Color-Shifting Overt Security Features with Magnetic Pigment Layers
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Solution Overview
Problem
Existing cholesteric liquid crystal polymers for security features have limited color gamut and require costly, time-consuming customization for specific colorshift effects, making it difficult to produce eye-catching, multi-colored overt security features that are easy to authenticate without external tools.
Innovation Solution
A security feature comprising a substrate with a color constant layer of magnetically oriented platelet-shaped magnetic pigment particles and an optically variable layer of cholesteric liquid crystal polymer, where the pigment particles are oriented at a specific elevation angle to create a multi-colored effect visible at different viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cholesteric liquid crystal polymers are used for security features, then colorshifting effect is achieved, but color gamut is limited and customization is costly and time-consuming
Solution Approach 1:
The invention segments the colorshifting effect into multiple independent cholesteric liquid crystal polymer layers, each with different pitch values producing different colors. This allows a single security feature to exhibit multiple colors simultaneously without requiring multiple separate customization processes, thereby expanding color gamut while maintaining ease of manufacture.
Solution Approach 2:
The invention uses composite structures combining multiple cholesteric liquid crystal polymer layers with different pitch values and/or chiral dopant concentrations. This composite approach enables a single material system to produce multiple colorshifting effects, achieving both broad color gamut and cost-effective manufacturing by eliminating the need for separate customization of individual color layers.
2Adaptability or versatility
If multiple cholesteric liquid crystal polymer layers with different pitch values are combined, then multi-colored effect is achieved, but layer alignment precision becomes difficult to control
Solution Approach 1:
The invention introduces a magnetic field as an intermediary tool to align the cholesteric liquid crystal polymer layers. By applying a magnetic field during the formation process, the helical structures of multiple layers can be simultaneously oriented in the desired direction, achieving precise multi-layer alignment without requiring complex mechanical positioning systems.
Solution Approach 2:
The invention utilizes changes in the pitch parameter of cholesteric liquid crystal polymer layers to achieve different colors. By precisely controlling the pitch values of individual layers during manufacturing, the invention can produce specific colorshifting effects while maintaining overall layer alignment, thus achieving multi-colored effects with controlled precision.
3Adaptability or versatility
If cholesteric liquid crystal polymer layers are applied on substrate, then security feature is formed, but production speed is reduced due to complex customization processes
Solution Approach 1:
The invention performs preliminary actions by pre-determining the pitch values and chiral dopant concentrations of cholesteric liquid crystal polymer layers during the formulation stage. This preliminary configuration allows the layers to be applied and aligned in a single manufacturing step without requiring subsequent customization or adjustment processes, thereby maintaining colorshifting effects while significantly increasing production speed.
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
The solution provides a reliable, predictable, and easy-to-implement method for producing overt security features with high counterfeiting resilience, allowing easy authentication by the human eye and resistance to copying.
Implementation Method 1
The helical superstructure provides for a periodic refractive index modulation throughout the liquid crystal material, which in turn results in a selective transmission/reflection of determined wavelengths of light (interference filter effect)
Implementation Method 2
a color constant layer (×20) comprising magnetically oriented platelet-shaped magnetic or magnetizable pigment particles
Data Source
AI summary
The present invention relates to the field of methods for producing eye-catching overt security features exhibiting colorshifting properties as anti-counterfeit means on security documents or security articles as well as decorative purposes. In particular, the overt security feature exhibits comprises a) a substrate (×10), a color constant layer (×20) comprising magnetically oriented platelet-shaped magnetic or magnetizable pigment particles and an optically variable layer (×30) comprising a cholesteric liquid crystal polymer (CLCP) reflecting light in the visible spectrum range, wherein the platelet-shaped magnetic or magnetizable pigment particles of the color constant layer (×20) have substantially a same elevation angle α.