# US 2018/0024455 A1 · Carrier core material

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- Number: US 2018/0024455 A1
- Document ID: US20180024455A1
- Status: Published application
- Kind: A1
- Application number: 15/656,018
- Filed: 2017-07-21
- Published: 2018-01-25
- Earliest claimed: 2016-07-22
- Assignees: Dowa Electronics Materials Co., Ltd.; Dowa IP Creation Co., Ltd.
- Applicants: Dowa Electronics Materials Co., Ltd.; Dowa IP Creation Co., Ltd.
- Inventors: Yuto KAMAI; Shinya SASAKI
- Web page: https://patentgrep.com/patent/US20180024455A1

## CPC

- G03G 9/1085: {with non-ferrous metal oxide, e.g. MgO-Fe2O3}
- G03G 9/1075: {Structural characteristics of the carrier particles, e.g. shape or crystallographic structure}
- G03G 9/1131: {Coating methods; Structure of coatings}
- G03G 9/1132: {Macromolecular components of coatings}
- G03G 9/1138: {Non-macromolecular organic components of coatings}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

A carrier core material is provided that is formed with ferrite particles which can uniformly adhere a coupling agent to the entire surface. A carrier core material is formed with ferrite particles, and the powder pH of the ferrite particles is equal to or more than 9. Here, the ferrite particles are preferably formed of Mn ferrite or Mn—Mg ferrite. The ferrite particles preferably contain 45 wt % or more but 65 wt % or less of Fe, 15 wt % or more but 30 wt % or less of Mn and 5 wt % or less of Mg.

## Claims

### Claim 1

A carrier core material that is formed with ferrite particles,
wherein a powder pH of the ferrite particles is equal to or more than 9.

### Claim 2 (depends on 1)

The carrier core material according to claim 1,
wherein the ferrite particles are formed of Mn ferrite or Mn—Mg ferrite.

### Claim 3 (depends on 1)

The carrier core material according to claim 1,
wherein the ferrite particles contain 45 wt % or more but 65 wt % or less of Fe, 15 wt % or more but 30 wt % or less of Mn and 5 wt % or less of Mg.

### Claim 4 (depends on 1)

The carrier core material according to claim 1,
wherein the ferrite particles contain 0.1 wt % or more but 3.0 wt % or less of Sr and/or Ca as a total amount.

### Claim 5 (depends on 1)

The carrier core material according to claim 1,
wherein a total content of elements of Al, Cr, Mo, Si and Ti in the ferrite particles is equal to or less than 0.15 wt %.

### Claim 6 (depends on 1)

The carrier core material according to claim 1,
wherein an average length RSm of the ferrite particles is equal to or more than 7 but equal to or less than 8 μm.

### Claim 7 (depends on 1)

The carrier core material according to claim 1,
wherein a maximum height Rz of the ferrite particles is equal to or more than 1.5 μm but equal to or less than 3.0 μm.

### Claim 8 (depends on 1)

The carrier core material according to claim 1,
wherein a magnetization σ1k is equal to or more than 50 Am2/kg but equal to or less than 70 Am2/kg.

### Claim 9 (depends on 1)

The carrier core material according to claim 1,
wherein a coupling agent is adhered to a surface of the ferrite particles.

### Claim 10 (depends on 9)

The carrier core material according to claim 9,
wherein the coupling agent is a coupling agent which includes at least one type selected from a group consisting of an amino group, an epoxy group, a methacryl group, a vinyl group, a mercapto group, an isocyanate group and an alkyl group.

### Claim 11 (depends on 9)

An electrophotographic development carrier,
wherein the electrophotographic development carrier has a resin coating layer on a surface of the carrier core material according to claim 9.

### Claim 12 (depends on 11)

An electrophotographic developer comprising:
the electrophotographic development carrier according to claim 11; and
a toner.

### Claim 13 (depends on 10)

An electrophotographic development carrier,
wherein the electrophotographic development carrier has a resin coating layer on a surface of the carrier core material according to claim 10.

### Claim 14 (depends on 13)

An electrophotographic developer comprising:
the electrophotographic development carrier according to claim 13; and
a toner.