# US 8,771,911 B2 · Magenta toner for electrophotography, developer, toner cartridge, process cartridge, image forming apparatus, and image forming method

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 8,771,911 B2
- Document ID: US8771911B2
- Status: Granted
- Kind: B2
- Application number: 13/463,307
- Filed: 2012-05-03
- Published: 2013-06-27
- Granted: 2014-07-08
- Earliest claimed: 2011-12-22
- Assignees: Fuji Xerox Co., Ltd.
- Applicants: Satoshi Kamiwaki; Akira Matsumoto; Yusuke Ikeda; Yukiaki Nakamura; Masanobu Ninomiya
- Inventors: Satoshi Kamiwaki; Akira Matsumoto; Yusuke Ikeda; Yukiaki Nakamura; Masanobu Ninomiya
- Web page: https://patentgrep.com/patent/US8771911B2

## CPC

- G03G 9/0806: {whereby chemical synthesis of at least one of the toner components takes place}
- G03G 9/08755: {Polyesters}
- G03G 9/092: {Quinacridones}
- G03G 9/0926: {characterised by physical or chemical properties}
- G03G 9/09708: {Inorganic compounds}
- G03G 9/09725: {Silicon-oxides; Silicates}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

A magenta toner for electrophotography, including: toner particles containing, a polyester resin, a coloring agent containing a solid solution of C.I. Pigment Violet 19 and C.I. Pigment Red 122, a release agent, and inorganic particles; and an external additive, wherein an average particle diameter of the inorganic particle is 0.75 times or more the average particle diameter of the coloring agent.

## Claims

### Claim 1

A magenta toner for electrophotography, comprising:
toner particles containing:
a polyester resin,
a coloring agent containing a solid solution of C.I. Pigment Violet 19 and C.I. Pigment Red 122,
a release agent, and
inorganic particles; and
an external additive,
wherein:
an average particle diameter of the inorganic particles is 0.75 times or more the average particle diameter of the coloring agent;
the inorganic particles have an average particle diameter of from 105 nm to 310 nm;
the inorganic particles are silica; and
the inorganic particles are present in an amount of from 0.3% by mass to 10% by mass in the toner particles.

### Claim 2 (depends on 1)

The magenta toner for electrophotography of claim 1, wherein the release agent has a melting temperature of from 70° C. to 100° C.

### Claim 3 (depends on 1)

The magenta toner for electrophotography of claim 1, wherein the release agent is Fischer-Tropsch wax.

### Claim 4 (depends on 1)

The magenta toner for electrophotography of claim 1, wherein an amount of the release agent is from 1 part by mass to 15 parts by mass based on 100 parts by mass of the polyester resin.

### Claim 5 (depends on 1)

The magenta toner for electrophotography of claim 1, wherein an amount of the solid solution is from 2% by mass to 30% by mass in the toner particles.

### Claim 6 (depends on 1)

The magenta toner for electrophotography of claim 1, wherein a ratio by mass of C.I. Pigment Violet 19 and C.I. Pigment Red 122 is 80:20 to 20:80.

### Claim 7 (depends on 1)

The magenta toner for electrophotography of claim 1, further comprising C.I. Pigment Red 238 or C.I. Pigment Red 269.

### Claim 8 (depends on 7)

The magenta toner for electrophotography of claim 7, wherein a ratio of the C.I. Pigment Red 238 and the C.I. Pigment Red 269 is from 30 parts by mass to 500 parts by mass based on 100 parts by mass of the solid solution.

### Claim 9 (depends on 1)

The magenta toner for electrophotography of claim 1, wherein the external additive contains silica.

### Claim 10 (depends on 9)

The magenta toner for electrophotography of claim 9, wherein the silica has a primary particle diameter of from 0.01 μm to 0.5 μm.

### Claim 11 (depends on 9)

The magenta toner for electrophotography of claim 9, wherein the external additive further contains a lubricant.

### Claim 12 (depends on 11)

The magenta toner for electrophotography of claim 11, wherein the lubricant has a primary particle diameter of from 0.5 μm to 8.0 μm.

### Claim 13 (depends on 1)

A magenta developer for electrophotography, comprising the magenta toner for electrophotography of claim 1.

### Claim 14 (depends on 13)

An image forming method, comprising:
charging a surface of the latent image holding member,
forming an electrostatic latent image on the surface of the latent image holding member,
developing the electrostatic latent image with the developer of claim 13 to form a toner image,
transferring the toner image onto a recording medium, and
fixing the toner image onto the recording medium.

### Claim 15 (depends on 14)

The image forming method of claim 14, wherein a fixing pressure in the fixing process is 4.0 kgf/cm2 or more.

### Claim 16 (depends on 14)

The image forming method of claim 14, wherein a process speed is 300 mm/sec or more.

### Claim 17 (depends on 1)

The magenta toner for electrophotography of claim 1, wherein the inorganic particles have an average particle diameter of from 125 nm to 290 nm.