Toner for developing electrostatic images

Patent metadata

Field	Value
Publication number	US-10539894-B2
Application number	US-201515503167-A
Country	US
Kind code	B2
Filing date	Aug 5, 2015
Priority date	Aug 18, 2014
Publication date	Jan 21, 2020
Grant date	Jan 21, 2020

Abstract

The present invention is to provide a toner for developing electrostatic images, which has an excellent balance between low-temperature fixability and heat-resistant shelf stability, which has good toner conveyance amount stability and printing durability, and which has less occurrence of fog in a high temperature and high humidity environment. Disclosed is a toner for developing electrostatic images, comprising colored resin particles containing a binder resin and a colorant, and an external additive, wherein the toner comprises, as the external additive, fine silica particles in an amount of 0.5 to 3.0 parts by mass with respect to 100 parts by mass of the colored resin particles, the fine silica particles having a hydrophobicity of 15 to 49% that is determined after a high-temperature and high-humidity incubation.

First claim

The invention claimed is:

1. A toner for developing electrostatic images, comprising colored resin particles containing a binder resin and a colorant, and an external additive,
wherein the toner comprises, as the external additive, fine silica particles in an amount of 0.5 to 2.0 parts by mass with respect to 100 parts by mass of the colored resin particles, the fine silica particles having been subjected to a hydrophobicity-imparting treatment with a silicon compound, and the fine silica particles having a hydrophobicity of 27 to 49% that is determined after a high-temperature and high-humidity incubation;
wherein the fine silica particles have a number average primary particle diameter of 50 to 500 nm; and
wherein the toner comprises, as the external additive, fatty acid metal salt particles having a number average primary particle diameter of 100 to 500 nm.

2. The toner for developing electrostatic images according to claim 1 , wherein a variation in hydrophobicity of the fine silica particles is 5 to 28% between a hydrophobicity determined before a high-temperature and high-humidity incubation and that determined after the high-temperature and high-humidity incubation.

3. The toner for developing electrostatic images according to claim 1 , wherein a total content of the external additive is 1.40 to 4.00 parts by mass with respect to 100 parts by mass of the colored resin particles.

4. The toner for developing electrostatic images according to claim 1 ,
wherein the colored resin particles are positively chargeable, and
wherein the fine silica particles are surface-treated to be positively chargeable.

Assignees

• Zeon Corp

Inventors

• Chiba Takeru

Classifications

• G03G9/09716

  treated with organic compounds · CPC title

• G03G9/09791

  Metallic soaps of higher carboxylic acids · CPC title

• G03G9/0904

  Carbon black · CPC title

• G03G9/09725

  Silicon-oxides; Silicates · CPC title

• C01B33/148 Primary

  Concentration; Drying; Dehydration; Stabilisation; Purification {(C01B33/1465 takes precedence)} · CPC title