# US 10,310,400 B2 · Developer for electrostatic latent image

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- Number: US 10,310,400 B2
- Document ID: US10310400B2
- Status: Granted
- Kind: B2
- Application number: 14/719,988
- Filed: 2015-05-22
- Published: 2015-11-26
- Granted: 2019-06-04
- Earliest claimed: 2014-05-26
- Assignees: Konica Minolta, Inc.
- Applicants: Konica Minolta, Inc.
- Inventors: Chiaki Yamada; Masahiro Anno
- Web page: https://patentgrep.com/patent/US10310400B2

## CPC

- G03G 9/0904: {Carbon black}
- G03G 9/091: {Azo dyes}
- G03G 9/0914: {Acridine; Azine; Oxazine; Thiazine-;(Xanthene-) dyes}
- G03G 9/0918: {Phthalocyanine dyes}
- G03G 9/092: {Quinacridones}
- G03G 9/122: {characterised by the colouring agents}
- G03G 9/132: {obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

A developer for electrostatic latent image contains toner particles. The toner particles contain a resin and a coloring agent, and the coloring agent includes a first coloring agent, a second coloring agent, and a third coloring agent. The first coloring agent is carbon black, the second coloring agent is one or more of C. I. Pigment Violet 19 and C. I. Pigment Violet 23, and the third coloring agent is one or more of C. I. Pigment Brown 23 and C. I. Pigment Brown 25. A content of the second coloring agent is not lower than 8 mass % and not higher than 25 mass % with respect to a total amount of the coloring agents.

## Claims

### Claim 1

A developer for electrostatic latent image, comprising toner particles,
said toner particles containing a resin and a coloring agent,
said coloring agent consisting of a first coloring agent, a second coloring agent, and a third coloring agent,
said first coloring agent being carbon black,
said second coloring, agent being one or more of C. I. Pigment Violet 19 and C. I. Pigment Violet 23,
said third coloring agent being one or more of C. I. Pigment Brown 23 and C. I. Pigment Brown 25,
a content of said first coloring agent being not lower than 40 mass % and not higher than 65 mass % with respect, to a total amount of said coloring agents,
a content of said second coloring agent being not lower than 8 mass % and not higher than 25 mass % with respect to the total amount of said coloring agents, and
a content of said third coloring agent being not lower than 20 mass % and not higher than 35 mass % with respect to a total amount of said coloring agents,
said resin being a polyester resin having an acid value of not lower than 5 mg KOH/g and not higher than 20 mg KOH/g.

### Claim 2 (depends on 1)

The developer for electrostatic latent image according to claim 1, wherein
said carbon black is acid carbon black.

### Claim 3 (depends on 1)

The developer for electrostatic latent image according to claim 1, being a liquid developer in which said toner particles are dispersed in an insulating liquid, wherein
a content of said coloring agents in said toner particles is not lower than 20 mass % and not higher than 40 mass %.

### Claim 4 (depends on 1)

The developer for electrostatic latent image according to claim 1, the content of said first coloring agent being not lower than 45 mass % and not higher than 60 mass % with respect to the total amount of said coloring agents.

### Claim 5 (depends on 4)

The developer for electrostatic latent image according to claim 4, the content of said first coloring agent being not lower than 45 mass % and not higher than 55 mass % with respect to the total amount of said coloring agents.

### Claim 6 (depends on 1)

The developer for electrostatic latent image according to claim 1, wherein
a mass ratio of said third coloring agent to said second coloring agent is 4:1 to 1:1.