Poly (lactic acid) fiber

Abstract

A poly(lactic acid) fiber has a strength at 90° C. of equal to or more than 0.8 cN/dtex and exhibits significantly satisfactory mechanical properties at high temperatures as compared with conventional poly(lactic acid) fibers.

1 - 25 . (canceled)  
   
   
       26 . A process for producing a poly(lactic acid) fiber, the process comprising the step of drawing a poly(lactic acid) undrawn yarn at such a drawn ratio (DR) as to satisfy the following condition:  
       0.85+( EL/ 100)≦ DR≦ 2.0+( EL/ 100)  
     wherein EL is the elongation (%) of the undrawn yarn.  
   
   
       27 . The process according to  claim 26  wherein the poly(lactic acid) undrawn yarn has a crystalline size in the (200) plane of equal to or more than 6 nm and is drawn at a temperature of equal to or higher than 85° C.  
   
   
       28 . The process according to  claim 26  wherein the poly(lactic acid) undrawn yarn has been obtained at a spinning speed of equal to or more than 4000 m/min.  
   
   
       29 . The process according to  claim 26  wherein the poly(lactic acid) undrawn yarn has a crystalline size in the (200) plane of less than 6 nm and is drawn at a temperature of equal to or higher than 110° C.  
   
   
       30 . The process according to  claim 26 , further comprising the step of subjecting the drawn yarn to heat treatment at a temperature of equal to or higher than 120° C.  
   
   
       31 . The process according to  claim 26  wherein the poly(lactic acid) undrawn yarn has Uster unevenness of less than or equal to 1.5%.  
   
   
       32 . The process according to  claim 26  wherein the drawing step is performed in a single stage.  
   
   
       33 . (canceled)  
   
   
       34 . A process for producing a poly(lactic acid) crimped yarn, the process comprising the step of crimping a poly(lactic acid) fiber obtained by the process as claimed in any one of  claims 26  to  32 .  
   
   
       35 . A fibrous article at least partially comprising the poly(lactic acid) fiber obtained by the process as claimed in  claim 26 .  
   
   
       36 . (canceled)  
   
   
       37 . A fibrous article at least partially comprising the poly(lactic acid) crimped yarn obtained by the process as claim in  claim 34.