Staple yarn manufacturing process

Abstract

The present invention is a staple-fiber yarn, an apparatus for producing the yarn, and a process for stretch breaking filament yarns to produce the staple yarn. The process enables the production of a plurality of products of lot size smaller than a large denier tow product. The process includes a draw zone, a tension control zone, a stretch-break zone and a consolidation zone to form a yarn of staple fibers.

1 . A process for making a staple yarn from a filament yarn comprising 
 (a) subjecting the filament yarn to an amount of tension at which filaments in the yarn are drawn,    (b) subjecting the yarn to an amount of tension at which the filaments in the yarn are not further drawn and are not broken,    (c) subjecting the yarn to an amount of tension at which filaments in the yarn are broken to form staple fibers, and    (d) consolidating the staple fibers to form a staple yarn.    
   
   
       2 . The process of  claim 1  wherein the filament yarn has not been drawn before being drawn in step (a).  
   
   
       3 . The process of  claim 1  wherein the filament yarn has been partially drawn before being drawn in step (a).  
   
   
       4 . The process of  claim 1  wherein the filament yarn is prepared from one or more polymers selected from the group consisting of polyester, polyamide and polypropylene.  
   
   
       5 . The process of  claim 1  further comprising steps of adding continuous filaments and/or consolidated staple yarn to the staple fibers as formed from step (c), and consolidating the continuous filaments and/or consolidated staple yarn with the staple fibers to from a staple yarn in step (d).  
   
   
       6 . The process of  claim 5  wherein the consolidated staple yarn is prepared from one or more materials selected from the group consisting of polymers, metals, glass and natural fibers.  
   
   
       7 . The process of  claim 1  further comprising steps of adding fully-drawn filament yarn, as a second yarn, to the yarn that is drawn in step (a), as a first yarn, and subjecting both the first and second yarns to tension in step (b) together.  
   
   
       8 . The process of  claim 7  wherein the second yarn is prepared from one or more materials selected from the group consisting of polyester, polyamide, polypropylene, aramid, acetate and regenerated cellulose.  
   
   
       9 . The process of  claim 1  wherein, in step (b), the filament yarn is subjected to a smaller amount of tension than it is subjected to in step (a).  
   
   
       10 . The process of  claim 1  wherein, in step (b), the filament yarn is subjected to the same amount of tension that it is subjected to in step (a).  
   
   
       11 . The process of  claim 1  wherein, in step (b), the filament yarn is subjected to a greater amount of tension than it is subjected to in step (a).  
   
   
       12 . A spinning apparatus for making a staple yarn from filament yarn comprising 
 (a) a draw zone wherein the yarn is subjected to an amount of tension at which filaments in the yarn are drawn,    (b) a tension control zone, into which the filament yarn is passed from the draw zone, wherein the yarn is subjected to an amount of tension at which the filaments in the yarn are not further drawn and are not broken,    (c) a stretch-break zone, into which the filament yarn is passed from the tension control zone, wherein the yarn is subjected to an amount of tension at which filaments in the yarn are broken to form staple fibers, and    (d) a consolidating zone, into which the staple fibers are passed from the stretch-break zone, wherein the staple fibers are consolidated to form a staple yarn.    
   
   
       13 . A staple yarn comprising staple fibers wherein the staple fibers have a weight average fiber length of less than about 6 inches, and a fiber length distribution in the range of from less than 1 inch to about 25 inches.  
   
   
       14 . The yarn of  claim 13  wherein more than 50% of the staple fibers have a length that is in the range of about 0.5 to about 1.5 times the weight average fiber length.  
   
   
       15 . The yarn of  claim 13  further comprising continuous filaments.