US Patent 9690223 Toner and method of manufacturing the same

A toner includes a plurality of toner particles each including a core and a shell layer residing on a surface of the core. The shell layer has a plurality of cavities each exposing the core. Each of the toner particles has a distribution of surface hardness, as measured by a scanning probe microscope in a state where no external additive adheres to the toner particle, satisfying that the surface hardness is at least 1.10 times a surface hardness Ss in at least 75% and no greater than 95% by area ratio of a surface of the toner particle, where Ss denotes the surface hardness at a location where the core is exposed through any of the cavities.