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

Patent metadata

Field	Value
Publication number	US-2022155701-A1
Application number	US-202017433591-A
Country	US
Kind code	A1
Filing date	Feb 20, 2020
Priority date	Feb 25, 2019
Publication date	May 19, 2022
Grant date	—

Abstract

The present invention provides: a ferrite particle containing a crystal phase component containing a perovskite crystal represented by the compositional formula RZrO 3 (where R is an alkaline earth metal element); and an electrophotographic developer carrier core material, an electrophotographic developer carrier, and an electrophotographic developer containing the ferrite particles.

First claim

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).

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

3 . The ferrite particle according to claim 1 , comprising 0.05% by mass or more and 2.50% by mass or less of the crystal phase component comprising the perovskite crystal 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.

4 . The ferrite particle according to claim 1 , having a ratio log L/log H between a logarithmic value of a resistance value L (log Ω) in a low-temperature and low-humidity environment (10° C., relative humidity 20%) and a logarithmic value of a resistance value H (log Ω) in a high-temperature and high-humidity environment (30° C., relative humidity 80%) being 1.0 or more and 1.15 or less when measured at a distance between electrodes of 2 mm and an applied voltage of 500 V.

5 . The ferrite particle according to claim 4 , having the resistance value H of 1.0×10 7 (Ω) or more and 1.0×10 9 (Ω) or less, and a saturation magnetization obtainable by a VSM measurement when a magnetic field of 1K·1000/4π·A/m is applied being 55 emu/g or more and 65 emu/g or less.

6 . The ferrite particle according to claim 1 , comprising a crystal phase component comprising a spinel crystal represented by the compositional formula: (MO)a(Fe 2 O 3 )b (provided that M represents at least one metal element selected from the group consisting of Fe, Mg, Mn, Cu, Zn, and Ni, and a+b=100 (mol %)) as a main component.

7 . The ferrite particle according to claim 1 , wherein the ferrite particle comprises 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

• C04B2235/96

  Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance · CPC title

• C04B2235/80

  Phases present in the sintered or melt-cast ceramic products other than the main phase · CPC title

• C04B2235/77

  Density · CPC title

• C04B2235/768

  Perovskite structure ABO3 · CPC title

• C04B2235/763

  Spinel structure AB2O4 · CPC title