Security Substrate With Composite IR-Particulate System
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Solution Overview
Problem
Current security substrates for secure documents, such as banknotes, face challenges in providing a unique infrared (IR) signature that is machine-readable in transmission while maintaining optical properties like whiteness and opacity, and often require the use of conventional fillers that can compromise security.
Innovation Solution
Incorporating a particulate system with metal oxides or metal oxide salts, such as TiO2 or SiO2, combined with doped tin oxide, which provides a unitary IR signature in the 700nm-1500nm spectral band, allowing for detection in transmission and potentially reducing the use of conventional fillers like titanium dioxide or kaolin, while offering electro-conductivity and avoiding interference with other security elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fillers like titanium dioxide or kaolin are used to maintain optical properties, then whiteness and opacity are preserved, but security is compromised due to lack of unique IR signature
Solution Approach 1:
The patent uses composite particles consisting of a core made of metal oxide or metal oxide salt (such as TiO2, SiO2, ZnO, ZrO2, CeO2, Al2O3, mica, or talc) coated with a shell of depleted metal oxide (such as SnO2, In2O3, Ga2O3, Bi2O3, Al2O3, or GeO2). This composite structure provides both the optical properties needed for paper substrates and the infrared absorption characteristics for security identification.
Solution Approach 2:
The invention applies different functional layers to different parts of the particle structure: the core provides optical properties (whiteness, opacity) while the depleted metal oxide shell provides infrared absorption. This local differentiation allows each part of the particle to contribute its specific function, resolving the contradiction between optical performance and security.
2Reliability
If IR-absorbing substances are incorporated to provide security signature, then security is improved, but optical properties like whiteness and opacity deteriorate
Solution Approach 1:
The patent uses composite particles consisting of a core made of metal oxide or metal oxide salt (such as TiO2, SiO2, ZnO, ZrO2, CeO2, Al2O3, mica, or talc) coated with a shell of depleted metal oxide (such as SnO2, In2O3, Ga2O3, Bi2O3, Al2O3, or GeO2). This composite structure provides both the optical properties needed for paper substrates and the infrared absorption characteristics for security identification.
Solution Approach 2:
The invention applies different functional layers to different parts of the particle structure: the core provides optical properties (whiteness, opacity) while the depleted metal oxide shell provides infrared absorption. This local differentiation allows each part of the particle to contribute its specific function, resolving the contradiction between optical performance and security.
3Illumination intensity
If conventional fillers are used extensively to maintain optical properties, then whiteness and opacity are preserved, but the substrate lacks electro-conductivity and unique security features
Solution Approach 1:
The patent uses composite particles consisting of a core made of metal oxide or metal oxide salt (such as TiO2, SiO2, ZnO, ZrO2, CeO2, Al2O3, mica, or talc) coated with a shell of depleted metal oxide (such as SnO2, In2O3, Ga2O3, Bi2O3, Al2O3, or GeO2). This composite structure provides both the optical properties needed for paper substrates and the infrared absorption characteristics for security identification.
Solution Approach 2:
The depleted metal oxide coating serves multiple functions simultaneously: it provides infrared absorption for security identification, contributes to electro-conductivity of the substrate, and maintains optical properties when combined with the appropriate core material. This multi-functionality resolves the contradiction between optical performance and security/electrical properties.
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 enables a secure, machine-readable IR signature that maintains the optical properties of the substrate, reduces the need for conventional fillers, and provides additional security features like electro-conductivity, enhancing the overall security and authenticity of documents.
Implementation Method 1
Incorporating a particulate system with metal oxides or metal oxide salts, such as TiO2 or SiO2, combined with doped tin oxide, which provides a unitary IR signature in the 700nm-1500nm spectral band, allowing for detection in transmission
Data Source
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Figure 3
AI summary
The present invention relates to a security substrate comprising, dispersed in the mass thereof, an IR-absorbing particulate system, comprising: a mixture of at least one filler consisting of at least one metal oxide or metal oxide salt and of at least one filler consisting of at least one poor metal in ionic, molecular or atomic form, and/or - at least one filler consisting of at least one metal oxide or metal oxide salt and of at least one poor metal in ionic, molecular or atomic form, said particulate system giving said substrate a specific response in transmission in the IR, preferably with an absorption peak in the IR, in particular between 700 and 1000 nm, better still with several absorption peaks in the IR, in particular between 700 and 1000 nm.