Nonwovens, Method for the Production Thereof and the Use Thereof

Abstract

The invention relates to a method for the production of nonwovens, in which a solution of cellulose carbamate in N-methylmorpholine-N-oxide is forced through the holes of a nozzle beam and is stretched by a multiple by means of an airflow. The fibre curtain which is formed is laid down on a perforated conveyer belt, washed and dried. The invention likewise relates to nonwovens of this type and the use thereof.

1 . Method for the production of nonwovens according to the meltblowing method, in which
 a spinning solution is forced through a nozzle block at increased temperature,   the fibres emerging from the nozzle block are subjected to a flow of temperature-controlled airflow, the result being stretching of the fibres with subsequent cooling,   the threads are coagulated by spraying with water,   the fibres are placed on a conveying device whilst forming a random orientation and   the solvent is removed by washing,   
       characterised in that 
       a solution of cellulose carbamate in N-methylmorpholine-N-oxide is used as spinning solution. 
     
     
         2 . Method according to  claim 1 , characterised in that the nozzle block has at least 20, in particular from 150 to 1500, nozzle holes per meter. 
     
     
         3 . Method according to  claim 1 , characterised in that the diameter of the nozzle holes is from 0.05 to 1 mm. 
     
     
         4 . Method according to  claim 1 , characterised in that the spinning solution temperature in the nozzle is 80 to 130° C. 
     
     
         5 . Method according to  claim 1 , characterised in that the spinning solution conveying quantity is from 0.25 to 1.5 g per nozzle hole and minute. 
     
     
         6 . Method according to  claim 1 , characterised in that the airflow has a temperature of 100 to 190° C. 
     
     
         7 . Method according to  claim 1 , characterised in that a pressure of 0.03 to 1.5 bar is set by the airflow in the nozzle. 
     
     
         8 . Method according to  claim 1 , characterised in that the nozzle output speed of the fibres is from 1 to 20 m/min. 
     
     
         9 . Method according to  claim 1 , characterised in that the threads are stretched by the factor 50 to 800 by means of the airflow. 
     
     
         10 . Method according to  claim 1 , characterised in that the spinning speed is in the range of 150 to 10000 m/min. 
     
     
         11 . Method according to  claim 1 , characterised in that the fibres have a diameter of at most 20 μm. 
     
     
         12 . Method according to  claim 1 , characterised in that the fibres have a fineness of at most 2.5 dtex. 
     
     
         13 . Method according to  claim 1 , characterised in that the fibres are sprayed at least 10 cm below the nozzle with water or with a mixture comprising N-methylmorpholine-N-oxide and water. 
     
     
         14 . Method according to  claim 13 , characterised in that the mixture contains from 0.5 to 20% by weight of N-methylmorpholine-N-oxide. 
     
     
         15 . Method according to  claim 1 , characterised in that the fibres are laid down on a perforated conveyer belt. 
     
     
         16 . Method according to  claim 1 , characterised in that the washing is effected by a water jet at high pressure. 
     
     
         17 . Method according to  claim 1 , characterised in that the nonwoven is pressed out and/or dried after washing. 
     
     
         18 . Method according to  claim 1 , characterised in that the spinning solution contains from 5 to 20% by weight of cellulose carbamate. 
     
     
         19 . Method according to  claim 1 , characterised in that the spinning solution contains 20 to 30% by weight of cellulose carbamate. 
     
     
         20 . Nonwoven comprising a random orientation of fibres made of cellulose carbamate, producible according to the method according to  claim 1 . 
     
     
         21 . Nonwoven according to  claim 20 , characterised in that the nonwoven has a basis weight of 20 to 500 g/m 2 . 
     
     
         22 . Nonwoven according to  claim 20 , characterised in that the nonwoven has a water retention capacity of at least 180%. 
     
     
         23 . Nonwoven according to  claim 20 , characterised in that the nonwoven has a strength in the longitudinal direction of at least 250 N/m. 
     
     
         24 . Nonwoven according to  claim 20 , characterised in that the nonwoven has a strength in the transverse direction of at least 80 N/m. 
     
     
         25 . Nonwoven according to  claim 20 , characterised in that the cellulose carbamate has a substitution degree DS of 0.1 to 1.5. 
     
     
         26 . Use of the nonwoven according to  claim 20  in medicine, in particular as operating theatre covers, bed sheets, wound coverings, gauzes or cotton wool pads. 
     
     
         27 . Use of the nonwoven according to  claim 20  as hygiene materials or cloths in the household. 
     
     
         28 . Use of the nonwoven according to  claim 20  as decorative nonwovens, in particular table cloths, serviettes or curtains. 
     
     
         29 . Use of the nonwoven according to  claim 20  as lining fleeces in the clothing industry. 
     
     
         30 . Use of the nonwoven according to  claim 20  as reinforcing material.