Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
  • G01N33/72—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving blood pigments, e.g. haemoglobin, bilirubin or other porphyrins; involving occult blood
• • 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
  • D01F9/16—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from products of vegetable origin or derivatives thereof, e.g. from cellulose acetate

Definitions

• the carbon fibers produced in this [56] Rdennm Cited manner are capable of withstanding the application of high UNITED STATES PATENTS stress during subsequent graphitization without breaking and can be stretched to a high degree. 3,305,315 2/1967 Bacon et al. ..23/209.1 3,412,062 1 1/1968 Johnson et al. ..260/37 12 Claims, No Drawings PROCESS FOR PRODUCING CARBON FIBERS BACKGROUND OF THE INVENTION 1.
• the present invention relates to an improved process for producing carbon fibers from cellulosic materials and to the fibers so produced.
• carbon is intended to include both the non-graphitic and graphitic forms of carbon.
• Carbon is an element which possesses many interesting arid useful chemical and physical properties. It is a material which both can be found in nature and produced synthetically.-Carbon is readily processible material and can be fashioned into almost any intricate shape or pattern. Today, the uses of carbon in commerce and industry are myriad.
• a textile form of fibrous graphite is disclosed and claimed in U.S. Pat. No. 3,l07,l52, which issued to C. E. Ford and C. V. Mitchell on Oct. l5, 1963.
• the process for producing fibrous graphite disclosed therein comprises heating a cellulosic starting material in an inert atmosphere at progressively higher temperatures for various times until a temperature of about 900 C. is achieved followed by further heating in a suitable protective atmosphere at higher temperatures until substantial graphitization occurs.
• the product produced by this process exhibits the chemical and physical properties generally associated with conventionally fabricated graphite while, at the same time, it retains the textile characteristics of the starting material.
• this material is produced by a process which comprises stretching a substantially all carbon fiber while it is being heated to graphitizing temperatures.
• this improved form of graphite fiber possesses properties which are unobtained in graphite fibers produced via the methods disclosed by both Soltes and Ford et al., the method of producing it suffers from at least one serious processing difficulty. Namely, the high force necessary to achieve both maximum strength and a high Young's modulus is a limiting factor during the stress graphitization of the already carbonized fiber. That is, in order to obtain optimum strength and modulus values, the amount of stress required is dangerously close to the breaking stress of the carbon fiber. Needless to say, such close limits are not conducive to a successful commercial operation.
• non-graphitic carbon fibers which are especially amenable to conventional stress graphitizing treatments. Briefly, that process comprises concurrently longitudinally stressing a partially carbonized cellulosic base fiber while subjecting it to a carbonizing temperature in the range of from about 250 to 900 C. so that a given length of the resultant, stretched fiber is at least 5 percent longer than it would have been had it been carbonized in a stress free manner.
• the so-produced non-graphitic carbon fibers exhibit a higher Young's modulus of elasticity than previously obtainable in non-graphitic carbon fibers produced by conventional techniques.
• the carbon fibers produced in this manner are capable of withstanding the application of significantly higher stress during subsequent graphitization without breaking than fibers produced in accordance with application, Ser. No. 6l0,789. As a result these fibers can be stretched to a greater degree than the fibers produced in accordance with application, Ser. No. 6l0,789. As is well known, the more that carbonized yarn is stretched during graphitization the higher are the tensile strength and Youngs modulus of the filaments of the resulting yarn.
• Fibers suitable for the practice of the invention are those which upon carbonization do not melt of fuse but which when so heat treated tend to lose their inherent orientation.
• fibers suitable for the practice of the invention are fibers of either natural or regenerated cellulosic origin which have been subjected to a pre-heat treatment to convert them to partially carbonized carbonaceous fibers. This is accomplished by first heating the raw cellulosic base fibers in either an inert or oxidizing atmosphere to a temperature in the range of from about to about 350 C. for fibers which have been treated with a carbonizing aid, such as phosphoric acid, or from about to about 350 C. for fibers which are untreated. Both of these techniques are described in detail in U.S. Pat. No. 3,305,315 which has been assigned to the same assignee as the instant application.
• EXAMPLE I An apparatus was constructed for stretching carbonaceous fibers, preferably in yarn form, at elevated temperatures.
• This apparatus consisted of two sets of canted stainless steel rolls, one for yarn payoff and the other for yarn takeup, mounted at opposite ends of a hollow electric resistance heated tube furnace about 18 inches in length.
• the drive motors for the rolls were connected to a control unit, and the rolls could be run at any desired ratio of takeup-to-payoff speeds, thereby controlling the actual shrinkage permitted to the yarn or the actual stretch applied to the yarn during its passage through the furnace.
• a yarn tension monitoring device with recorder was mounted between the yarn payoff rolls and the furnace.
• a nitrogen atmosphere was maintained within the electric furnace during operation to protect the yarn against damage by oxidation.
• the furnace temperature was read with an optical pyrometer.
• the furnace was heated to a temperature-of 1,350" C. and a partially pre-carbonized yarn (prepared by heating a 2 ply, 720 filaments per ply, 1,650 denier rayon yarn to a temperature of about 250 C.) was passed through the furnace while the yarn takeup and payoff rolls were operated so as to put the yarn under an applied tension or stress.
• the stress carbonized yarn prepared in this manner was then cooled to room temperature and subsequently stress-graphitized under the maximum tension that the yarn could withstand without frequent breakage (predetermined by applying varying tension to the yarn).
• a furnace similar to that employed for stress carbonizing the yarn was employed for the stress graphitization. The furnace was heated to 2,900 C. for this purpose.
• the partially carbonized cellulosic starting material inherently shrinks while it is being completely carbonized.
• the change in the length of any given length of partially carbonized yarn due to its passage through the carbonization furnace is easily computed from the difference in speeds of the takeup and the payoff rolls.
• the percent of effective stretch can then be determined by taking the difference in length between a unit length of stress-carbonized material and a similar unit length of material carbonized in a stress-free manner and dividing that value by the length of the stress-free carbonized material followed by multiplying the obtained value by 100.
• a process for producing non-graphitic carbon fiber which comprises carbonizing a partially carbonized carbonaceous fiber produced by the heat treatment of a fiber of cellulosic origin at a temperature in the range of from about 100 to about 350 C. by subjecting it to an initial carbonizing temperature within the range of from l,900 to 2,l00 C. while under an applied tensional force sufficient to cause a percent efi'ective stretch of at least 5 percent of the fiber.
• non-graphitic carbon fiber is stress graphitized by heating said fiber to a temperature of about 2,900 C. while applying a stressing force thereto sufficient to permanently stretch said fiber.

