or hollow alumina, the latter being less demanding of fluidizing medium, up to a level shown at 17.
  • the compressed air flowing through the duct 16 and through the perforated bottom 15 causes the ballotini to be fluidized in a well-known fashion.
  • the heaters 18 are used to heat the ballotini to a required temperature which in the present instance is 220 C. although it would be possible to use a temperature in the range 200 to 400 C., the lesser range 200-350 being preferred.
  • the fiber emerging from the drive unit 11 passes over the rollers 19 in a tortuous path whereby the total path length in the fluidized bed is made to be relatively large.
  • the speed of the drive unit and the path length in the fluidized bed may be arranged to give the fibers a treatment time of approximately 7 hours in the bed.
  • the fiber While the fiber is immersed in the fluidized bed it will be appreciated that it will be caused to remain at the temperature of the bed, that is, 220 C., and the compressed air used to fluidize the bed will provide an oxidizing atmosphere around the fiber. In this way the fiber will be subjected to a preoxidizing treatment equivalent to that which could be carried out in a normal air furnace but because of the high capacity of the bed and the rapid transfer rate taking place in it there will be very little danger of the temperature of the fibers departing from the required temperature.
  • a single bed may be used with a reduced treatment time; if a lengthy treatment (e.g. 7 hours) is used it may be necessary to use a plurality of beds in series to avoid fluidization problems in the lee of the fiber sheet. If such a plurality of beds is used they may be arranged to give a temperature gradient overall, which may improve oxidation performance.
  • the inlet duct 30 will provide a temperature gradient from ambient temperature at its top end to the bed temperature at its lower end; thus the fiber is gradually heated to the bed temperature rather than being plunged into the high-temperature bed. This temperature gradient will dry the incoming fiber, preventing a lowering of the melting point, and will prevent the formation of gaseous pockets formed by the too rapid volatilization of included solids.
  • the second drive unit 20 which comprises a plurality of rollers 21 similar to those of the drive unit 11.
  • the second unit may be arranged to provide, in conjunction with the first unit 11, some stretch of the fiber within the bed.
  • a stretch of l4 percent has been found to efl'ectively replace the tension normally generated within the fibers when an air preoxidation is used.
  • the drive unit 20 passes preoxidized fiber into a pyrolysis furnace 22 which is not described in detail but is such as to enable the fiber to be heated to a temperature of l,000 C. over a time period of some one-half to 3 hours and then to cool naturally to room temperature.
  • the fiber On leaving the furnace 22 the fiber has had the majority of its constituents, other than carbon, driven off and is fairly pure carbon fiber having reasonably good structural properties for use as a reinforcement in a matrix.
  • the carbon fiber On leaving the furnace 22 the carbon fiber is wound onto a takeup spool 23 via a roller 24 and may then be used as a reinforcement.
  • a fluidized bed was used in which the fibers were treated by winding a layer on a frame and immersing under the surface of the ballotini.
  • one instance 12 fibers were chosen from a batch treated using the conditions outlined above and were found to have a mean breaking stress of 282Xl0 p.s.i., and a mean modulus of 27.6Xl0 p.s.i.
  • the fibers were wound in two layers on the frame in an attempt to provoke a run-away of the reaction.
  • the preoxidation temperature was raised to 250 C.
  • FIG. 2 apparatus is shown which is suitable for the postoxidation of fiber.
  • fiber which is 1% denier carbon fiber produced by the pyrolysis of polyacrylonitrile fiber
  • a drive unit 41 which comprises a plurality of rollers 42 some of which are driven and which are in frictional engagement with the fiber.
  • the drive unit 41 pulls the fiber from the supply drum 40 and transports it into a fluidized bed 43.
  • the fluidized bed 43 comprises a container 44 having a perforated bottom 45, the lower face of which is supplied with compressed air from the duct 46.
  • the space above the per forated bottom 45 is filled with hollow alumina ballotini up to a level shown at 47. lmmersed in the ballotini are electrical-resistance heaters 48 and a plurality of rollers 49.
  • rollers 49 are preferably mounted for rotation on air bearings (not shown), which are supplied with compressed air from the duct 46 to maintain their operation. Alternatively they may be arranged to be situated in the cold zone of the bed below the heaters.
