Toray Industries, Inc.

Sanyo Chemical Industries, Ltd.

Atsushi Sumida

Shizuo Watanabe

Motoi Itoh

Minoru Yoshinaga

Itsuki Taniguchi

Nobuyuki Matsubara

Teruo Koseki

Toyokazu Minakuchi

Toru Hiramatsu

Satosi Hamada

Hiroshi Hasegawa

Hajime Torigata

Manabu Saito

Keiichiro Ozaki

A sizing agent for carbon fibers which comprises, as the indispensable ingredients, an epoxy resin having a viscosity of more than 1,000 P but up to 20,000 P at 50 .degree. C. and a urethane compound prepared from a polyol having an oxyalkylene unit with a polyisocyanate.

Sizing agent for carbon fiber and carbon fiber treated with said sizing

Carbon fiber superior in processability and in physical properties as a composite is obtained by treating carbon fiber with an epoxy resin composition incorporating a polyalkylene ether glycol derivative represented by the following general formula (I) or (II): ##STR1## wherein R.sub.1 is alkylene of C.sub.1 to C.sub.30, R.sub.2 is alkyl of C.sub.1 to C.sub.30, R.sub.3 and R.sub.4 are each hydrogen or methyl, R.sub.5 is glycidyl, X is ether linkage (--O--) or ester linkage ##STR2## m and n are integers of 1 to 20.

Carbon fiber and process for preparing same

A process for producing carbon fiber is disclosed, which comprises a preoxidation step for heating precursor fibers in an oxidizing atmosphere and converting them into partially oxidized fibers, an oxidizing step for heating the partially oxidized fibers in an oxidizing atmosphere and converting them into oxidized fibers, and a carbonization step for heating the oxidized fibers in an inert atmosphere and converting them into carbonized fibers, in which in the preoxidation step the precursor fibers are heated at a temperature of about 200.degree. to 250.degree. C. and in which a portion or the whole of the exhaust gas from the oxidation step is supplied into the preoxidation step as the oxidation atmosphere gas and the exhaust gas from the preoxidation step is subjected to a burning treatment.

Process for producing carbon fiber

A method of producing carbon fibers in which an exhaust gas generated in a heat-treating stage of the production of carbon fibers is divided into two portions, one portion thereof being decomposed by the action of an oxidizing catalyst and subsequently being blended with the other portion, to be reused. According to said method, the heat loss in the exhaust gas disposal process can be substantially reduced and the efficiency of heat-treating can be improved and in consequence, various troubles due to the decomposed products contained in the heat-treating atmosphere such as surface damage, fuzziness and individual fiber breakage, etc. can be avoided.

Method of producing carbon fibers

A bundle of continuous carbon filament fibers treated with a sizing agent containing as an active component a water-dispersible resin composition consisting of about 65% to 95% by weight of water-dispersible urethane compound having at least one epoxy group and at least one quaternary ammonium group and about 5% to 35% by weight of an epoxy resin. The bundle has an excellent fretting resistance, is extremely handleable, and produces a carbon fiber-reinforced composite material having excellent physical properties.

Continuous carbon filament fiber bundles

Disclosed is a carbon fiber of improved oxidation resistance, which has a specific volume resistance of at least about 1.2.times.10.sup.-3 ohm cm, and containing at least about 2 wt. % of nitrogen and less than about 0.07 wt. % of total metal impurities. The carbon fiber is produced by using as the precursor fiber an acrylonitrile copolymer fiber, which copolymer is comprised of at least 95 mole % of units derived from acrylonitrile and not more than 5 mole % of units derived from a carboxyl group containing monoethylenically unsaturated monomer or monomers; the hydrogen atom of at least one --COOH contained in each of the units derived from the carboxyl group-containing monomer or monomers being replaced with a cation selected from ##STR1## wherein R is H, (C1-3) alkyl or phenyl; the replacement being to such an extent that the units having the cation occupy at least 0.1 mole %, based on the copolymer; and which copolymer contains less than about 0.05 wt. % of the total metal impurities. All of the aqueous baths used in the course of producing the carbon fiber, i.e., aqueous coagulating, drawing, washing and oiling baths, are prepared from deionized or distilled water, and the aqueous oiling bath is prepared by using a cationic or nonionic oiling agent.

Growing community of inventors

Ehime, Japan

Atsushi Sumida