Lyocell Staple Fiber

Abstract

The present invention relates to Lyocell staple fiber consisting of a plurality of cut filaments, which is characterized in that at least part of said cut filaments exhibit an overall cross-sectional shape which is a bi- or multi-filar cross-sectional shape resulting from notionally partially overlapping two or more fiber cross-sectional shapes.

1 . A Lyocell staple fiber consisting of a plurality of cut filaments, wherein at least part of said cut filaments exhibit an overall cross-sectional shape which is a bi- or multi-filar cross-sectional shape resulting from notionally partially overlapping two or more fiber cross-sectional shapes. 
   
   
       2 . The Lyocell staple fiber according to  claim 1 , wherein at least part of, preferably all of said partially overlapped cross-sectional shapes are essentially circular shapes. 
   
   
       3 . The Lyocell staple fiber according to  claim 2 , wherein said two or more partially overlapped circular shapes have essentially the same diameter. 
   
   
       4 . The Lyocell staple fiber according to  claim 2 , wherein one or more of said partially overlapped circular shapes has/have a higher diameter than the rest of said overlapped circular shapes. 
   
   
       5 . The Lyocell staple fiber according to  claim 1 , wherein said overall cross-sectional shape is a bi-filar cross-sectional shape resulting from notionally overlapping two essentially circular shapes. 
   
   
       6 . The Lyocell staple fiber according to  claim 1 , wherein said overall cross-sectional shape is a tri-filar cross-sectional shape resulting from notionally overlapping three essentially circular shapes. 
   
   
       7 . The Lyocell staple fiber according to  claim 6 , wherein said three overlapped circular shapes are arranged in a row. 
   
   
       8 . The Lyocell staple fiber according to  claim 7 , wherein said three overlapped circular shapes are arranged in the form of a triangle. 
   
   
       9 . (canceled) 
   
   
       10 . The Lyocell staple fiber according to  claim 1 , wherein said overall cross-sectional shape is a quadri-filar cross-sectional shape resulting from notionally overlapping four essentially circular shapes. 
   
   
       11 . The Lyocell staple fiber according to  claim 10 , wherein said four overlapped circular shapes are arranged in a row. 
   
   
       12 . The Lyocell staple fiber according to  claim 10 , wherein said four overlapped circular shapes are arranged in the form of a square, a parallelogram, or a rhombus. 
   
   
       13 . The Lyocell staple fiber according to  claim 10 , wherein said four overlapped circular shapes are arranged in the form of a triangle, with one of said circular shapes forming the centre of said triangle. 
   
   
       14 . (canceled) 
   
   
       15 . The Lyocell staple fiber according to  claim 1 , wherein said overall cross-sectional shape is a multi-filar cross-sectional shape resulting from notionally overlapping five or more, preferably five or seven essentially circular shapes. 
   
   
       16 . The Lyocell staple fiber according to  claim 1 , wherein at least one of said partially overlapped cross-sectional shapes is a non-circular cross-sectional shape. 
   
   
       17 . Lyocell staple fiber according to  claim 16 , wherein said non-circular cross-sectional shape is a multilobal, preferably trilobal, or triangular shape. 
   
   
       18 . The Lyocell staple fiber according to any of the preceding claims, wherein essentially all of the cut filaments exhibit essentially the same overall cross-sectional shape. 
   
   
       19 . The Lyocell staple fiber according to  claim 1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  10 ,  11 ,  12 ,  13 ,  15 ,  16 , or  17 , wherein said overall cross-sectional shape is hollow. 
   
   
       20 . The Lyocell staple fiber according to  claim 1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  10 ,  11 ,  12 ,  13 ,  15 ,  16 , or  17 , wherein it exhibits a fiber tenacity in conditioned state which is higher by at least 15%, preferably at least 20%, than the fiber tenacity of a comparison Lyocell staple fiber of the same decitex, wherein all cut filaments of said comparison Lyocell staple fiber exhibit an essentially round cross-section. 
   
   
       21 . The Lyocell staple fiber according to  claim 1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  10 ,  11 ,  12 ,  13 ,  15 ,  16 , or  17 , wherein it exhibits a decitex-related flexural rigidity of at least 0.5 mN·mm 2 /tex 2 , preferably more than 0.6 mN·mm 2 l/tex 2 . 
   
   
       22 . A process for the manufacture of a Lyocell staple fiber according to  claims 1 , comprising the steps of
 extruding a solution of cellulose dissolved in an aqueous tertiary amine-oxide through a spinneret exhibiting a plurality of spinneret orifices whereby filaments are formed   conducting said filaments via an air gap into a precipitation bath   drawing said filaments in said air gap   blowing air on said filaments in said air gap   precipitating said filaments in said precipitation bath   cutting said precipitated filaments in order to form cut filaments,   wherein   at least part of said spinneret orifices consists of an assembly of two or more holes being located adjacent such that when the solution is extruded through said holes, the filaments extruded from said holes are partially fused to form one fused filament.   
   
   
       23 . The process according to  claim 22 , wherein at least part of, preferably all of said holes have a circular shape. 
   
   
       24 . The process according to  claim 23 , wherein all of said holes have the same diameter. 
   
   
       25 . The process according to  claim 23 , wherein at least one or more of said holes has/have a higher diameter than the rest of said holes. 
   
   
       26 . (canceled) 
   
   
       27 . The process according to  claim 22 , wherein said spinneret orifice consists of two to fiver or seven holes, each having a circular shape. 
   
   
       28 - 38 . (canceled) 
   
   
       39 . The process according to any one of  claims 22 , wherein all of said spinneret orifices consist of an identical assembly of holes in terms of the geometrical arrangement, the shape and the size of said holes. 
   
   
       40 . The process according to  claim 39 , wherein said spinneret orifices are positioned in a plurality of parallel rows and in that, within each of said rows, all assemblies of holes are oriented essentially parallel to each other. 
   
   
       41 . The process according to  claim 40 , wherein said air blown on said filaments in the air gap is directed onto said filaments
 in case of a row arrangement of said holes, essentially parallel to the direction of said row   in case of a triangle arrangement of said holes, essentially parallel to the direction of one of the base lines of said triangle   in case of a square arrangement of said holes, essentially parallel to the direction of one of the base lines of said square   in case of other geometrical arrangement of said holes, essentially parallel to the direction of the main orientation axis of said arrangement   
   
   
       42 - 43 . (canceled) 
   
   
       44 . A product comprising the Lyocell staple fiber according to  claim 1  wherein the product is selected from the group consisting of medical-, hygiene-, household textiles, technical- and apparel applications, such as wound dressings, laparotomy pads, bed pads, tampons, sanitary towels, wipes, incontinence products, pillows, duvets, towels, carpets, pile fabrics, damask, satin, insulation materials, reinforcement fiber for polymers, paper or concrete, textile articles, such as knitted or woven textile articles, shirtings, velour, chinos, cotton-like hand fabrics and garments made thereof. 
   
   
       45 . The Lyocell fiber according to  claim 5 ,  6 ,  7 ,  8 ,  10 ,  11 ,  12 ,  13  or  15 , wherein said filaments exhibit a decitex of from about 0.5 to 8 dtex, preferably 0.5 to 4 dtex.