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• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Hematology (AREA)
• Chemical & Material Sciences (AREA)
• Molecular Biology (AREA)
• Biomedical Technology (AREA)
• Immunology (AREA)
• Urology & Nephrology (AREA)
• Food Science & Technology (AREA)
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• Cell Biology (AREA)
• Biotechnology (AREA)
• Medicinal Chemistry (AREA)
• Physics & Mathematics (AREA)
• Analytical Chemistry (AREA)
• Microbiology (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Pathology (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Textile Engineering (AREA)
• Inorganic Fibers (AREA)

Priority Applications (7)

Applications Claiming Priority (1)

Publications (1)

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Cited By (8)

Citations (5)

• 1969
  • 1969-07-30 US US846228A patent/US3652221A/en not_active Expired - Lifetime
• 1970
  • 1970-04-08 CA CA079518A patent/CA919890A/en not_active Expired
  • 1970-04-22 DE DE2019382A patent/DE2019382C3/de not_active Expired
  • 1970-04-30 CH CH653570A patent/CH525158A/fr not_active IP Right Cessation
  • 1970-04-30 BE BE749860D patent/BE749860A/xx unknown
  • 1970-04-30 FR FR7015964A patent/FR2056175A5/fr not_active Expired
  • 1970-04-30 GB GB2081870A patent/GB1316844A/en not_active Expired

Patent Citations (5)

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