Coating Compositions for Security Elements and Holograms
AssigneeBASF SE
InventorsNikolay A. GRIGORENKO, Michelle Richert
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Abstract
The present invention relates to the use of coating compositions, comprising shaped transition metal, especially silver, particles and a binder, wherein the ratio of pigment to binder is preferably such that the resulting coating shows an angle dependent colour change, for the production of security elements and holograms. When the coating compositions of the present invention are used in coating a hologram the obtained products show a an angle dependent colour change (flip/flop effect), different colours in reflection and transmission, an extremely bright OVD image and extremely strong rainbow effect, high purity and contrast.
Claims16
A coating composition, comprising:
- shaped transition metal particles having a longest dimension of edge length of from 15 nm to 600 nm and a thickness of from 2 to 40 nm;
- and
- a binder,
- wherein a ratio of the shaped transition metal particles to binder is such that a coating formed from the coating composition shows a variation of color as a function of the viewing angle, and
- wherein the transition metal is Ag, Cu, Pd or Au.
Dependencies are inferred from the claim text.