Toners for electrostatic-image development, cartridge employing toner for electrostatic-image development, and image-forming apparatus

Abstract

An object of the invention is to provide a toner which is effective in improving image quality while inhibiting white-background fouling, residual-image phenomenon (ghost), blurring (suitability for solid printing), and the like that occur depending on the proportion of a fine powder having a particle diameter not larger than a specific value, and which has satisfactory removability in cleaning, mitigates problems concerning fouling, etc. in long-term use even on a high-speed printer, and attains excellent image stability. Another object is to provide an image-forming apparatus and a toner cartridge each employing the toner. The invention provides a toner for electrostatic-image development satisfying all of the following (1) to (4) or a toner for electrostatic-image development which is a toner containing a charge control agent and satisfying all of the following (5) to (7). The invention further provides an image-forming apparatus and a toner cartridge each employing the toner. (1) To have a volume-median diameter (Dv50) of from 4.0 μm to 7.5 μm. (2) To have an average degree of circularity of 0.93 or higher. (3) A volume-median diameter (Dv50) of the toner and population number % of toner particles having a particle diameter of from 2.00 μm to 3.56 μm (Dns) in the toner satisfy the relationship Dns≦0.233 EXP(17.3/Dv50). (4) To have a coefficient of variation in number of 24.0% or lower. (5) To have a volume-median diameter (Dv50) of from 4.0 μm to 7.5 μm. (6) A volume-median diameter (Dv50) of the toner and population number % of toner particles having a particle diameter of from 2.00 μm to 3.56 μm (Dns) in the toner satisfy the relationship Dns≦0.233 EXP(17.3/Dv50). (7) When the charge control agent on the toner surface is cleaned, the resultant depressions have an average diameter of 500 nm or smaller.