| 摘要 |
PROBLEM TO BE SOLVED: To make maintainable a high image density and low fog for a long time even when a recovered toner is again supplied to a developing device for use by using a toner prepared by depositing (externally adding) silica having little coarse aggregated particles on the toner surface. SOLUTION: This toner for a recycling system is prepared by depositing hydrophobic silica on the surface of color fine particles containing at least a binder resin, coloring agent and charge controlling agent. The hydrophobic silica contains particles having <=5.04 μm diameter based on the volume by >=60 vol.% and particles having <=20.2 μm diameter based on the volume by >=90 vol.%. The hydrophobic silica used is only required to be prepared as hydrophobic by using a silane and/or titanium coupling agent or polysiloxane such as silicone oil, and its preferable hydrophobicity degree is >=50 calculated as wettability with methanol. The silica used is prepared by subjecting hydrophilic silica to hydrophobic treatment, pulverizing in a mixer or the like which gives high shearing force, and controlling to obtain desired distribution grain size with using a mechanical or gas flow type pulverizing machine and a classifying machine. |
