Toner for development of electrostatic image, method of producing the same, electrostatic image developer, toner cartridge, process cartridge, and image forming apparatus

1. A toner for development of an electrostatic image, the toner comprising colored particles comprising:

a crystalline polyester resin having a melting temperature Tm 1 (° C.) of approximately 50 to approximately 100° C.;

a non-crystalline polyester resin; and

a coloring agent, wherein

the temperature Tm 2 (° C.) of an endothermic peak derived from the crystalline polyester resin in a first process of raising temperature and the temperature Tm 3 (° C.) of an endothermic peak derived from the crystalline polyester resin in a second process of raising temperature, in differential scanning calorimetry based on JIS K7121:1987, satisfying the following relationships (1) and (2):

0≦(Tm1−Tm2)<2  (1)

4<(Tm1−Tm3)≦15  (2),

the crystalline polyester resin comprises an acid-derived constituent component derived from a linear dicarboxylic acid and an alcohol-derived constituent component derived from a linear aliphatic diol having 7 to 20 carbon atoms, and

the linear dicarboxylic acid is selected from the group consisting of adipic acid, sebacic acid, 1,10-decanedicarboxylic acid, lower alkyl esters thereof, and anhydrides thereof.

2. The toner of claim 1 , wherein the content of the crystalline polyester resin in the colored particles is approximately 3 to approximately 40 wt %.

3. The toner of claim 1 , wherein the content, among all acid-derived constituent components, of acid-derived constituent components (a constituent component derived from a dicarboxylic acid having a double bond and a constituent component derived from a dicarboxylic acid having a sulfonic acid group) other than an aliphatic dicarboxylic acid-derived constituent component and an aromatic dicarboxylic acid-derived constituent component in the crystalline polyester resin is approximately 1 to approximately 20 constituent-mol %.

4. The toner of claim 1 , wherein the content of the aliphatic diol-derived constituent component among alcohol constituent components of the crystalline polyester resin is approximately 90 constituent-mol % or higher.

5. The toner of claim 1 , wherein the molecular weight (weight-average molecular weight Mw) of the crystalline polyester resin is approximately 2,000 to approximately 12,000.

6. The toner of claim 1 , wherein the acid value of the crystalline polyester resin is approximately 2 to approximately 30 mg KOH/g.

7. The toner of claim 1 , wherein the weight-average molecular weight of the non-crystalline polyester resin is approximately 5,000 to approximately 50,000.

8. The toner of claim 1 , wherein the glass transition temperature (Tg) of the non-crystalline polyester resin is approximately 40 to approximately 80° C.

9. The toner of claim 1 , wherein the toner further comprises a releasing agent in an amount of approximately 0.5 to approximately 50 wt % based on the whole amount of the toner.

10. The toner of claim 1 , wherein the crystalline polyester resin is present in a dispersed state in the colored particles, and the number-average dispersion diameter of the crystalline polyester resin in the colored particles is in the range of approximately 0.05 to approximately 1.0 μm.

11. An electrostatic image developer comprising the toner for development of an electrostatic image of claim 1 .

12. The developer of claim 11 , further comprising a carrier including an electroconductive particle-containing coating resin.

13. A toner cartridge comprising at least a toner stored therein, the toner being the toner for development of an electrostatic image of claim 1 .

14. A process cartridge comprising at least a developer-holding member and accommodating the electrostatic image developer of claim 11 .

15. An image forming apparatus comprising an image-holding member, a developing unit for developing with a developer as a toner image an electrostatic image formed on the image-holding member, a transfer unit for transferring the toner image formed on the image-holding member onto a recording member, and a fixing unit for fixing the toner image transferred onto the recording member, the developer being the electrostatic image developer of claim 11 .

16. A method of producing the toner of claim 1 , which comprises respectively dissolving or dispersing at least a coloring agent, a non-crystalline polyester resin and a crystalline polyester resin in a solvent to prepare a liquid mixture of a toner composition, dispersing and suspending the liquid mixture of the toner composition in an aqueous solvent to prepare a dispersed suspension of the toner composition, and removing the solvent from the dispersed suspension of the toner composition.

17. The toner of claim 1 , wherein the toner is produced by a dissolution suspension method comprising:

dissolving or dispersing at least the crystalline polyester resin, the non-crystalline polyester resin, and the coloring agent in a solvent to prepare a liquid mixture of a toner composition;

dispersing and suspending the liquid mixture of a toner composition in an aqueous solvent to prepare a dispersed suspension of the toner composition; and

removing the solvent from the dispersed suspension of the toner composition.

18. The toner of claim 1 , wherein the linear aliphatic diol having 7 to 20 carbon atoms is selected from the group consisting of 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol.

19. The toner of claim 1 , wherein the crystalline polyester resin is obtained by polymerizing sebacic acid with decanediol, and the non-crystalline polyester resin is obtained by polymerizing alkenylsuccinic acid with an alkylene glycol adduct of bisphenol.