Modified perfluoropolymer sheet material and methods for making same

Abstract

A coated fabric includes a reinforcement, a first coating disposed on the reinforcement, and a second coating disposed on the first coating. The first coating includes perfluoropolymer. The second coating includes perfluoropolymer and a silicone polymer in an amount in a range of 2 wt % to 30 wt %.

What is claimed is: 
     
         1 . A coated fabric comprising:
 a reinforcement material; and   a coating overlying the reinforcement material, the coating comprising perfluoropolymer and a silicone polymer in an amount in a range of 2 wt % to 30 wt %;   wherein the coated fabric has a permeability of not greater than 0.001 cuin/min.   
     
     
         2 . The coated fabric of any one of  claim 1 , wherein the coated fabric has a trapezoidal tear strength in the machine direction of at least 13 lbs. 
     
     
         3 . The coated fabric of any one of  claim 1 , wherein the coated fabric has a coating adhesion of at least 1.8 lb/in. 
     
     
         4 . The coated fabric of any one of  claim 1 , wherein the coated fabric exhibits a Strength Retention of at least 25%. 
     
     
         5 . The coated fabric of any one of  claim 1 , wherein the perfluoropolymer comprises polytetrafluoroethylene (PTFE), hexafluoropropylene (HFP), fluorinated ethylene propylene (FEP), perfluoroalkyl vinyl ether (PFA), a combination thereof. 
     
     
         6 . The coated fabric of  claim 5 , wherein the perfluoropolymer comprises polytetrafluoroethylene (PTFE). 
     
     
         7 . The coated fabric of any one of  claim 1 , wherein the silicone polymer is derived from a precured silicone polymer dispersion. 
     
     
         8 . A sheet material comprising a blend of perfluoropolymer and silicone polymer, the blend comprising the silicone polymer in an amount in a range of 2 wt % to 30 wt %. 
     
     
         9 . The sheet material of  claim 8 , wherein the sheet material comprises a single layer, the single layer comprising the blend. 
     
     
         10 . The sheet material of  claim 8 , wherein the sheet material has a Gurley Directional Ratio of not greater than 1. 
     
     
         11 . The sheet material of  claim 8 , wherein the sheet material has a Tear Directional Ratio of at least 0.77. 
     
     
         12 . The sheet material of  claim 8 , wherein the sheet material has a total thickness of at least 9 mils and a Gurley stiffness of not greater than 550. 
     
     
         13 . A method of forming a coated fabric, the method comprising:
 dispensing a fabric;   applying a first emulsion coating to the fabric, the first emulsion comprising a perfluoropolymer;   fusing the first emulsion coating to form a first layer;   applying a second emulsion coating on the first emulsion coating, the second emulsion coating comprising a blend of perfluoropolymer and silicone polymer in an amount in a range of 2 wt % to 30 wt %; and   fusing the second emulsion coating to form a second layer.   
     
     
         14 . The method of  claim 13 , further comprising semifusing the second emulsion coating following applying the second emulsion coating and prior to fusing the second emulsion coating. 
     
     
         15 . The method of  claim 14 , further comprising calendering the second emulsion coating following semifusing the second emulsion coating. 
     
     
         16 . The method of  claim 15 , further comprising contacting the second emulsion coating with a perfluoropolymer film following semifusing the second emulsion coating, wherein fusing the second emulsion coating includes fusing the second emulsion coating while in contact with the perfluoropolymer film. 
     
     
         17 . The method of  claim 13 , further comprising applying a third emulsion coating on the second emulsion coating. 
     
     
         18 . The method of  claim 17 , wherein the third emulsion coating comprises a perfluoropolymer, a silicone, or a combination thereof. 
     
     
         19 . The method of  claim 17 , further comprising:
 semifusing the third emulsion coating;   contacting the third emulsion coating with a film; and   fusing the third emulsion coating while in contact with the film.   
     
     
         20 . The method of  claim 17 , further comprising:
 semifusing the third emulsion coating;   calendering the third emulsion coating; and   fusing the third emulsion coating.