Magnetic toner

摘要

A magnetic toner contains magnetic toner particles containing a binder resin and a magnetic body, and inorganic fine particles present on the surface of the magnetic toner particles, wherein the inorganic fine particles present on the surface of the magnetic toner particles contain metal oxide fine particles, the metal oxide fine particles containing silica fine particles, and optionally containing titania fine particles and alumina fine particles, and a content of the silica fine particles being at least 85 mass % with respect to a total mass of the silica fine particles, the titania fine particles and the alumina fine particles, when a coverage ratio A (%) is a coverage ratio of the magnetic toner particles' surface by the inorganic fine particles and a coverage ratio B (%) is a coverage ratio of the magnetic toner particles' surface by the inorganic fine particles that are fixed to the magnetic toner particles' surface, the magnetic toner has a coverage ratio A and a coverage ratio B/coverage ratio A in prescribed ranges, wherein the magnetic toner has a dielectric constant ∈′ and a dielectric loss tangent in prescribed ranges.

主权项

1. A magnetic toner comprising
magnetic toner particles comprising a binder resin and a magnetic body, and inorganic fine particles present on the surface of the magnetic toner particles, wherein; the inorganic fine particles present on the surface of the magnetic toner particles comprise metal oxide fine particles, the metal oxide fine particles containing silica fine particles, and optionally containing titania fine particles and alumina fine particles, and a content of the silica fine particles being at least 85 mass % with respect to a total mass of the silica fine particles, the titania fine particles and the alumina fine particles, wherein; when a coverage ratio A (%) is a coverage ratio of the magnetic toner particles' surface by the inorganic fine particles and a coverage ratio B (%) is a coverage ratio of the magnetic toner particles' surface by the inorganic fine particles that are fixed on the magnetic toner particles' surface, the magnetic toner has a coverage ratio A of at least 45.0% and not more than 70.0% and a ratio [coverage ratio B/coverage ratio A] of the coverage ratio B to the coverage ratio A of at least 0.50 and not more than 0.85, and wherein the magnetic toner has a dielectric constant ∈′, at a frequency of 100 kHz and a temperature of 30° C., of at least 30.0 pF/m and not more than 40.0 pF/m and has a dielectric loss tangent (tan δ) of not more than 9.0×10−3.