Color image forming method and color toner forming method

1. A color image forming method comprising:

charging a photosensitive body so as to form a latent image;

developing the latent image with a color toner so as to form a toner image on the photosensitive body;

transferring the toner image to an image transfer body via an intermediate transfer body so as to form a non-fixed transfer image; and

fixing the non-fixed transfer image to the an image transfer body,

wherein:

the fixing comprises thermally fixing the toner image to the an image transfer body by using:

a heating body installed in a fixed manner for heating the transfer body; and

a pressurizing member which is positioned opposite to the heating body via a film-like member, brought into contact with the heating body with pressure, and rotated so as to press-contact the transfer body to the heating body;

the color toner comprises a toner particle comprising crystals of a crystalline resin, crystals of a releasing agent and a non-crystalline resin;

when the color toner is subjected to dynamic viscoelasticity measurement employing a sine wave vibration method, a minimum value of the relaxation elasticity H in a relaxation spectrum obtained from frequency dispersion characteristics when a measurement frequency measured at 60 and 80° C. is 0.1 to 100 rad/sec and a measurement strain at a frequency of 6.28 rad/sec is 0.1%, is in a range of about 10 to 900 Pa/cm 2 ; and

a relaxation time λ corresponding to the minimum value is in a range of about 1 to 10,000 sec.

2. The color image forming method according to claim 1 , wherein a gradient K, which is a frequency dispersion curve of a storage elasticity with frequency dispersion characteristics measured at 60° C. with a measurement strain set at a measurement frequency of 6.28 rad/sec being 0.1%, is in a range of about 0.12 to 0.87 Pa/cm 2 ·° C.

3. The color image forming method according to claim 1 , wherein a thickness of the heating body is in a range of about 0.1 to 6.0 mm.

4. The color image forming method according to claim 1 , wherein a thickness of the film-like member is in a range of about 10 to 35 μm.

5. The color image forming method according to claim 1 , wherein a transportation speed of the film-like member is in a range of about 50 to 360 mm/sec.

6. The color image forming method according to claim 1 , wherein a melting point of the crystalline resin is in a range of about 50 to 120° C.

7. The color image forming method according to claim 1 , wherein the non-crystalline resin comprises a polyester comprising cyclohexane dicarboxylic acid as a component thereof.

8. The color image forming method according to claim 1 , wherein a glass transition temperature of the non-crystalline resin is approximately 40° C. or more.

9. The color image forming method according to claim 1 , wherein a softening point of the non-crystalline resin is in a range of about 60 to 90° C.

10. The color image forming method according to claim 1 , wherein a ratio of the crystalline resin to the non-crystalline resin is in a range of approximately 5/95 to 70/30 by mass ratio.

11. The color image forming method according to claim 1 , wherein a peak temperature of a maximum endothermic-peak of the releasing agent is in a range of about 50 to 110° C.

12. The color image forming method according to claim 1 , wherein inside of the toner particle, the crystals of the crystalline resin and the crystals of the releasing agent coexist in a form that the crystals of the crystalline resin and the crystals of the releasing agent are included as island structures and the non-crystalline resin is included as a sea structure; the shape of the crystalline resin crystals is block-shaped; and a longer side length of the crystals of the releasing agent is in a range of about 0.5 to 1.5 μm.

13. The color image forming method according to claim 12 , wherein an aspect ratio of the crystalline resin crystals defined by a shorter side length of the crystalline resin crystals relative to a longer side length of the crystalline resin crystals is in a range of about 0.6 to 1.0.

14. The color image forming method according to claim 1 , wherein a volume average particle diameter of the toner particle is in a range of about 3 to 9 μm.

15. The color image forming method according to claim 1 , wherein a shape factor SF 1 of the toner particle is in a range of about 110 to 140.

16. The color image forming method according to claim 1 , wherein the color toner is formed by a method comprising:

aggregating respective particles in a releasing agent dispersion by using aluminum ions in a mixture that is obtained by mixing a colorant dispersion, the releasing agent dispersion, and a resin particle dispersion comprising crystalline resin particles and first non-crystalline resin particles, so as to form aggregated particles;

adhering second non-crystalline resin particles to the aggregated particles; and

coalescing the second non-crystalline resin particles to the aggregated particles by terminating growth of the aggregated particles adhered to the second non-crystalline resin particles and then heating to a temperature which is equal to or higher than a glass transition temperature of the second non-crystalline resin particles,

wherein:

an average diameter of each of the crystalline resin particles, the first non-crystalline resin particles and the second non-crystalline resin particles is equal to or less than 1 μm; and

the second non-crystalline resin particles have a different solubility parameter SP value from that of the aggregated particles.