Undrawn multifilament, method for producing the same, multifilament, method for producing the same, staple, and method for producing the same

Abstract

The present invention is directed to an undrawn multifilament including 30 or more individual filaments. In the undrawn multifilament, the individual filaments contain a poly(3-hydroxyalkanoate) resin and a nucleating agent, the mean of the finenesses of the individual filaments is 30 dtex or less, and the coefficient of variation of the finenesses of the individual filaments is 33% or less.

1 . An undrawn multifilament comprising at least 30 individual filaments, wherein
 the individual filaments comprise a poly(3-hydroxyalkanoate) resin and a nucleating agent,   a mean of finenesses of the individual filaments is 30 dtex or less, and   a coefficient of variation of the finenesses of the individual filaments is 33% or less.   
     
     
         2 . The undrawn multifilament according to  claim 1 , wherein the poly(3-hydroxyalkanoate) resin comprises a poly(3-hydroxybutyrate) resin. 
     
     
         3 . A stretched multifilament comprising at least 30 individual filaments, wherein
 the individual filaments comprise a poly(3-hydroxyalkanoate) resin and a nucleating agent,   a mean of finenesses of the individual filaments is 20 dtex or less, and   a coefficient of variation of the finenesses of the individual filaments is 33% or less.   
     
     
         4 . A staple comprising a cut piece of the multifilament according to  claim 3 , wherein the staple has a length of 20 cm or less. 
     
     
         5 . An undrawn multifilament production method for obtaining an undrawn multifilament by melt spinning, the method comprising:
 (A) conducting the melt spinning comprising discharging a melt using a spinning nozzle having at least 30 discharge holes to obtain at least 30 raw filaments in a molten state; and   (B) blowing a gas having a temperature of from 0 to 50° C. onto the at least 30 raw filaments in the molten state to cool the at least 30 raw filaments and obtain an undrawn multifilament, wherein   the melt comprises a poly(3-hydroxyalkanoate) resin and a nucleating agent,   a mean of finenesses of individual filaments of the undrawn multifilament is 30 dtex or less, and   in (B), a coefficient of heat transfer between the gas and the at least 30 raw filaments in the molten state is at least 60 W/(m 2 ·K).   
     
     
         6 . The undrawn multifilament production method according to  claim 5 , wherein in (B), the coefficient of heat transfer is at least 125 W/(m 2 ·K). 
     
     
         7 . The undrawn multifilament production method according to  claim 5 , wherein in (B), a speed of the gas blown onto the at least 30 raw filaments is at least 0.1 m/s. 
     
     
         8 . A multifilament production method comprising:
 obtaining an undrawn multifilament using the undrawn multifilament production method according to  claim 5 ; and   the step of (C) stretching the undrawn multifilament by a stretching roll unit at a stretching ratio of at least 1.5 to obtain a multifilament.   
     
     
         9 . The multifilament production method according to  claim 8 , wherein
 in (B), the gas having a temperature of from 0 to 50° C. is blown onto the at least 30 raw filaments in the molten state to cool the at least 30 raw filaments to below 50° C. and obtain the undrawn multifilament, and   in (C), the undrawn multifilament is heated, and a heated undrawn multifilament is stretched by the stretching roll unit.   
     
     
         10 . A staple production method comprising:
 obtaining a multifilament using the multifilament production method according to  claim 8 ; and   cutting the multifilament to obtain a staple having a length of 20 cm or less.