Toray Industries, Inc.

Jun Watanabe

Fumihiko Tanaka

Haruki Okuda

Tomoko Ichikawa

Takaaki Yamashita

Yuuki Okishima

Naohiro Matsumoto

Masafumi Ise

Kengo Hayashida

Naoki Muraki

A carbon fiber bundle that satisfies retaining a twist count of 2 turns/m or more when suspended with one end fixed and the other end free; having a single fiber diameter of 6.1 &#x3bc;m or more and a heat loss rate at 450&#xb0; C. of 0.15% or less, and formula (1) wherein Lis crystallite size and &#x3c0;is an orientation parameter of crystallites determined from bulk measurement of the entire fiber bundle: &#x3c0;&#x3e;4.0&#xd7;L+73.2 (1); and a carbon fiber bundle that satisfies: retaining a surface layer twist angle of 0.2&#xb0; or more when suspended with one end fixed and the other end free; having a single fiber diameter of 6.1 &#x3bc;m or more and a heat loss rate at 450&#xb0; C. of 0.15% or less, and formula (1).

Carbon fiber bundle and production method therefor

Carbon fibers achieve a high elongation percentage and a high tensile modulus of resin-impregnated strands while being lightweight. The carbon fibers are configured such that: the void content in a cross section of the fibers in the axial direction, the cross section including the long axis of a cross section of the fibers in the radial direction, is at least 0.3% by area, but not more than 5.0% by area; the average aspect ratio of the voids is at least 2.0, but not more than 50; and the average width of the voids in the cross section of the fibers in the radial direction is at least 3 nm, but not more than 100 nm.

Carbon fibers, and production method therefor

A bundle of carbon fibers has a value A obtained from a nonlinear approximation formula of a stress &#x3c3;-strain &#x3b5; curve in a tensile strength test of resin-impregnated strands and an orientation parameter &#x3a0; (%) of crystallites in a wide-angle x-ray diffraction measurement which satisfy a predetermined relational expression, and has tensile strength with a predetermined value or more, and tensile modulus within a predetermined range and a product E&#xd7;d/W of a ratio d/W of a single-fiber diameter d to a loop width W just before loop fracture evaluated by a single-fiber loop test and a tensile modulus E of the strands has a predetermined value or more, or apparent single-fiber stress has a predetermined value or more when the number of fiber breaks by a single-fiber fragmentation method for a single-fiber composite is 0.30 breaks/mm and when the number of the fiber breaks by the single-fiber fragmentation method for the single-fiber composite is 0.30 breaks/mm, the number of fiber breaks by a double-fiber fragmentation method for the single-fiber composite is within a predetermined range.

Bundle of carbon fibers and method of manufacturing the same

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.

Growing community of inventors

Ehime, Japan

Jun Watanabe