| 摘要 |
PURPOSE:To obtain a high image density which is stable from an initial period without fogging and splashing and to reproduce the stable image which is not affected by age and the change of temp. and humidity by incorporating magnetic toner, pulverous negative chargeability silicic acid powder and oxide powder of lanthanoid elements into a magnetic developer. CONSTITUTION:This one-component negative chargeability magnetic developer consists of the magnetic toner, pulverous negative chargeability silicic acid powder and oxide powder of lanthanoid elements. The pulverous silicic powder is effective when said powder is used at 0.01-20pts.wt. per 100pts.wt. toner. Said powder exhibits the negative electrostatic chargeability having excellent stability when the powder is added to the toner more particularly preferably at 0.05-5pts.wt. The oxide of the lanthanoid group elements which can be adequately used is exemplified by lanthanum oxide, cerium oxide, praseodymium oxide, neodium oxide, samarium oxide, terbium oxide and thulium oxide. These metallic oxides are incorporated into the developer at 0.1-20wt%, more preferably 0.2-5wt% per 100pts.wt. toner. The grain size thereof is preferably <=5mu, more preferably in a 0.01-3mu range. |
