Patent ID: 7018764

Claim:
A toner for developing electrostatic images, comprising a colorant and a binder resin, said toner containing a reactive polymer which cross-links when heated to a temperature that is higher than 100° C., and having a shape factor SF1 of 110 to 140 represented by: SF 1 = ML 2 /(4 A/ π×100) wherein, ML represents a maximum length (μm) of the toner, and A represents a projected area (μm 2 ) of the toner; wherein the toner has a layered-structure containing at least a shell layer provided so as to cover the surface thereof, and a core layer provided on an inner side of the shell layer; and the binder resin is contained in the core layer and the shell layer, and a glass transition temperature of a binder resin contained in the core layer is lower than a glass transition temperature of a binder resin contained in the shell layer.