Toray Industries, Inc.

Haruki Okuda

Fumihiko Tanaka

Jun Watanabe

Naohiro Matsumoto

Tomoko Ichikawa

Masanori Sueoka

Yuuki Okishima

Masafumi Ise

Tomohisa Noguchi

Takayuki Yomo

Kengo Hayashida

Yusuke Hiraike

Naoki Muraki

Yuki Sada

Yuki Sado

Misato Takenaka

Yoshimasa Suzuki

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

A carbon fiber bundle has a relationship among a crystallite size Lc (nm), a single-fiber compressive strength Fc (GPa) measured by a compressive fragmentation method of single-fiber composites, and an initial modulus E(GPa) in a resin-impregnated strand tensile test simultaneously satisfies formulas (1) to (3), and Lc is 4.00 nm or less:&#x2265;1.3&#xd7;10/&#x2212;0.3&#x2003;&#x2003;(1)&#x2264;80&#xd7;+155&#x2003;&#x2003;(2)&#x2265;330&#x2003;&#x2003;(3).

Carbon fiber bundle, manufacturing method therefor, prepreg, and carbon fiber-reinforced composite material

A carbon fiber bundle is characterized in that a ratio (n/N) of a number n of pairs wherein a flaw of 50 nm in size or more is present on at least one of the fracture surfaces forming the pair to a total number N of pairs of fiber fracture surfaces selected at random after performing a single fiber tensile test for a gauge length of 10 mm is 35% or less, and in that a single-fiber diameter d is 4.3 &#x3bc;m or more.

Carbon fiber bundle and method of manufacturing same

A carbon fiber bundle includes single-fibers 40% or more of which have a quasi-oval cross section perpendicular to a fiber direction and meet both Equations (1) and (2): 1.03&#x2264;La/Lb&#x2264;1.20 (1) and 1.05&#x2264;Ld/Lc&#x2264;1.25 (2), wherein La is length of a long axis defined as a line segment connecting two points farthest away from each other on a circumference of the quasi-oval cross section of a single-fiber; Lb is length of a short axis defined as a line segment extending perpendicular to the long axis, passing through a midpoint of the long axis, and connecting two points on the circumference; and Lc and Ld are defined as length of a shorter one and that of a longer one, respectively.

Carbon fiber bundle and stabilized fiber bundle

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.

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

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Ehime, Japan

Haruki Okuda