Electroblowing web formation process

Abstract

An improved electroblowing process is provided for forming a fibrous web of nanofibers wherein polymer stream is issued from a spinning nozzle in a spinneret with the aid of a forwarding gas stream and a resulting nanofiber web is collected on a collection means. The process includes applying a high voltage to the collection means and grounding the spinneret such that an electric field is generated between the spinneret and the collection means of sufficient strength to impart an electrical charge on the polymer as it issues from the spinning nozzle.

1 . An electroblowing process for forming a fibrous web comprising: 
 (a) issuing a polymer stream from a spinning nozzle in a spinneret whereupon a fibrous web is formed, the web having an electric charge of a positive or negative polarity, and    (b) collecting the fibrous web on a collection means, wherein a voltage is applied to the collection means, the voltage having a polarity opposite that of the fibrous web, and wherein the spinneret is substantially grounded, such that an electric field is generated between the spinneret and the collection means of sufficient strength to impart an electrical charge on the polymer stream as it issues from the spinning nozzle.    
   
   
       2 . The process of  claim 1  wherein the polymer stream is a stream of polymeric solution.  
   
   
       3 . The process of  claim 1  wherein the polymer stream is a stream of molten polymer.  
   
   
       4 . The process of  claim 1  wherein the polymer stream is electrically conductive.  
   
   
       5 . The process of  claim 1  wherein the collection means is a conductive moving collection belt having a collection surface.  
   
   
       6 . The process of  claim 5  wherein the conductive moving collection belt is porous and wherein the process further comprises applying suction to the collection belt on the side opposite the collection surface.  
   
   
       7 . The process of  claim 1  wherein the collection means is a nonconductive moving collection substrate superposed over a conductive element supported by a nonconductive support structure and wherein the voltage is applied to the conductive element.  
   
   
       8 . The process of  claim 7  wherein the nonconductive moving collection substrate is breathable and the conductive element is porous and wherein the process further comprises applying suction to the nonconductive support structure on the side opposite the collection substrate.  
   
   
       9 . The process of  claim 1  wherein the distance from the spinneret to the collection surface is between about 1 and about 200 cm.  
   
   
       10 . The process of  claim 1  wherein the distance from the spinneret to the collection surface is between about 10 and about 50 cm.  
   
   
       11 . The process of  claim 1  wherein the voltage is between about 1 and about 500 kV.  
   
   
       12 . The process of  claim 1  wherein the voltage is between about 10 and about 100 kV.  
   
   
       13 . The process of  claim 1  wherein the polarity of the charged web is negative and the polarity of the voltage applied to the collection means is positive.  
   
   
       14 . The process of  claim 1  wherein the polarity of the charged web is positive and the polarity of the voltage applied to the collection means is negative.  
   
   
       15 . The process of  claim 1  wherein the distance between the spinning nozzle and the collection surface is less than the distance between the spinneret and the collection means.  
   
   
       16 . The process of  claim 7 , wherein the conductive element is stationary.  
   
   
       17 . The process of  claim 5 , wherein the collection means further comprises a nonconductive moving collection substrate supplied from a supply roll which is fed over the conductive moving collection belt.