Abstract: Efficient production of high quality oxidized fiber bundles and carbon fiber bundles is described, comprising a step for heat-treating aligned acryl based fiber bundles in an oxidizing atmosphere while turning them back on guide rollers installed on both ends outside the furnace body of a hot gas heating type oxidation furnace wherein: supply nozzles for supplying hot gas into a heat treatment chamber are installed at an end in the traveling direction of the acryl based fiber bundles; a fiber bundle traveling passage(s) exists above and/or below each nozzle; hot gas is supplied from the supply face(s) located above and/or below the acryl based fiber bundle; and the requirements (1) and (2) are satisfied where Vf and V are defined as described. 1.5 m/s?Vf?15 m/s ??(1) 1.

Abstract: A spinneret includes: a plate including a plurality of nozzle holes formed therein. In the plates, the plurality of nozzle holes are formed in a substantially rectangular area on a principal surface, the rectangular area includes a non-forming zone that intersects with nozzle hole rows, the non-forming zone continuously extending from one long side of the rectangle to the other long side, and the non-forming zone including no nozzle holes, in nozzle hole rows with which the non-forming zone intersects out of the nozzle hole rows, in each of the nozzle hole rows, the nozzle hole is not formed on a part where the non-forming zone intersects with a position of the regular interval at which the nozzle holes are aligned, and the nozzle hole corresponding to number of the unformed nozzle holes is additionally formed in a short side direction of the nozzle hole row.

Abstract: A pack for spinning is provided with a kneading part disposed on a spinneret. The kneading part includes: an introduction plate including a plurality of first introduction holes for introducing a melted polymer; and a plurality of kneading units including a supply plate including a plurality of independent supply grooves into which the polymer introduced from the introduction holes flows and one or more supply holes disposed in each of the supply grooves, and a converging plate including a plurality of converging grooves in which a plurality of grooves into which the polymer supplied from the supply holes flows are intersected and a plurality of second introduction holes disposed in each of the converging grooves.

Abstract: An object of the present invention is to provide a ligand-immobilized sea-island composite fiber in which generation of fine particles due to peeling of a sea component from an island component and generation of fine particles due to destruction of a fragile sea component are both suppressed. The present invention provides a sea-island composite fiber comprising a sea component and island components, in which a value (L/S) obtained by dividing the average total length (L) of the perimeter of all island components in a cross section perpendicular to the fiber axis by the average cross-sectional area (S) of the cross section is from 1.0 to 50.0 ?m?1, a distance from the surface to the outermost island component is 1.9 ?m or less, and an amino group-containing compound is covalently bonded to a polymer constituting the sea component at a charge density of 0.1 ?mol or more and less than 500 ?mol per 1 gram dry weight.

Abstract: Provided herein is a method for producing an acrylonitrile based fiber bundle by dry-jet wet spinning technique that serves to allow a high-grade, high-quality acrylonitrile based fiber bundle to be produced stably even if the traveling speed of the coagulated fibers is increased or the number of spinneret discharge holes is maximized in an attempt to enhance the production efficiency. The production method for an acrylonitrile based fiber bundle is characterized by first extruding a spinning dope solution through a plurality of discharge holes in a spinneret, then allowing the spinning dope solution to run downward into a coagulation bath liquid stored in a coagulation bath to form coagulated fibers, turning the coagulated fibers upward on a direction changing guide part located in the coagulation bath liquid below the spinneret, and pulling them out of the coagulation bath liquid, wherein certain requirements are met.

Abstract: An object of the present invention is to provide a ligand-immobilized sea-island composite fiber in which generation of fine particles due to peeling of a sea component from an island component and generation of fine particles due to destruction of a fragile sea component are both suppressed. The present invention provides a sea-island composite fiber comprising a sea component and island components, in which a value (L/S) obtained by dividing the average total length (L) of the perimeter of all island components in a cross section perpendicular to the fiber axis by the average cross-sectional area (S) of the cross section is from 1.0 to 50.0 ?m?1, a distance from the surface to the outermost island component is 1.9 ?m or less, and an amino group-containing compound is covalently bonded to a polymer constituting the sea component at a charge density of 0.1 ?mol or more and less than 500 ?mol per 1 gram dry weight.

Abstract: A spinneret includes: a plate including a plurality of nozzle holes formed therein. In the plates, the plurality of nozzle holes are formed in a substantially rectangular area on a principal surface, the rectangular area includes a non-forming zone that intersects with nozzle hole rows, the non-forming zone continuously extending from one long side of the rectangle to the other long side, and the non-forming zone including no nozzle holes, in nozzle hole rows with which the non-forming zone intersects out of the nozzle hole rows, in each of the nozzle hole rows, the nozzle hole is not formed on a part where the non-forming zone intersects with a position of the regular interval at which the nozzle holes are aligned, and the nozzle hole corresponding to number of the unformed nozzle holes is additionally formed in a short side direction of the nozzle hole row.

Abstract: A pack for spinning is provided with a kneading part disposed on a spinneret. The kneading part includes: an introduction plate including a plurality of first introduction holes for introducing a melted polymer; and a plurality of kneading units including a supply plate including a plurality of independent supply grooves into which the polymer introduced from the introduction holes flows and one or more supply holes disposed in each of the supply grooves, and a converging plate including a plurality of converging grooves in which a plurality of grooves into which the polymer supplied from the supply holes flows are intersected and a plurality of second introduction holes disposed in each of the converging grooves.

