IR-Transparent and Absorbing Inks for Security Elements
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Solution Overview
Problem
Existing security elements for documents of value, such as banknotes and passports, face challenges in maintaining distinguishability under infrared illumination due to abrasion and dirt accumulation, which complicates authentication and increases the risk of counterfeiting.
Innovation Solution
The use of IR-transparent and IR-absorbing printing inks with distinct reflectance values, applied to a plastic film substrate, provides enhanced security features by ensuring a minimum 20% reflectance difference even after abrasion and dirt accumulation, combined with additional features like fluorescence and metallization, to create hidden security layers that can be verified using IR cameras.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional printing inks are used on security elements, then the security element can be manufactured with standard materials and processes, but the distinguishability under infrared illumination deteriorates due to abrasion and dirt accumulation
Solution Approach 1:
The patent applies different ink formulations to different functional areas of the security element. IR-transparent inks are used for machine-readable codes and security features that require high distinguishability under infrared illumination, while IR-absorbing inks are used for visible text and patterns. This local differentiation ensures that critical security features maintain their infrared contrast even when subjected to abrasion and dirt accumulation.
Solution Approach 2:
The patent uses composite ink formulations combining IR-transparent and IR-absorbing materials with different reflectance properties. The IR-transparent inks contain pigments or dyes that allow infrared radiation to pass through or reflect, while IR-absorbing inks contain materials that absorb infrared radiation. This composite approach creates security features with enhanced durability and distinguishability under infrared illumination despite environmental degradation.
2Reliability
If multiple printing inks with different IR properties are applied to increase security features, then the protection against counterfeiting is enhanced, but the device complexity increases
Solution Approach 1:
The patent divides the security element into distinct zones or layers, each printed with specific ink formulations. Machine-readable codes and critical security features are printed with IR-transparent inks, while visible text and decorative elements use IR-absorbing inks. This segmentation allows for targeted application of different ink types, enhancing counterfeit protection while managing printing process complexity through organized production workflows.
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 solution significantly enhances the authenticity verification of documents by maintaining visible contrast under infrared illumination, reducing counterfeiting risks through multi-layered security features that remain effective throughout the document's lifespan.
Implementation Method 1
the at least one IR-transparent printing ink has a first reflectance value of > 90%
Implementation Method 2
the at least one IR-absorbing printing ink has a second reflectance value of < 50% in the infrared wavelength range
Implementation Method 3
the security element according to the invention can also have other printing features, such as fluorescence (full-surface, striped, single-color, multi-color)
Data Source
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AI summary
The invention relates to a security element for application to a surface of a valuable document or at least partial embedding into a substrate of the valuable document, for example a banknote or a passport, wherein the security element consists of a plastics film. According to the invention, at least one printing ink which is transparent in the infrared wavelength range of electromagnetic radiation (referred to hereinafter as IR-transparent printing ink) and has a first reflectance value and at least one printing ink which is absorbent in the infrared wavelength range of electromagnetic radiation (referred to hereinafter as IR-absorbing printing ink) and has a second reflectance value are applied to the plastics film of the security element, the separation between the first and second reflectance values being at least 40%.