| 摘要 |
<p>PROBLEM TO BE SOLVED: To secure a proper charge amount, to decrease an excessive toner fog on a photoreceptor and to avoid contamination on a white base of a printed material by mixing polyester-based negative electrification toner particles with inorganic fine powder having a large particle size and inorganic fine powder having a small particle size both treated with a specified treating agent to prepare the toner. SOLUTION: The parts by weight (Wa) of inorganic fine powder (a) having <80 m2/g BET specific surface area and treated with a silane coupling agent or silicone oil, and the parts by weight (Wb) of inorganic fine powder (b) having >=80 m2/g BET specific surface area and treated with a silane coupling agent or silicone oil added to 100 pts.wt. of toner particles are controlled to satisfy the formulae. In the formulae, f is the coating rate (%), Dt is the volume average particle diameter (μm) of the toner particles, da and db are average particle diameters (μm) of the inorganic fine powder (a) and inorganic fine powder (b), respectively, andρt,ρa,ρb are true specific gravities of the toner particles, inorganic fine powder (a) and inorganic fine powder (b), respectively. The average particle diameter of the toner is preferably 4 to 20μm.</p> |
