Highlighting color toner images with fluorescing toners
View Patent ↗Fluorescing highlights can be provided in selected portions of non-color image areas of a printed toner image using fluorescing dry toner particles, such as fluorescing magenta and fluorescing yellow dry toner particles. Before fixing, each fluorescing dry toner particle comprises a polymeric binder phase and a fluorescing colorant that emits at one or more λ max wavelengths of at least 420 nm and up to and including 690 nm and that is dispersed within the polymeric binder phase.
1. A method for providing a highlighted color toner image, the method comprising:
developing one or more color latent images in one or more color image areas using corresponding non-fluorescing color toner particles to form a non-fluorescing composite color toner image on a first receiver material,
prior to or subsequently to developing the non-fluorescing composite color toner image on the first receiver material, developing one or more selected portions of non-color image areas outside the one or more color image areas on the first receiver material with only fluorescing dry toner particles to provide a developed fluorescing toner highlight in the one or more selected portions of the non-color image areas,
transferring the non-fluorescing composite color toner image and the developed fluorescing toner highlight in the one or more non-color image areas, to a final receiver material to form a non-fluorescing composite color toner image and a fluorescing toner highlight in the one or more selected portions of the non-color image areas, and
fixing the non-fluorescing composite color toner image and the fluorescing toner highlight on the final receiver material,
so as to provide a covering power of the fluorescing dry toner particles in the fluorescing toner highlight of at least 350 cm 2 /g and up to and including 1100 cm 2 /g and such that the covering power of the fluorescing dry toner particles in the fluorescing toner highlight is up to and including 70% of the covering power of the non-fluorescing composite color toner image,
wherein, before fixing, each fluorescing dry toner particle comprises a polymeric binder phase and a fluorescing colorant that emits at one or more peak wavelengths of at least 420 nm and up to and including 690 nm and that is dispersed within the polymeric binder phase.
2. The method of claim 1 , wherein the fluorescing toner dry particles have a mean volume weighted diameter (D vol ) of at least 4 μm and up to and including 20 μm.
3. The method of claim 1 , wherein the fluorescing dry toner particles comprise a yellow fluorescing colorant that emits at one or more peak wavelengths of at least 510 nm and up to and including 570 nm.
4. The method of claim 3 , wherein the fluorescing dry toner particles comprise a yellow fluorescing colorant that is selected from the group consisting of coumarins, naphthalimides, perylenes, and anthrones.
5. The method of claim 1 , wherein the fluorescing dry toner particles comprise a magenta fluorescing colorant that emits at one or more peak wavelengths of at least 510 nm and up to and including 590 nm.
6. The method of claim 5 , wherein the fluorescing dry toner particles comprise a magenta fluorescing colorant that is selected from the group consisting of rhodamines, perylenes, naphthalimides, and anthrones.
7. The method of claim 1 , wherein the covering power of the fluorescing dry toner particles in the fluorescing toner highlight is at least 400 cm 2 /g and up to and including 600 cm 2 /g and the covering power of the non-fluorescing composite color toner image is at least 1700 and up to and including 2100 gm 2 /g.
8. The method of claim 1 , wherein the reflection density of the fluorescing dry toner particles in the fluorescing toner highlight is less than 1.
9. The method of claim 1 , wherein the fluorescing colorant is present in the fluorescing dry toner particles in an amount of at least 5 weight % and up to and including 24 weight %, based on the total fluorescing dry toner particle weight.
10. The method of claim 1 , wherein the fluorescing 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.
11. The method of claim 1 , wherein the fluorescing dry toner particles further comprise a charge control agent, wax, lubricant, fuser release aid, or any combination of these materials.
12. The method of claim 1 , wherein the fluorescing dry toner particles further comprise, on their outer surface, a fuser release aid, flow additive particles, or both of these materials.
13. The method of claim 1 , wherein the receiver material is a sheet of paper or a polymeric film.
14. The method of claim 1 , comprising forming non-fluorescing cyan, non-fluorescing yellow, non-fluorescing magenta, and non-fluorescing black toner images in the non-fluorescing composite color toner image.
15. The method of claim 1 , comprising:
prior to or subsequently to developing the non-fluorescing composite color toner image and before transferring and fixing the non-fluorescing composite color toner image and the developed fluorescent toner highlight to the receiver material:
applying fluorescing magenta dry toner particles in one or more selected portions of non-color image areas to provide a fluorescing magenta toner highlight in the one or more selected portions of non-color image areas, and
prior to or subsequently to applying the fluorescing magenta dry toner particles, applying fluorescing yellow dry toner particles in one or more different selected portions of non-color image areas to provide a fluorescing yellow toner highlight in the one or more different selected portions of the non-color image areas.
16. The method of claim 1 , wherein fluorescing dry toner particles exhibit an optical density of at least 0.2 at maximum exposure to irradiating light.