Stretched film of void-containing thermoplastic resin and process for producing the same

Abstract

To provide a stretched film of void-containing thermoplastic resin having an attractive force between sheets is 50 g or less. The stretched film of void-containing thermoplastic resin has no charge therein and can be processed secondarily with lesser electrostatic disturbance even in a low-humidity environment.

1 . A process for producing a stretched film comprising:
 stretching a thermoplastic resin film to form a stretched film of void-containing thermoplastic resin, and   applying a direct-current voltage superimposed on a high voltage of high frequency to the stretched film to obtain a stretched film of void-containing thermoplastic resin having an attractive force between sheets of the film wherein the attractive force is 50 g or less.   
     
     
         2 . The process for producing a stretched film according to  claim 1 , which further comprises coating an antistatic agent on at least one side of the film obtained by the application of the direct-current voltage superimposed on a high voltage of high frequency. 
     
     
         3 . The process for producing a stretched film according to  claim 1 , which further comprises coating a pigment on at least one side of the film obtained by the application of the direct-current voltage superimposed on a high voltage of high frequency. 
     
     
         4 . The process for producing a stretched film according to  claim 1 , wherein the stretched film having an attractive force of 50 g or less has a charge potential of the film surface wherein the charge potential is −10 to 10 kV. 
     
     
         5 . The process for producing a stretched film according to  claim 1 , wherein the direct-current voltage is superimposed on the high voltage of high frequency so that the stretched film can have a charge potential of the film surface wherein the charge potential is −10 to 10 kV. 
     
     
         6 . The process for producing a stretched film according to  claim 1 , wherein the direct-current voltage is superimposed on the high voltage of high frequency so that the stretched film can have a charge potential of the film surface wherein the charge potential is 0 kV. 
     
     
         7 . The process for producing a stretched film according to  claim 1 , which further comprises detecting the charge potential of the stretched film after the application of the direct-current voltage superimposed on a high voltage of high frequency. 
     
     
         8 . The process for producing a stretched film according to  claim 7 , which further comprises:
 controlling the direct-current voltage to shift the high voltage of high frequency to the negative side when the detected charge potential is positive, or   controlling the direct-current voltage to shift the high voltage of high frequency to the positive side when the detected charge potential is negative.   
     
     
         9 . The process for producing a stretched film according to  claim 1 , wherein the thermoplastic resin film contains at least one of inorganic fine powder and organic filler. 
     
     
         10 . The process for producing a stretched film according to  claim 1 , wherein the thermoplastic resin film contains at least one of inorganic fine powder and organic filler in an amount of 0.1 to 65 wt %. 
     
     
         11 . The process for producing a stretched film according to  claim 1 , wherein the thermoplastic resin film contains an antistatic agent. 
     
     
         12 . The process for producing a stretched film according to  claim 1 , wherein the thermoplastic resin film has two or more layers. 
     
     
         13 . The process for producing a stretched film according to  claim 1 , wherein the thermoplastic resin is a polyolefin resin. 
     
     
         14 . The process for producing a stretched film according to  claim 1 , wherein the stretched film having an attractive force of 50 g or less has a rate of voids of 0.1 to 60%. 
     
     
         15 . The process for producing a stretched film according to  claim 1 , wherein the stretched film having an attractive force of 50 g or less has an opacity of 5 to 100%. 
     
     
         16 . A stretched film produced by the process of  claim 1 .