| 摘要 |
<p>PURPOSE: To provide binary system developer which contains no charge control agent which becomes a major cause of a spent so as to provide sufficient chargeability, prevent toner from scattering at the time of copying, and provide sufficient transfer efficiency and a copy image having required density stably for many hours. CONSTITUTION: A toner particle contains resin for fixing and magnetic powders dispersed in the resin. The resin for fixing is composed of a component which contains styrene acrylic resin having an anion polar group. The styrene acrylic resin satisfies the following conditions: (a) a peak of molecular weight of resin exists in 4,000-30,000, (b) the average molecular weight of resin is 70,000-200,000, (c) the acid value of resin is 4-20, a particle of carrier has a core particle and a covering layer which covers the core particle, the core particle is composed of a predetermined magnetic material, and the covering layer is composed of a resin component which contains thermosetting resin and thermoplastic resin.</p> |
