| 摘要 |
PROBLEM TO BE SOLVED: To obtain a toner having good fluidity which does not cause splashing of a toner or thinning in the latter half of a black solid image and to obtain a high-quality image by preparing such a toner that contains particles having a specified sphericity or lower in a specified proportion or smaller and contains a binder resin, coloring agent and non-heavy metal charge controlling agent. SOLUTION: This developer contains toner particles having <0.93 sphericity by <21% and contains a binder resin and a coloring agent. The charge controlling agent used does not contain heavy metals. By using a toner with higher sphericity to improve the fluidity, the contact times between the toner and the carrier per unit time are increased and more charges are accumulated in the toner and the carrier in a short time. As a result, electrification is carried out with fast rising while splashing of the toner or thinning in the latter half of a solid image can be prevented. The fluidity of the developer is also influenced by the particle sizes of the toner and the carrier. Since higher image quality and a smaller size f a device are required, it is necessary to determine a proper particle size as well as the proper sphericity in order to obtain enough fluidity. |
