| 摘要 |
<p>PURPOSE: To prevent spending even in a high-speed copying machine, to maintain stable triboelectric chargeability over a long period of time and to improve durability by incorporating fineα-alumina powder into a coating resin layer. CONSTITUTION: Fineα-alumina powder is incorporated into a coating resin layer on the surface of a carrier. Thisα-alumina hasα-crystal structure and is next to diamond in hardness. The Mohs hardness of the alumina is 9 and the alumina has such high electric insulating property as 1,015Ωcm volume resistivity. The fineα-alumina powder is, e.g. pulverized molten alumina or high purity alumina. At the time of stirring in a developing unit, the fineα-alumina powder dispersed in the coating resin layer of the resultant carrier polishes the surface of the carrier by the contact of the particles of the carrier with each other to prevent the spending of the carrier and stability of triboelectric charge is satisfactorily maintained over a long period of time.</p> |
