Granted Patent B2

US 12,601,986 · App. 17/557,284 · Granted Apr 14, 2026

Inventors: Tomomi Harashima (Shizuoka, JP); Junichi Watanabe (Shizuoka, JP); Hiroshi Yamashita (Shizuoka, JP); Shinya Nakayama (Shizuoka, JP)

Assignee: Ricoh Company, Ltd.

G03G9/08755G03G9/08795G03G13/0133

Abstract

Claims (65)

1 . A toner, comprising:

toner base particles, each toner base particle including

a crosslinked component,

wherein the crosslinked component includes a nonlinear polymer obtained from reaction of polyester resin and HDI isocyanurate, terminals of which are metal ion crosslinked, and

a glass transition temperature Tg of the nonlinear polymer as measured by differential scanning calorimetry is −60° C. or higher but lower than 0° C.; and

wherein the toner contains a THF-insoluble fraction with respect to a total mass of the toner, the content of which is between 15% and 35% by mass; and

wherein the metal ion crosslink of the nonlinear polymer includes two or more divalent or higher metal ions.

2 . A toner comprising

toner base particles, each of the toner base particles including

a crosslinked component,

wherein the crosslinked component includes a binder resin, and the binder resin includes a tetrahydrofuran (THF) insoluble component,

the THF insoluble component includes a nonlinear polymer obtained from reaction of polyester resin and HDI isocyanurate, terminals of which are metal ion crosslinked,

wherein an amount of the THF insoluble component is from 15% by mass through 35% by mass, and

a glass transition temperature Tg of the THF insoluble component as measured by differential scanning calorimetry is −60° C. or higher but lower than 0° C.,

wherein the metal ion crosslink of the nonlinear polymer includes two or more divalent or higher metal ions.

3 . The toner according to claim 1 ,

wherein the two divalent or higher metal ions have mutually different valencies.

4 . The toner according to claim 1 ,

wherein a difference in an ionic radius between the two divalent or higher metal ions is 50 μm or greater.

5 . A developer, comprising:

a carrier; and

the toner according to claim 1 .

6 . A toner storage unit, comprising:

a container; and

the toner according to claim 1 , wherein the toner is stored in the container.

7 . A method for producing a toner, the method comprising:

mixing an aqueous medium and an oil phase including a prepolymer that is a nonlinear reactive precursor, to generate a nonlinear polymer through an elongation reaction,

or a cross-linking reaction, or both of the prepolymer and a curing agent, to thereby form toner base particles,

wherein the toner is the toner according to claim 1 .

8 . A method for producing a toner, the method comprising:

mixing an aqueous medium and an oil phase including a prepolymer that is a nonlinear reactive precursor, and an active hydrogen group-containing compound, to generate a nonlinear polymer through an elongation reaction, or a cross-linking reaction, or both of the prepolymer and a curing agent, to thereby form toner base particles,

wherein the toner is a toner according to claim 1 .

9 . A method for producing a toner, the method comprising:

removing an organic solvent from an oil phase prepared by dissolving or dispersing in the organic solvent a polyester resin and a prepolymer that is a nonlinear reactive precursor through phase-transfer emulsification, followed by mixing with a dispersion liquid including a crystalline polyester resin to prepare a mixture solution; and

the crystalline polyester resin in the mixture solution to aggregate to form toner base particles to produce a toner,

wherein the toner is the toner according to claim 1 .

10 . An image forming apparatus, comprising:

an electrostatic latent image bearer;

an electrostatic latent image forming unit configured to form an electrostatic latent image on the electrostatic latent image bearer;

a developing unit configured to develop the electrostatic latent image with a toner to form a visible image;

a transferring unit configured to transfer the visible image onto a recording medium; and

a fixing unit configured to fix the visible image transferred to the recording medium,

wherein the toner is the toner according to claim 1 .

11 . An image forming method, comprising:

forming an electrostatic latent image on an electrostatic latent image bearing member;

developing the electrostatic latent image with a toner to form a visible image;

transferring the visible image onto a recording medium; and

fixing the visible image transferred on the recording medium,

wherein the toner is the toner according to claim 1 .

12 . Resin particles each comprising

a crosslinked component,

wherein the crosslinked component includes a binder resin, and the binder resin includes a tetrahydrofuran (THF) insoluble component,

the THF insoluble component includes a nonlinear polymer obtained from reaction of polyester resin and HDI isocyanurate, terminals of which are metal ion crosslinked, and

a glass transition temperature Tg of the THF insoluble component as measured by differential scanning calorimetry is −60° C. or higher but lower than 0° C.,

wherein the metal ion crosslink of the nonlinear polymer includes two or more divalent or higher metal ions.

13 . The toner according to claim 1 ,

wherein the two or more divalent or higher metal ions are selected from the group consisting of magnesium ion/calcium ion, magnesium ion/aluminum ion, aluminum ion/gallium ion, and aluminum ion/strontium ion.

14 . A toner, comprising:

toner base particles, each toner base particle including

a crosslinked component,

wherein the crosslinked component includes a nonlinear polymer having 3 or more branches, terminals of which are metal ion crosslinked, and

a glass transition temperature Tg of the nonlinear polymer as measured by differential scanning calorimetry is −60° C. or higher but lower than 0° C.; and

wherein the toner contains a THF-insoluble fraction with respect to a total mass of the toner, the content of which is between 15% and 35% by mass; and

wherein the metal ion crosslink of the nonlinear polymer includes two or more divalent or higher metal ions,

wherein the two or more divalent or higher metal ions include any one of a strontium ion, a gallium ion, an indium ion, and a thallium ion.

Assignments (2)

Priority Claims (3)

Continuity (1)

References Cited (91)