Toner for development of electrostatic images

1. A process for forming an image, the process comprising:

printing an electrostatic image with a toner comprising a binder resin, a colorant and a wax,

wherein the wax that is in a state of being contained in the toner has at least one melting point falling within a range of from 55° C. to 90° C.,

wherein a dust emission (Dt) from the toner satisfies formula (1):

101≤ Dt≤ 195,449/ Vp− 1,040  (1),

wherein:

Dt represents a dust emission per minute (CPM) when heating the toner; and

Vp represents a printing speed (sheets/min) in terms of A4 short side feed in an image forming device, and Vp is 171.2 or less,

wherein the dust emission (Dt) is measured in a draft, which is controlled at a temperature of 22-28° C. and humidity of 50-60%, by:

heating a heating unit disposed in the draft to a temperature of 200° C.;

immediately lowering the temperature of the heating unit to 100° C.;

while maintaining the heating unit at 100° C., counting a first background emission (BG 1 ) for 1 minute with a dust counter disposed in the draft, placing from 1.0-1.1 grams of the toner in an sample cup having a diameter of 6 cm at the center of the heating unit, and counting a second background emission (BG 2 ) for 1 minute with the dust counter;

ramping the temperature of the heating unit and the sample cup for 60 minutes to a temperature of 200° C., and holding the heating unit and the sample cup at 200° C. for 5 minutes;

counting, at intervals of 1 minute with the dust counter, dust emitted for a 65 minutes, wherein the dust emission (Dt) of the toner is equal to a total of the 65 dust emission values counted in the 65 minute interval minus 65 times the background emission (BG), which is a mean value of BG 1 and BG 2 .

2. The process of claim 1 , wherein the dust emission (Dt) from the toner satisfies formula (2):

101≤ Dt≤ 117,262/ Vp− 1,039  (2)

wherein Vp is 102.8 or less.

3. The process of claim 2 , wherein the dust emission (Dt) from the toner satisfies formula (3):

101≤ Dt≤ 71,653/ Vp− 1,039  (3)

wherein Vp is 62.8 or less.

4. The process of claim 3 , wherein the dust emission (Dt) from the toner satisfies formula (4):

101≤ Dt≤ 52,104/ Vp− 1,039  (4)

wherein Vp is 45.7 or less.

5. The process of claim 1 , wherein the value of Vp is 20 or more.

6. The process of claim 1 , wherein the value of Vp is 30 or more.

7. The process of claim 1 , wherein the wax that is in a state of being contained in the toner has at least one melting point in a range of from 55° C. to lower than 70° C., and at least one melting point in a range of from 70° C. to 80° C.

8. The process of claim 7 , wherein the toner comprises at least two types of waxes of a wax component X and a wax component Y,

wherein the dust emission from the wax component Y is larger than the dust emission from the wax component X,

wherein the dust emission from the wax component X and the wax component Y is measured in the same manner as the dust emission of the toner (Dt) except that each of the wax component X and the wax component Y is placed in the sample cup alone rather than the toner, and

wherein the content of the wax component X is larger than the content of the wax component Y.

9. The process of claim 8 , wherein the proportion of the wax component Y in all the wax components is from 0.1% by mass to less than 10% by mass.

10. The process of claim 9 , wherein the toner comprises at least two types of waxes of a wax component X and a wax component Y, and

wherein the dust emission from the wax component X is 50,000 CPM or less, and the dust emission from the wax component Y is 100,000 CPM or more.

11. The process of claim 10 , wherein the toner has a region in which an abundance ratio of the wax component Y is larger than that of the wax component X, and the region exists more in the outer region of the toner than in the center region thereof.

12. The process of claim 11 , wherein the toner has a shell/core structure, and

wherein the wax contained in the shell of the shell/core structure comprises substantially the wax component Y alone, and the wax contained in the core of the shell/core structure contains substantially the wax component X alone.

13. The process of claim 7 , wherein the toner comprises at least two types of waxes of a wax component X and a wax component Y, and

wherein the dust emission from the wax component X is 50,000 CPM or less, and the dust emission from the wax component Y is 100,000 CPM or more, and

wherein the dust emission from the wax component X and the wax component Y is measured in the same manner as the dust emission of the toner (Dt) except that each of the wax component X and the wax component Y is placed in the sample cup alone rather than the toner.

14. The process of claim 13 , wherein the toner has a region in which an abundance ratio of the wax component Y is larger than that of the wax component X, and the region exists more in the outer region of the toner than in the center region thereof.

15. The process of claim 14 , wherein the toner comprises at least two types of waxes of a wax component X and a wax component Y,

wherein the dust emission from the wax component Y is larger than the dust emission from the wax component X, and

wherein the content of the wax component X is larger than the content of the wax component Y.

16. The process of claim 15 , wherein the proportion of the wax component Y in all the wax components is from 0.1% by mass to less than 10% by mass.