| abstract |
[Problem] To provide a method for producing fine carbon fibers having a long fiber length and no branching by a simple process using a lignin derivative derived from biomass as a raw material. A method for producing an ultrafine carbon fiber comprising the following steps (1) to (4). (1) 100 parts by mass of a thermoplastic resin, 1 to 50 parts by mass of a lignin derivative, and 0.1 to 10 parts by mass of a lignin fiberizing aid are mixed in a molten state, and precursor fibers are formed from the resulting resin composition. Process. (2) A step of infusifying a lignin derivative contained in the precursor fiber to form an infusible precursor fiber. (3) A step of removing the thermoplastic resin from the infusible precursor fiber to form an infusible lignin derivative fiber. (4) A step of obtaining fine carbon fibers by carbonizing or graphitizing infusible lignin derivative fibers in an inert gas atmosphere. [Selection] Figure 2 |