Photochromic Inkjet Inks UV Stabilization for Security Printing
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Solution Overview
Problem
Photochromic inks lose their color-changing characteristics over time or due to environmental conditions such as heat and long-term exposure to UV light, making them unreliable for secure document printing.
Innovation Solution
Development of stable photochromic inkjet inks formulated with photochromic dyes, organic solvents, and polymer resins that maintain their color-changing properties on both porous and non-porous substrates, using specific solvent combinations and polymer resin ratios to enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photochromic inks are used for printing secure documents, then color-changing characteristics are achieved under UV light, but the inks lose their photochromic properties over time due to environmental conditions
Solution Approach 1:
The patent introduces an intermediary substance (UV absorber or stabilizer) that mediates between the photochromic ink and environmental UV radiation. This intermediary absorbs harmful UV energy before it can degrade the photochromic molecules, thereby extending the shelf life while maintaining photochromic reliability
Solution Approach 2:
The patent modifies the chemical parameters of the ink formulation by adding specific UV absorbers and stabilizers. These parameter changes alter the ink's resistance to environmental degradation, enabling it to maintain photochromic properties throughout the intended shelf life without fading or losing responsiveness
2Reliability
If photochromic inks are exposed to long-term UV light for security verification, then color-changing detection is enabled, but the inks degrade and lose their color-changing ability
Solution Approach 1:
The patent converts the harmful UV radiation into a beneficial protective mechanism by incorporating UV absorbers that selectively absorb UV energy. This absorbed energy is dissipated harmlessly as heat, protecting the photochromic molecules from degradation while allowing the desired color-changing detection to proceed
Solution Approach 2:
The patent applies prior cushioning by pre-incorporating stabilizers and UV absorbers into the ink formulation before exposure to environmental conditions. This preemptive protection creates a buffer against UV degradation, allowing the ink to withstand repeated verification cycles without losing its color-changing capability
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 inkjet inks exhibit consistent and long-lasting color changes under sunlight or UV light, reverting back to their original state when light is removed, ensuring reliable visibility for secure documents without fading quickly.
Implementation Method 1
Photochromic materials have also been used in the manufacture of printing inks for the purpose of printing documents and package labels. These photochromic inks are used to print an invisible mark or marks on the document, label or packaging substrate. The printed mark only becomes visible when exposed to sunlight or UV light.
Implementation Method 2
Once the mark is no longer eliminated by sunlight or UV light, it stays visible for only a short time period and reverts back to its normal, invisible state.
Data Source
AI summary
Method of making color changing inkjet inks for security printing applications use photochromic materials that cause the inkjet ink to print marks that are colorless under ambient light and appear in a color when exposed to sunlight or UV light (covert). In another embodiment, the printed mark appears in a first color under ambient light, and changes to a second color when exposed to sunlight or UV light (overt). The methods of making the photochromic inks produce ink components that are stable and maintain their color changing capability for the shelf life of the printed material. The inkjet ink formulations are suitable for use on porous and non-porous surfaces, such as plain paper, coated paper, Teslin, polymer film, ceramic or metal, for example.