Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
  • D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
  • D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
  • D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
  • D01F9/145—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from pitch or distillation residues

Definitions

• the present invention relates to a method for producing pitch-based carbon fiber.
• Carbon fibers made from pitch-based materials can produce products with lower manufacturing costs and higher elastic modulus than carbon fibers made from organic synthetic fibers such as polyacrylonitrile as a precursor. It is expected that it can be a cheaper and higher-performance material because it is easier.
• pitch-based carbon fibers have a tensile strength of about 20 O kg Z mm 2 or less, have poor quality stability, and cannot be said to be sufficiently satisfactory.
• the molecular aggregation state of the fiber cross section (hereinafter referred to as a higher-order cross-sectional structure) varies depending on the spinning conditions. Basically, molecules form crystals in the concentric direction of the fiber (so-called onion type), or form crystals in the radial direction from the center of the fiber (radial type).
• the occurrence of the above-mentioned defects and the formation of the higher-order structure of the cross section vary depending on the physical properties of the spinning pitch, but are most affected by the spinning conditions and fluctuate. Therefore, in order to improve the quality stability of carbon fiber, even if the physical properties of the spinning pitch are slightly different, it is possible to produce a carbon fiber with a constant high-order cross-sectional structure with almost no defects. It is necessary to establish spinning technology. In other words, it hardly generates defects such as cracks, cracks, and voids, and stably forms an onion-type structure, a Z-type structure, or a random-type structure, which is a high-order sectional structure effective for expressing high tensile strength. Technology is required.
• the present invention relates to a method for producing pitch-based carbon fiber in which a pitch-based material is melt-spun, made infusible, and carbonized, and the molten pitch is formed into a circular, irregular or slit-type cavity before reaching a final nozzle hole.
• the present invention relates to a method for producing pitch-based carbon fiber, wherein the fiber is spun through a nozzle hole.
• a pitch-based graphite fiber can be produced by graphitization in the carbonization step. Therefore, in the present specification, carbonization includes graphitization, and carbon fiber is used as including graphite fiber.
• the molten pitch-based material is passed through a circular, irregular or slit-type part of the cavities provided in front of the final nozzle hole, so that the shear stress applied to the final nozzle hole is 12 times or more.
• the shear stress applied to the molten pitch-based material in a part of the cavity is less than 1/2 of the shear stress at the final nozzle. In some cases, the desired effect is not fully exhibited.
• the present invention when shear stress is applied by a method other than the cavitation method, for example, through a gap between dense fillers, the desired effect cannot be obtained. Furthermore, when shear stress is applied to the molten pitch-based material at a part of the cavities and the spinning is immediately performed from the final nozzle hole without maintaining a state in which shear stress is not substantially applied, the present invention is also applicable. The effect of the invention is not exhibited.
• the cross section of the part of the cavity used in the present invention may be circular, slit type (or rectangular type), or other irregular type (square, cross, Y-shaped, etc.). Is also good. . Kiyabira Li one cross-sectional area ⁇ beauty length also, as long as it is capable of adding the required shear stress is not particularly limited, usually the cross-sectional area 5 X 1 0 - 3 ⁇
• the cross-sectional area is substantially the total cross-sectional area of the opening of a part of the cab.
• the time required to maintain the molten pitch between the part of the cavity and the final nozzle hole without substantially applying shear stress to the molten pitch depends on the type and properties of the pitch used, the spinning temperature, and the pitch discharge per unit time.
• the amount differs more shapes of some Kiyabirari and nozzle holes, but are not particularly limited, is usually time melting peak Tutsi of 1 0 3 to 1 0 5 times the time through a portion Kiyabira Li I like it.
• the portion hereinafter referred to as the stress relaxation portion was hollowed out so that no shear stress works except for the outer wall of the pack and / or the nozzle introduction hole. Shall be.
• the spinning pitch used in the present invention can be obtained by subjecting a pitch-like substance to thermal polycondensation in an inert gas flow.
• the pitch-like substance may be any of petroleum pitch, coal pitch and pyrolysis residue pitch from organic compounds, and has a softening point (measured by a softening point measuring device of METTLER, Switzerland). 8 0 to 3 2 5. C's are preferred.
• coal-based pitch such as coal tar or coal tar pitch is used as a raw material