  • the compressed air flowing through the duct 46 and through the perforated bottom 45 causes the ballotini to be fluidized in a well-known fashion.
  • the heaters 46 are used to heat the ballotini and air to a required temperature which in the present instance is 450 C. although it would be possible to use a temperature in the range 400' to 500 C., the lesser range 400-450 being preferred.
  • the fiber'emerging from the drive unit 41 passes over the rollers 49 in a tortuous path whereby the total path length in the fluidized bed is made to be relatively large.
  • the speed of the drive unit and the path length in the fluidized bed may be arranged to give the fibers a treatment time of approximately -15 minutes in the bed.
  • the fiber is immersed in the fluidized bed, it will be appreciated that it will be caused to remain at the temperature of the bed, that is 450 C., and the compressed air used to fluidize the bed will provide an oxidizing atmosphere around the fiber. in this way the carbon fiber will be subjected to a surface etching treatment equivalent to that which could be carried out in a normal air furnace but, because of the high heat capacity of the bed, and the rapid transfer rate taking place in it, there will be very little danger of the temperature of the fibers department from the required temperature.
  • the fluidized bed will virtually preclude any such happening.
  • the temperature control possible when carrying out these processes in a fluidized bed leads to the possibility of raising the treatment temperature to a limit which would be dangerous if carried out in a normal air furnace. In this way the treatment time may well be considerably reduced.
  • a single bed may be used with a reduced treatment time; if a lengthy treatment is used it may be necessary to use a plurality of beds in series to avoid fluidization problems in the lee of the fiber sheet. If such a plurality of beds is used they may be arranged to give a temperature gradient overall, which may improve etching performance.
  • a second drive unit 50 which comprises a plurality of rollers 51 similar to those of the drive unit 41.
  • the drive unit 50 passes the carbon fiber onto a takeup spool 53 via a roller 54 and may then be used as a reinforcement.
  • carbon fibers described were made from polyacrylonitrile as a starting fiber, it would be possible to use other suitable copolymers of polyacrylonitrile or a difierent polymer, such for instance as a cellulose, polyamide etc.
  • the ballotini referred to above could be replaced-by balls or spheres of other materials; thus if the fluidized bed is to be used at very high temperatures, silica sand particles may be used.
  • the etching treatment described above has a dual purpose. As described in our prior British application No. 58492/66 it etches away surface flaws which otherwise might reduce the strength of the carbon fibers. Also it has been discovered that the etching process reacts on the fiber surface in such a way as to enable considerably better adhesion between thefibers and other material which forms the matrix, thereby considerably improving the interlarninar shear strength of the composite material.
  • the method described above is highly advantageous in that it enables precise control of the treatment temperature, enabling what is a mildly exothermic reaction to be accurately controlled without any risk of explosion and also enabling treatment temperatures to be increased while remaining reasonably safe.
  • the present invention uses the fluidizing medium of the bed as one of the reagents in the chemical reaction involved, thereby enabling it to serve a dual purpose and avoiding the necessity for separate supplies of reagent and fluidizing medium.
  • a surface treatment bed in which the fibers are arranged to lie along the surface of a long shallow bed. This method allows the use of a bed of simple design with low air pressure, and might prove advantageous for long treatment times.
  • step (a) is conducted at a temperature of about 200 to 400 C.
  • step (a) is conducted from one-half to 3 hours.
  • step (a) is conducted in said bed of heated particles and said fibers enter the bed by way of a duct which is supplied with hot gas from the bed, so that a temperature gradient is established in said duct.
  • step (a) is conducted in said bed of heated particles and said fluidizing medium is air.
  • a bed of heated particles and the fluidizing medium comprises chlorine.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Textile Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Inorganic Fibers (AREA)
US804639A 1968-03-06 1969-03-05 Method of manufacturing carbon fibers Expired - Lifetime US3615212A (en)

