Coloured Microstructure Security Elements Using Selective Microchannel Wicking
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Solution Overview
Problem
Existing methods for producing high-contrast colored microstructures in security elements face challenges such as the formation of toning films, which reduce contrast, and are often complex and not sufficiently selective in applying color to microstructures.
Innovation Solution
A method involving embossing to create microchannels in an embossing lacquer layer, utilizing the wicking effect to selectively fill these channels with colored lacquer while avoiding wetting the surrounding surface, achieved by precise control of surface energy and channel geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional printing or deposition processes are used to produce micromotif elements, then the production process is simple, but the minimum size of the structures is limited by the resolution of the deposition process
Solution Approach 1:
The patent replaces conventional mechanical printing or deposition processes with an embossing process. The embossing process uses a physical stamping mechanism to create micromotif elements directly in the carrier substrate, achieving higher resolution without being limited by the resolution constraints of deposition processes. This substitution of the production mechanism enables finer feature sizes while maintaining process feasibility.
2Manufacturing precision
If imprinting material is used to cover only elevations or fill only depressions of embossed structure, then selective coloring is achieved, but the viscosity must be precisely matched to transfer conditions which is difficult to control
Solution Approach 1:
The patent changes the physical state and application parameters of the coloring material. Instead of using high-viscosity imprinting materials that require precise viscosity matching, the invention uses a low-viscosity liquid coloring material applied after the embossing process. The liquid form allows easy spreading and filling of the embossed structures without requiring precise viscosity control, while still achieving selective coloring through the embossed geometry.
3Manufacturing precision
If excess ink is doctored off mechanically from embossed structures, then some selectivity is achieved, but a toning film remains on the surface that limits maximum achievable contrast
Solution Approach 1:
The patent extracts and removes the harmful toning film that forms on the surface during the coloring process. By using a liquid coloring material that can be easily removed, the invention eliminates the need for complex mechanical doctoring processes. The liquid form allows complete removal of excess material, achieving high contrast without leaving residual toning films that would reduce the maximum achievable contrast.
4Manufacturing precision
If a protective layer is applied to prevent toning film formation, then contrast is improved, but numerous additional process steps are required which makes the procedure extremely complex
Solution Approach 1:
The patent applies a preliminary action by using a liquid coloring material that inherently prevents toning film formation without requiring additional protective layers. The liquid form of the coloring material allows it to be applied directly to the embossed structures and easily removed, eliminating the need for subsequent protective layer application and removal steps. This preliminary approach to problem prevention avoids the complexity of multi-step protective layer processes.
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
Enables high-contrast colored microstructures without toning films, achieved through precise and selective application of colored lacquer to microchannels, ensuring maximum contrast and simplicity in the production process.
Implementation Method 1
Applying a colored lacquer, which exclusively wets and fills the microchannels, to the cured embossing lacquer layer
Data Source
Figure 1~1a
Figure 2a~2c
AI summary
The invention relates to a method for producing a security element having a coloured microstructure, comprising the following steps: a) providing a carrier substrate (6); b) applying an embossing lacquer layer (3) onto the carrier substrate (6); c) introducing microchannels (2) into a region of the embossing lacquer layer (3) provided for the coloured microstructure; d) curing the embossing lacquer layer (3); e) applying a colour lacquer (4), which wets and fills only the microchannels (2), onto the cured embossing lacquer layer (3); and f) optionally applying a functional layer or a protective lacquer layer (5) after the colour lacquer (4) has dried and/or cured. This prevents formation of a toning film, and therefore a maximum contrast can be achieved for the coloured microstructures.