UV-Vis Curable Security Coatings with Oriented Pigments
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Solution Overview
Problem
Current methods for producing overt security features with flake-shaped multilayer interference pigments face challenges in achieving high-speed production with reliable and easy implementation, while maintaining excellent optical properties and counterfeiting resilience, particularly with solvent-free or low VOC UV-Vis radiation curable inks.
Innovation Solution
A method involving a UV-Vis radiation curable coating composition applied to a substrate, comprising cycloaliphatic epoxides, cationic photoinitiators, and pigments with surface modifiers, followed by a top coating composition applied via contactless fluid microdispensing, allowing for rapid curing and distinct optical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If UV-Vis radiation curable inks are used for high-speed production, then productivity is improved, but the pigments exhibit random orientation leading to poor optical characteristics
Solution Approach 1:
The patent applies preliminary action by pre-treating the flake-shaped pigments with hydrophobic compounds (such as silicones, fluorinated compounds, or surfactants) before incorporating them into the UV-Vis radiation curable ink composition. This pre-treatment ensures that the pigments are predisposed to orient themselves in a controlled manner during the rapid curing process, thereby achieving good optical characteristics even at high production speeds without requiring gradual drying time
Solution Approach 2:
The patent changes the chemical and physical parameters of the ink composition by incorporating specific hydrophobic additives and adjusting the composition to include compounds that facilitate pigment orientation during rapid curing. This parameter change allows the system to maintain pigment alignment under the accelerated conditions of UV-Vis radiation curing
2Object-affected harmful factors
If water-based security inks are used, then environmental compliance is improved, but the drying process becomes long and complex
Solution Approach 1:
The patent utilizes phase transition by employing UV-Vis radiation curable inks that transition from a liquid state during application to a solid cured state through photopolymerization. This phase transition occurs instantaneously upon exposure to UV-Vis radiation, eliminating the need for long evaporation-based drying processes required by water-based inks, thereby reducing drying time while maintaining environmental compliance through reduced VOC content
3Loss of time
If UV-Vis radiation curable inks are used, then drying time is reduced, but pigment orientation becomes random
Solution Approach 1:
The patent applies preliminary action by pre-treating the flake-shaped pigments with hydrophobic compounds (such as silicones, fluorinated compounds, or surfactants) before incorporating them into the UV-Vis radiation curable ink composition. This pre-treatment ensures that the pigments are predisposed to orient themselves in a controlled manner during the rapid curing process, thereby achieving good optical characteristics even at high production speeds without requiring gradual drying time
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 the production of eye-catching overt security features with enhanced optical properties and easy authentication, suitable for high-speed industrial production without the need for external devices.
Implementation Method 1
a step a) of applying on a substrate (x20) surface a UV-Vis radiation curable coating composition, said UV-Vis radiation curable coating composition being in a first, liquid state so as to form a coating layer (x10)... subsequently to step b), a step c) of curing the coating layer (x10) and the one or more indicia (x30)
Data Source
AI summary
The present invention relates to the field of methods for producing eye-catching overt security features exhibiting one or more indicia as anti-counterfeit means on security documents or security articles as well as decorative purposes. In particular, the present invention provides methods for producing security features that can be easily, directly and unambiguously authenticated by the human without any external device or tool, wherein said security features comprised a cured UV-Vis radiation cationically or hybrid curable coating composition and cured one or more indicia, said composition comprising an ink vehicle and pigments comprising a flake-shaped non-metallic or metallic substrate comprising one or more at least partial coating layers, an at least partial surface treatment layer made of one or more surface modifiers based on perfluoropolyethers.