Abstract: [Problem] To provide a sizing-agent-coated carbon fiber bundle in which, even when the sizing-agent-coated carbon fiber bundle has superior handling properties, the sizing agent on the sizing-agent-coated carbon fiber bundle exhibits excellent solubility in water and the adhesion amount of remaining sizing agent is reduced. [Solution] A sizing-agent-coated carbon fiber bundle obtained by applying polyethylene glycol and/or a surfactant to a carbon fiber bundle as a sizing agent, wherein all of the following conditions (i)-(iii) are satisfied. (i) The adhesion amount of the sizing agent is 0.15-0.80 parts by mass (inclusive) per 100 mass parts of the sizing-agent-coated carbon fiber bundle 100. (ii) The dry F-F friction coefficient is 0.39 or less. (iii) The adhesion amount of the sizing agent after washing for 50 seconds under the conditions disclosed in the specification is 0.12 parts by mass or less per 100 parts by mass of the sizing-agent-coated carbon fiber bundle 100.

Abstract: 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?La/Lb?1.20 (1) and 1.05?Ld/Lc?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.

Abstract: Provided is a sizing-coated carbon fiber bundle that exhibits good spreadability in a step for spreading sizing-coated carbon fibers even in the case in which said carbon fibers exhibit a high adhesiveness with respect to a thermoplastic resin. Provided is a sizing-coated carbon fiber bundle that contains, as sizing components, at least a compound (A) containing an amino group or an amide group.

Abstract: Provided is a sizing-coated carbon fiber bundle that exhibits good spreadability in a step for spreading sizing-coated carbon fibers even in the case in which said carbon fibers exhibit a high adhesiveness with respect to a thermoplastic resin. Provided is a sizing-coated carbon fiber bundle that contains, as sizing components, at least a compound (A) containing an amino group or an amide group.

Abstract: 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?La/Lb?1.20 (1) and 1.05?Ld/Lc?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.