Enhancing color toner images with fluorescing magenta toners
A composite color toner image can be enhanced by applying a separate fluorescing toner image over it to provide an enhanced color toner image having a “pinkish” fluorescing effect. This separate fluorescing toner image is obtained using visible fluorescing dry magenta toner particles. Each of these toner particles consists essentially of a polymeric binder phase and a visible fluorescing colorant that emits at one or more peak wavelengths of at least 510 nm and up to and including 590 nm and that is dispersed within the polymeric binder phase.
1. A method for providing an enhanced color toner image, the method comprising:
forming one or more latent images,
developing the one or more latent images with non-fluorescing cyan, non-fluorescing yellow, non-fluorescing magenta, and non-fluorescing black toner particles, in any desired sequence, to form a composite non-fluorescing color toner image,
developing visible fluorescing magenta dry toner particles in close proximity with the composite non-fluorescing color toner image to provide an enhanced composite color toner image,
transferring the enhanced composite color toner image to a receiver material to form a transferred enhanced composite color toner image, and
fixing the transferred enhanced composite color toner image to the receiver material to form a higher chroma image,
wherein each visible fluorescing magenta dry toner particle consists essentially of a polymeric binder phase and a visible fluorescing colorant that emits at one or more peak wavelengths of at least 510 nm and up to and including 590 nm and that is dispersed within the polymeric binder phase, and
wherein a covering power of the visible fluorescing dry magenta toner particles in the transferred enhanced composite color toner image is at least 350 cm 2 /g and up to and including 1100 cm 2 /g, and the covering power of each of the non-fluorescing cyan, non-fluorescing yellow, non-fluorescing magenta, and non-fluorescing black toner particles in the transferred enhanced composite color toner image is at least 1500 cm 2 /g and up to and including 2300 cm 2 /g.
2. The method of claim 1 , wherein the covering power of the visible fluorescing magenta dry toner particles in the transferred enhanced composite color toner image is at least 400 cm 2 /g to and including 600 cm 2 /g, and the covering power of each of the non-fluorescing cyan, non-fluorescing yellow, non-fluorescing magenta, and non-fluorescing black toner particles in the transferred enhanced composite color toner image is at least 1700 cm 2 /g to and including 2100 cm 2 /g.
3. The method of claim 1 , wherein the visible fluorescing magenta dry toner particles comprise a rhodamine class fluorescing colorant that emits at one or more peak wavelengths of at least 520 nm and up to and including 590 nm, that is present in an amount of at least 0.5 weight % and up to and including 10 weight %, based on the total visible fluorescing magenta toner particle weight.
4. The method of claim 1 , wherein the visible fluorescing magenta dry toner particles have a mean volume weighted diameter (D vol ) before fixing of at least 4 μm and up to and including 20 μm.
5. The method of claim 1 , wherein the visible fluorescing magenta dry toner particles have a mean volume weighted diameter (D vol ) before fixing of at least 5 μm and up to and including 12 μm.
6. The method of claim 1 , wherein the visible fluorescing magenta dry toner particles further comprise a charge control agent, wax, lubricant, fuser release aid, or any combination of these materials.
7. The method of claim 1 , wherein the visible fluorescing magenta dry toner particles further comprise, on their outer surface, a fuser release aid, flow additive particles, or both of these materials.
8. The method of claim 1 , wherein the receiver material is a sheet of paper or a polymeric film.
9. The method of claim 1 , comprising forming non-fluorescing cyan, non-fluorescing yellow, non-fluorescing magenta, non-fluorescing black, and visible fluorescing magenta toner images on the receiver material using at least five sequential toner stations in a color electrophotographic printing machine, which sequential toner stations are equipped with the non-fluorescing cyan, non-fluorescing yellow, non-fluorescing magenta, non-fluorescing black, and visible fluorescing magenta dry toner particles, respectively.
10. The method of claim 1 , wherein the transferred enhanced composite color toner image on the receiver material has a higher chroma of at least 7% compared to the composite non-fluorescing color toner image at the same image density.
11. The method of claim 1 , wherein the transferred enhanced composite color toner image on the receiver material has a higher chroma of at least 9% compared to the composite non-fluorescing color toner image at the same image density.