Security Element Embossing and Lift-Off Registration
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Solution Overview
Problem
Existing methods for producing security elements with optically active properties struggle to ensure an exact register match between the optically active structure and the reflection layer, leading to potential vulnerabilities in anti-forgery measures.
Innovation Solution
A method involving the use of radiation-curable embossing lacquer layers with introduced nanostructures and microchannels, where the wicking effect is utilized to selectively apply a lift-off lacquer and subsequently a metallic reflection layer, ensuring precise alignment without tolerances by using embossing and lift-off techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional embossing and coating methods are used to produce security elements, then the production process is simple and cost-effective, but an exact register match between the optically active structure and the reflection layer cannot be ensured
Solution Approach 1:
The method applies a lift-off lacquer layer to the embossed security element before applying the reflection layer. The lift-off lacquer layer is selectively removed in specific areas, creating a mask that guides the reflection layer deposition. This preliminary masking action ensures that the reflection layer is deposited only in the desired areas with exact register match to the optically active structures, eliminating alignment tolerances that would otherwise exist in conventional direct coating methods
Solution Approach 2:
The lift-off lacquer layer serves as an intermediary masking layer between the embossed security element and the reflection layer. This intermediate layer enables precise control over where the reflection layer is deposited, acting as a temporary mask that can be selectively removed. The intermediary layer facilitates the exact register match by providing a controllable barrier that defines the boundaries of the reflection layer application area
2Ease of manufacture
If the reflection layer is applied over the entire surface, then coverage is complete and simple, but the reflection layer must be selectively removed from non-optically active areas requiring additional processing steps
Solution Approach 1:
Instead of applying the reflection layer only to the desired areas directly (which would be complex), the method inverts the approach by applying the reflection layer to the entire surface and then selectively removing it from areas where it should not be present. The lift-off lacquer layer is removed in non-optically active areas, and the reflection layer is subsequently removed from these same areas, creating the desired pattern through selective removal rather than selective application
3Reliability
If partial gaps are provided in the reflection layer using washing processes or etching techniques, then security against forgery is increased, but the production process becomes more complex and time-consuming
Solution Approach 1:
The method merges the creation of partial gaps in the reflection layer with the lift-off process. The lift-off lacquer layer is removed in specific areas to create gaps, and the reflection layer is subsequently removed from these same areas in a single integrated process. This combines what would otherwise be separate operations (creating gaps and removing reflection layer) into one unified lift-off step, improving production efficiency while maintaining the security benefits of partial gaps
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a security element with an exact match between optically active nanostructures and the metallic reflection layer, enhancing security against forgery by ensuring exclusive presence of the reflection layer within the optically active areas, thus providing improved authenticity verification.
Implementation Method 1
wherein the wicking effect is utilized to selectively apply a lift-off lacquer
Implementation Method 2
radiation-curable embossing lacquer layers with introduced nanostructures
Implementation Method 3
subsequently a metallic reflection layer, ensuring precise alignment without tolerances
Data Source
Figure 1~1a
Figure 2a~2e
AI summary
The invention relates to a method for manufacturing a security element having optically active security features, characterized by the following process steps: a) providing a carrier substrate; b) applying a radiation-curable embossing lacquer layer; c) introducing nanostructures into at least a first sub-area simultaneously with introducing microchannels into at least a second sub-area of the radiation-curable lacquer layer; d) curing the radiation-curable lacquer layer; e) applying a solvent- or water-soluble lift-off lacquer layer, wherein this lacquer layer exclusively wets and fills the microchannels; f) applying a reflective layer; g) removing the solvent- or water-soluble lacquer layer by action of a solvent or water; h) optionally applying a further functional layer or a protective lacquer layer.