Closed air circulation toner rounding
View Patent ↗Toner is rounded by vigorously mixing less than about 5 percent by weight of particulate silica to the total weight of a starting toner in a closed, recirculating air system. The starting toner contains at least about 4.5 percent by weight of the starting toner of a wax and additionally contains at least 5 percent by weight of the starting toner of a softening agent. The temperature during the mixing is no more than 13 degrees C. above the onset of the glass transition temperature of the starting toner. The final toner comprises rounded starting toner having particulate silica embedded during the mixing process.
1. The method of rounding electrostatic toner comprising vigorously mixing in a closed, recirculating air system a mixture of about 96.5 percent or more by weight starting toner and between about 3.5 and 5 percent by weight particulate silica, said starting toner having by weight of said starting toner at least 4.5 percent by weight wax and at least 2 percent by weight softening agent.
2. The method of claim 1 in which the temperature during said vigorous mixing in no more than 13 degrees C. above the onset of the glass transition temperature of said starting toner.
3. The method as in claim 2 in which said softening agent is pentaerythritol tetrabenzoate.
4. The method as in claim 1 in which said particulate silica has an average primary particle size of about 30 nanometers.
5. The method as in claim 4 in which said silica is about 4 percent by weight of the weight of said starting toner.
6. The method as in claim 5 in which said softening agent is about 5 percent by weight of the weight of said starting toner.
7. The method as in claim 6 in which said softening agent is pentaerythritol tetrabenzoate.
8. The method of claim 6 in which the temperature during said vigorous mixing in no more than 13 degrees C. above the onset of the glass transition temperature of said starting toner.
9. The method as in claim 8 in which said softening agent is pentaerythritol tetrabenzoate.
10. The method as in claim 5 in which said softening agent is pentaerythritol tetrabenzoate.
11. The method as in claim 4 in which said softening agent is about 5 percent by weight of the weight of said starting toner.
12. The method as in claim 11 in which said softening agent is pentaerythritol tetrabenzoate.
13. The method as in claim 4 in which said softening agent is pentaerythritol tetrabenzoate.
14. The method as in claim 1 in which said silica is about 4 percent by weight of the weight of said starting toner.
15. The method as in claim 14 in which said softening agent is about 5 percent by weight of the weight of said starting toner.
16. The method as in claim 14 in which said softening agent is pentaerythritol tetrabenzoate. The method as in claim 1 in which said softening agent is pentaerythritol tetrabenzoate.
17. The method as in claim 15 in which said softening agent is pentaerythritol tetrabenzoate.
18. The method as in claim 1 in which said softening agent is about 5 percent by weight of the weight of said starting toner.
19. The method as in claim 18 in which said softening agent is pentaerythritol tetrabenzoate.
20. The method as in claim 1 in which said softening agent is pentaerythritol tetrabenzoate.