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Application Number Priority Date Filing Date Title
GB1081968 1968-03-06

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BE (1) BE729382A (enrdf_load_stackoverflow)
GB (1) GB1232461A (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4256607A (en) * 1976-10-05 1981-03-17 Toho Beslon Co., Ltd. Process for production of activated carbon fibers
US4285831A (en) * 1976-10-05 1981-08-25 Toho Beslon Co., Ltd. Process for production of activated carbon fibers
WO1997020768A1 (en) * 1995-12-07 1997-06-12 Sandia Corporation Methods of preparation of carbon materials for use as electrodes in rechargeable batteries
US20070148455A1 (en) * 2005-11-16 2007-06-28 Ladama, Llc Fire retardant compositions and methods and apparatuses for making the same
WO2007059510A3 (en) * 2005-11-16 2008-02-14 Ladama Llc Fire retardant compositions and methods and apparatuses for making the same
US20080113175A1 (en) * 2005-11-16 2008-05-15 Ladama, Llc Fire retardant compositions and methods and apparatuses for making the same
US20130197116A1 (en) * 2012-01-31 2013-08-01 Jack Elijah Williams, III Ultra High Strength Chalk Based Composition
TWI414653B (zh) * 2005-11-16 2013-11-11 Ladama Llc 製造阻燃耐熱紗線之方法及裝置
US8850784B2 (en) 2005-11-16 2014-10-07 Lorica International Corporation Fire retardant compositions and methods and apparatuses for making the same

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3011981A (en) * 1958-04-21 1961-12-05 Soltes William Timot Electrically conducting fibrous carbon
US3285696A (en) * 1960-08-25 1966-11-15 Tokai Denkyoku Seizo Kabushiki Method for the preparation of flexible carbon fibre
US3412062A (en) * 1964-04-24 1968-11-19 Nat Res Dev Production of carbon fibres and compositions containing said fibres
US3476703A (en) * 1967-02-21 1969-11-04 Nat Res Dev Treatment of carbon fibres and composite materials including such fibres
US3508871A (en) * 1963-05-29 1970-04-28 Carborundum Co Carbonizing fibrous materials

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3011981A (en) * 1958-04-21 1961-12-05 Soltes William Timot Electrically conducting fibrous carbon
US3285696A (en) * 1960-08-25 1966-11-15 Tokai Denkyoku Seizo Kabushiki Method for the preparation of flexible carbon fibre
US3508871A (en) * 1963-05-29 1970-04-28 Carborundum Co Carbonizing fibrous materials
US3412062A (en) * 1964-04-24 1968-11-19 Nat Res Dev Production of carbon fibres and compositions containing said fibres
US3476703A (en) * 1967-02-21 1969-11-04 Nat Res Dev Treatment of carbon fibres and composite materials including such fibres

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4256607A (en) * 1976-10-05 1981-03-17 Toho Beslon Co., Ltd. Process for production of activated carbon fibers
US4285831A (en) * 1976-10-05 1981-08-25 Toho Beslon Co., Ltd. Process for production of activated carbon fibers
WO1997020768A1 (en) * 1995-12-07 1997-06-12 Sandia Corporation Methods of preparation of carbon materials for use as electrodes in rechargeable batteries
US20070148455A1 (en) * 2005-11-16 2007-06-28 Ladama, Llc Fire retardant compositions and methods and apparatuses for making the same
WO2007059510A3 (en) * 2005-11-16 2008-02-14 Ladama Llc Fire retardant compositions and methods and apparatuses for making the same
US20080113175A1 (en) * 2005-11-16 2008-05-15 Ladama, Llc Fire retardant compositions and methods and apparatuses for making the same
US7937924B2 (en) 2005-11-16 2011-05-10 Lorica International, Inc. Fire retardant compositions and methods and apparatuses for making the same
US8117815B2 (en) 2005-11-16 2012-02-21 Ladama, Llc Fire retardant compositions and methods and apparatuses for making the same
TWI414653B (zh) * 2005-11-16 2013-11-11 Ladama Llc 製造阻燃耐熱紗線之方法及裝置
US8850784B2 (en) 2005-11-16 2014-10-07 Lorica International Corporation Fire retardant compositions and methods and apparatuses for making the same
US20130197116A1 (en) * 2012-01-31 2013-08-01 Jack Elijah Williams, III Ultra High Strength Chalk Based Composition

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BE729382A (enrdf_load_stackoverflow) 1969-08-18
GB1232461A (enrdf_load_stackoverflow) 1971-05-19

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