| abstract |
To provide an aqueous polytetrafluoroethylene (PTFE) emulsion which does not substantially contain ammonium perfluorooctanoate, and which is obtained by emulsion polymerization. Further, to provide a PTFE fine powder which is obtained from the aqueous PTFE emulsion and is excellent in a paste extrusion processability, and a porous material. n An aqueous polytetrafluoroethylene emulsion obtained by carrying out emulsion polymerization of tetrafluoroethylene alone or together with another copolymerizable monomer in an aqueous medium, wherein a fluorinated emulsifier of the formula (1): n XCF 2 CF 2 (O) m CF 2 CF 2 OCF 2 COOA n wherein X is a hydrogen atom or a fluorine atom, A is a hydrogen atom, an alkali metal or NH 4 , and m is an integer of 0 or 1, is used in an amount of from 1,500 to 20,000 ppm, based on the final yield of polytetrafluoroethylene. |