US Patent 7771694 Crimped carbon fiber and production method thereof

A crimped carbon fiber having a multilayer structure comprising a hollow structure in the inside, with the inner layer part having a carbon structure containing a herringbone structure and the outer layer part having a carbon structure differing from the carbon structure of the inner layer part. A method for producing a crimped carbon fiber, comprising contacting a carbon source and/or a catalyst source with a sulfur source in a heating zone to produce a vapor grown carbon fiber, wherein the ratio of the molar number of sulfur atom in the sulfur source to the molar number of the catalyst metal atom is 2.0 or more.