Security enhanced printed products and methods
View Patent ↗Printed products, printing methods and methods for verifying authenticity of a printed product are provided. In one aspect, the printed product has a receiver and an image formed thereon by an electrophotographic process using toner particles, said image having at least one raised portion, wherein at least parts of said raised portion of said image comprise phosphorescent or fluorescent toner particles.
1. A method for forming a printed product on a receiver member, said method comprising:
applying a plurality of toner layers on said receiver member for forming an image such that said image has at least one raised portion, said raised portion comprising a layer of phosphorescent or fluorescent toner particles; and fusing said toner layers to said substrate, wherein after fusing, a raised portion remains at least 15 μm above a surrounding area of the fused toner layers so that the raised portion is visible from a side elevation.
2. The method of claim 1 , wherein the layer of phosphorescent toner particles is formed as an outer layer of at least a part of a surface of said raised portion.
3. The method of claim 1 , wherein said raised portion is at least partially formed by:
applying at least one first toner layer of a first colour, and
applying said layer of phosphorescent or fluorescent toner particles on top of at least portions of said first toner layer.
4. The method of claim 1 , wherein said raised portion is at least partially formed by using large toner particles of a standard general average mean volume weighted diameter of more than 18 μm.
5. The method of claim 1 , wherein said large toner particles have a standard general average mean volume weighted diameter of between 20 μm to 50 μm.
6. The method of claim 1 , wherein said large toner particles have a standard general average mean volume weighted diameter of between 20 μm to 30 μm.
7. The method of claim 1 , wherein said phosphorescent or fluorescent toner particles have a standard general average mean volume weighted diameter of more than 18 μm, preferably more than 20 μm.
8. The method of claim 1 , wherein said image comprises at least one non-raised portion formed by standard toner particles of a standard general average mean volume weighted diameter of less than 15 μm, preferably less than 10 μm.
9. The method of claim 1 , wherein said image is formed as a multi-colour image having raised portions overlaid thereon.