| 摘要 |
1,135,921. Moulding P.T.F.E. DAIKIN KOGYO CO. Ltd. 11 Jan., 1966 [12 Jan., 1965], No. 1287/66. Heading B5A. [Also in Division C3] Articles are formed by moulding a powder comprising spheroidal granules of polytetrafluoroethylene of average particle size below 5000 microns, angle of repose below 45 degrees, surface areas as measured by nitrogen adsorption at least 2 square metres per gram, surface smoothness not less than 15 seconds and anisotropic expansion factor not more than 1.16. In Example 12 the powder is preformed into annular sheets using an automatic compression moulding machine made up of a mould, a table, a feeder box with a hole in its bottom, and a hopper. The table has inset therein an annular moulding space defined by a cylindrical cavity of diameter 83 mm. having at its centre a mandrel of external diameter 44 mm. The depth of the annulus is 7 mm. and above it is a cylindrical, vertically-movable punch adapted to press down into the annulus.
|
