Ultrafine polyamide fiber, and melt-spinning method and device therefor

Ultrafine polyamide fiber comprising polyamide fiber with a single yarn fineness of 0.10 dtex or more and 0.50 dtex or less and an average number of fuzzes of 1.0 or less per 12,000 m of a filament in a length direction.

A melt-spinning method for ultrafine polyamide fiber having a single yarn fineness of 0.10 dtex or more and 0.50 dtex or less and having an average of 1.0 or less fuzzes per 12,000 m in a length direction, wherein melt-spun yarns discharged from a spinning spinneret provided with discharge holes arranged circumferentially in the outer circumferential portion of the spinning spinneret are cooled by a cooling apparatus located below a central portion of the spinning spinneret and cool the melt-spun yarns by applying cooling air from either inside or outside of the melt-spun yarns discharged from the discharge holes, a finishing oil is supplied by a circular finishing oil supply apparatus having a disk-like guide portion located vertically below the cooling apparatus and that is in contact with the single yarns at its outer circumferential portion and also having a circular finishing oil-discharging slit located directly above the guide portion and arranged along the outer circumference of the guide and, subsequently, the yarns are bundled by a bundle-guide type finishing oil supply apparatus while receiving a second-stage finishing oil supply.

A melting spinning apparatus that produces ultrafine polyamide fiber having a single yarn fineness of 0.10 dtex or more and 0.50 dtex or less and having an average of 1.0 or less fuzzes per 12,000 m in a length direction, comprises:

• a spinning spinneret provided with discharge holes arranged circumferentially in an outer circumferential portion of the spinning spinneret, and a cooling apparatus located below a central portion of the spinning spinneret and cools the melt-spun yarns by applying cooling air from inside or outside of the melt-spun yarns discharged from the discharge holes, and
• a circular finishing oil supply apparatus having a disk-like guide portion located vertically below the cooling apparatus and in contact with the single yarns at an outer-circumferential portion, a circular finishing oil-discharging slit located directly above the guide portion and arranged along an outer circumference of the guide, and a bundle-guide type finishing oil supply apparatus located thereunder and intended to bundle the yarns while performing a second-stage finishing oil supply.