US Patent 7217486 Toner and image-forming apparatus using the toner

The present invention provides a toner containing toner mother particles containing a binder resin and a colorant having added thereinto external additives, e.g., positively electrifiable silica fine particles, negatively electrifiable silica fine particles, titanium oxide fine particles and a long chain fatty acid or a salt thereof, wherein the external additives are added by multistage process, thereby is low in desorption of external additives, has the electrification property for a long period of time, shows high flowability and transfer efficiency, and is not accompanied by the reduction of image density.