Ferrite particles, electrophotographic developer carrier core material, electrophotographic developer carrier, and electrophotographic developer

Patent metadata

Field	Value
Publication number	US-12436480-B2
Application number	US-202117915345-A
Country	US
Kind code	B2
Filing date	Mar 17, 2021
Priority date	Mar 31, 2020
Publication date	Oct 7, 2025
Grant date	Oct 7, 2025

Abstract

The present invention relates to a ferrite particle containing a crystal phase component containing a perovskite crystal represented by a compositional formula: RZrO3 (provided that R represents an alkaline earth metal element), having a surface roughness Rz of 0.8 μm or more and 3.5 μm or less, and having a standard deviation Rzσ of the surface roughness Rz falling in a range represented by the following formula 0.15×Rz≤Rzσ≤0.60×Rz. The ferrite particle can be used as an electrophotographic developer carrier core material. In addition, an electrophotographic developer carrier and an electrophotographic developer can be obtained.

First claim

The invention claimed is:

1. A ferrite particle,
comprising a crystal phase component comprising a perovskite crystal represented by the compositional formula: RZrO 3 (provided that R represents an alkaline earth metal element),
having a surface roughness Rz of 0.8 μm or more and 3.5 μm or less, and
having a standard deviation Rzσ of the surface roughness Rz falling in a range represented by the following formula:
0.15× Rz≤Rzσ≤ 0.60× Rz   (1)

comprising the crystal phase component comprising the perovskite crystal in an amount of 0.05% by mass or more and 4.0% by mass or less when a phase composition analysis of a crystal phase constituting the ferrite particle is performed by a Rietveld analysis of an X-ray diffraction pattern.

2. The ferrite particle according to claim 1 , wherein the surface roughness Rz is 1.0 μm or more and 2.5 μm or less.

3. The ferrite particle according to claim 1 , wherein the standard deviation Rzσ of the surface roughness Rz is in a range represented by the following formula:
0.20× Rz≤Rzσ≤ 0.42× Rz   (2).

4. The ferrite particle according to claim 1 , wherein the R is at least one element selected from the group consisting of Sr, Ca, and Ba.

5. The ferrite particle according to claim 1 , having an apparent density in a range represented by the following formula:
1.90≤ Y≤ 2.50

provided that Y in the formula represents the apparent density (g/cm 3 ) of the ferrite particle.

6. The ferrite particle according to claim 1 , having a flow rate of 26 sec/50 g or more and 42 sec/50 g or less.

7. The ferrite particle according to claim 1 , wherein the ferrite particle is a spinel ferrite particle having a crystal phase component comprising a spinel crystal represented by the compositional formula: (MnO)x(MgO)y(Fe 2 O 3 )z (provided that 15≤x≤50, 2≤y≤35, 45≤z≤60, x+y+z=100 (mol %)) as a main component.

8. An electrophotographic developer carrier core material, comprising the ferrite particle described in claim 1 .

9. An electrophotographic developer carrier, comprising the ferrite particle described in claim 1 and a resin coating layer provided on a surface of the ferrite particle.

10. An electrophotographic developer, comprising the electrophotographic developer carrier described in claim 9 and a toner.

11. The electrophotographic developer according to claim 10 , used as a replenishment developer.

Assignees

• Powdertech Co Ltd

Inventors

• Ishikawa Makoto
• Uemura Tetsuya

Classifications

• G03G9/1132

  Macromolecular components of coatings · CPC title

• G03G9/0821

  characterised by physical parameters (magnetic parameters G03G9/083) · CPC title

• C04B2235/963

  Surface properties, e.g. surface roughness · CPC title

• C04B2235/768

  Perovskite structure ABO3 · CPC title

• C04B2235/763

  Spinel structure AB2O4 · CPC title