Toner, method of forming the toner, and image forming method and apparatus using the toner

1. A toner comprising:

a binder resin which is at least a resin selected from the group consisting of modified polyester resins and unmodified polyester resins; and

a colorant;

the product toner having a volume-average particle diameter (Dv) to a number-average particle diameter (Dn) ratio (Dv/Dn) ranging from 1.00 to 1.30, and the toner having a shape factor SF-1 ranging from 140 to 200.

2. The toner of claim 1 , wherein the ratio (Dv/Dn) ranges from 1.00 to 1.20.

3. The toner of claim 1 , wherein the shape factor SF-1 ranges from 150 to 180.

4. The toner of claim 1 , wherein the toner has the shape of a spindle.

5. The toner of claim 1 , wherein the volume-average particle diameter (Dv) ranges from 3.0 to 7.0 μm.

6. The toner of claim 1 , wherein the toner further comprises particles having a volume-average particle diameter not greater than 3.0 μm in an amount ranging from 1 to 10%.

7. The toner of claim 1 , wherein the toner is prepared by a method comprising:

dispersing a modified polyester resin which is reactive with active hydrogen, a colorant and a release agent in an aqueous medium with a dispersant to form a first dispersion liquid;

reacting the modified polyester resin in the first dispersion liquid with a member selected from the group consisting of crosslinking agents and elongation agents to form a second dispersion liquid including a reaction product; and

removing the aqueous medium from the second dispersion liquid.

8. The toner of claim 7 , wherein the aqueous medium comprises an organic solvent.

9. The toner of claim 8 , wherein the organic solvent is removed from the second dispersion liquid at a temperature ranging from 10 to 50° C. after the second dispersion liquid is stirred in a stirring tank without a baffle and a protrusion.

10. The toner of claim 1 , wherein the binder resin comprises a tetrahydrofuran soluble resin having a molecular weight distribution in which a main peak is present between 2,500 and 10,000 molecular weight units, and a tetrahydrofuran insoluble resin in an amount ranging from 1 to 25% by weight based on total weight of the toner.

11. The toner of claim 10 , wherein the toner comprises the tetrahydrofuran soluble resin having a molecular weight less than 2,500 in an amount of 0.1 to 5.0% by weight based on total weight of the toner.

12. The toner of claim 1 , wherein the modified polyester resin has a glass transition point ranging from 40 to 70° C. and an acid value of from 1 to 30 mg KOH/g.

13. A two-component developer comprising a toner and a carrier, wherein the toner is the toner according to claim 1 .

14. An image forming method comprising:

charging an electrostatic latent image bearer;

irradiating the electrostatic latent image bearer with light to form an electrostatic latent image thereon;

developing the electrostatic latent image with the toner of claim 1 to form a toner image on the electrostatic latent image bearer;

transferring the toner image onto a receiving material;

fixing the toner image on the receiving material; and

cleaning a surface of the electrostatic latent image bearer with a blade to remove toner residue thereon.

15. An image forming apparatus comprising:

a charger configured to charge an electrostatic latent image bearer;

an irradiator configured to irradiate the electrostatic latent image bearer with light to form an electrostatic latent image thereon;

an image developer configured to develop the electrostatic latent image with the toner of claim 1 to form a toner image on the electrostatic latent image bearer;

a transferor configured to transfer the toner image onto a receiving material;

a fixer configured to fix the toner image on the receiving material; and

a cleaner configured to clean the electrostatic latent image bearer with a blade to remove a residue of the toner thereon.

16. The image forming apparatus of claim 15 , wherein the fixer fixes the toner image on the receiving material by passing the toner image through two rollers upon application of heat and a surface pressure not greater than 1.5×10 5 Pa.