Patent ID: 7541127
Filing Date: 2009-06-02
Classification: G03G

Abstract:
1. A toner for developing electrostatic image comprising a colored particle containing a binder resin and a colorant, and an external additive, wherein the toner for developing electrostatic image has a volume average particle diameter of 4.0 to 8.0 μm and an average circularity of 0.940 to 0.980, wherein the external additive includes an inorganic microparticle (A) having a small particle diameter with a number average primary particle diameter of from 5 to 14 nm, an inorganic microparticle (B) having a medium particle diameter with a number average primary particle diameter of from 15 to 90 nm, and a particle (C) having a large particle diameter with a number average primary particle diameter of from 100 to 500 nm, wherein a hydrophobicity measured by a methanol method of the inorganic microparticle (A) having a small particle diameter and/or the inorganic microparticle (B) having a medium particle diameter is from 50 to 100%, wherein an added amount of the external additive is from 0.01 to 3 parts by weight with respect to 100 parts by weight of the colored particle, and wherein the toner for developing electrostatic image has a uniaxial collapsing stress of 0.8 to 1.5 kPa and an internal frictional angle of 30 to 45° when a maximum consolidation stress is 0.