Surface modified magnetic carriers using hydrophobized titania

Patent metadata

Field	Value
Publication number	US-9841702-B2
Application number	US-201615367637-A
Country	US
Kind code	B2
Filing date	Dec 2, 2016
Priority date	Dec 23, 2014
Publication date	Dec 12, 2017
Grant date	Dec 12, 2017

Abstract

A method for providing a developer mix having tribocharge uniformity across varying temperature and humidity conditions is provided. Tribocharge uniformity is achieved in the developer mix by performing the step of treating the surface of the polymer coated magnetic carrier particles with hydrophobized titania surface additives before the polymer coated magnetic carrier particles are mixed with the toner particles. The surface treatment with the hydrophobized titania surface additives can be either a spherical, disk, or spindle shaped.

First claim

What is claimed is:

1. A method for forming a developer mix to be used in an electrophotographic imaging device comprising:
providing toner particles formed an emulsion aggregation process;
providing magnetic carrier particles having a polymer coating on its outer surface;
surface treating the outer surface of the polymer coated magnetic carrier particles with hydrophobized titania extra particular additives: and
mixing the toner particles and the hydrophobized titania surface treated polymer coated magnetic carrier particles.

2. The method of claim 1 further comprising the steps of screening the hydrophobized titania surface treated polymer coated magnetic carrier particles to remove the hydrophobized titania extra particular additives having large agglomerates prior to the mixing of the hydrophobized titania surface treated polymer coated magnetic carrier particles and the toner particles.

3. The method of claim 1 , wherein the polymer coating is acrylic.

4. The method of claim 1 wherein the polymer coated magnetic carrier particles have a ferrite core.

5. The method of claim 1 , wherein the hydrophobized titania extra particular additives have a spherical shape.

6. The method of claim 5 , wherein the spherical hydrophobized titania extra particular additives have a primary particle size of 40 nm and an anatase crystal form.

7. The method of claim 5 , wherein the spherical shaped hydrophobized titania extra particular additives have a primary particle size of 15 nm and an anatase crystal form.

8. The method of claim 1 , wherein the hydrophobized titania extra particular additives have a disk shape.

9. The method of claim 8 , wherein the disk shaped hydrophobized titania extra particular additives have a primary particle size of 40 nm and an anatase crystal form.

10. The method of claim 8 , wherein the disk shaped hydrophobized titania extra particular additives have a primary particle size of 40 nm and an anatase-rutile crystal form.

11. The method of claim 1 , wherein the hydrophobized titania extra particular additives have a spindle shape.

12. The method of claim 11 , wherein the spindle shaped hydrophobized titania extra particular additives have a primary particle size of 5 nm×60 nm and a rutile crystal form.

13. The method of claim 1 , wherein the hydrophobized titania extra particular additives have an acicular shape.

14. The method of claim 13 , wherein the acicular shaped hydrophobized titania extra particular additives have a primary particle size of 130 nm×1.68 μm and a rutile crystal form.

15. The method of claim 1 , wherein the hydrophobizing agent is a silane.

16. A method for forming a developer mix to be used in an electrophotographic imaging device comprising:
providing toner particles formed using an emulsion aggregation process;
providing magnetic carrier particles having a polymer coating on their outer surface;
surface treating the outer surface of the polymer coated magnetic carrier particle with hydrophobized titania extra particular additives;
screening the hydrophobized titania surface treated polymer coated magnetic carrier particles to remove large agglomerates of the hydrophobized titania extra particular additives: and

mixing the toner particles with the screened hydrophobized titania surface treated polymer coated magnetic carrier particles.

Assignees

• Lexmark Int Inc

Inventors

• Srinivasan Kasturi Rangan
• Blassingame Michael Anthony

Classifications

• G03G9/1133

  obtained by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• G03G9/1075

  Structural characteristics of the carrier particles, e.g. shape or crystallographic structure · CPC title

• G03G9/0815

  Post-treatment · CPC title

• G03G9/0804 Primary

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

• G03G9/0808

  by dry mixing the toner components in solid or softened state · CPC title