Infrared Security Inks Using Metal Compounds
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Solution Overview
Problem
Current security images in banknotes and other articles rely on carbon black for infrared reflectance, which can be detected by counterfeiters, and existing organic infrared-absorbing compounds are expensive, difficult to synthesize, and have poor light fastness.
Innovation Solution
A composition using metal, metal salts, metal oxides, or metal nitrides as infrared-absorbing materials, such as reduced indium tin oxide, titanium nitride, and neodymium oxide, which absorb radiation in the 800-900 nm range without producing a strongly colored image, providing a secure and durable security feature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon black is used as the infrared-absorbing material to achieve less than 50% radiation reflectance at 800-900 nm, then the security image can be detected by third party verifiers, but the image becomes dull grey and easily detected by counterfeiters
Solution Approach 1:
The patent replaces carbon black with metal compounds (such as iron oxide, copper chromate, zinc oxide) that provide similar infrared absorption properties but with different visual characteristics. These metal compounds maintain the required security feature detectability while avoiding the dull grey appearance that alerts counterfeiters to the presence of carbon black.
Solution Approach 2:
The patent changes the chemical composition parameter of the infrared-absorbing material from carbon black to metal compounds. This parameter change maintains the infrared absorption characteristic (less than 50% reflectance at 800-900 nm) while altering the visible appearance to be less obvious to counterfeiters, thus resolving the contradiction between security detectability and counterfeiting detection.
2Reliability
If complex organic infrared-absorbing compounds are used to achieve infrared absorption, then the security image can be detected, but the compounds are expensive and difficult to synthesize
Solution Approach 1:
The patent substitutes complex organic infrared-absorbing compounds with simpler metal compounds (such as metal oxides, sulfates, chromates) that are cheaper to produce and easier to synthesize. These metal compounds provide the necessary infrared absorption properties without the high synthesis costs and complexity associated with organic compounds.
Solution Approach 2:
The patent extracts the essential function of infrared absorption from complex organic compounds and achieves it through simpler metal compounds. By taking out the complex organic structure and replacing it with metal-based materials, the patent maintains the functional requirement (infrared absorption for security detection) while dramatically simplifying the manufacturing process.
3Reliability
If complex organic infrared-absorbing compounds are used to provide infrared absorption, then the security feature can be detected, but the compounds have poor light fastness
Solution Approach 1:
The patent replaces complex organic infrared-absorbing compounds with metal compounds (such as iron oxide, copper chromate, zinc oxide) that exhibit superior light fastness properties. These metal compounds are more stable under prolonged light exposure and maintain their infrared absorption characteristics without the degradation associated with organic compounds.
Solution Approach 2:
The patent employs metal compounds as composite infrared-absorbing materials that combine the necessary infrared absorption properties with enhanced stability. These metal-based composite materials provide both the functional requirement (infrared absorption) and the stability requirement (light fastness) that complex organic compounds cannot simultaneously achieve.
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 use of these materials offers a secure and cost-effective solution for creating invisible or pale-colored security images that are detectable only under infrared radiation, enhancing the authenticity verification of banknotes and other articles while resisting degradation over time.
Implementation Method 1
the infrared-absorbing material absorbs radiation in the 800-900 nm range
Implementation Method 2
with the required radiation reflectance characteristics at 800-900 nm
Data Source
AI summary
Composition including an oleophilic base ink composition having dispersed therein particles of an infrared-absorbing material wherein the infrared-absorbing material is selected from reduced indium tin oxide, titanium nitride, zirconium nitride, molybdenum metal, copper chromate, lanthanum hexaboride, neodymium oxide, neodymium chloride, dysprosium oxide and praseodymium oxide.