| 摘要 |
PURPOSE:To obtain a high-quality image by externally adding a specified amount of positively chargeable surface treated silica to the magnetic toner obtained by dispersing a magnetic powder into a binder resin. CONSTITUTION:The positively chargeable surface treated silica is externally added in an amount of >= 0.4 weight % to the magnetic toner having a volume average particle diameter of <= 10mum and the magnetic powder dispersed into the binder resin. The fine silica particles to be used are surface treated to impart positive chargeability, preferably, by using a silane compound having an onium salt structure and an amino group, thus permitting the obtained developer to be high in chargeable quantity, good in fluidity, and to form an image superior in quality not deteriorated in density even under high temperature and high humidity. |
