PURPOSE: To obtain an electophotographic developer having high triboelectrostatic chargeability and high fluidity and to form satisfactory picture images without generating defective transfer by adding externally specified two kinds of inorganic material powder to toner particles.
CONSTITUTION: Two kinds of fine inorganic material powder are added externally to toner particles wherein primary particle size of each inorganic fine powder is regulated to <10 mμm and <30 mμm, respectively, and particle size of large particles is regulated to ≥ twice of that of small particles. Suitable inorganic fine powder is that of tin oxide, fluorinated graphite, carbon black, SiC, etc. Thus, transfer characteristic of an electrophotographic toner is improved and satisfactory stability against environmental change thereof is also improved while maintaining high triboelectrostatic chargeability and high fluidity. Thus, distinct picture quality are maintained even if the toner is used a room temp. and under normal humidity at high temp. and in high humidity, or at low temp. in low humidity.
AKAGI HIDEYUKI
ISHII YUKIHIRO
HASHIMOTO TAKESHI
| JPS62174772A | 1987-07-31 |
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