Security elements and method for their manufacture
AssigneeBASF SE
InventorsMichelle RICHERT, Oliver SEEGER, Nikolay A. GRIGORENKO
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Abstract
The present invention relates to complex security elements based on liquid crystal coatings which are subsequently coated with specific metallic nano-shaped metal particles, a method for their manufacture, in particular on a glass, paper or on a plastic substrate and a security product obtainable using the security element. The security element may contain additionally an embossed surface relief microstructure, especially an optically variable image (an optically variable device, OVD), such as a hologram. A further aspect of the invention is the use of such a security element for the prevention of counterfeit or reproduction of a document of value.
Claims19
A security element comprising:
- a) a substrate with a surface side and a reverse side,
- b) a coating on at least a portion of the substrate, the coating including at least one liquid crystal compound, wherein the coating is applied on the reverse side of the substrate if the substrate is transparent or translucent, or on the surface side if the substrate is transparent, translucent, reflective or opaque and;
- c) another coating on at least a portion of the coating that includes the liquid crystal compound, or on the surface side of the substrate if the coating that includes the liquid crystal compound is placed on the reverse side of the substrate,
- the another coating comprising platelet shaped transition metal particles having a longest dimension of edge length of from 5 nm to 1000 nm, and a thickness of from 2 nm to 100 nm.
-15. (canceled)
Dependencies are inferred from the claim text.