| 摘要 |
<p>PURPOSE: To provide a binary system developer that contains no electrostatic charge control agent utterly, whose toner is excellent in electrifiability and occurrence of its charge failure is yet more checked by way of reducing the formation of a reverse polarity toner, while this developer is less in toner scattering, sufficient enough in transfer efficiency, thereby making the required density copied image stably securable for hours, and the stability of a transfer image is also made so as to be satisfied to the full. CONSTITUTION: This is a binary system developer comprising a toner and a carrier. This toner includes toner grains which contain a kind of fixing resin and a specified rate of magnetic powder, and this fixing resin consists of a composition containing a resin having both low and high molecular bodies with an anionic polar group each, and an acid number of the low molecular body is smaller as compared with that of the high molecular body. Carrier grains have a core grain consisting of the specified magnetic material and a covered layer covering this core grain. In this connection, this covered layer consists of a resin composition containing sane resin with a cationic polar group.</p> |
