Toray Industries, Inc.

Kengo Hayashida

Tomoko Ichikawa

Fumihiko Tanaka

Haruki Okuda

Jun Watanabe

Yuuki Okishima

Masafumi Ise

Masaki Nakano

Hirotada Endo

Naoki Muraki

A method produces an acrylic fiber bundle that are cleaned in one or more washing baths including an inflow portion and an outflow portion for a cleaning solution; at least one of the washing baths is a counterflow washing bath in which the cleaning solution flows into from the inflow portion located at a lower stream side position of a traveling direction of coagulated thread bundles, and flows out from the outflow portion located at an upper stream side position of the traveling direction of the coagulated thread bundles; and an average of coefficients of variation CV of linear speeds of the cleaning solution in the inflow portion of the counterflow washing bath is 0.30 or less, and an average of coefficients of variation CV of linear speeds of the cleaning solution in the outflow portion of the counterflow washing bath is 0.30 or less.

Method of producing acrylic fiber bundle and method of producing carbon fiber bundle

A sizing agent-coated carbon fiber bundle has a sizing agent containing an aliphatic epoxy compound (C) and an aromatic epoxy compound (D) coated on the carbon fiber bundle, wherein the carbon fiber in the carbon fiber bundle is the one which exhibits, when measured by single-fiber composite fragmentation method, a number of fiber breaks of at least 2.0/mm when apparent single-fiber stress is 15.3 GPa and the number of fiber breaks of up to 1.7/mm when the apparent single-fiber stress is 12.2 GPa.

Sizing agent-coated carbon fiber bundle, carbon fiber bundle production method, and prepreg

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Ehime, Japan

Kengo Hayashida