# US 9,040,217 B2 · Carrier, two-component developer using the same, and image-forming apparatus using said developer

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- Number: US 9,040,217 B2
- Document ID: US9040217B2
- Status: Granted
- Kind: B2
- Application number: 12/393,313
- Filed: 2009-02-26
- Published: 2009-09-10
- Granted: 2015-05-26
- Earliest claimed: 2008-02-28
- Assignees: Sharp Kabushiki Kaisha
- Applicants: Kazuki Takatsuka; Tatsuo Imafuku; Takahiro Bito; Takeshi Satoh; Masaki Ueji
- Inventors: Kazuki Takatsuka; Tatsuo Imafuku; Takahiro Bito; Takeshi Satoh; Masaki Ueji
- Web page: https://patentgrep.com/patent/US9040217B2

## CPC

- G03G 9/1136: {containing silicon atoms}
- G03G 9/1137: {being crosslinked}
- G03G 9/1138: {Non-macromolecular organic components of coatings}
- G03G 9/1139: {Inorganic components of coatings}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

The present invention provides a carrier for a two-component electrophotographic developer, comprising a core particle and a thermoset silicone resin layer coated thereon, wherein said layer comprises a charge control agent and is formed by heat-treatment at a temperature below the melting point of said charge control agent.

## Claims

### Claim 1

A carrier for a two-component electrophotographic developer, comprising a core particle and a thermoset silicone resin layer coated thereon, wherein said layer comprises a charge control agent and is formed by heat-treatment at a temperature below the melting point of said charge control agent.

### Claim 2 (depends on 1)

The carrier according to claim 1, wherein said charge control agent is an organic silicon complex compound represented by the general formula (1):
wherein R1, R2 and R3 each independently represent hydrogen atom, or a substituted or unsubstituted, alkyl, cycloalkyl, aryl or aralkyl group; and X+ represents an organic or inorganic cation,
or a calixarene compound represented by the general formula (2):
wherein x+y=n; x and y are each an integer equal to or greater than 1; n is an integer from 4 to 8; the x and y repeating units can occur in any order; R1, R2, R3 and R4 each independently represent hydrogen atom, an optionally branched alkyl group having 1 to 12 carbon atoms, an optionally substituted aralkyl group having 7 to 12 carbon atoms, or an optionally substituted phenyl group.

### Claim 3 (depends on 1)

The carrier according to claim 1, wherein said thermoset silicone resin layer is formed by coating said core particle with a thermosetting silicone resin not containing said charge control agent, and then with a thermosetting silicone resin containing said charge control agent, and subsequently by said heat treatment at a temperature below the melting point of said charge control agent.

### Claim 4 (depends on 3)

The carrier according to claim 3, wherein said thermosetting silicone resin containing said charge control agent further comprises a conductive agent.

### Claim 5 (depends on 1)

The carrier according to claim 1, wherein said thermoset silicone resin layer is a dimethyl silicone resin layer.

### Claim 6 (depends on 1)

The carrier according to claim 1, wherein said core particle comprises ferrite.

### Claim 7 (depends on 1)

A two-component electrophotographic developer comprising the carrier according to claim 1 and a toner.

### Claim 8 (depends on 7)

An electrophotographic image-forming apparatus which comprising the two-component developer according to claim 7 as a developer.