To obtain a toner giving an image free from voids, ensuring stable electrostatic chargeability, not causing fusion to a blade and having a long service life by specifying the relation between the circularity and number percentage of toner particles.
This toner consists essentially of a bonding resin and a colorant. In a range of ≥1.6μm particle diameter equivalent to the diameter of a circle, the number percentage of toner particles each having circularity of <0.90 is ≤10% and that of toner particles each having circularity of 0.90 to <0.94 is ≤18%. Circularity is given by dividing the peripheral length of a circle having the same area as the projection area of a particle image by the peripheral length of the particle image. Particle diameter equivalent to the diameter of a circle is the diameter of a circle having the same area as the projection area of a toner particle. Toner particles having 5-20μm volume average particle diameter are produced by a melting, kneading and pulverizing method or a polymn. method, 0.05-0.2wt.% inorg. oxide is stuck to the surfaces of the toner particles and the particles are made circular by treatment with impact, compressive force and heat.
OKUNO RYOZO
SHIRAI TOSHIYUKI
