Emulsion aggregation high-gloss toner with calcium addition
View Patent ↗Toner including toner particles having a calcium-containing material at least in a surface portion of the toner particle, wherein the toner particles contain calcium in an amount of from 20 ppm to about 300 ppm of calcium by dry weight of the toner. Developer including a carrier and a toner, wherein the toner includes toner particles having a calcium-containing material at least in a surface portion of the toner particles. In an emulsion aggregation process for making toner particles, the toner particles are treated with calcium. The addition of calcium to the toner particles improves toner performance by lowering cohesion and charging, thereby generating an image of high gloss.
1. A toner comprising toner particles having a calcium-containing material only in a surface portion of the toner particles as a result of the toner particles having been treated with the calcium-containing material after aggregation, wherein:
the toner particles contain calcium in an amount of from about 20 ppm to about 300 ppm of calcium by dry weight of the toner,
the toner particles contain a first silica and at least a second silica,
the first silica has an average primary particle size of about 5 nm to about 50 nm, and the second silica has an average primary particle size of about 100 nm to about 200 nm, and
the toner has a q/d charge displacement level from about 4 to about 11 mm.
2. The toner of claim 1 , wherein the toner particles further comprise at least one resin, at least one colorant, and optional external additives.
3. The toner of claim 2 , wherein the at least one resin is a styrene/acrylate resin.
4. The toner of claim 2 , wherein the optional external additives comprise a titania, an optional cerium oxide and an optional zinc stearate.
5. The toner of claim 2 , wherein the toner particles further comprise a wax.
6. The toner of claim 5 , wherein the wax is selected from polyethylene wax and distilled polyethylene wax.
7. The toner of claim 1 , wherein the toner particles contain aluminum in an amount of from about 100 ppm to about 500 ppm by dry weight of the toner.
8. The toner of claim 1 , wherein the toner has a triboelectric charge from about 30 μC/g to about 70 μC/g.
9. A developer comprising a carrier and the toner according to claim 1 .
10. A developer according to claim 9 , wherein the developer has a triboelectric charge from about 30 μC/g to about 70 μC/g.
11. A process for making toner particles comprising forming toner particles by emulsion aggregation; and treating the toner particles with a calcium-containing material after aggregation, wherein:
the calcium-containing material is only in a surface portion of the toner particles as a result of the treating with the calcium-containing material,
the toner particles contain calcium in an amount of from about 20 ppm to about 300 ppm of calcium by dry weight of the toner,
the toner particles contain a first silica and at least a second silica,
the first silica has an average primary particle size of about 5 nm to about 50 nm, and the second silica has an average primary particle size of about 100 nm to about 200 nm, and
the toner has a q/d charge displacement level from about 4 to about 11 mm.
12. The process according to claim 11 , wherein the toner particles are treated with a calcium chloride solution.
13. The process according to claim 11 , wherein the forming of the toner particles by emulsion aggregation comprises generating an emulsion of resin by dispersing the resin in water; optionally adding to the emulsion at least one colorant dispersion, at least one wax dispersion and/or at least one surfactant; heating the emulsion and adding at least one coagulant to the emulsion, wherein the aggregate grows to a desired size; adding an optional sequestering agent; and optionally further increasing the temperature by heating to coalesce the toner particles.
14. The process according to claim 13 , wherein adding the optional sequestering agent is added and substantially removes ions introduced via the coagulant.
15. The process according to claim 13 , wherein the toner particles are washed with deionized water and de-watered after aggregation.
16. The process according to claim 13 , wherein the latex is a styrene acrylate latex.
17. The process according to claim 13 , wherein the at least one coagulant is an aluminum containing coagulant.
18. The process according to claim 11 , wherein the toner has a triboelectric charge from about 30 μC/g to about 70 μC/g.