Toner, developer, developing device and image forming apparatus

Abstract

A toner is provided. The toner includes toner particles, and silica particles and inorganic fine particles that are externally added to the toner particles, the inorganic fine particles having an average primary particle size smaller than that of the silica particles. The toner particles have a shape factor SF-1 of 130 or more and 140 or less, a shape factor SF-2 of 120 or more and 130 or less, and a volume average particle size of 5 [mu]m or more and 8 [mu]m or less. The silica particles have an average primary particle size of 80 nm or more and 150 nm or less, and an amount of water of 1.5% by weight or less. A particle size distribution of the silica particles is a logarithmic normal distribution, and a value of geometric standard deviation [sigma]g of the particle size of the silica particles is less than 1.30.

Description

Technical field [0001] The present invention relates to a toner used for developing a latent image in an electrophotographic method or an electrostatic printing method, a developer containing the toner, a developing device and an image forming device using the developer. Background technique [0002] In recent years, image forming apparatuses that develop latent images to form images have been studied for higher image quality from various angles. As one of the specific trends, the improvement of the developer to improve the resolution and sharpness, In particular, toner particle size reduction and near-sphericalization are progressing. However, with the progress of toner particle size reduction and near-sphericalization, transferability and cleanability are reduced, and the image quality tends to decrease. [0003] In response to such problems, attempts have been made to improve transferability and cleaning properties by adding an external additive with a particle diameter of abou...

AI Technical Summary

Problems solved by technology

[0008] However, in Japanese Patent Application Laid-Open No. 2005-202132, the water content contained in the external additive with large particle size is not considered.

In particular, when an external additive with a large particle size containing more than 6.0% by weight of water is added to the toner, the charge-to-mass ratio of the toner in the printing durability test decreases, so that the image quality of the formed image decreases, and the color toning effect decreases. Problems such as agent scattering in the machine

In addition, the particle size distribution of external additives with large particle diameters is wide, so when the amount of external additives with large particle diameters is increased in order to ensure cleaning performance, the number of particles with small particle diameters (especially 30 nm or less) increases, and the particles Covers the surface of the toner particles more than necessary, thus suppressing the bleeding effect of the release agent contained in the toner particles, which may adversely affect the fixability

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