• the method described in Japanese Patent Application Laid-Open No. 57-88016 is followed. By previously heat-treating the raw material pitch with an aromatic reducing solvent at 350 to 500, the spinnability can be further improved, but the spinning pitch should be spinnable. It is not particularly limited.
• the cross-sectional area of the final nozzle hole used in the present invention is not particularly limited, but is usually about 5 ⁇ 10 3 to 10 1 ram 2 o
• the pitch fiber obtained as described above is infusibilized in a conventional manner, for example, in an oxygen atmosphere at a temperature of about 300 to 340, and in the case of carbonization, nitrogen, carbon dioxide, 100 to 2000 in an atmosphere such as argon. C, 200 to 300 in argon for graphitization.
• nitrogen, carbon dioxide 100 to 2000 in an atmosphere such as argon.
• C 200 to 300 in argon for graphitization.
• FIGS. 1 and 2 are schematic diagrams showing the higher-order sectional structure of a carbon fiber obtained by the method of the present invention.
• FIGS. 3 to 5 show Examples 1 and 2.
• FIGS. 6 and 7 are scanning electron micrographs showing the higher-order cross-sectional structure of the carbon fiber obtained in Comparative Examples 4 and 5, and FIGS. 6 and 7 show the higher-order cross-sectional structure of the carbon fiber obtained in Comparative Examples 4 and 5. It is a scanning electron micrograph showing the structure.
• the cross-section higher-order structure of the carbon fiber obtained by the present invention has an onion-type structure in part or all (see FIGS. 1 and 2). If part of the structure is onion-type, the onion-type structure exists in the inner layer and the random-type structure (Fig. 1 (a)) or the radial-type structure (Fig. 1 (b) )) Exists.
• ⁇ is the pressure difference (dyneZ ci)
• ⁇ is the effective cavity or nozzle length (cm)
• r is the cavity or nozzle radius (cm)
• the finally obtained carbon fiber hardly has micro defects such as cracks, voids and the like inside.
• Softening point '1 1 0. C, quinoline-insoluble content 0.18%, benzene-insoluble content 35%, a mixed solution of 1 part by weight of coal tar pitch and 2 parts by weight of hydrogenated heavy anthracene oil in an autoclave 4 3 After heating with stirring at 0 ° C for 60 minutes, the mixture was heated with a pressurized filter and then heated under reduced pressure at 300 to remove hydrogenated heavy lanthanum oil to obtain reduced pitch. .
• Table 1 shows the properties of the two types of hot polycondensation pitches obtained by selecting the reaction time and temperature as Xo. 1-2.
• -Reference Example 2- The same coal tar pitch as in Reference Example 1 was subjected to a thermal polycondensation reaction in the same manner as in Reference Example 1 without undergoing heat treatment under mixing with hydrogenated heavy vanthracene oil.
• Table 1 shows the properties of the resulting hot polycondensation pitch as No. 3.
• the softening point is a softening point measuring device manufactured by METTLER SWITZERLAND.
• the pitch fibers thus obtained are in air at 300. C for 30 minutes, then heat up to 1200 in N 2 gas atmosphere. 0 Heated to obtain carbon fiber.
• Table 2 shows the average time (hr) during which a pitch fiber having a diameter of 10 m can be continuously spun without causing yarn breakage, and the higher-order sectional structure and defect content of the carbon fiber obtained above.
• Table 4 shows the higher-order cross-sectional structure and defect content of the obtained carbon fiber, and the average time (hr) for continuously spinning a pitch fiber having a diameter of 10 m without causing thread breakage.
• Example 1 Using the same spinning device as in Example 1 except that the size of the capillaries was 0.3 in diameter and 0.6 ram in length (100 pieces), the thermal weight obtained in Reference Example 1 was used. Condensed pitch No. 1 was spun. In this spinning process, the pitch was subjected to a shear stress of about 30% of the shear stress applied to the final nozzle hole in a part of the cavity. The obtained pitch fibers were infusibilized and carbonized under the same conditions as in Example 1 to obtain carbon fibers.
• Table 4 shows the sectional higher-order structure and defect content of the carbon fiber.
• the cross section of the carbon fiber obtained in this comparative example shows the higher-order structure.
• Fig. 6 shows a ⁇ -type electron micrograph (approximately 2800 times) of Comparative Example 5
• the obtained pitch fiber was subjected to infusibilization and carbonization under the same conditions as in Examples 1 to 3 to obtain a carbon fiber.
• Table 4 shows the sectional higher-order structure and the defect content of the carbon fiber, and a scanning electron micrograph (approximately 400 ⁇ magnification) showing the sectional higher-order structure of the carbon fiber obtained in this comparative example. ) Is shown in Fig. 7.
• Example 1 shown in Table 2 and Comparative Example 5 are shown in Table 4.
• the higher-order cross-sectional structure is a radial type and contains defects. The rate is also high.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Inorganic Fibers (AREA)
• Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)

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Citations (4)

• 1986
  • 1986-01-22 JP JP1284886A patent/JPS62170527A/ja active Granted
• 1987
  • 1987-01-22 WO PCT/JP1987/000041 patent/WO1990007594A1/ja unknown

Patent Citations (4)

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