Methods for making elastic composite yarns

Abstract

Methods are provided to make composite yarns having a filamentary core with at least one elastic performance filament and at least one inelastic control filament. A fibrous sheath, preferably formed from spun staple fibers, surrounds the filamentary core, preferably substantially along the entire length thereof. The at least one elastic performance filament most preferably includes a spandex and/or a lastol filament. The at least one inelastic control filament is most preferably formed of a textured polymer or copolymer of a polyamide, a polyester, a polyolefin and mixtures thereof. Preferably, the fibrous sheath is formed of synthetic and/or natural staple fibers, most preferably staple cotton fibers. The elastic composite fibers find particular utility as a component part of a woven textile fabric, especially as a stretch denim fabric, which exhibits advantageous elastic recovery of at least about 95.0% (ASTM D3107).

What is claimed is: 
     
         1 . An elastic composite yarn comprising a filamentary core comprised of at least one elastic performance filament and at least one control filament, and a fibrous sheath comprised of spun staple fibers surrounding the filamentary core. 
     
     
         2 . An elastic composite yarn according to  claim 1 , wherein the at least one elastic performance filament comprises a spandex and/or a lastol filament 
     
     
         3 . An elastic composite yarn according to  claim 1 , wherein the control filament comprises a textured filament formed of a polymer or copolymer of a polyamide, a polyester, a polyolefin and mixtures thereof. 
     
     
         4 . An elastic composite yarn according to  claim 1 , wherein the fibrous sheath comprises synthetic and/or natural staple fibers. 
     
     
         5 . An elastic composite yarn according to  claim 1 , wherein the fibrous sheath comprises cotton fibers. 
     
     
         6 . An elastic composite yarn according to  claim 1 , wherein the elastic performance filament has a draft ratio of at least about 2.0, and wherein the control filament has a draft ratio of about 1.0. 
     
     
         7 . An elastic composite yarn according to  claim 6 , wherein the elastic performance filament has a draft ratio of at least about 3.0. 
     
     
         8 . An elastic composite yarn according to  claim 1 , wherein at least one of the elastic performance filament and the control filament has a denier of between about 10 to about 140. 
     
     
         9 . An elastic composite yarn according to  claim 1 , wherein each of the at least one of the elastic performance filament and the control filament has a denier of about 70. 
     
     
         10 . An elastic composite yarn according to  claim 9 , wherein the fibrous sheath is ring spun from a cotton staple fiber roving having a cotton hank yarn count of between about 0.35 to about 1.00. 
     
     
         11 . A woven fabric which comprises at least one elastic composite yarn as in  claim 1  present as a warp and/or filling yarn in the fabric. 
     
     
         12 . A woven fabric as in  claim 11 , in the form of a denim fabric which exhibits a percent elastic recovery of at least about 95.0% according to ASTM D3107. 
     
     
         13 . A woven fabric as in  claim 11 , having a plain weave, a twill weave or a satin weave pattern. 
     
     
         14 . Apparatus for making a composite elastic yarn comprising:
 a spinning section for spinning a fibrous sheath around a filamentary core comprised of at least one elastic performance filament and at least one control filament; and   draw ratio controllers operatively associated with each of the at least one elastic performance filament and the at least one control filament, the draw ratio controllers supplying the at least one elastic performance filament to the spinning section at a draw ratio which is at least two times the draw ratio of the control filament supplied to the spinning section.   
     
     
         15 . Apparatus as in  claim 14 , wherein the draw ratio controller for the at least one elastic performance filament supplies the at least one elastic performance filament to the spinning section at a draft ratio which is at least three times the draft ratio of the at least one control filament. 
     
     
         16 . Apparatus as in  claim 14 , wherein the fibrous sheath is spun from a roving of synthetic and/or natural staple fibers, and wherein the apparatus further comprises a draw ratio control which controls the draw ratio of the roving so that the roving is supplied to the spinning section at a draw ratio which is substantially the same as the draw ratio of the control filament. 
     
     
         17 . Apparatus as in  claim 14 , wherein the spinning section comprises a ring-spinning assembly.