| 摘要 |
<p>1478382 Pressure-fixable electrographic developer powder MINNESOTA MINING & Mfg CO 28 June 1974 [29 June 1973] 28901/74 Heading G2H The developer is a flowable dry powder comprising thermoplastic, spheroidal particles, the binder material of which has a conductivity of at most 10<SP>-12</SP> mho/cm and which comprises (a) 50 to 100 parts by weight of a wax component having a melting point between 45‹C and 150‹C, and (b) 2 to 50 parts by weight of thermoplastic resin having a softening point above 60‹C, wherein electrically conductive particles are firmly anchored in the binder material at least on or near the surface region of the spheroidal particles, the electrically conductive particles having a conductivity of at least 10<SP>-2</SP>mho/cm and an average diameter below 100 millimicrons and wherein the essentially spheroidal particles exhibit: (a) an electrical conductivity ranging monatonically without decreasing from between 10<SP>-11</SP> and 10<SP>-4</SP> mho/cm in a 100v/cm DC electrical field to between 10<SP>-8</SP> and 10<SP>-3</SP>mho/cm in a 10,000v/cm DC electrical field, (b) an average particle diameter below 20 microns, and (c) a ratio of the volume of the electrically conductive particles to the total particle volume of between 0À01/100 and 4/100. The binder material may include other materials, e.g. magnetically permeable particles such as magnetite. The conductive particles may comprise carbon black. A flow agent, such as finely divided silica, may be mixed with the developer powder.</p> |
