Abstract: A tapered hollow shaft made of a fiber reinforced composite material, which comprises: (a) at least one angle layer consisting essentially of polyacrylonitrile-based carbon fibers having a tensile modulus ranging from 200 to 500 GPa and a tensile strength ranging from 4000 to 5600 MPa; (b) at least one straight layer consisting essentially of polyacrylonitrile-based carbon fibers having a tensile modulus ranging from 200 to 460 GPa and a tensile strength ranging from 3500 to 5600 MPa; (c) at least one reinforcing layer consisting essentially of pitch-based carbon fibers or polyacrylonitrile-based carbon fibers each having a compressive breaking strain of 1.7 to 5.0%, a tensile modulus ranging from 5 to 160 GPa, a tensile strength ranging from 500 to 3000 MPa and a density ranging from 1.5 to 1.

Abstract: Disclosed is a plate-like carbon fiber-reinforced composite material comprising carbon fibers, wherein that the carbon fibers have a strain at compressive break of 1.7 to 5%, a tensile elastic modulus of 5 to 160 GPa, and a density of 1.5 to 1.9 g/cm3 and further in that the composite comprising said carbon fibers cause no delamination by an impact energy of less than 1.4 J/mm in the test of compression after impact in accordance with JIS K 7089.

Abstract: The resent invention provides a carbon fiber which enables a molded article produced from a fiber-reinforced composite material using the carbon fiber to exhibit excellent flexibility and to be freed from defects such as bending. According to the method of the present invention the carbon fiber is produced by a two-stage infusibilizing process, namely carrying out a first-stage infusibilization of a pitch-based fiber, which is obtained from mesophase pitch having a softening point of 200 to 400° C. and a true density of 1.30 to 1.38 g/cm3, in a mixed gas atmosphere having a nitrogen dioxide concentration of 1 to 5% by volume and an oxygen concentration of 5 to 50% by volume, the balance being an inert gas or steam, at a temperature between 100 and 200° C. and then carrying out a second-stage infusibilization of the product of the first-stage infusibilization in a mixed gas atmosphere having a nitrogen dioxide concentration of 0.

Abstract: A guide roll comprising an inside layer made of a fiber-reinforced material which consists essentially of an epoxy resin composition as a matrix and at least one kind of reinforcing fibers selected from the group consisting of carbon fibers, glass fibers, alumina fibers, aramide fibers, polyester fibers and polyethylene fibers, and an outside layer which consists essentially of a fluororesin.