To produce a molded product of a carbon fiber reinforced plastic, for example, it is known that a sheet-like carbon fiber composite material is used as a raw material for molding, and the carbon fiber composite material is press molded (stamping molding) into a predetermined shape at predetermined conditions of temperature and pressure. In such a molding, in particular, when the shape to be molded is a complicated shape, the carbon fiber composite material as a raw material for molding is required with a high flowability to be molded into a desired carbon fiber reinforced form over the all parts of the complicated shape. If the flowability of the carbon fiber composite material is low, not only a good moldability cannot be obtained, but also the mechanical properties of a molded product become low, and there is a possibility that the dispersion of the mechanical properties becomes great.
As conventional technologies, in JP-A-2003-183692, although a carbon fiber sheet excellent in tensile strength, prepared by stacking a carbon fiber non-woven fabric and a carbon fiber refined material at a condition to entangle them by needle punch or water jet, is disclosed, even if such a sheet is used as a carbon fiber composite material as a raw material for molding as described above, because entanglement of fibers with each other is strong, flowability at the time of molding is low.
Further, in JP-A-2004-169225, although a reinforcement material of a fiber reinforced plastic excellent in tensile strength, prepared by bundling inorganic fibers (glass fibers, carbon fibers or the like) with a natural polymer and binding the obtained fiber bundles with a binder (a thermoplastic resin, a thermosetting resin, an elastomer or the like), is disclosed, because the fibers are bound to each other by the binder, the flowability at the time of molding is low. Further, a natural polymer such as a starch is used as the bundling agent, the bundling agent is deteriorated when made into a composite material by impregnating a thermoplastic resin, and therefore, it is difficult to obtain a molded product having high properties.
Furthermore, in JP-A-2008-201005, although a carbon fiber sheet with a high plane flatness and a high tensile strength, prepared by stacking a carbon fiber felt and a carbon fiber paper, is disclosed, even if such a sheet is used as a carbon fiber composite material, because the carbon fiber paper part is high in dispersibility of single fibers of carbon fibers but strong in entanglement of carbon fibers with each other, the flowability at the time of molding is low.
It could therefore be helpful to provide a carbon fiber composite material which can exhibit a high flowability at the time of molding, and which can yield a molded product having good mechanical properties with minimized dispersion, that have not been achieved in conventional carbon fiber composite materials.
USPTO Backgrounds
USPTO Backgrounds