Abstract: A sea-island composite fiber in which island components are interspersed in a sea component on a fiber cross-section, wherein the island components have a composite structure formed with two or more different polymers joined together, and the ratio (L/D) of the length (L) of the joint section of the island component and the diameter (D) of the composite island component is 0.1 to 10.0. The sea-island composite fiber has satisfactory high-order processability, and therefore can be produced with high productivity and quality using existing equipment, and thin fibers obtained by removing the sea component have functions of structure control while having an excellent tactile impression.

Abstract: A composite spinneret that discharges a composite polymer composed of an island polymer and a sea polymer, the composite spinneret satisfying (1) and (2): (1) the composite spinneret comprises: a distribution device; a nozzle plate; a flow contraction plate; and (2) the nozzle plate has a nozzle hole collection including a plurality of discharge holes, and at least one sea-island discharge hole group including any of (i) to (v): (i) the sea discharge holes and the island discharge hole; (ii) the composite polymer discharge holes; (iii) the sea discharge holes and the composite polymer discharge holes; (iv) the island discharge holes and the composite polymer discharge holes; and (v) the sea discharge holes, the island discharge holes and the composite polymer discharge holes.

Abstract: A sea-island composite fiber includes island component fibers having a circumscribed circle diameter of 10 to 1000 nm, a circumscribed circle diameter variation of 1 to 20%, a non-circularity of 1.2 to 5.0, and a non-circularity variation of 1 to 10%.

Abstract: A sea-island composite fiber includes two or more kinds of island components having different cross section shapes of which an irregularity difference is 0.2 or more in a same fiber cross section, wherein at least one kind of island component has an irregularity of 1.2 to 5.0 and an irregularity coefficient of variation of 1.0 to 10.0%.

Abstract: A sea-island composite fiber in which island components are interspersed in a sea component on a fiber cross-section, wherein the island components have a composite structure formed with two or more different polymers joined together, and the ratio (L/D) of the length (L) of the joint section of the island component and the diameter (D) of the composite island component is 0.1 to 10.0. The sea-island composite fiber has satisfactory high-order processability, and therefore can be produced with high productivity and quality using existing equipment, and thin fibers obtained by removing the sea component have functions of structure control while having an excellent tactile impression.

Abstract: An islands-in-sea fiber includes island components and a sea component arranged to surround the island components, wherein the island components and the sea component are composed of at least two polymers and are provided on a fiber cross-section in a direction perpendicular to the fiber axis. The islands-in-sea fiber is a raw yarn for a combined filament yarn, which can be used to produce a cloth having good tension and drape and an excellent color-developing property. An islands-in-sea fiber in which at least two types of island components having different diameters are arranged on the same fiber cross section, the islands-in-sea fiber characterized in that at least one type of the island components have diameters of 10-1000 nm and have fluctuations in diameters of 1.0-20.0%.

Abstract: The fiber cross-section of an island-in-a-sea composite fiber perpendicular to the fiber axis, the island component and sea component are arranged such that the sea component surrounds the island components. The composite cross-section is very consistent, and the fiber has excellent post-processibility. The island-in-a-sea composite fiber wherein diameter of the island component is 10 to 1000 nm, variation of the island component diameter is 1.0 to 20.0%, modification ratio is 1.00 to 1.10, and variation of the modification ratio is 1.0 to 10.0%.

Abstract: A multicomponent fiber includes a sea component and an island component, wherein in cross-section observation of the multicomponent fiber, the multicomponent fiber includes a sea-island region with the plurality of island components arranged in the sea component; and one or more sea component regions formed only of the sea component between the sea-island region, and a width (H) of the sea component region is larger than a maximum value of a distance (W) between island components existing in the sea-island region and neighboring each other.

Abstract: A sea-island composite fiber includes two or more kinds of island components having different cross section shapes of which an irregularity difference is 0.2 or more in a same fiber cross section, wherein at least one kind of island component has an irregularity of 1.2 to 5.0 and an irregularity coefficient of variation of 1.0 to 10.0%.

Abstract: A sea-island composite fiber includes island component fibers having a circumscribed circle diameter of 10 to 1000 nm, a circumscribed circle diameter variation of 1 to 20%, a non-circularity of 1.2 to 5.0, and a non-circularity variation of 1 to 10%.

Abstract: A composite spinneret for discharging a composite polymer stream consisting of at least two or more component polymers, which includes a metering plate having multiple metering holes for metering respective component polymers, a distribution plate with multiple distribution holes formed in the distribution grooves for joining the polymer streams discharged from the metering holes, and a discharge plate.

Abstract: A sea-island composite fiber has an island component which is ultrafine fibers having a noncircular cross-section, the ultrafine fibers being uniform in the degree of non-circularity and in the diameter of the circumscribed circle. The sea-island composite fiber includes an easily soluble polymer as the sea component and a sparingly soluble polymer as the island component, and the island component has a circumscribed-circle diameter of 10-1,000 nm, a dispersion in circumscribed-circle diameter of 1-20%, a degree of non-circularity of 1.2-5.0, and a dispersion in the degree of non-circularity of 1-10%.