Stretch polyester/cotton spun yarn

Abstract

The invention provides a bicomponent polyester staple fiber and a spun yarn comprising cotton and a bicomponent polyester staple. The fiber of the invention exhibits unexpectedly good crimp and cardability properties, and the yarn has unusually high stretch characteristics and excellent uniformity.

1 - 6 . (canceled)  
     
     
         7 . A process for making a spun yarn comprising the steps of: 
 a) providing bicomponent staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) and having 
 (i) tow crimp development value of about 35% to about 70%;  
 (ii) tow crimp index value of about 14% to about 45%;  
 (iii) length of about 1.3 cm to about 5.5 cm; and  
 (iv) linear density of about 0.7 decitex per fiber to about 3.0 decitex per fiber;  
   b) providing cotton;    c) combining at least the cotton and the bicomponent staple fiber so that the bicomponent staple fiber is present at a level of about 20 wt % to about 65 wt % based on the total weight of the blended fibers and the cotton is present at a level of about 35 wt % to about 80 wt % based on total weight of the blended fibers;    d) carding the blended fibers to form a card sliver;    e) drawing the card sliver;    f) doubling and redrawing the card sliver up to about 3 times;    g) converting the drawn sliver to roving; and    h) ring-spinning the roving to form the spun yarn having a total boil-off shrinkage of at least about 22%.    
     
     
         8 . The process of  claim 7  wherein the bicomponent staple fiber has a tow crimp development value of about 40% to about 60% and a tow crimp index value of about 14% to about 27%, wherein the difference between the crimp index and the crimp development values is about 24% to about 35% absolute.  
     
     
         9 . The process of  claim 7  wherein the spun yarn has a coefficient of variation of mass of no higher than about 22%, step c) is an intimate blending step, and the bicomponent staple fiber is present at a level of about 20 wt % to less than 50 wt %.  
     
     
         10 . canceled  
     
     
         11 . A process for making a spun yarn comprising the steps of: 
 a) providing bicomponent staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate);    b) providing cotton;    d) separately carding the bicomponent staple fiber and the cotton to form a bicomponent staple fiber card sliver and a cotton card sliver;    e) draw-frame blending the bicomponent staple fiber card sliver and the cotton card sliver so that (i) the bicomponent fiber is present at a level of from about 20 wt % to about 65 wt %; and (ii) the cotton is present at a level of from about 35 wt % to about 80 wt %, based on total weight of the blended fibers;    f) doubling and redrawing the blended card sliver of step (e) up to about 3 times;    g) converting the drawn sliver to roving; and    h) ring-spinning the roving to form the spun yarn having a total boil-off shrinkage of at least about 22%.    
     
     
         12 . The process of  claim 7  wherein the difference between the crimp index and the crimp development values of the bicomponent staple fiber is about 24% to about 35% absolute.  
     
     
         13 . A process for making a spun yarn comprising the steps of: 
 a) providing bicomponent staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) and having 
 (i) tow crimp development value of about 35% to about 70%;  
 (ii) tow crimp index value of about 14% to about 45%;  
 (iii) length of about 1.3 cm to about 5.5 cm; and  
 (iv) linear density of about 0.7 decitex per fiber to about 3.0 decitex per fiber;  
   b) providing cotton;    c) combining at least the cotton and the bicomponent staple fiber so that the bicomponent staple fiber is present at a level of about 20 wt % to about 65 wt % based on the total weight of the blended fibers and the cotton is present at a level of about 35 wt % to about 80 wt % based on total weight of the blended fibers; and    d) carding the blended fibers to form a card sliver,    wherein the spun yarn has a total boil-off shrinkage of at least about 22%.    
     
     
         14 . The process of  claim 13  further comprising a step of drawing the card sliver.  
     
     
         15 . A process for making a spun yarn comprising the steps of: 
 a) providing bicomponent staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate);    b) providing cotton; and    c) separately carding bicomponent staple fiber and cotton to form a bicomponent staple fiber card sliver and a cotton card sliver,    wherein the spun yarn has a total boil-off shrinkage of at least about 22%.    
     
     
         16 . The process of  claim 15  further comprising a step of draw-frame blending the bicomponent staple fiber card sliver and the cotton card sliver so that (i) the bicomponent fiber is present at a level of from about 20 wt % to about 65 wt %; and (ii) the cotton is present at a level of from about 35 wt % to about 80 wt %, based on total weight of the blended fibers.