Patent ID: 11932971
Assignee: TORAY INDUSTRIES, INC.
Field: Textile and paper machines (Mechanical engineering)
Classification: CPC D | IPC D

Claim 0:
1. A method of producing a precursor fiber for carbon fiber comprising:
extruding a spinning dope solution comprising a polyacrylonitrile copolymer solution from a spinneret into the air,
immersing the spinning dope solution in a coagulation bath liquid stored in a coagulation bath to obtain a coagulating fiber bundle,
redirecting traveling of the coagulating fiber bundle by a first guide immersed in the coagulation bath disposed below the spinneret, and
pulling the coagulating fiber bundle out of the coagulation bath liquid into the air to prepare a coagulated fiber bundle, which is then subjected to at least a washing step in water, stretching step, oil agent applying step, and drying step,
wherein a depth-directional coagulation bath immersion length, which means a distance between a starting point of the immersion of the spinning dope solution in the coagulation bath liquid and the first guide immersed in the coagulation bath where traveling of the coagulating fiber bundle is redirected, is 3 to 40 cm,
wherein the coagulating fiber bundle redirected by the first guide immersed in the coagulation bath is redirected again at least by a second guide immersed in the coagulation bath, the second guide being immersed in the coagulation bath and located in the coagulation solution below a straight line running from an exit point where the coagulating fiber bundle is pulled out into the air to the first guide immersed in the coagulation bath,
wherein a redirection angle (B) of the coagulating fiber bundle on the first guide immersed in the coagulation bath is 90° to 150°.