Patent ID: 6300408
Filing Date: 2001-10-09
Classification: B01J,C08J

Abstract:
A modified polytetrafluoroethylene granular powder obtained by granulating a pulverized modified polytetrafluoroethylene powder prepared by suspension-copolymerizing 99 to 99.999% by mole of tetrafluoroethylene with 1 to 0.001% by mole of perfluoro(vinyl ether), in water under coexistence of a nonionic surfactant which has a hydrophobic segment comprising a poly(oxyalkylene) unit having 3 or 4 carbon atoms and a hydrophilic segment comprising a poly(oxyethylene) unit and an organic liquid which forms liquid-liquid interface with water, wherein:(1) the granular powder has an electrostatic charge of not more than 50V,(2) the granular powder has an angle of repose of not more than 38 degrees,(3) the granular powder has an apparent density of not less than 0.7 g/cm.sup.3 and less than 0.8 g/cm.sup.3,(4) the granular powder having an average particle size of not less than 150 .mu.m and less than 250 .mu.m has flowability f of 2 to 3 sec/50 g and particle stability s of 2 to 3 sec/50 g,(5) the granular powder having an average particle size of 250 to 1000 .mu.m has flowability f of 1 to 2 sec/50 g and particle stability s of 1 to 2 sec/50 g,(6) the granular powder has 1 to 1.3 of a particle stability coefficient s/f which is represented by particle stability s/flowability f,(7) a molded article obtained by molding the granular powder has a surface roughness of not more than 2.0 .mu.m, and(8) a 0.1 mm thick skived sheet obtained by molding the granular powder has a break down voltage of not less than 12 kV.