Core spun yarn comprising short cellulosic staple fibers and polymeric fibers and process for its production

Abstract

A yarn comprising a filament core and a staple fiber sheath, said staple fiber sheath is made of, or comprises at least 95% by weight of, a blend of first fibers and second fibers, wherein said first fibers are natural cellulosic fibers and said second fibers are synthetic fibers, characterized in that: the weight ratio of said first fibers to said second fibers is in the range of 65/35 to 35/65, preferably said ratio being in the range 40/60 to 60/40, more preferably about 50/50; wherein the elongation at break of the polyester filaments of the filament core, measured according to DIN ISO 2062, is in the range of 5% to 15%, more preferably between 10% and 12%.

1 . A yarn comprising a filament core including polyester filaments and a staple fiber sheath, said staple fiber sheath comprising at least 95% by weight of a blend of first fibers and second fibers, wherein said first fibers are natural cellulosic fibers and said second fibers are synthetic fibers, wherein the weight ratio of said first fibers to said second fibers is in the range of 65/35 to 35/65, and wherein the elongation at break of the polyester filaments of the filament core, measured according to DIN ISO 2062, is in the range of 5% to 15. 
     
     
         2 . The yarn of  claim 1 , wherein an average length of the natural cellulosic fibers is between 6 and 16 mm. 
     
     
         3 . The yarn of  claim 1 , wherein an average length of the synthetic fibers is between 25 and 40 mm. 
     
     
         4 . The yarn of  claim 1 , wherein the first fibers are cotton fibers. 
     
     
         5 . The yarn of  claim 1 , wherein the second fibers are polyester or polyamide fibers. 
     
     
         6 . The yarn of  claim 1 , wherein the second fibers have tenacity higher than 6 g/den, according to ASTM D3822. 
     
     
         7 . The yarn of  claim 1 , wherein the filament core comprises at least one elastolefin filament. 
     
     
         8 . The yarn of  claim 7 , wherein the at least one elastolefin filaments filament has a draft between 4.0 and 6.0. 
     
     
         9 . A method for producing a yarn comprising the steps of:
 selecting a filament core comprising a plurality of polyester filaments, wherein elongation at break of the polyester filaments of the filament core is in the range of 5% to 15in accordance with DIN ISO 2062;   selecting first fibers that are natural cellulosic fibers;   selecting second fibers that are synthetic fibers;   providing a staple fiber sheath, comprising at least 95% by weight of a blend of said first fibers and said second fibers, wherein the weight ratio of said first fibers to said second fibers is in the range of 65/35 to 35/65; and   combining said filament core and said staple fiber sheath via ring spinning to obtain a core-sheath yarn.   
     
     
         10 . The method of  claim 9 , wherein the first fibers are recycled cotton fibers. 
     
     
         11 . The method of  claim 9 , wherein the polyester filaments of the core comprise recycled polyester. 
     
     
         12 . The method of  claims 9 , wherein the second fibers are obtained via cutting of a filament into staple fibers, the filament having tenacity higher than 6 g/den according to ASTM D3822. 
     
     
         13 . The method according to  claim 9 , further comprising dyeing the yarn is dyed in a bath where two different dyes are present. 
     
     
         14 . The method according to  claim 13 , wherein the first fibers are cotton fibers, the second fibers are polyester fibers, and the two different dyes comprise a VAT dye and a disperse dye. 
     
     
         15 . The yarn of  claim 1 , wherein said staple fiber sheath comprises 100% by weight of said blend of first fibers and second fibers, the weight ratio of said first fibers to said second fibers is in the range of 60/40 to 40/60 and wherein the elongation at break of the polyester filaments of the filament core is between 10% and 12% according to DIN ISO 2062. 
     
     
         16 . The yarn of  claim 1 , wherein the second fibers have a tenacity greater than 8 g/den according to ASTM D3822. 
     
     
         17 . The yarn of  claim 2 , wherein the average length of the synthetic fibers is between 25 and 40 mm and the first fibers are cotton fibers 
     
     
         18 . The method according to  claim 9 , wherein the elongation at break of the polyester filaments of the filament core is between 10% and 12% in accordance with DIN ISO 2062 and the weight ratio of said first fibers to said second fibers is about 50/50. 
     
     
         19 . The method according to  claim 9 , wherein the filament core comprises at least one elastolefin filament. 
     
     
         20 . The method of  claim 10 , wherein the polyester filaments of the core comprise recycled polyester.