Nonwoven cellulose fiber fabric with tailored liquid wicking capability

Abstract

It is described a nonwoven cellulose fiber fabric directly manufactured from a lyocell spinning solution. The fabric comprises a network of substantially endless fibers. The fabric is characterized by at least one of the following features: (i) a rate of liquid spread is at least 3000 mm2 within 5 minutes; (ii) a water absorbing capability is characterized by a wicking speed of at least 0.25 gram water per 1 gram fabric and 1 second. It is further described a method and a device for manufacturing such a fabric, a product or composite comprising such a fabric, and various use applications for such a fabric.

1 . A nonwoven cellulose fiber fabric, in particular directly manufactured from a lyocell spinning solution, the fabric comprising
 a network of substantially endless fibers, wherein the fabric exhibits a water absorbing capability with   a rate of liquid spread of at least 3000 mm 2  within 5 minutes.   
     
     
         2 . The fabric as set forth in  claim 1 , wherein the rate of liquid spread within 5 minutes is at least 4000 mm 2 , in particular 5000 mm 2 , and further in particular 5500 mm 2 . 
     
     
         3 . The fabric as set forth in  claim 1 , wherein along a first direction within the fabric the rate of liquid spread has a first value and along a second direction within the fabric the rate of liquid spread has a second value, the second direction being perpendicular to the first direction value, wherein
 the first value and the second value differ from each other by less than 20%, in particular by less than 10% or   the first value and the second value differ from each other by more than 20%, in particular by more than 30% and further in particular by more than 40%.   
     
     
         4 . A nonwoven cellulose fiber fabric, in particular directly manufactured from a lyocell spinning solution, the fabric comprising
 a network of substantially endless fibers, wherein the fabric exhibits a water absorbing capability with a wicking speed of at least 0.25 gram water per 1 gram fabric and 1 second.   
     
     
         5 . The fabric as set forth in  claim 4 , wherein the wicking speed is at least 0.30 gram water per 1 gram fabric and 1 second, in particular at least 0.35 gram water per 1 gram fabric and 1 second, and further in particular at least 0.40 gram water per 1 gram fabric and 1 second. 
     
     
         6 . The fabric as set forth in  claim 1 , wherein at least a part of the fibers are integrally merged at merging positions, wherein in particular a merging factor of the fibers is in a range between 0.2% and 100%, in particular in a range between 0.5% and 15%. 
     
     
         7 . The fabric as set forth in  claim 1 , wherein different ones of the fibers are located at least partially in different distinguishable layers, wherein in particular the fabric comprises at least one of the following features:
 fibers of different layers are integrally connected at at least one inter-layer merging position between the layers;   different ones of the fibers being located at least partially in different layers differ concerning fiber diameter, in particular differ concerning an averaged fiber diameter;   fibers of different layers have the same fiber diameter, in particular have substantially the same averaged fiber diameter;   fibers networks of different layers provide different functionality, wherein the different functionality in particular comprises at least one of the group consisting of different wicking, different anisotropic behavior, different liquid absorbing capability, different cleanability, different optical properties, different roughness, different smoothness, and different mechanical properties.   
     
     
         8 . The fabric as set forth in  claim 1 , wherein the fiber network comprises at least one of the following features:
 within one and the same fiber different fiber sections differ concerning fiber diameter by more than 50% in relation to the smallest diameter of this fiber;   different fibers differ concerning fiber diameter by more than 50% in relation to the smallest diameter of one of the fibers.   
     
     
         9 . The fabric as set forth in  claim 1 , wherein the fiber network comprises at least one of the following features:
 at least 3%, in particular at least 5%, of the fibers have a non-circular cross sectional shape having a roundness of not more than 90%;   at least 1%, in particular at least 3%, of the fibers have a non-circular cross sectional shape having a roundness of not more than 80%, in particular of not more than 70%.   
     
     
         10 . The fabric as set forth in  claim 1 , wherein the fibers have a copper content of less than 5 ppm and/or have a nickel content of less than 2 ppm. 
     
     
         11 . A method of manufacturing nonwoven cellulose fiber fabric, in particular a fabric as set forth in  claim 1 , directly from a lyocell spinning solution, the method comprising
 extruding the lyocell spinning solution through a jet with orifices supported by a gas flow into a coagulation fluid atmosphere to thereby form substantially endless fibers;   collecting the fibers on a fiber support unit to thereby form the fabric; and   adjusting process parameters of the manufacturing process so that the fabric exhibits a rate of liquid spread of at least 3000 mm 2  within 5 minutes or the fabric exhibits a water absorbing capability with a wicking speed of at least 0.25 gram water per 1 gram fabric and 1 second.   
     
     
         12 . A device for manufacturing nonwoven cellulose fiber fabric directly from a lyocell spinning solution, in particular for manufacturing a fabric as set forth in  claim 1 , the device comprising
 a jet with orifices configured for extruding the lyocell spinning solution supported by a gas flow;   a coagulation unit configured for providing a coagulation fluid atmosphere for the extruded lyocell spinning solution to thereby form substantially endless fibers;   a fiber support unit configured for collecting the fibers to thereby form the fabric; and   a control unit configured for adjusting process parameters so that the fabric exhibits a rate of liquid spread of at least 3000 mm 2  within 5 minutes or the fabric exhibits a water absorbing capability with a wicking speed of at least 0.25 gram water per 1 gram fabric and 1 second.   
     
     
         13 . A method of using a nonwoven cellulose fiber fabric according to  claim 1  for at least one of the group consisting of a wipe, a household sheet, a filter, a hygiene product, a medical application product, a geotextile, agrotextile, clothing, a product for building technology, an automotive product, a furnishing, an industrial product, a product related to leisure, beauty, sports or travel, and a product related to school or office. 
     
     
         14 . A product or composite comprising a nonwoven cellulose fiber fabric as set forth in  claim 1 .