Stock material or miscellaneous articles – Self-sustaining carbon mass or layer with impregnant or...
Patent
1997-01-24
1998-07-21
Cain, Edward J.
Stock material or miscellaneous articles
Self-sustaining carbon mass or layer with impregnant or...
428311, 428375, 428378, D01F 922
Patent
active
057833052
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a finish for the precursors to be processed into carbon fibers.
BACKGROUND OF THE INVENTION
Carbon fibers are produced in industrial processes from the precursors comprising polyacrylonitrile, rayon, polyvinyl alcohol, or pitch, which are converted into carbon fibers being subjected to oxidative stabilization at 250.degree.-300.degree. C. in oxygen, and then subjected to carbonization at 300.degree.-2000.degree. C. in an inert atmosphere. Carbon fibers are broadly applied as the fibrous materials to reinforce composites owing to their high performance.
In the above-mentioned industrial processes for carbon fiber production, the oxidative stabilization and the carbonization operation sometimes encounter troubles, such as adhered or fused precursors, fluffs on precursors, and precursor breakage due to the friction between precursors and machinery surface. Such troubles lead to poor quality and performance of the resultant carbon fibers.
The above-mentioned troubles are variable depending on the finish variants applied to precursors. For example, finishes having poor heat resistance fail to prevent precursors from adhesion or fusion, and related defect on precursors.
Various methods for eliminating such adhered or fused precursors and defect on precursors by applying silicone oils have already been proposed in the prior arts, for example, those disclosed in Japanese Patent Publication No. 24136 of 1977 (U.S. Pat. No. 4,009,248), Japanese Patent Laid-Open Nos.135510 and 203878 of 1988, and Japanese Patent Laid-Open No.306682 of 1989 (U.S. Pat. No. 4,973,620). The high heat-resistance, sufficient lubricity between fiber strands, and high detachability of silicone oils are well known to those skilled in the art. And the prior arts, including patent publications, have already proved that the said performance of silicone oils are effective to decrease adhered or fused precursors to some extent throughout the conversion process of carbon fiber production.
On the other hand, the strong hydrophilicity of silicone oils is apt to accumulate static charge on the precursors applied with silicone oils. The static charge on precursors causes fluffs, wraps on rolls or guides, and precursor breakage in the production process of precursors or in the conversion processes in carbon fiber production leading to decreased production efficiency. In addition, a part of silicone oils changes into silicon oxide in the oxidative stabilization of precursors, or into silicon nitride in the subsequent carbonization in nitrogen atmosphere. The silicon oxide and silicon nitride deposit on carbon fibers or in furnaces resulting in poor carbon fiber quality or damaged furnaces.
A production method of high-performance carbon fiber is disclosed in Japanese Patent Laid-Open No.264918 of 1988 (U.S. Pat. No.4,522,801), wherein an acrylonitrile precursor subjected to oxidative stabilization is applied with an aqueous preparation containing a polyethylene oxide of which molecular weight is more than 100,000, a cellulose etherified with ethylether or hydroxyethylether, and/or polyvinyl methylether, and dried before the precursor is fed to carbonization process. In the said patent, the preparation is described to be effective for improving the cohesion of precursors so as to prevent fluffs of the bundle of precursors, to separate adhered precursors, and to prevent damage on precursor surface. However, the polyethylene oxide and other components in the aqueous preparation are not satisfiably heat resistant for preventing precursors from adhesion, while they impart sufficient cohesion to precursors.
In Japanese Patent Laid-Open No. 30425 of 1982, a heat-resistant finish for synthetic fibers including polyamide and polyester fibers, is disclosed. The high heat resistance of the finish contributes to no generation of fume or tar-like residue, a pollutant in working area, at each heating step throughout fiber production process and down-stream processing stages. The said patent includes the finish
REFERENCES:
patent: 4009248 (1977-02-01), Kishimoto et al.
patent: 4522801 (1985-06-01), Yoshinari et al.
patent: 4973620 (1990-11-01), Ona et al.
Kanamori Junji
Komatsubara Tomoo
Masaki Takao
Nakagawa Mikio
Nakanishi Seizi
Cain Edward J.
Matsumoto Yushi-Seiyaku Co. Ltd.
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