US Patent 10578990 Toner

A toner comprising a toner particle that contains a binder resin and a colorant, wherein (1) an average circularity of the toner is at least 0.960, (2) an onset temperature Tε (° C.) of a storage elastic modulus E′ of the toner, as determined by a powder dynamic viscoelastic measurement, is from 50° C. to 70° C., and (3) in a differential curve obtained by differentiation, by load, of a load-displacement curve provided by measurement of the strength of the toner by a nanoindentation procedure, with the horizontal axis being load (mN) and the vertical axis being displacement (μm), the load X that provides the maximum value in the differential curve in the load region from 0.20 mN to 2.30 mN is from 1.00 mN to 1.50 mN.