Patent ID: 7939238

Claim:
A method of preparing a toner, comprising: dissolving or dispersing a prepolymer composition comprising an isocyanate-containing polyester-based prepolymer, a colorant, and a wax in an organic solvent to prepare a liquid, dispersing said liquid in an aqueous medium to obtain a dispersion, polymerizing said prepolymer present in said dispersion by a polyaddition reaction in the presence of an amine to obtain a reaction mixture comprising, dispersed therein, particles of a toner composition comprising the colorant and an urea-modified polyester obtained from the prepolymer; removing the organic solvent from said particles to obtain toner particles dispersed in an aqueous medium; heating said toner particles dispersed in the aqueous medium at a temperature of from about 50° C. to the melting point of said wax so that no more than 30% by weight of toner particles have a sphericity of less than 0.95, thereby reducing the irregular shaped toner particles; and filtering, washing and drying the heated toner particles dispersed in the aqueous medium to obtain dried toner particles, wherein said toner has an average sphericity of 0.96 or more; said toner binder contains an unmodified polyester in addition to the modified polyester, the weight ratio of said modified polyester to said unmodified polyester is in the range of 5:95 to 80:20; and the toner binder has an acid value of 1 to 30 mg KOH/g.