Process for Producing a Porous Track Membrane

Abstract

Porous track membranes are produced by exposing a polymeric film to a bombardment of heavy ions to provide the film with a track density, and etching pores into the resulting tracked film with an etching solution to provide the film with a density of the pores corresponding to the track density under conditions to maintain turbulent flow. An alkaline etching solution is used that contains salts of alkali metals in sufficient concentration to increase the boiling point of the resulting alkali-metal-containing solution to temperatures in excess of about 100 up to about 150° C.

1 . A process for producing a porous track membrane useful in the separation of materials from a fluid comprising the steps of:
 a) exposing a polymeric film to a bombardment of heavy ions to provide the film with a track density; and   b) etching pores into the resulting tracked film with an etching solution to provide the film with a density of the pores corresponding to the track density under turbulent flow.   
   
   
       2 .- 14 . (canceled) 
   
   
       15 . A process for producing a porous track membrane useful in the separation of materials from a fluid comprising the steps of:
 a) exposing a fluropolymeric film to a bombardment of heavy ions to provide the film with a track density;   b) cutting the resulting tracked film into a plurality of separate sections; and   c) etching the sections of tracked film with an etching solution to provide the sections of film with a density of pores corresponding to the track density under conditions to maintain a turbulent flow.   
   
   
       16 .- 29 . (canceled) 
   
   
       30 . A process for producing a porous track membrane useful in the separation of materials from a fluid comprising the steps of:
 a) exposing a continuous roll of polymeric film of to a bombardment of heavy ions to provide the film with a track density; and   b) etching the continuous roll of tracked film as the roll passes through an etching solution to provide the sections of film with a density of pores corresponding to the track density under conditions to maintain turbulent flow.   
   
   
       31 .- 42 . (canceled)