Toray Industries, Inc.

Naohiro Matsumoto

Fumihiko Tanaka

Haruki Okuda

Jun Watanabe

Takaaki Yamashita

Yuki Sada

Yuki Sado

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 from which a carbon fiber composite material having high tensile strength can be obtained has the following configuration. Specifically, the carbon fiber bundle has a strand elastic modulus of 265-300 GPa, strand strength of at least 6.0 GPa, and knot strength of at least 820 N/mm, and includes at least 30,000 filaments.

Carbon 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.

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Ehime, Japan

Naohiro Matsumoto