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US 2015/0241845 A1Published application
Security elements and method for their manufacture
AssigneeBASF SE
InventorsMichelle Richert, Roland Fleury, Nikolay A. Grigorenko, Frank Knocke
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Abstract
The present invention relates to complex security elements based on recording materials for optical elements with refractive index modulation, in particular, holograms, which are subsequently coated with specific metallic nano-shaped metal particles, a method for their manufacture, in particular on a paper or on a plastic substrate and a security product obtainable using the security element. 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.
Claims16
1:
- A security element, comprising:
- a) a substrate;
- b) a component with refractive index modulation, which is obtained by exposing a recording material to actinic radiation and thereon;
- and
- c) a coating on at least a portion of the refractive index modulated layer comprising platelet shaped transition metal particles having a longest dimension of edge length of from 15 nm to 1000 nm and a thickness of from 2 nm to 100 nm.
2 more elements
2:
- The security element according to claim 1 wherein the coating, component c) comprises additionally an embossed surface relief microstructure.
3:
- The security element according to claim 1, wherein the metal is selected from the group consisting of Cu, Ag, Au, Zn, Cd, Ti, Cr, Mn, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt.
4:
- The security element according to claim 3, wherein the shaped transition metal particles have a longest dimension of edge length of from 15 to 1000 nm and a thickness of 2 to 100 nm and comprise hexagonal, triangular, and/or truncated triangular prisms, wherein the prisms make up more than 20% of the total number of shaped transition metal particles.
5:
- The security element according to claim 1, wherein
- the coating of component c) comprises a binder selected from the group consisting of nitrocellulose, ethyl cellulose, cellulose acetate, cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB), alcohol soluble propionate (ASP), vinyl chloride, vinyl acetate copolymers, vinyl acetate, vinyl, acrylic, polyurethane, polyamide, rosin ester, hydrocarbon, aldehyde, ketone, urethane, polythyleneterephthalate, terpene phenol, polyolefin, silicone, cellulose, polyamide, polyester and rosin ester resins or is a photopolymerisable composition comprising an ethylenically unsaturated monomer and/or oligomer and a photoinitiator.
6:
- The security element according to claim 1, wherein the recording material of component b) is a photopolymerisable composition comprising an ethylenically unsaturated monomer and/or oligomer and a photoinitiator.
7:
- The security element according to claim 1, wherein both, the recording material of component b) and the coating of component c) are photopolymerisable compositions comprising an ethylenically unsaturated monomer and/or oligomer and a photoinitiator.
8:
- The security element according to claim 5, wherein the photoinitiator is selected from the group consisting of benzophenone, alpha-hydroxy ketone type compounds, alpha-alkoxy ketone type compounds, alpha-amino ketone type compounds, mono and bisacylphosphine oxide compounds, phenylglyoxylate compounds, oxim ester compounds and onium salt compounds and mixtures thereof.
9:
- The security element according to claim 5, wherein the photoinitiator comprises an arylborate and a dye as sensitizer.
10:
- The security element according to claim 1, wherein the substrate comprises glass, plastic or paper.
11:
- A method for forming the security element of claim 1, the method comprising:
- a) depositing a recording material on a substrate;
- b) exposing the recording material to modulated actinic radiation carrying holographic information, thereby producing a volume hologram;
- and
- c) coating the volume hologram at least in part with a coating comprising platelet shaped transition metal particles having a longest dimension of edge length of from 15 nm to 1000 nm and a thickness of from 2 nm to 100 nm.
2 more elements
12:
- The method according to claim 11, wherein the recording material, component b) has a thickness of from 0.1 μm to 100 μm in the dry or cured state.
13:
- The method according to claim 11, wherein the coating, component c) has a thickness of from 0.5 μm to 50 μm in the dry or cured state.
14:
- The method according to claim 11 wherein the security element formed shows an angle dependent color change upon viewing.
15:
- A security product comprising a security element according to claim 1, wherein the security product is selected from the group consisting of banknotes, credit cards, identification documents, pharmaceutical apparel, software, compact discs, tobacco packaging and other products or packaging prone to counterfeiting or forgery.
16:
- A method for preventing counterfeit or reproduction, comprising applying the security element according to claim 1 on a document of value, right, identity, a security label or a branded good.