Electrostatic image developing toner, electrostatic image developer, toner cartridge, process cartridge and image forming apparatus

1. An electrostatic image developing toner comprising a binder resin; and a colorant, and satisfying following conditions (1) and (2):

0.02 ≦C A /C B ≦0.20  (1)

1 ≦Nt/St≦ 15  (2)

wherein

C A represents an amount of a carboxyl group and its salt on a surface of the toner,

C B represents an amount of a carboxyl group and its salt in the entire toner,

Nt represents an amount of a nitrogen element on the surface of the toner, and

St represents an amount of a sulfur element on the surface of the toner, and wherein the binder resin comprises:

a unit derived from a nitrogen-containing aromatic polymerizable monomer; and

a unit derived from a nitrogen-containing aliphatic polymerizable monomer.

2. The electrostatic image developing toner according to claim 1 , wherein

the nitrogen-containing aromatic polymerizable monomer comprises:

an ethylenically unsaturated bond conjugated to an aromatic ring; and

a nitrogen atom.

3. The electrostatic image developing toner according to claim 2 , wherein

the binder resin comprises, in a side chain thereof, the nitrogen atom of the nitrogen-containing aromatic polymerizable monomer.

4. The electrostatic image developing toner according to claim 1 , having a shape factor SF1 of from about 120 to about 140.

5. The electrostatic image developing toner according to claim 1 , further comprising:

an external additive that comprises an oxide containing a nitrogen atom.

6. The electrostatic image developing toner according to claim 1 , having GSD p of about 1.40 or less and 1.20 or more, the GSD p being represented by a following formula:

GSD p ={( D 84p )/( D 16p )} 0.5

wherein

D 16p represents a 16% diameter in terms of the number of toner particles accumulated from a smaller particle diameter side, and

D 84p represents a 84% diameter in terms of the number of toner particles accumulated from a smaller particle diameter side.

7. The electrostatic image developing toner according to claim 1 , wherein

the sulfur element on the surface of the toner is contained as a mercapto group (—SH) or a thioether bond (—S—).

8. The electrostatic image developing toner according to claim 1 , wherein

the binder resin has a glass transition temperature of from about 50° C. to about 70° C.

9. The electrostatic image developing toner according to claim 1 , further comprising:

a releasing agent.

10. The electrostatic image developing toner according to claim 9 , wherein

the releasing agent is contained in an amount of from about 1 wt % to about 20 wt % based on a total amount of toner particles.

11. An electrostatic image developer comprising:

the electrostatic image developing toner according to claim 1 ; and

a carrier.

12. The electrostatic image developer according to claim 11 , wherein

the carrier comprises at least one of a fluorine atom and a silicon atom.

13. The electrostatic image developer according to claim 11 , wherein

a shape factor SF1 of the carrier and a shape factor SF1 of the toner differ by from about 5 to about 20.

14. A toner cartridge comprising:

the electrostatic image developing toner according to claim 1 .

15. A process cartridge comprising:

a latent image carrier; and

at least one member selected from the group consisting of:

an electrically charging device that electrically charges the latent image carrier,

a developing device that develops an electrostatic latent image formed on the latent image carrier with a developer to form a toner image, and

a cleaning device that removes a toner remaining on a surface of the latent image carrier,

wherein the developer is the electrostatic image developer according to claim 11 .

16. An image forming apparatus comprising:

a latent image carrier;

an electrically charging device that electrically charges the latent image carrier;

an exposure device that exposes the electrically charged latent image carrier to form an electrostatic latent image on the latent image carrier;

a developing device that develops the electrostatic latent image with a developer to form a toner image; and

a transfer device that transfers the toner image onto a recording material from the latent image carrier,

wherein the developer is the electrostatic image developer according to claim 11 .

17. The electrostatic image developing toner according to claim 1 , wherein

the nitrogen-containing aromatic polymerizable monomer has an ethylenically unsaturated bond conjugated to an aromatic ring.

18. The electrostatic image developing toner according to claim 1 , wherein

the nitrogen-containing aromatic polymerizable monomer is selected from the group consisting of aminostyrene, nitrostyrene, cinnamamide, and cinnamonitrile.