Two-component developer for developing electrostatic latent image

Abstract

An object of the present invention is to provide a two-component developer for developing an electrostatic latent image capable of suppressing variation in charge amount of a toner and obtaining a high-quality image for a long period of time. So the two-component developer for developing an electrostatic latent image contains: toner particles having toner mother particles and an external additiveon a surface of the toner mother particles; and carrier particles, wherein the external additive contains alumina particles; the alumina particles are subjected to a surface modification with a hydrophobilizing agent; among the hydrophobilizing agent existing on the surface of the alumina particles after the surface modification, a ratio of the hydrophobilizing agent in a state of being liberatedfrom the surface is 20% or less when extraction treatment is performed under a predetermined condition; the alumina particles have a number average primary particle diameter in the range of 5 to 60 nm; and the carrier particles have a resin covering layer, and the resin covering layer is formed with an alicyclic (meth)acrylate monomer.

Description

technical field [0001] The present invention relates to a two-component developer for developing an electrostatic latent image. More specifically, the present invention relates to a two-component developer for developing an electrostatic latent image capable of suppressing fluctuations in the charge amount of the toner and obtaining a high-quality image over a long period of time. Background technique [0002] As the function of the external additive of the toner for developing an electrostatic latent image (hereinafter also simply referred to as "toner"), for example, improvements in chargeability and fluidity can be cited. The external additives are usually fine powders of inorganic oxides, and silica particles, titania particles, alumina particles and the like can be used. Silica particles are effective in improving fluidity, but have a problem of excessively increasing the charge amount of the toner especially in a low-temperature and low-humidity environment due to the...

AI Technical Summary

Problems solved by technology

Silica particles are effective in improving the fluidity, but due to their high negative chargeability, there is a problem that the charge amount of the toner is excessively increased especially in a low-temperature and low-humidity environment

However, there is a problem that when the titanium dioxide particles are transferred to the carrier particles in high-coverage printing, the charge transfer of the carrier particles is accelerated due to the low resistance, resulting in a decrease in the charge amount of the toner.

However, there are following problems: In order to make the titanium dioxide particles have the same level of resistance as the carrier particles, the amount of surface modification will be excessive, and the excess surface modifier will cause the modifiers to coagulate with each other due to the release of the carrier particles, and the fluidity will deteriorate. Decreased charge amount of toner

However, heat-curable general silicone resins have a problem of being unable to sufficiently suppress fluctuations in charge amount due to the environment due to their high hygroscopicity.

Images