Nonwoven cellulose fiber fabric with increased water holding capability and low basis weight

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 exhibits a water holding capability of at least 850 mass percent. Further, the fabric comprises a mass per unit area which is smaller than 25 gram per square meter. 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 holding capability of at least 850 mass percent, and the fabric comprises a mass per unit area which is lower than 25 gram per square meter. 
     
     
         2 . The fabric according to  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.   
     
     
         3 . The fabric according to  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 optical properties, different liquid holding capability, different cleanability, different roughness, different smoothness, and different mechanical properties. 
 
     
     
         4 . The fabric according to  claim 1 , wherein 
       fiber networks in different layers have different merging factors, or 
       fiber networks in different layers have at least approximately the same merging factor. 
     
     
         5 . The fabric according to  claim 1 , wherein 
       the mass per unit area is between 5 and 25 gram per square meter, in particular between 8 and 20 gram per square meter. 
     
     
         6 . The fabric according to  claim 1 , wherein 
       the fabric exhibits a water holding capability of at least 900 mass percent, in particular of at least 950 mass percent and further in particular of at least 1000 mass percent. 
     
     
         7 . The fabric according to  claim 1 , wherein 
       the fabric exhibits an oil holding capability of at least 800 mass percent, in particular of at least 1500 mass percent, and further in particular of at least 2000 mass percent. 
     
     
         8 . The fabric according to  claim 1 , wherein 
       the fiber network comprises at least one of the following features:
 different sections of the same fiber differ concerning fiber diameter so that a ratio between a largest fiber diameter of this fiber and a smallest fiber diameter of this fiber is more than 1.5; 
 different fibers differ concerning fiber diameter so that a ratio between a largest fiber diameter of one of the fibers and a smallest fiber diameter of another one of the fibers is more than 1.5. 
 
     
     
         9 . The fabric according to  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 according to  claim 1 , wherein 
       at least part of the fibers are integrally merged at merging positions, wherein in particular a merging factor of the fibers is in a range between 0.1% and 100%, in particular in a range between 0.2% and 15%, and further in particular in a range between 0.5% and 10%. 
     
     
         11 . The fabric according to  claim 1 , wherein 
       at least some individual fibers are twisted with each other and/or 
       at least one fiber structure is twisted with another fiber structure. 
     
     
         12 . A method of manufacturing nonwoven cellulose fiber fabric, in particular a fabric according to  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 water holding capability of at least 850 mass percent, and the fabric comprises a mass per unit area which is smaller than 25 gram per square meter.   
     
     
         13 . A device for manufacturing nonwoven cellulose fiber fabric directly from a lyocell spinning solution, in particular for manufacturing a fabric according to  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 water holding capability of at least 850 mass percent, and the fabric comprises a mass per unit area which is smaller than 25 gram per square meter.   
     
     
         14 . 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 dryer 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. 
     
     
         15 . A product or composite comprising a nonwoven cellulose fiber fabric according to  claim 1 .