| 摘要 |
<p>PURPOSE:To realize the magnetic toner having stable development characteristics with simple constitution, small size and high performance. CONSTITUTION:This toner 7 is used for an electrophotographic system constituted to form an electrostatic latent image on a photosensitive drum 1 internally having a stationary magnet 2 by using this drum, to attract the magnetic toner 7 in a toner pool 6 after the formation of this electrostatic latent image and to recover the toner 7 of non-image parts. The magnetic toner 7 is composed of at least a binder resin, magnetic material and external additives and has a static bulk density of 0.45 to 0.60g/cm<3> and the true sp. gr. of 1.6 to 2.1g/cm<3>. The BET specific surface area by a nitrogen attraction method is <=4V/g and the amt. of the external additives is 0.5 to 2wt.%. The pulverizing stage among the production stages of the magnetic toner 7 is formed by a mechanical pulverizing method composed of a circular columnar rotating body having ruggedness on its surface and rotating at a high speed and a stationary body having ruggedness on its surface disposed at a narrow spacing from this rotating body.</p> |
