| abstract |
To obtain a high concentration aqueous PTFE dispersion containing PTFE at a concentration of from 60 to 75 mass % by dissolving from 0.001 to 0.1 mass %, based on the mass of PTFE, of a specific carboxylic acid salt such as ammonium laurate in a low concentration aqueous dispersion of polytetrafluoroethylene (PTFE) comprising from 1 to 40 mass % of PTFE fine particles, from 0.0001 to 0.02 mass %, based on the mass of PTFE, of a specific fluorine-containing carboxylic acid type emulsifier (for example, ammonium perfluorooctanoate), and from 1 to 20 mass %, based on the mass of PTFE, of a specific nonionic surfactant, and then concentrating the low concentration aqueous dispersion of PTFE. The present invention provides a process for producing a high concentration aqueous PTFE dispersion containing PTFE at a high concentration by using, as a starting material, a low concentration aqueous dispersion of PTFE containing a fluorine-containing carboxylic acid type emulsifier (PFCA) at a low concentration, and an aqueous PTFE dispersion obtained from the high concentration aqueous PTFE dispersion. |