Multifilament and method for producing the same

Abstract

A method for producing a multifilament, comprising (A) heat-melting a raw material composition to obtain a molten product and discharging the molten product through the discharge holes to obtain a plurality of raw filaments in a molten state; and (B) blowing gases onto the plurality of raw filaments, comprising (B1) blowing a first gas onto the plurality of raw filaments in the molten state to cool raw filaments and (B2) blowing a second gas onto the plurality of raw filaments cooled in (B1). In (B1), a temperature of the first gas is (Tc−45° C.) to (Tc−30° C.), Tc is a crystallization temperature of the poly(3-hydroxyalkanoate) resin, and in (B2), a temperature of the second gas is higher than the temperature of the first gas, and is (Tc−30° C.) to (Tc−10° C.). The raw material composition contains a poly(3-hydroxyalkanoate) resin. An average value of fineness of the single filaments is 15 dtex or less.

1 : A method for producing a multifilament comprising a plurality of single filaments by melt spinning by using a spinning nozzle that includes a plurality of discharge holes, the method comprising:
 (A) heat-melting a raw material composition to obtain a molten product and discharging the molten product through the discharge holes to obtain a plurality of raw filaments in a molten state; and   (B) blowing gases onto the plurality of raw filaments,   wherein:   the raw material composition comprises a poly(3-hydroxyalkanoate) resin;   (B) comprises (B1) blowing a first gas onto the plurality of raw filaments in the molten state to cool the plurality of raw filaments and (B2) blowing a second gas onto the plurality of raw filaments that have been cooled in (B1);   in (B1), a temperature of the first gas is from (Tc−45° C.) to (Tc−30° C.), wherein Tc is a crystallization temperature of the poly(3-hydroxyalkanoate) resin;   in (B2), a temperature of the second gas is higher than the temperature of the first gas, and is from (Tc−30° C.) to (Tc−10° C.); and   an average value of fineness of single filaments is 15 dtex or less.   
     
     
         2 : The method according to  claim 1 , wherein in (B1), the temperature of the first gas is from (Tc−40° C.) to (Tc−30° C.). 
     
     
         3 : The method according to  claim 1 , wherein in (B1), a speed of the first gas is from 0.1 to 1.0 m/s. 
     
     
         4 : The method according to  claim 1 , wherein in (B2), a speed of the second gas is from 0.005 to 1.5 m/s. 
     
     
         5 : The method according to  claim 1 , wherein a value obtained by subtracting the temperature of the first gas from the temperature of the second gas is from 5 to 25° C. 
     
     
         6 : The method according to  claim 1 , wherein the poly(3-hydroxyalkanoate) resin includes a poly(3-hydroxybutyrate) resin. 
     
     
         7 : A multifilament comprising a plurality of single filaments, wherein:
 the single filaments each contain a poly(3-hydroxyalkanoate) resin;   an average value of fineness of the single filaments is 15 dtex or less; and   a fusion rate of the single filaments is 10% or less.   
     
     
         8 : The multifilament according to  claim 7 , wherein a maximum height roughness of the single filaments is from 0.10 to 0.50 μm. 
     
     
         9 : The method according to  claim 2 , wherein in (B1), a speed of the first gas is from 0.1 to 1.0 m/s. 
     
     
         10 : The method according to  claim 2 , wherein in (B2), a speed of the second gas is from 0.005 to 1.5 m/s. 
     
     
         11 : The method for producing a multifilament according to  claim 2 , wherein a value obtained by subtracting the temperature of the first gas from the temperature of the second gas is from 5 to 25° C. 
     
     
         12 : The method for producing a multifilament according to  claim 2 , wherein the poly(3-hydroxyalkanoate) resin includes a poly(3-hydroxybutyrate) resin.