Method for producing a toner

Patent metadata

Field	Value
Publication number	US-12140905-B2
Application number	US-202117336386-A
Country	US
Kind code	B2
Filing date	Jun 2, 2021
Priority date	Jun 8, 2020
Publication date	Nov 12, 2024
Grant date	Nov 12, 2024

Abstract

A production method of a toner having a toner particle that contains a binder resin and an external additive that is externally added to the toner particle, wherein the production method has a toner particle dispersion step of obtaining a toner particle dispersion by dispersing the toner particle and an inorganic dispersant in an aqueous medium; and an external addition step of externally adding the external additive to the toner particle through addition of the external additive to the toner particle dispersion.

First claim

What is claimed is:

1. A method for producing a toner comprising a toner particle comprising a binder resin, and having an external additive, the method comprising the steps of:
dispersing the toner particle and an inorganic dispersant in an aqueous medium to obtain an aqueous dispersion of the toner particle;
adding the external additive to the aqueous dispersion; and
fixing the external additive to the toner particle in the aqueous dispersion, wherein
the toner particle dispersion is held at a temperature of T1 (° C.) for at least 15 minutes during or after the step of adding, or during or after the step of fixing, where Tg−10° C.<T1<Tg+25° C. and Tg (° C.) is the glass transition temperature of the toner particle, and
in the step of dispersing, a coverage ratio of the inorganic dispersant relative to the surface of the toner particle that is dispersed in the toner particle dispersion is 20 to 50 area %.

2. The method for producing a toner of claim 1 , wherein the inorganic dispersant has a volume-basis median diameter of 30 to 200 nm.

3. The method for producing a toner of claim 1 , wherein the external additive has primary particles with a number-average particle diameter of 100 to 300 nm.

4. The method for producing a toner of claim 1 , wherein in the step of dispersing A×B≤7000, where A (area %) is a coverage ratio of the inorganic dispersant relative to the surface of the toner particle that is dispersed in the toner particle dispersion, and B (nm) is a number-average particle diameter of primary particles of the external additive.

5. The method for producing a toner of claim 1 , wherein the inorganic dispersant comprises an inorganic salt.

6. The method for producing a toner of claim 1 , wherein the inorganic dispersant comprises a polyvalent metal salt of phosphoric acid.

7. The method for producing a toner of claim 1 , wherein the external additive comprises (i) an inorganic fine particle or (ii) an organic-inorganic composite fine particle containing said inorganic fine particle and an organic fine particle, and
the inorganic fine particle is at least one member selected from the group consisting of a silica fine particle, an alumina fine particle, a titania fine particle, a strontium titanate fine particle and a complex oxide fine particle thereof.

8. The method for producing a toner of claim 1 , wherein the step of adding and fixing is carried out with a stirring device that delivers high shear forces, the stirring device being provided inside a vessel, and
10<P/V<110 and P=1.05×(f/60) 3 ×(d/1000) 5 where V (m 3 ) is a volume of liquid present in the vessel, P(KW) is power used by the stirring device, d (mm) is a blade diameter of a stirring blade, and f (rpm) is a rotational speed of the blade in the stirring device.

9. The method for producing a toner of claim 1 , wherein the external additive is silica fine particles.

10. The method for producing a toner of claim 1 , wherein the aqueous medium contains an organic solvent in a content of 10 mass % or less based on a total mass of the aqueous medium; and
the aqueous medium contains a surfactant in a content of 0.01 mass % or less based on a total mass of the aqueous medium.

11. The method for producing a toner of claim 1 , wherein the aqueous medium contains an organic solvent in a content of 1 mass % or less based on a total mass of the aqueous medium; and
the aqueous medium contains a surfactant in a content of 0.0001 mass % or less based on a total mass of the aqueous medium.

12. The method for producing a toner of claim 1 , wherein the aqueous medium does not contain any organic solvent.

13. The method for producing a toner of claim 1 , wherein the aqueous medium does not contain any surfactant.

14. The method for producing a toner of claim 1 , wherein the aqueous medium does not contain any organic solvent, and does not contain any surfactant.

Assignees

• Canon Kk

Inventors

• Yamashita Shohei
• Tsujino Takeshi
• Asaoka Junya
• Sasano Yuu
• Terui Yuhei
• Inoue Koki
• Amano Shota

Classifications

• G03G9/0819

  characterised by the dimensions of the particles · CPC title

• G03G9/09708

  Inorganic compounds · CPC title

• G03G9/08711

  with esters of acrylic or methacrylic acid · CPC title

• G03G9/0804 Primary

  whereby the components are brought together in a liquid dispersing medium · CPC title