Color holographic foil
The invention refers to a color holographic foil for protection of goods and documents from forgery and falsification. It includes successively placed foil base ( 1 ), release layer ( 2 ), embossing layer ( 3 ), reflective layer ( 4 ) and adhesive layer ( 5 ). The embossing layer comprises smooth areas ( 6 ) and micro-relief areas ( 7 ). The thickness of the optical reflective layer ( 4 ) is inversely proportional to the depth of the depressions in the micro-relief areas. At least two of the micro-relief areas are dyed areas ( 10 ) with embossing layer colored with a dye in different saturations of a single color tone. The saturation is directly proportional to the depth of the depressions. At least one dyed area is a multi-bonded area ( 11 ), having at least one micro-relief boundary ( 12 ) and at least one smooth boundary ( 13 ). The topography of the micro-relief in said multi-bonded areas is different from the topography of the neighbouring dyed areas.
1 . A color holographic foil, including a base, on which a release layer, an embossing layer, an optical reflective layer having a thickness, and an adhesive layer are successively arranged, said embossing layer comprising smooth areas without any micro-relief and micro-relief areas, containing protrusions and depressions with a depth, and at least two micro-relief areas are dyed areas, where said embossing layer is colored with a dye, and at least one dyed area is a multi-bonded area, said multi-bonded area has at least one micro-relief boundary fully or partially bordering with said dyed areas, and at least one smooth boundary fully bordering with said smooth areas, characterized in that, the adhesive layer is arranged over the optical reflective layer, and a distance between said smooth boundary and the nearest micro-relief boundary is smaller than 0.2 mm, and wherein the micro-relief topography in said multi-bonded area differs from the micro-relief topography in corresponding neighbouring dyed areas, and said embossing layer in said dyed areas and in said multi bonded areas is colored in different saturations of a single color tone, wherein the distance between two neighbouring depressions is between 0.1 μm and 50 μm, and the depth of said depressions is from 0.05 μm to 2 μm, and the thickness of said reflective layer in said smooth areas is constant, ranging between 15 nm and 100 nm, and in said micro-relief areas thickness is variable and inversely proportional to the depth of the depressions and is at least 20% thinner than in said smooth areas.
2 . The color holographic foil, according to claim 1 , characterized in that said reflective layer is of transparent dielectric with a refraction index greater than 1.8.
3 . The color holographic foil, according to claim 1 , characterized in that said reflective layer is of one of the following metals: Al, Cu, Ag, Au, Cr.
4 . The color holographic foil, according to claim 3 , characterized in that said reflective layer only covers said dyed areas and said multi-bonded areas.
5 . The color holographic foil, according to claim 4 , characterized in that additional colored layer of polymer ink in a chosen single color tone is provided over said reflective layer in said dyed areas and in said multi-bonded areas.
6 . The color holographic foil, according to claim 5 , characterized in that said additional colored layer is of a luminescent ink.
7 . The color holographic foil, according to claim 1 , characterized in that said dyed areas and said multi-bonded areas are colored with a luminescent dye.