Process for producing polytetrafluoroethylene fine powder
AssigneeDaikin Industries, Ltd.
InventorsMasayoshi Miyamoto, Taku Yamanaka, Yasuhiko Sawada
Life of this patent
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Abstract
A process for producing a polytetrafluoroethylene fine powder including: (1) a step of preparing an aqueous dispersion containing polytetrafluoroethylene, water and a surfactant (A); (2) a step of initiating coagulation of the polytetrafluoroethylene in said aqueous dispersion by agitating said aqueous dispersion; (3) a step of adding a surfactant (B) after the step (2); (4) a step of terminating coagulation after the step (3); (5) a step of collecting a wet powder of the polytetrafluoroethylene; and (6) a step of drying the wet powder of the polytetrafluoroethylene.
Claims8
A process for producing a polytetrafluoroethylene fine powder,
- the process comprising:
- (1) a step of preparing an aqueous dispersion containing polytetrafluoroethylene, water and a surfactant (A);
- (2) a step of initiating coagulation of the polytetrafluoroethylene in said aqueous dispersion by agitating said aqueous dispersion;
- (3) a step of adding a surfactant (B) after the step (2);
- (4) a step of terminating coagulation after the step (3);
- (5) a step of collecting a wet powder of the polytetrafluoroethylene;
- and
- (6) a step of drying the wet powder of the polytetrafluoroethylene.
A polytetrafluoroethylene fine powder consisting of a TFE homopolymer, wherein a standard specific gravity is 2.160 to 2.230;
- average particle size is 300 to 800 μm;
- apparent density is 0.40 to 0.52 g/ml;
- compression ratio is 1.20 or less;
- and aggregate disintegration degree with 50-sec vibration is 60% or more.
A polytetrafluoroethylene fine powder consisting of a TFE homopolymer, wherein a standard specific gravity is 2.130 to 2.160, average particle size is 300 to 800 μm;
- apparent density is 0.40 to 0.52 g/ml;
- compression ratio is 1.20 or less;
- and aggregate disintegration degree with 50-sec vibration is 40% or more.
A polytetrafluoroethylene fine powder consisting of a modified PTFE, wherein a standard specific gravity is 2.140 to 2.230;
- extrusion pressure at RR (Reduction Ratio) 1500 is 80 MPa or less;
- average particle size is 300 to 800 μm;
- apparent density is 0.40 to 0.52 g/ml;
- compression ratio is 1.20 or less;
- and aggregate disintegration degree with 50-sec vibration is 70% or more.
A polytetrafluoroethylene fine powder consisting of a modified PTFE, wherein a standard specific gravity is 2.140 to 2.230;
- extrusion pressure at RR (Reduction Ratio) 1500 is 60 MPa or less;
- average particle size is 300 to 800 μm;
- apparent density is 0.40 to 0.52 g/ml;
- compression ratio is 1.20 or less;
- and aggregate disintegration degree with 50-sec vibration is 70% or more.
Dependencies are inferred from the claim text.