Removing fluorosurfactant from aqueous fluoropolymer dispersion using sorbent pouches

Abstract

A process for reducing the fluorosurfactant content of an aqueous fluoropolymer dispersion by filling a container with fluoropolymer dispersion, inserting into the container a fabric pouch containing a fluorosurfactant sorbent so that the sorbent contacts the fluorosurfactant-containing aqueous fluoropolymer dispersion in the container and retains the fluorosurfactant to reduce fluorosurfactant content of said fluorosurfactant-containing aqueous fluoropolymer dispersion, and removing the fabric pouch from the container.

1 . A process for reducing fluorosurfactant content of a fluorosurfactant-containing aqueous fluoropolymer dispersion comprising: 
 filling a container with said fluorosurfactant-containing aqueous fluoropolymer dispersion;    inserting into said container a fabric pouch containing a fluorosurfactant sorbent so that said sorbent contacts said fluorosurfactant-containing aqueous fluoropolymer dispersion in said container and retains said fluorosurfactant to reduce fluorosurfactant content of said fluorosurfactant-containing aqueous fluoropolymer dispersion; and    removing said fabric pouch from said container.    
     
     
         2 . The process of  claim 1  further comprising treating said sorbent in said fabric pouch to remove said fluorosurfactant.  
     
     
         3 . The process of  claim 2  further comprising reusing said fabric pouch in the process of  claim 1 .  
     
     
         4 . The process of  claim 2  further comprising recovering said fluorosurfactant for reuse.  
     
     
         5 . The process of  claim 1  where said sorbent is ion exchange resin.  
     
     
         6 . The process of  claim 5  wherein said ion exchange resin is anion exchange resin.  
     
     
         7 . The process of  claim 1  wherein the amount of said sorbent contacted with said fluorosurfactant-containing aqueous fluoropolymer dispersion is selected to reduce the fluorosurfactant content to no greater than a predetermined level.  
     
     
         8 . The process of  claim 7  wherein said predetermined level is no greater than about 300 ppm.  
     
     
         9 . The process of  claim 7  wherein said predetermined level is no greater than about 100 ppm.  
     
     
         10 . The process of  claim 7  wherein said predetermined level is no greater than about 50 ppm.  
     
     
         11 . The process of  claim 1  further comprising moving either said fluorosurfactant-containing aqueous fluoropolymer dispersion or said pouch to impart movement in relation to each other during said contacting.  
     
     
         12 . The process of  claim 11  further comprising moving said pouch in relation to the dispersion during said contacting.  
     
     
         13 . The process of  claim 11  further comprising moving said dispersion in relation to said pouch during said contacting.  
     
     
         14 . The process of  claim 1  wherein said fluoropolymer dispersion is a concentrated fluoropolymer dispersion containing nonionic surfactant.  
     
     
         15 . The process of  claim 1  wherein said dispersion has a fluoropolymer solids concentration of about 15 to about 70 weight percent.  
     
     
         16 . The process of  claim 1  wherein said dispersion has a fluoropolymer solids concentration of about 25 to about 65 weight percent.  
     
     
         17 . The process of  claim 1  wherein said process is carried out during the manufacture of the aqueous fluoropolymer dispersion.  
     
     
         18 . The process of  claim 17  wherein said process is carried out as part of the dispersion concentration operation or during temporary storage prior to filling shipping containers.  
     
     
         19 . The process of  claim 17  wherein said container is a fixed vessel.