Carbon fiber bundle, prepreg, and fiber-reinforced composite material
An object of the present invention is to provide a carbon fiber which exhibits excellent strength development rate when used in a composite material. The present invention that solves the problems is a carbon fiber which simultaneously satisfies the following formulae (1) and (2): Lc/d ≤3 (1) TS× d×Lc >6.0×10 5 (2) wherein: Lc is an X-ray crystallite size (Å), d is a filament diameter (μm), and TS is a strand tensile strength (MPa).
1. A carbon fiber which simultaneously satisfies the following formulae (1), (2), (A), and (B):
Lc/d≤ 2.9 (1)
TS× d×Lc> 6.0×10 5 (2)
75≤X-ray crystal orientation degree (%)≤81.9 (A)
1.72≤specific gravity (g/cm 3 )≤1.76 (B)
wherein:
Lc is an X-ray crystallite size (Å),
d is a filament diameter (μm), and
TS is a strand tensile strength (MPa),
and which satisfies:
the strand tensile strength of the carbon fiber is 4,700 MPa or more, and
the X-ray crystallite size of the carbon fiber is 19 to 21 Å.
2. The carbon fiber according to claim 1 , which further satisfies the following formula (3):
TS× d ×TM>9.5×10 6 (3)
wherein:
TS is a strand tensile strength (MPa),
d is a filament diameter (μm), and
TM is a strand tensile modulus (GPa).
3. A prepreg which is obtained by impregnating the carbon fiber according to claim 2 with a matrix resin.
4. A fiber-reinforced composite material comprising the carbon fiber according to 2 and a matrix resin.
5. A prepreg which is obtained by impregnating the carbon fiber according to claim 1 with a matrix resin.
6. A fiber-reinforced composite material comprising the carbon fiber according to claim 1 and a matrix resin.
7. The carbon fiber according to claim 1 , wherein the strand tensile strength is 4,700 to 5,200 MPa.