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

Abstract

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

1 - 10 . (canceled) 
     
     
         11 . 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. 
     
     
         12 . The ultrafine polyamide fiber as defined in  claim 11 , wherein Uster unevenness in a filament in a length direction is 1.0% or less. 
     
     
         13 . The ultrafine polyamide fiber as defined in  claim 11 , having a total fineness of 15 to 300 dtex and containing 30 or more filaments. 
     
     
         14 . The ultrafine polyamide fiber as defined  claim 12 , having a total fineness of 15 to 300 dtex and containing 30 or more filaments. 
     
     
         15 . The ultrafine polyamide fiber as defined in  claim 11 , wherein filaments have a modified cross section. 
     
     
         16 . The ultrafine polyamide fiber as defined in  claim 12 , wherein filaments have a modified cross section. 
     
     
         17 . The ultrafine polyamide fiber as defined in  claim 13 , wherein filaments have a modified cross section. 
     
     
         18 . The ultrafine polyamide fiber as defined in  claim 14 , wherein filaments have a modified cross section. 
     
     
         19 . The ultrafine polyamide fiber as defined in  claim 11 , wherein the single yarns contained in the ultrafine polyamide fiber have a circular filament cross section, orientation parameters of the single yarns with a circular cross section are such that a ratio of an orientation parameter of a surface portion of the single yarn to an orientation parameter of a central portion of the single yarn is 1.10 or more. 
     
     
         20 . The ultrafine polyamide fiber as defined in  claim 12 , wherein the single yarns contained in the ultrafine polyamide fiber have a circular filament cross section, orientation parameters of the single yarns with a circular cross section are such that a ratio of an orientation parameter of a surface portion of the single yarn to an orientation parameter of a central portion of the single yarn is 1.10 or more. 
     
     
         21 . The ultrafine polyamide fiber as defined in  claim 13 , wherein the single yarns contained in the ultrafine polyamide fiber have a circular filament cross section, orientation parameters of the single yarns with a circular cross section are such that a ratio of an orientation parameter of a surface portion of the single yarn to an orientation parameter of a central portion of the single yarn is 1.10 or more. 
     
     
         22 . The ultrafine polyamide fiber as defined in  claim 14 , wherein the single yarns contained in the ultrafine polyamide fiber have a circular filament cross section, orientation parameters of the single yarns with a circular cross section are such that a ratio of an orientation parameter of a surface portion of the single yarn to an orientation parameter of a central portion of the single yarn is 1.10 or more. 
     
     
         23 . 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. 
     
     
         24 . The method as defined in  claim 23 , wherein the cooling apparatus cools the melt-spun yarns by supplying cooling air from inside of the melt-spun yarns discharged from the discharge holes. 
     
     
         25 . The method as defined in  claim 23 , wherein the cooling apparatus satisfies:
 (1) distance (L) from a face of the spinning spinneret to a cooling start position of the cooling apparatus is as follows: 10 mm≦L≦70 mm, and   (2) cooling air provided at the cooling start position has a flow speed of 15 to 60 m/min.   
     
     
         26 . The method as defined in  claim 24 , wherein the cooling apparatus satisfies:
 (1) distance (L) from a face of the spinning spinneret to a cooling start position of the cooling apparatus is as follows: 10 mm≦L≦70 mm, and   (2) cooling air provided at the cooling start position has a flow speed of 15 to 60 m/min.   
     
     
         27 . 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.   
     
     
         28 . The melt-spinning apparatus for ultrafine polyamide fiber as defined in  claim 27 , wherein the cooling apparatus cools the melt-spun yarns by supplying cooling air from inside of the melt-spun yarns discharged from the discharge holes.