| 摘要 |
<p>PURPOSE: To provide a toner that contains no electrostatic charge control agent being mainly attributable to a spent at time of copying, which is sufficient enough in electrifiability, no scattering at time of copying, and also adequate enough in transfer efficiency, thereby stably securing the required density copied image for hours, and a charge failure due to being spent to a grain surface of a carrier of styrene or a low molecular body being strong in a minus electrification tendency is solved, whereby the tone charge can be stabilized for a long period of time, and thus the promotion of yet more long-livedness in the toner containing no electrostatic charge control agent is made achievable. CONSTITUTION: This is a binary system developer containing toner grains inclusive of fixing resin and magnetic powder dispersed in this resin. This fixing resin is a composition comprising resin with an anionic polar group. The resin contains a low molecular copolymer containing a monomer with styrene and the anionic polar group and a high molecular copolymer, and a constituent ratio of the styrene in this low molecular copolymer is less than 70%. In this connection, the magnetic powder is contained in the toner grains at the rate of 5 pt.wt from 0.1 to 100 pt.wt in the fixing resin.</p> |
