# US 7,608,378 B2 · Developing agent and method for manufacturing the same

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- Number: US 7,608,378 B2
- Document ID: US7608378B2
- Status: Granted
- Kind: B2
- Application number: 11/445,865
- Filed: 2006-06-02
- Published: 2007-12-06
- Granted: 2009-10-27
- Earliest claimed: 2006-06-02
- Assignees: Kabushiki Kaisha Toshiba; Toshiba Tec Kabushiki Kaisha
- Inventors: Takashi Urabe; Tsuyoshi Ito; Motonari Udo; Masahiro Ikuta
- Web page: https://patentgrep.com/patent/US7608378B2

## CPC

- G03G 9/0804: {whereby the components are brought together in a liquid dispersing medium}
- G03G 9/0815: {Post-treatment}
- G03G 9/0817: {Separation; Classifying}
- G03G 9/0819: {characterised by the dimensions of the particles}
- G03G 9/0827: {characterised by their shape, e.g. degree of sphericity}
- G03G 9/08795: {characterised by their chemical properties, e.g. acidity, molecular weight, sensitivity to reactants}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

A method for manufacturing a developing agent by mixing a coarsely granulated mixture containing a binder resin and a coloring agent with an aqueous medium and mechanically stirring the resulting mixed solution to finely granulate the coarsely granulated mixture, thereby forming a fine particle.

## Claims

### Claim 1

A method for manufacturing a developing agent, comprising:
melt kneading and pulverizing a mixture containing at least a binder resin and a coloring agent to form a granulated mixture having a first volume average particle size;
mixing the granulated mixture with an aqueous medium to form a mixed solution;
mechanically stirring the mixed solution to finely granulate said granulated mixture to form a fine particle having a second volume average particle size small than the first volume average size; and
coagulating the fine particle to form a coagulated particle having a third volume average particle size smaller than the first volume average size and larger than the second volume average particle size.

### Claim 2 (depends on 1)

The method for manufacturing a developing agent according to claim 1, wherein first volume average particle size is 0.05 to 10 mm.

### Claim 3 (depends on 1)

The method for manufacturing a developing agent according to claim 1, wherein the mechanical stirring is carried out at a temperature of a glass transition point of the binder resin or higher.

### Claim 4 (depends on 1)

The method for manufacturing a developing agent according to claim 1, wherein in the step for mixing the mixture with an aqueous medium, at least one member of a surfactant and a pH adjuster is added to the aqueous medium.

### Claim 5 (depends on 4)

The method for manufacturing a developing agent according to claim 4, wherein the pH adjuster is an amine compound.

### Claim 6 (depends on 4)

The method for manufacturing a developing agent according to claim 4, wherein the surfactant is an anionic surfactant.

### Claim 7 (depends on 1)

The method for manufacturing a developing agent according to claim 1, wherein the second volume average particle size is 0.05 to 10 μm.

### Claim 8 (depends on 1)

The method for manufacturing a developing agent according to claim 1, wherein the third volume average particle size is 1 to 15 μm.

### Claim 9 (depends on 1)

The method for manufacturing a developing agent according to claim 1, wherein the coagulated particle has a circularity of from 0.8 to 1.0.

### Claim 10 (depends on 1)

The method for manufacturing a developing agent according to claim 1, wherein the granulated mixture contains at least one of a wax and a charge controlling agent.

### Claim 11 (depends on 1)

The method for manufacturing a developing agent according to claim 1, wherein the binder resin has an acid value of 1 or more.

### Claim 12 (depends on 1)

The method for manufacturing a developing agent according to claim 1, wherein in the step for forming a coagulated particle, a plural number of the fine particle is coagulated by employing at least one process among adjustment of pH, addition of a surfactant, addition of a water-soluble metallic salt, addition of an organic solvent, and temperature adjustment.

### Claim 13

A developing agent containing a coagulated particle of fine particles which are obtained by melt kneading and pulverizing a mixture containing a binder resin and a coloring agent, mixing the resulting granulated mixture with an aqueous medium and mechanically stirring the mixture,
wherein the granulated mixture has a first volume average particle size, and the fine particle has a second volume average particle size smaller than the first volume average particle size, and the coagulated particle has a third volume average particle size smaller than the first volume average particle size and larger than the second volume average particle size.

### Claim 14 (depends on 13)

The developing agent according to claim 13, wherein the first volume average particle size is 0.05 to 10 mm.

### Claim 15 (depends on 13)

The developing agent according to claim 13, wherein the second volume average particle size is 0.005 to μm.

### Claim 16 (depends on 13)

The developing agent according to claim 13, wherein the third volume average particle size is 1 to 15 μm.