Toray Industries, Inc.

Keiichi Ishio

Masaki Nakano

Koichi Aizu

Seiji Nagano

Fumiya Yano

Yuma Matsubara

Takuya Nagasaka

Naoyuki Furukawa

A method of producing a fiber is provided, the method including extruding, from a spinneret, a spinning dope solution containing a fiber-forming polymer dissolved in a solvent, once allowing the solution to run in air, and then guiding the solution into the liquid of a coagulation bath to allow coagulation, wherein a gas-phase portion formed in a vertically downward direction from an extrusion surface of the spinneret to the liquid surface of the coagulation bath has a unidirectional air flow, and has an air flow rate per unit time (Af) which satisfies, in relation to the amount of the solvent in the spinning dope solution per unit time (As) in the gas-phase-portion volume (Vh), the relational expression 0.0008 m&#x2264;Af/(As/Vh)&#x2264;0.0015 m. A method of producing a fiber, which, in dry-jet wet spinning, suppresses occurrence of dew condensation in the spinneret, and reduces deterioration of the appearance caused by winding on rollers in the subsequent process or by fuzzing or yarn break in the stretching process, to enable significant improvement of the productivity and the appearance as a whole, is provided.

Fiber production method and carbon fiber production method

Provided is a method for manufacturing a combined yarn bundle including the steps of bringing the two or more carbon fiber precursor yarns which travel approximately parallel to one another into contact with a first roller at a wrap angle of 20&#xb0; or more. Then, the two or more carbon fiber precursor yarns are split into two and brought into contact with a pair of second rollers, so that the carbon fiber precursor yarns are rotated approximately 90&#xb0; between the first roller and the pair of second rollers. Next, the carbon fiber precursor yarns delivered from one second roller are brought into contact with a third front roller and a third rear roller, and the carbon fiber precursor yarns delivered from the other second roller are brought into contact with the third rear roller without bringing them into contact with the third front roller, so that these carbon fiber precursor yarns are combined on the third rear roller. Thereafter, the carbon fiber precursor yarns delivered from the third rear roller are brought into contact with a fourth roller to obtain a combined yarn bundle. A ratio of a distance L between axes of the first roller and of the pair of second rollers to a yarn width W of the carbon fiber precursor yarn on the first roller, L/W, is 18 or more and a tension of the combined yarn bundle after delivered from the fourth roller is 0.11 cN/dtex or more.

Method for manufacturing combined yarn bundle, and method for manufacturing carbon fiber in which resulting combined yarn bundle is used (as amended)

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Ehime, Japan

Keiichi Ishio