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 - 44 . (canceled) 
     
     
         45 . A process for the manufacture of a Lyocell staple fiber, 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,   said process being characterized in that 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; and   in case of other geometrical arrangement of said holes, essentially parallel to the direction of the main orientation axis of said arrangement.   
     
     
         46 . The process according to  claim 45 , wherein all of said holes have a circular shape. 
     
     
         47 . The process according to  claim 46 , wherein all of said holes have the same diameter. 
     
     
         48 . The process according to  claim 46 , wherein at least one or more of said holes has/have a higher diameter than the rest of said holes. 
     
     
         49 . The process according to  claim 48 , wherein the ratio of the cross-sectional area of the hole(s) with the higher diameter to the cross-sectional area of the hole(s) with a smaller diameter is from more than 1:1 to 16:1. 
     
     
         50 . The process according to  claim 45 , 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. 
     
     
         51 . The process according to  claim 50 , 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. 
     
     
         52 . The process according to  claim 45 , wherein the diameter of said holes in said hole assembly is from 35 to 200 μm. 
     
     
         53 . The process according to  claim 45 , wherein the distance from the centre of one hole to the centre of the next adjacent hole in said hole assembly is from 100 to 500 μm, preferably 150 to 250 μm. 
     
     
         54 . The process according to  claim 45 , wherein at least one of said holes has a non-circular shape. 
     
     
         55 . The process according to  claim 54 , wherein said non-circular shape is a multilobal, preferably trilobal, or triangular shape. 
     
     
         56 . A Lyocell staple fiber consisting of a plurality of cut filaments, obtainable by a process according to  claim 46 , 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 and wherein all of said partially overlapped cross-sectional shapes are essentially circular shapes. 
     
     
         57 . The Lyocell staple fiber according to  claim 56 , wherein said two or more partially overlapped circular shapes have essentially the same diameter. 
     
     
         58 . The Lyocell staple fiber according to  claim 56 , wherein one or more of said partially overlapped circular shapes has/have a higher diameter than the rest of said overlapped circular shapes. 
     
     
         59 . The Lyocell staple fiber according to  claim 56 , wherein said overall cross-sectional shape is a bi-filar cross-sectional shape resulting from notionally overlapping two essentially circular shapes. 
     
     
         60 . The Lyocell staple fiber according to  claim 56 , wherein said overall cross-sectional shape is a tri-filar cross-sectional shape resulting from notionally overlapping three essentially circular shapes. 
     
     
         61 . The Lyocell staple fiber according to  claim 60 , wherein said three overlapped circular shapes are arranged in a row. 
     
     
         62 . The Lyocell staple fiber according to  claim 60 , wherein that said three overlapped circular shapes are arranged in the form of a triangle. 
     
     
         63 . The Lyocell staple fiber according to  claim 56 , wherein said overall cross-sectional shape is a quadri-filar cross-sectional shape resulting from notionally overlapping four essentially circular shapes. 
     
     
         64 . The Lyocell staple fiber according to  claim 63 , wherein said four overlapped circular shapes are arranged in a row. 
     
     
         65 . The Lyocell staple fiber according to  claim 63 , wherein said four overlapped circular shapes are arranged in the form of a square, a parallelogram, or a rhombus. 
     
     
         66 . The Lyocell staple fiber according to  claim 63 , 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. 
     
     
         67 . The Lyocell staple fiber according to  claim 56 , wherein said filaments exhibit a decitex of from 0.5 to 8 dtex. 
     
     
         68 . The Lyocell staple fiber according to  claim 56 , wherein said overall cross-sectional shape is a multi-filar cross-sectional shape resulting from notionally overlapping five or more essentially circular shapes. 
     
     
         69 . The Lyocell staple fiber according to  claim 56 , wherein essentially all of the cut filaments exhibit essentially the same overall cross-sectional shape. 
     
     
         70 . The Lyocell staple fiber according to  claim 56 , wherein said overall cross-sectional shape is hollow. 
     
     
         71 . The Lyocell staple fiber according to  claim 56 , wherein the fiber exhibits a fiber tenacity in conditioned state which is higher by at least 15% 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. 
     
     
         72 . The Lyocell staple fiber according to  claim 56 , wherein the fiber exhibits a decitex-related flexural rigidity of at least 0.5 mN.mm 2 /tex 2 . 
     
     
         73 . A product comprising the staple fiber according to  claim 56  wherein said 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. 
     
     
         74 . The process according to  claim 49 , wherein the ratio of the cross-sectional area of the hole(s) with the higher diameter to the cross-sectional area of the hole(s) with a smaller diameter is from more than 1.6 to 1 to 2.7 to 1. 
     
     
         75 . The Lyocell staple fiber according to  claim 67 , wherein said filaments exhibit a decitex of from 0.5 to 4 dtex. 
     
     
         76 . The Lyocell staple fiber according to  claim 68 , wherein said overall cross-sectional shape is a multi-filar cross-sectional shape resulting from notionally overlapping five or seven essentially circular shapes. 
     
     
         77 . The Lyocell staple fiber according to  claim 72 , wherein the fiber exhibits a decitex-related flexural rigidity of more than 0.6 mN.mm 2 /tex 2 . 
     
     
         78 . The Lyocell staple fiber according to  claim 71 , wherein the fiber exhibits a fiber tenacity in conditioned state which is higher by at least 20% than the fiber tenacity of a comparison Lyocell staple fiber of the same decitex.