# US 8,785,097 B2 · Erasable toner and process for production thereof

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- Number: US 8,785,097 B2
- Document ID: US8785097B2
- Status: Granted
- Kind: B2
- Application number: 13/537,426
- Filed: 2012-06-29
- Published: 2013-01-10
- Granted: 2014-07-22
- Earliest claimed: 2011-07-08
- Assignees: Toshiba Tec Kabushiki Kaisha
- Applicants: Takayasu Aoki; Motonari Udo; Tsuyoshi Itou; Masahiro Ikuta; Takafumi Hara
- Inventors: Takayasu Aoki; Motonari Udo; Tsuyoshi Itou; Masahiro Ikuta; Takafumi Hara
- Web page: https://patentgrep.com/patent/US8785097B2

## CPC

- G03G 9/0928: {Compounds capable to generate colouring agents by chemical reaction}
- G03G 9/0806: {whereby chemical synthesis of at least one of the toner components takes place}
- G03G 9/0812: {Pretreatment of components}
- G03G 9/08711: {with esters of acrylic or methacrylic acid}
- G03G 9/08753: {Epoxyresins}
- G03G 9/08755: {Polyesters}
- G03G 9/08766: {Polyamides, e.g. polyesteramides}
- G03G 9/08768: {Other polymers having nitrogen in the main chain, with or without oxygen or carbon only}
- G03G 9/08791: {characterised by the presence of specified groups or side chains}
- G03G 9/08793: {Crosslinked polymers}
- G03G 9/08795: {characterised by their chemical properties, e.g. acidity, molecular weight, sensitivity to reactants}
- G03G 9/08797: {characterised by their physical properties, e.g. viscosity, solubility, melting temperature, softening temperature, glass transition temperature}
- G03G 9/09: Colouring agents for toner particles
- G03G 9/0926: {characterised by physical or chemical properties}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

Disclosed is a decolorable toner produced by aggregating dispersed fine particles of a color material containing at least a color-forming compound, a color-developing agent and a decoloring agent with dispersed fine particles containing at least a binder resin having a carboxyl group, then adding a compound having a carbodiimide group or an epoxy group reactive with the carboxyl group of the binder resin, and thereafter fusing the aggregate particles, respectively in an aqueous medium. The thus obtained decolorable toner can suppress the generation of fine powder by the release of erasable color material fine particles from the toner particles.

## Claims

### Claim 1

A decolorable toner comprising:
toner particles comprising a binder resin having a carboxyl group, a microencapsulated color material comprising a color-forming compound, a color-developing agent and a decoloring agent; and
a crosslink coating disposed on the toner particles said crosslink coating comprising a compound having a carbodiimide group or an epoxy group, wherein such compound is reactive with the carboxyl group of the binder resin.

### Claim 2 (depends on 1)

The toner according to claim 1, wherein the toner particles each comprise an aggregate of particles, said aggregate further comprising particles of the microencapsulated color material and of the binder resin.

### Claim 3 (depends on 1)

The toner according to claim 1, wherein the binder resin having a carboxyl group is a polyester-based resin or a styrene-acrylic resin.

### Claim 4

A process for production of a decolorable toner, comprising:
aggregating dispersed particles of a microencapsulated color material comprising at least a color-forming compound, a color-developing agent and a decoloring agent with dispersed fine particles comprising at least a binder resin having a carboxyl group to form aggregate particles in an aqueous medium,
adding a compound having a carbodiimide group or an epoxy group reactive with the carboxyl group of the binder resin into the aqueous medium to surface-treat the aggregate particles with the compound, and
fusing the aggregate particles in the aqueous medium.

### Claim 5 (depends on 4)

The process according to claim 4, wherein after forming the aggregate particles, the aggregate particles are encapsulated by adding a dispersion of particles comprising at least a binder resin having a carboxyl group to have the particles adhere to the aggregate particles, thereby coating the aggregate particles therewith.

### Claim 6 (depends on 4)

The process according to claim 4, wherein the formation of the aggregate particles is performed at a temperature lower than the decolorized temperature of the color material particles.

### Claim 7

A decolorable toner comprising aggregate particles, wherein each aggregate particle further comprises particles of a polyester binder resin, and particles of a microencapsulated color material, said microencapsulated color material further comprising a color-forming compound, a color-developing agent and a decoloring agent, wherein a surface region of the aggregate particles comprises a reactive compound having a carbodiimide group or an epoxy group.

### Claim 8 (depends on 7)

The toner according to claim 7, wherein the surface region of the aggregate particles is composed only of a binder resin having a carboxyl group.