Bicomponent fiber and yarn comprising such fiber

1. A spun yarn having a cotton count of about 14 to about 60 and comprising bicomponent staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate), said spun yarn having about 0.1 to about 150 thin regions per 1000 yards, about 0.1 to about 300 thick regions per 1000 yards, about 0.1 to about 260 neps per 1000 yards, and a boil-off shrinkage of about 27% to about 45%, wherein the bicomponent staple fiber is present at a level of about 30 wt % to about 100 wt %, based on total weight of the spun yarn.

2. The spun yarn of claim 1 further comprising a staple fiber selected from the group consisting of cotton, synthetic cellulosic, and acrylic fibers, wherein the bicomponent is present at about 30 wt % to about 70 wt %, based on total weight of the spun yarn.

3. The spun yarn of claim 2 wherein the selected staple fiber is cotton, and the bicomponent staple fiber has an aspect ratio A:B of about 2.6:1 to about 3.9:1 wherein A is a fiber cross-section major axis length and B is a fiber cross-section minor axis length.

4. The spun yarn of claim 1 having a quality factor of about 0.1 to about 650.

5. The spun yarn of claim 1 wherein said bicomponent staple fiber has a free fiber length retention of about 40% to about 85%.

6. The spun yarn of claim 2 further comprising about 1 wt % to about 69 wt % poly(ethylene terephthalate) monocomponent staple fiber.

7. The spun yarn of claim 2 having a total boil-off shrinkage of from about 27% to about 45% and a coefficient of variation of mass from about 10% to about 18%.

8. The spun yarn of claim 7 having a total boil-off shrinkage of from about 30% to about 45% and a coefficient of variation of mass from about 12% to about 16%.

9. The spun yarn of claim 2 having a quality factor of from about 0.1 to about 650 and a total boil-off shrinkage of from about 27% to about 45%.

10. The spun yarn of claim 9 having a quality factor of from about 1 to about 300 and a total boil-off shrinkage of from about 30% to about 45%.

11. A fabric selected from the group consisting of knits and wovens and comprising the spun yarn of claim 1 .

12. The fabric of claim 11 further comprising a bicomponent staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate), said bicomponent staple fiber having:

a) a substantially oval cross-section shape having an aspect ratio A:B of about 2:1 to about 5:1 wherein A is a fiber cross-section major axis length and B is a fiber cross-section minor axis length;

b) a polymer interface substantially perpendicular to the major axis;

c) a cross-section configuration selected from the group consisting of side-by-side and eccentric sheath-core;

d) a tenacity at 10% elongation of about 1.1 cN/dtex to about 3.5 cN/dtex;

e) a free fiber length retention of about 40% to about 85%, and

f) a tow crimp development value of about 30% to 55%.