TONER AND METHOD OF PREPARING THE TONER

Abstract

A toner is provided including a binder resin, a colorant, and a release agent, which has a volume average particle diameter (Dv) of from 3 to 9 μm, and wherein the binder resin and the release agent form a sea-island structure in which the island formed of the release agent is dispersed in the sea formed of the binder resin in a cross-sectional image of the toner obtained by a transmission electron microscope (TEM), and the following relationships are satisfied: IB>IA and IB>IC, wherein each of IA, IB, and IC represents an area ratio (%) of the island in an outermost region (A) of the cross-sectional image of the toner, an intermediate region (B) thereof located under the outermost region (A), and an innermost region (C) thereof located under the intermediate region (B); and a method of preparing the toner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages of the present invention will become apparent upon consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a cross-sectional view illustrating an embodiment of the toner of the present invention;

FIG. 2 is another cross-sectional view illustrating an embodiment of the toner of the present invention;

FIG. 3 is a schematic view illustrating an embodiment of a process cartridge using the toner of the present invention; and

FIG. 4 is a schematic view illustrating an embodiment of a fixing device for fixing the toner of the present invention.

Claims

1. A toner, comprising: a binder resin;a colorant; anda release agent,wherein the toner has a volume average particle diameter (Dv) of from 3 to 9 μm, andwherein the binder resin and the release agent form a sea-island structure in which the island formed of the release agent is dispersed in the sea formed of the binder resin in a cross-sectional image of the toner obtained by a transmission electron microscope (TEM), and the following relationships are satisfied: IB>IA and IB>IC

2. The toner according to claim 1, wherein the following relationships are further satisfied: 0≦IA≦5, 3≦IB≦70, 0≦IC 5, and IC>IA

3. The toner according to claim 1, wherein the toner has an average circularity of from 0.930 to 0.995.

4. The toner according to claim 1, wherein the toner has at least one endothermic peak in a temperature range of from 60 to 90° C., when measured by a differential scanning calorimeter (DSC).

5. The toner according to claim 4, wherein the endothermic peak has a half bandwidth not larger than 8° C.

6. The toner according to claim 1, wherein the toner comprises the release agent in an amount of from 3 to 15 parts by weight based on 100 parts by weight of the binder resin.

7. The toner according to claim 1, wherein the release agent is a hydrocarbon wax.

8. The toner according to claim 1, wherein the toner has a ½ method temperature (T½) of from 110 to 140° C., when measured by a flow tester.

9. The toner according to claim 1, wherein each of the intermediate region (B) and the innermost region (C) comprises a binder resin (R1), and the outermost region (A) comprises a binder resin (R2), wherein the binder resin (R1) comprises a resin (R11) having a polyester skeleton, and the binder resin (R2) comprises a vinyl copolymer resin (V), andwherein a weight ratio (i.e., (A)/((B)+(C))) of the outermost region (A) to the sum of the intermediate region (B) and the innermost region (C) is from 0.05 to 0.5.

10. The toner according to claim 9, wherein the binder resin (R2) is formed by subjecting particles of the vinyl copolymer resin (V) to at least one process selected from the group consisting of aggregation and fusion.

11. The toner according to claim 9, wherein the binder resin (R2) has a weight average molecular weight not larger than 50,000 and a glass transition temperature of from 40 to 80° C.

12. The toner according to claim 9, wherein the binder resin (R1) comprises a modified polyester resin (R12) having at least one of a urethane and a urea bond.

13. The toner according to claim 12, wherein the modified polyester resin (R12) comprises a modified polyester resin (R14) formed by subjecting a modified polyester resin (R13) having an isocyanate group at its end and an amine to at least one of an elongation reaction and a cross-linking reaction.

14. The toner according to claim 1, wherein the following relationship is further satisfied: (⅓)Dp≦Dw≦(⅔)Dp

15. The toner according to claim 14, wherein the release agent has a particle diameter distribution property such that at least two peaks are present.

16. A method of preparing a toner, comprising: dissolving or dispersing core constituents comprising a resin having a polyester skeleton or precursor thereof, a colorant, a release agent in an organic solvent to prepare a core constituent mixture liquid;dispersing the core constituent mixture liquid in an aqueous medium to prepare a first dispersion comprising core particles in which the release agent is locally present at the surfaces or near the surfaces thereof,adding a second dispersion comprising a particulate vinyl copolymer resin (V) to the first dispersion to adhere the particulate vinyl copolymer resin (V) to the core particles.

17. The method of preparing a toner according to claim 16, further comprising: removing the organic solvent from the first dispersion before adding the second dispersion to the first dispersion.

18. The method of preparing a toner according to claim 16, further comprising: adding a metal salt having 1 to 3 valences to the first dispersion when the second dispersion is added thereto.

19. The method of preparing a toner according to claim 16, further comprising: heating the mixture to a temperature of not less than a glass transition temperature of the particulate vinyl copolymer resin after adding the second dispersion to the first dispersion.

20. The method of preparing a toner according to claim 16, further comprising: heating the mixture to a temperature at which the particulate vinyl copolymer resin is fused on the core particles after adding the second dispersion to the first dispersion.

21. The method of preparing a toner according to claim 16, wherein the core constituent mixture liquid further comprises a modified polyester resin (R13) having an isocyanate group at its end and an amine capable of reacting with the modified polyester resin (R13).

22. The method of preparing a toner according to claim 16, wherein the aqueous medium comprises a particulate resin (P) as a dispersion stabilizer.