| 摘要 |
PURPOSE:To form a magnetic brush soft on its top and to obtain a developer prevented from agglomeration of a carrier by incorporating a carrier composed of ferromagnetic particles and a carrier formed by dispersing a magnetic powder into a binder resin and an insulating toner. CONSTITUTION:A magnetic carrier is made of a ferromagnetic material composed of the oxide of a metal, such as Ni, Mn, Mg, or Zn, and Fe oxide, and it has 35-95mum average particle diameter, and 10<7>-10<10>ohm.cm volume resistivity. Another carrier is prepared by dispersing a magnetic powder, such as iron powder or magnetic iron oxide powder, having <=3mum average particle diameter into a binder resin and it has 20-55mum average particle diameter smaller than said ferromagnetic carrier and 10>=10<12>ohm.cm volume resistivity. A mixture of the former ferromagnetic carrier in an amt. of 20-80wt% of the total carrier and the latter carrier, and an insulating toner are mixed to prepare a developer. A magnetic brush is formed from this toner by using a rotary magnetic roller. The developer thus obtained is good in conveyability and a superior copy can be obtained without causing white streaks. |
