Patent ID: 8871414

Claim:
A positively chargeable toner for electrostatic image development, comprising a binder resin and a mixture of a styrene resin and a quaternary ammonium salt functional group-containing resin of a copolymer of an addition-polymerizable monomer having a quaternary ammonium salt functional group, a styrene monomer and acrylic monomer, wherein the mixture of the styrene resin and the quaternary ammonium salt functional group-containing resin forms domains, which are not compatible with the binder resin, in the binder resin, the binder resin is a polyester resin which is a polycondensate of one or more alcohol components selected from bivalent, trivalent or higher-valent alcohols and one or more carboxylic acid components selected from bivalent, trivalent or higher-valent carboxylic acids, and the number % of the sum of N1 to N29 (Nn: number of domains consisting of the mixture of the styrene resin and the quaternary ammonium salt functional group-containing resin of which the diameter of domains dispersed is no less than 0.01×n μm to less than 0.01×(n+1) μm; n: a positive integer of 1 or more) versus the total number of domains consisting of the charge control resin, for which the diameter of domains dispersed of no less than 50 by number of domains consisting of the mixture of the styrene resin and the quaternary ammonium salt functional group-containing resin have been measured using an image of magnification 10,000× taken by a scanning electron microscope, is no less than 98% by number.