COMPOSITION REVELATRICE PERFECTIONNEE

摘要

1347568 Making spherical particles XEROX CORP 19 April 1971 [23 March 1970] 24975/71 Heading B3A [Also in Divisions B5 and G2] A method of making spherical particles of substantially uniform size comprises cutting rods of a malleable metal into lengths substantially equal to the rod diameter and continuously impingeing the cut rods against a rigid surface. The particles are used in a developer for latent electrostatic images. The rods are of steel, copper, nickel, aluminium, brass and the like and are drawn down to a diameter of 50-1000 microns. Stainless steel wire when cut is fed to a vibrating mill containing ceramic balls of large diameter relative to the particles and occupying about 80% of the mill volume. Alternatively cut aluminium, brass or low carbon steel wire is impinged against hardened steel targets by a centrifugal throwing wheel and is recirculated via a bucket conveyer. The rods may be cut either individually or in sheaths and the cut rods may also be worked in ball mills, tumbling mills, blast mills and the like. The particles may be coated by conventional techniques to alter their triboelectric properties.