# US 2014/0154623 A1 · Carrier core particles for electrophotographic developer, carrier for electrophotographic developer, electrophotographic developer and method for manufacturing the carrier core particles

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- Number: US 2014/0154623 A1
- Document ID: US20140154623A1
- Status: Published application
- Kind: A1
- Application number: 14/175,276
- Filed: 2014-02-07
- Published: 2014-06-05
- Earliest claimed: 2010-06-14
- Assignees: Dowa IP Creation Co., Ltd.; Dowa Electronics Materials Co., Ltd.
- Applicants: Dowa IP Creation Co., Ltd.; Dowa Electronics Materials Co., Ltd.
- Inventors: Takeshi KAWAUCHI
- Web page: https://patentgrep.com/patent/US20140154623A1

## CPC

- G03G 9/1132: {Macromolecular components of coatings}
- G03G 9/1075: {Structural characteristics of the carrier particles, e.g. shape or crystallographic structure}
- G03G 9/108: {Ferrite carrier, e.g. magnetite}
- G03G 9/113: having coatings applied thereto
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

The carrier core particles for electrophotographic developer include a core composition expressed by a general formula Fe3O4 as a main ingredient and 30 ppm to 400 ppm Na. Such carrier core particles can reduce environmental dependency thereof, while optimizing the resistivity.

## Claims

### Claim 1

(canceled)

### Claim 2

(canceled)

### Claim 3

A carrier for an electrophotographic developer comprising:
a carrier core including core composition particles expressed by a general formula Fe3O4 as a main ingredient and additive particles containing 30 ppm to 400 ppm Na; and
a resin coating surfaces of the carrier core particles.

### Claim 4

An electrophotographic developer used to develop electrophotography, comprising:
a carrier that includes a carrier core having core composition particles expressed by a general formula Fe3O4 as a main ingredient and additive particles containing 30 ppm to 400 ppm Na, and a resin coating surfaces of the carrier core particles; and
a toner that can be triboelectrically charged by frictional contact with the carrier for development of electrophotography.

### Claim 5

(canceled)

### Claim 6

(canceled)

### Claim 7 (depends on 3)

The carrier for an electrophotgraphic developer according to claim 3, wherein the Na content is limited to a range from 50 ppm to 200 ppm.

### Claim 8 (depends on 4)

The electrophotgraphic developer used to develop electrophotography according to claim 4, wherein the Na content is limited to a range from 50 ppm to 20 ppm.