摘要 |
<p>PURPOSE:To eliminate the decrease of picture density and the occurrence of white void and to prolong service life by using a binder resin of specified copolymer and subjecting a toner fine powder obtd. by kneading the binder resin, magnetic material and additives to surface modifying treatment and simultaneously coating the magnetic material and forming spherical toner fine particles. CONSTITUTION:The magnetic toner consists of a binder resin, magnetic material and external additive. The binder resin consists of copolymers expressed by formula I and formula II and has 1X10<4>-5X<5> (poise) melt viscosity at 135 deg.C and 3X10<3>-3X10<5> (poise) melt viscosity at 145 deg.C. The binder resin, magnetic material and additives are kneaded, pulverized and classified to obtain a toner fine powder. The toner fine powder in a dispersed state is treated with hot air for surface modification so that coating of the magnetic material and forming of spherical toner powder particles are simultaneously and instantaneously performed. In formulae I and II, R1 is H or CH3, R2 is H or alkyl group of 1-5 carbon number, and R3 is H or alkyl group of 1-20 carbon number.</p> |