PURPOSE: To obtain a developer which does not deteriorate for continuous copying even when a thermoplastic resin having low softening point is used, and to decrease the consumption of electric power by constituting the developer of an inner area substantially consisting of a thermoplastic resin and a coloring agent and a surface area substantially consisting of a thermoplastic resin and first fine particles.
CONSTITUTION: In the developer 10, the nucleus toner 1 has such a structure that first fine particles 4 are embedded in a nucleus containing a thermoplastic resin 3 and a coloring agent 2. These first fine particles have higher hardness than the thermoplastic resin in the nucleus and are present near the surface of the nucleus toner 1. The nucleus toner consists of a surface area from its surface to the depth where the first fine particles are present, and an inner area inside of the surface area. The surface area of the nucleus toner 1 substantially consists of the thermoplastic resin 3 and first fine particles 4, while the inner area substantially consists of the thermoplastic resin 3 and the coloring agent 2. Most of the first fine particles 4 are embedded near the surface.
IZUMI TAKAO
TAKAGI OSAMU
HASHIMOTO YOSHIYA
KASAI TOSHIHIRO
