Methods of making a mixture for a ptfe membrane with inorganic materials, and compositions related thereto

Abstract

Method for making a mixture used in the production of a polytetrafluoroethylene (PTFE) membrane including porous inorganic materials. The mixture includes PTFE resin, a lubricating agent, and a porous inorganic material. The mixture may be further processed to form a PTFE membrane.

1 . A method for making a polytetrafluoroethylene membrane comprising porous inorganic materials, the method comprising the steps of:
 (a) mixing a polytetrafluoroethylene resin having a weight, a lubricating agent having a weight, and a porous inorganic material having a weight,   wherein the weight of the lubricating agent comprises between 15 and 25 percent of the weight of the polytetrafluoroethylene resin,   wherein the weight of the porous inorganic material comprises up to 10 percent of the weight of the polytetrafluoroethylene resin, and   wherein the porous inorganic material has at least one dimension less than 100 nm;   (b) forming a preform comprising a mixture of the polytetrafluoroethylene resin, the lubricating agent, and the porous inorganic material;   (c) extruding the preform to form a tape having a thickness between 1 and 100 mil;   (d) calendaring the tape to facilitate evaporation of the lubricating agent;   (e) tentering the tape through biaxially stretching in a first direction and a second direction perpendicular to the first direction to form a membrane; and   (f) sintering the membrane at a temperature between 400° F. and 750° F. for a period of time between 1 and 120 seconds, wherein the membrane after sintering has a thickness between 0.05 and 20 mil.   
     
     
         2 . The method of  claim 1 , wherein step (a) comprises the steps of:
 mixing the polytetrafluoroethylene resin with the lubricating agent in a V blender for a period of time between 1 and 60 minutes to form a resin/lubricant mixture;   wicking the resin/lubricant mixture for a period of time between 1 and 120 hours; and   mixing the resin/lubricant mixture with the porous inorganic material in a V blender for a period of time between 1 and 60 minutes.   
     
     
         3 . The method of  claim 1 , wherein the lubricating agent comprises an isoparaffinic solvent. 
     
     
         4 . The method of  claim 2 , wherein the porous inorganic material comprises an activated nanocarbon, a carbon nanotube, a carbon fiber, a zeolite, a catalyst, silicon dioxide, or a mixture thereof. 
     
     
         5 . The method of  claim 2 , wherein the porous inorganic material has at least one dimension less than 50 nm. 
     
     
         6 . The method of  claim 2 , wherein the porous inorganic material has at least one dimension less than 30 nm. 
     
     
         7 . The method of  claim 2 , wherein the porous inorganic material has a specific surface area greater than 10 m 2 /g. 
     
     
         8 . The method of  claim 2 , wherein the porous inorganic material has a specific surface area greater than 50 m 2 /g. 
     
     
         9 . The method of  claim 2 , wherein the porous inorganic material has a specific surface area greater than 90 m 2 /g. 
     
     
         10 . A method of incorporating a porous inorganic material into a mixture comprising a polytetrafluoroethylene resin and a lubricating agent, the method comprising the steps of:
 (a) mixing the polytetrafluoroethylene resin with the lubricating agent in a V blender for a period of time between 1 and 60 minutes to form a resin/lubricant mixture;   (b) wicking the resin/lubricant mixture for a period of time between 1 and 120 hours; and   (c) mixing the resin/lubricant mixture with the porous inorganic material in a V blender for a period of time between 1 and 60 minutes;   wherein a weight of the lubricating agent comprises between 15 and 25 percent of a weight of the polytetrafluoroethylene resin,   wherein a weight of the porous inorganic material comprises up to 10 percent of the weight of the polytetrafluoroethylene resin, and   wherein the porous inorganic material has at least one dimension less than 100 nm.   
     
     
         11 . The method of  claim 10 , wherein step (b) occurs at a temperature between 40° F. and 200° F. 
     
     
         12 . The method of  claim 10 , wherein the lubricating agent comprises an isoparaffinic solvent. 
     
     
         13 . The method of  claim 10 , wherein the porous inorganic material comprises an activated nanocarbon having a specific surface area greater than 90 m 2 /g and having at least one dimension less than 50 nm. 
     
     
         14 .- 18 . (canceled)