Electrostatic image developing toner, method for manufacturing electrostatic image developing toner, developer, and image forming method

1. An electrostatic image developing toner comprising:

a toner matrix particle having an adhering particle adhered onto the surface of a central particle, wherein

a volume average value of a ratio X of a peripheral length PM of the toner matrix particle to a circle-corresponding diameter D of the toner matrix particle is from 3.6 to 5.0,

a volume average value of a particle diameter of the toner matrix particle is from 2 μm to 8 μm,

a volume average value of a particle diameter of the adhering particle is from 100 nm to 500 nm, and

the adhering particle is embedded into the surface of the central particle at a depth of not more than ¼ of the diameter of the adhering particle.

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

the central particle comprises a binder resin, and

the binder resin is a polyester resin or an acrylic resin.

3. The electrostatic image developing toner according to claim 1 , wherein the binder resin has a softening temperature of from 90° C. to 150° C.

4. The electrostatic image developing toner according to claim 1 , wherein the binder resin has a glass transition temperature of from 50° C. to 75° C.

5. The electrostatic image developing toner according to claim 1 , wherein the binder resin has a weight average molecular weight of from 8,000 to 150,000.

6. The electrostatic image developing toner according to claim 1 , wherein the binder resin has an acid number of from 5 mg-KOH/g to 30 mg-KOH/g.

7. The electrostatic image developing toner according to claim 1 , wherein the adhering particle is an organic resin particle.

8. The electrostatic image developing toner according to claim 1 , wherein a number average value of a proportion of a projected area of the adhering particle to a total projected area of the toner matrix particle by SEM observation is from 20% to 80%.

9. The electrostatic image developing toner according to claim 1 , wherein a circle-corresponding diameter of the toner matrix particle is from 2 μm to 8 μm.

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

the central particle further comprises a release agent, and

the release agent is melted at any temperature of from 70° C. to 140° C.

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 is coated with a coating resin, and

the coating resin comprises a resin particle and/or a conductive particle in a dispersion state.

13. The electrostatic image developer according to claim 12 , wherein the coating resin comprises a nitrogen-containing resin.

14. The electrostatic image developer according to claim 12 , wherein the conductive particle is a carbon black having a DBP oil absorption of from 50 mL/100 g to 250 mL/100 g.

15. The electrostatic image developer according to claim 11 , wherein an electrical resistance of the carrier in a magnetic brush state in an electric field of 10 4 V/cm is from 10 8 Ωcm to 10 13 Ωcm.

16. A method for forming an image comprising:

charging an image holding member;

forming an electrostatic latent image on the surface of the image holding member;

developing the electrostatic latent image formed on the surface of the image holding member with the electrostatic image developer according to claim 11 ;

transferring the toner image formed on the surface of the image holding member onto the surface of a transfer-receiving material; and

fixing the transferred toner image onto a medium to be recorded.

17. The method for forming an image according to claim 16 , wherein a most surficial layer of a heating member which is used in the fixing step has surface energy of from 30×10 −3 N/m to 3,000×10 −3 N.

18. The electrostatic image developing toner according to claim 1 , wherein an addition amount of the adhering particle is from 10% to 40%.