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% and comprising cotton and a bicomponent staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) wherein the bicomponent fiber has: 
 a crimp development value of at least about 35%;    a crimp development value no higher than about 70%;    a crimp index value at least 15%;    a crimp index value no higher than about 45%;    a length of at least about 1.3 cm;    a length no higher than about 5.5 cm;    a linear density of at least about 0.7 decitex per fiber; and    a linear density of no higher than about 3.0 decitex per fiber;    wherein the bicomponent fiber is present at a level of at least about 20 wt %, based on total weight of the spun yarn;    wherein the bicomponent fiber is present at a level no higher than about 65 wt %, based on total weight of the spun yarn;    wherein the cotton is present at a level of at least about 35 wt %, based on total weight of the spun yarn; and    wherein the cotton is present at a level no higher than about 80 wt %, based on total weight of the spun yarn.    
     
     
         2 . The spun yarn of  claim 1  wherein the bicomponent fiber has a crimp index value of at least about 20% and the bicomponent fiber has a crimp index value no higher than about 30%.  
     
     
         3 . The spun yarn of  claim 1  wherein a coefficient of variation of linear density is no higher than about 22%, and the bicomponent fiber has a decitex per fiber no higher than about 2.5.  
     
     
         4 . The spun yarn of  claim 1  wherein the bicomponent 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 at least about 4.0 dN/tex, and the bicomponent staple fiber has a tenacity-at-break of no higher than 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 the bicomponent staple fiber;  
 b) providing cotton;  
 c) combining by intimate blending at least the cotton and the bicomponent staple fiber so that: 
 the bicomponent fiber is present at a level of at least about 20 wt %;  
 the bicomponent fiber is present at a level no higher than about 65 wt %;  
 the cotton is present at a level of at least about 35 wt %; and  
 the cotton is present at a level no higher than 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 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, and the ring-spinning provides a twist multiplier of about 3 to 5.5.  
     
     
         8 . The process of  claim 6  wherein the bicomponent fiber has a decitex per fiber no higher than about 2.5.  
     
     
         9 . The process of  claim 6  wherein the spun yarn has a coefficient of variation of linear density 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.  
     
     
         10 . A fabric selected from the group consisting of knits and wovens and comprising the spun yarn of  claim 1.