Toho Rayon Co., Ltd.

Toho Belson Co., Ltd.

Toho Beslon Co., Ltd.

Tetsuro Shigei

Hiroyasu Ogawa

Kazuhisa Saito

Kazuhiro Ichimaru

Tomoaki Kanno

Tomoki Koseki

Hiroshi Sugeno

A method for producing graphite fiber comprising graphitizing carbon fiber having a strength of 500 kgf/mm.sup.2 or more and a modulus of elasticity of from 27,000 to 33,000 kgf/mm.sup.2, and having at least on the surface of the fibers, from 0.2 to 2% by weight of an epoxy resin as a sizing agent, from 0.005 to 0.10% by weight of silicon and 0.005 to 0.02% by weight of phosphorus based on the weight of carbon fiber having said epoxy resin, silicon and phosphorus.

Method for producing graphite fiber

A process for electrolytically treating the surface of a carbon fiber without using a surface treatment bath, comprising forming a flow of an electrolyte solution in the form of a liquid film or column at at least one anode and at at least one cathode which alternate along the direction of the length of the carbon fiber, and passing carbon fiber strands through the flows of the electrolyte solution to apply electric current to the carbon fiber strands.

Process for the surface treatment of carbon fiber strands

An acrylic fiber having applied thereto a polyoxyalkylene aminopolysiloxane compound having a viscosity of from 5 to 500 poises at 25.degree. C. and which is represented by formula (I) as an oiling agent: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, and R.sub.6 each represents a lower alkyl group or an aryl group,

Precursor for production of preoxidized fibers or carbon fibers

A carbonaceous fiber having a carbon content of from 70 to 90%, a high tensile strength and a high modulus of elasticity, which is produced by a method which comprises preoxidizing an acrylic fiber in an oxidizing atmosphere at a temperature of from 10.degree. to 60.degree. C. below the decomposition point of said fiber, to prepare a preoxidized fiber having a degree of orientation of not less than 78% at an angle of X-ray diffraction (2.theta.) of 25.degree. and a specific gravity of from 1.30 to 1.40, pyrolyzing the preoxidized fiber in an inert gas atmosphere by passing the fiber firstly through a lower temperature zone having a temperature of not higher than 750.degree. C. and then through a higher temperature zone having a temperature of from 750.degree. to 950.degree. C., during the pyrolysis controlling the tension of the fiber so that the change of the fiber length during pyrolyzing is from +16% to -8.8% based on the length of the preoxidized fiber.

High-strength carbonaceous fiber

A method for producing carbon fibers exhibiting excellent adhesive properties to resins and having high strength and heat-oxidation resistance, comprising electrically treating high strength carbon fiber in an aqueous solution of a sulfuric acid salt under conditions such that the current density is from about 0.05 to 0.5 A/m.sup.2 and the product of current density, voltage, and processing time is from about 0.02 to 8 A-V-min/m.sup.2, while continuously moving the carbon fiber as an anode in the aqueous solution.

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Shizuoka, Japan

Tetsuro Shigei