To provide a negatively chargeable toner having excellent rising property for electrification and uniformity in the method of nonmagnetic single component development so that high-quality images without any stain in images can be continuously obtained even when the toner is used for a fast process machine.
The negatively chargeable toner for the method of nonmagnetic single component development contains a binder resin, release agent, negatively chargeable controlling agent, coloring agent and external additive. The main component of the binder resin is polyester having ≥5 mgKOH/g acid value obtained by condensation polymerization of a carboxylic acid component and an alcohol component containing alkylene oxide adduct of bisphenol A expressed by formula (I) by ≥5 mol%. In formula, R represents a 2-3C alkylene group and each of x and y is a positive number with the sum of x and y ranging from 1 to 16. The toner contains melamine resin fine particles as the external additive having a triazine structure and 0.09 to 0.8 μm volume average particle size.
SAKAEDA AKIHIRO
SATA SHINICHI
