# US 2017/0255115 A1 · Method of producing toner for developing electrostatic images

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- Number: US 2017/0255115 A1
- Document ID: US20170255115A1
- Status: Published application
- Kind: A1
- Application number: 15/440,573
- Filed: 2017-02-23
- Published: 2017-09-07
- Earliest claimed: 2016-03-02
- Assignees: Konica Minolta, Inc.
- Applicants: Konica Minolta, Inc.
- Inventors: Naoya TONEGAWA; Takanari Kayamori; Masaharu Matsubara; Kouji Sekiguchi; Atsushi Iioka
- Web page: https://patentgrep.com/patent/US20170255115A1

## CPC

- G03G 9/09392: {Preparation thereof}
- G03G 9/09321: {obtained by reactions only involving carbon-to-carbon unsaturated bonds}
- G03G 9/09328: {obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds}
- G03G 9/09364: {obtained by reactions only involving carbon-to-carbon unsaturated bonds}
- G03G 9/09371: {obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

A method of producing a toner for developing electrostatic images includes Steps I to III is provided. The toner includes a toner matrix particle having a core-shell structure. The toner matrix particle includes a core particle including an amorphous resin A and a crystalline material, and a shell including an amorphous resin B. The shell includes a phase of the amorphous resin B that is not fused with the core particle at the interface. The amorphous resin A differs from the amorphous resin B.

## Claims

### Claim 1

A method of producing a toner for developing electrostatic images, the toner comprising a toner matrix particle having a core-shell structure, wherein
the toner matrix particle comprising a core particle comprising an amorphous resin A and a crystalline material, and a shell comprising an amorphous resin B,
the shell comprising a phase of the amorphous resin B that is not fused with the core particle at the interface, and
the amorphous resin A differing from the amorphous resin B, the method comprising the steps of:
Step I) dispersing at least the amorphous resin A and the crystalline material in an aqueous medium to prepare a dispersion, and adjusting a temperature of the dispersion to be equal to or higher than (a glass transition temperature (Tg-a) of the amorphous resin A+10)° C. and equal to or lower than (a melting point (Tm-c) of the crystalline material+10)° C., to prepare a core particle dispersion through coagulation and coalescence of at least the amorphous resin A and the crystalline material;
Step II) cooling the core particle dispersion prepared in Step I to a temperature equal to or lower than the glass transition temperature (Tg-a) of the amorphous resin A; and
Step III) adjusting a temperature of the core particle dispersion to be equal to or higher than (the glass transition temperature (Tg-a) of the amorphous resin A+5)° C. and equal to or lower than (a glass transition temperature (Tg-b) of the amorphous resin B+3)° C. after Step II, and then adding a dispersion of the amorphous resin B to the core particle dispersion.

### Claim 2 (depends on 1)

The method according to claim 1, wherein Expressions 1 and 2 are satisfied in Step III:
pHb≦pHa, and Expression 1:
2≦pHb≦5 Expression 2:
where pHa represents the pH of the core particle dispersion at 25° C., and pHb represents the pH of the dispersion of the amorphous resin B at 25° C.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the core particle dispersion cooled in Step II contains a core particle having a shape factor SF-2 of 105 to 140.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the amorphous resin B added in Step III is a particle having a volume median particle size of 30 to 300 nm.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the amorphous resin A is a styrene-acrylic resin, and the amorphous resin B is a polyester resin.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the amorphous resin A is a polyester resin, and the amorphous resin B is a styrene-acrylic resin.

### Claim 7 (depends on 5)

The method according to claim 5, wherein the polyester resin is an amorphous polyester resin chemically bonded to a styrene-acrylic resin.

### Claim 8 (depends on 6)

The method according to claim 6, wherein the polyester resin is an amorphous polyester resin chemically bonded to a styrene-acrylic resin.

### Claim 9 (depends on 7)

The method according to claim 7, wherein the amorphous polyester resin chemically bonded to the styrene-acrylic resin has a styrene-acrylic content of 5 to 30 mass %.

### Claim 10 (depends on 8)

The method according to claim 8, wherein the amorphous polyester resin chemically bonded to the styrene-acrylic resin has a styrene-acrylic content of 5 to 30 mass %.

### Claim 11 (depends on 1)

The method according to claim 1, wherein the amorphous resin A has a glass transition temperature Tg-a of 35 to 50° C.

### Claim 12 (depends on 1)

The method according to claim 1, wherein the amorphous resin B has a glass transition temperature Tg-b of 53 to 63° C.

### Claim 13 (depends on 1)

The method according to claim 1, wherein the crystalline material comprises a crystalline resin or a release agent selected from a hydrocarbon wax and an ester wax, and the crystalline material has a melting point (Tm-c) equal to or higher than (a glass transition temperature (Tg-b) of the amorphous resin B+3)° C.

### Claim 14 (depends on 1)

The method according to claim 1, wherein the ratio of the mass of the amorphous resin B added in Step III to the total mass of a binder resin is 5 to 35.