Plastic toner and method for producing such a plastic toner
View Patent ↗A toner and to a method for producing a plastic toner, especially for electrophotography. The base material for the toner, a powder for powder coating, is used and has a grain size distribution of from 1 to 20 μm, particularly 5 to 15 μm, and has additional charge control agents and additives on the surface. According to the method, convected powders for powder coating are used as the base material. In a mixing step, the powders are mixed with charge control agents (CCA) for improving surface charge and optionally in a further mixing step with additives for improving the flow properties, the adhesive power and the agglomeration propensity.
1. A method for producing a plastic toner for electrophotography, the method comprising:
using finished convected powder as base materials for powder coating, the powder including a pressure-setting plastic base and a hardener and having a grain size distribution of 1 to 20 μm;
charging the powder in a dry mixing process with charge control agents for improving a surface charge, wherein a concentration of the charge control agents is selected between >0 and 5 weight-%;
charging the powder in a further mixing process with additives, wherein at least one of aerosils and silanes are employed as the additives and a concentration of the additives is selected to be between >0 and 5 weight-%;
wherein at least one powder charge material selected from the group including epoxides, polyesters, polyurethanes, melamines, acrylates, and combinations thereof are used as the base materials.
2. The process claim in accordance with claim 1 , wherein the powder for powder coating has a grain size distribution of 5 μm to 15 μm.
3. The method in accordance with claim 2 , wherein a grinding and sifting process is performed prior to the dry mixing process, which matches the grain size distribution in the base materials as required for electrophotographic transfer.
4. The method in accordance with claim 2 , wherein the concentration of the charge control agents is <2 weight-%.
5. The method in accordance with claim 4 , wherein the concentration of the additives is <2 weight-%.
6. The method in accordance with claim 3 , wherein the dry mixing process is performed in one of an eccentric tumbling mixer and a vane mixer, and required grinding and sifting process is performed in a counter-current grinder.
7. A plastic toner for electrophotography produced according to the method of claim 6 .
8. A plastic toner for electrophotography produced according to the method of claim 1 .
9. The method in accordance with claim 1 , wherein a grinding and sifting process is performed prior to the dry mixing process, which matches the grain size distribution in the base materials as required for electrophotographic transfer.
10. The method in accordance with claim 1 , wherein the concentration of the charge control agents is <2 weight-%.
11. The method in accordance with claim 1 , wherein the concentration of the additives is <2 weight-%.
12. The method in accordance with claim 1 , wherein the dry mixing process is performed in one of an eccentric tumbling mixer or a vane mixer, and required grinding and sifting process is performed in a counter-current grinder.