| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a negative charging toner that has excellent fluidity, excellent charging stability upon printing a great number of sheets and excellent durability without inducing irregularity in a printed image. SOLUTION: The method for manufacturing a negative charging toner includes subjecting a mixture containing at least a resin and an organic solvent to phase inversion emulsification in an aqueous medium, granulation, cleaning-dehydration processes and drying to obtain toner mother particles, and externally adding a plurality of external additive particles to the toner mother particles in multiple stages by using a spherical mixing tank. In the method, the toner mother particles to be dried are prepared in such a manner that the organic solvent content of the particles is controlled to 200 to 1,000 ppm, external additive particles having an average particle size of 30 to 50 nm are added by 0.1 to 3.0 mass%, and the average circularity of the toner mother particles is controlled to 0.94 to 0.99. COPYRIGHT: (C)2007,JPO&INPIT
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