Stretch polyester/cotton spun yarn

Abstract

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

What is claimed is:  
     
         1 . A spun yarn having a total boil-off shrinkage of at least about 22% comprising cotton and a bicomponent staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) said bicomponent staple fiber having: 
 a) a crimp development value of from about 35% to about 70%;    b) a crimp index value of from about 15% to about 45%;    c) a length of from about 1.3 cm to about 5.5 cm; and    d) a linear density of from about 0.7 decitex per fiber to about 3.0 decitex per fiber;    wherein the bicomponent staple fiber is present at a level of from about 20 wt %, to about about 65 wt %, based on total weight of the spun yarn; and wherein the cotton is present at a level of from about 35 wt % to about 80 wt %, based on total weight of the spun yarn.    
     
     
         2 . The spun yarn of  claim 1  wherein the bicomponent staple fiber has a crimp index value of from about 20% to about 30%.  
     
     
         3 . The spun yarn of  claim 1  having a coefficient of variation of mass no higher than about 22%, and wherein said bicomponent staple fiber has a decitex per fiber no higher than about 2.5.  
     
     
         4 . The spun yarn of  claim 1  wherein the bicomponent staple fiber is present at a level of less than 50 wt %, based on the total weight of spun yarn.  
     
     
         5 . The spun yarn of  claim 1  wherein the bicomponent staple fiber has a tenacity-at-break of from about 4.0 dN/tex to about 5.5 dN/tex, and the bicomponent staple fiber is present at a level of at least about 35 wt %, based on the total weight of spun yarn.  
     
     
         6 . A process for making the spun yarn of  claim 1  comprising the steps of: 
 a) providing bicomponent staple fiber having 
 (i) crimp development value of from about 35% to about 70%;  
 (ii) crimp index value of from about 15% to about 45%;  
 (iii) length of from about 1.3 cm to about 5.5 cm; and  
 (iv) linear density of from about 0.7 decitex per fiber to about 3.0 decitex per fiber;  
 
 b) providing cotton;  
 c) combining the cotton and the bicomponent staple fiber so that the bicomponent staple fiber is present at a level of from 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 from 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.  
 
     
     
         7 . The process of  claim 6  wherein the bicomponent staple fiber has a crimp index value of at least about 20% and is present at a level of less than 50 wt %, based on the total weight of the blended fibers.  
     
     
         8 . The process of  claim 6  wherein the spun yarn has a coefficient of variation of mass of no higher than about 22% and the bicomponent staple fiber is present at a level of at least about 35 wt %, based on the total weight of the blended fibers.  
     
     
         9 . A fabric selected from the group consisting of knits and wovens and comprising the spun yarn of  claim 1  made by the process of  claim 6 .  
     
     
         10 . A process for making the spun yarn of  claim 1  comprising the steps of: 
 a) providing bicomponent staple fiber;  
 b) providing cotton;  
 d) separately carding bicomponent staple fiber and 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.