| 摘要 |
PROBLEM TO BE SOLVED: To provide a one component nonmagnetic toner that is hardly lightly aggregated even in high temperature storage and during high temperature operation and hardly causes density thinning or variance in triboelectric contrast during continuous printing. SOLUTION: The one component nonmagnetic toner contains: 100 parts by mass of color particles containing a colorant and a binder resin having a glass transition temperature of 40 to 50°C and a softening point of 100 to 120°C; and an external additive agent containing: 0.5 to 2.0 parts by mass of hydrophobic rutile-anatase titanium oxide particles (a) having a major axial diameter of 20 to 50 nm; 0.5 to 2.0 parts by mass of hydrophobic monodispersion spherical large silica particles (b) having a number average primary particle diameter of 50 to 250 nm; and 0.5 to 3.0 parts by mass of hydrophobic small silica particles (c) having a number average primary particle diameter of 7 to 16 nm, a two-component charge amount (5-min value) of -100 to 0μC/g and a bulk density of 0.1 to 0.5 g/cm<SP>3</SP>. The external additive agent is added in a multi-stage process, and the hydrophobic rutile-anatase titanium oxide particles (a) are added to the coloring particles at first in the multi-stage process to obtain the toner. COPYRIGHT: (C)2009,JPO&INPIT
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