| 摘要 |
PURPOSE:To easily produce microballoons with a low density and a good flowability by introducing minute liq. droplets of polytetrafluoroethylene or its precursor into a specified high-temp. atmosphere. CONSTITUTION:A soln. or dispersion contg. polytetrafluoroethylene or its precursor dissolved or dispersed in a liq. medium is converted into minute liq. droplets and introduced into an atmosphere with a temp. high enough to vaporize the medium quickly and to sinter or melt polytetrafluoroethylene. As the medium vaporizes quickly at the surface of the droplets. polytetrafluoroethylene or its precursor dissolved or dispersed in the droplets precipitates along the interfaces of the droplets to form spheres. While the remaining medium vaporizes and dissipates, polytetrafluoroethylene moves in the centrifugal direction, hollowing the droplet insides, and forming microballoons. Pref. the microballoons have an average particle diameter of 0.1-300mum, a bulk density of 0.001-1.5g/cm<3>, and a true density of 0.01-2.0g/cm<3>. |
