Security Thread Masking Structure Using Nanoscale Fillers
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Solution Overview
Problem
Existing security threads in secured documents are challenging to make less visible under reflected light without compromising their legibility under transmitted light, as current solutions either increase opacity or complicate the manufacturing process.
Innovation Solution
A security element with a masking structure comprising a mixture of at least two nanoscale fillers, preferably including colloidal silica and titanium dioxide, which scatters light to reduce visibility under reflection while maintaining transparency under transmitted light, allowing for luminescent properties and optimal masking without opacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a masking layer is applied to the security thread, then the visibility of the thread under reflected light is decreased, but the visibility of the text under transmitted light is also decreased
Solution Approach 1:
The patent changes the physical parameters of the masking layer by using nanoscale filler particles (1-100 nm) with specific refractive indices (1.4-1.6) dispersed in a binder. This nanoscale parameter change allows the masking layer to scatter visible light effectively while maintaining transmission of UV radiation, thus reducing reflected light visibility without compromising transmitted text legibility or UV luminescence properties
Solution Approach 2:
The patent creates a composite masking layer combining inorganic nanoscale fillers (such as silica, titanium dioxide, or zinc oxide) with an organic binder. This composite structure provides both the light-scattering properties needed for masking and the UV transparency required for luminescence, resolving the contradiction between masking effectiveness and information preservation
2Object-affected harmful factors
If a masking layer of increased thickness is applied, then the masking effect is improved, but the visibility of the text under transmitted light is further decreased
Solution Approach 1:
The patent utilizes the parameter of particle size at the nanoscale (1-100 nm) to achieve high light-scattering efficiency in a thin layer. The nanoscale dimensions provide a large surface area to volume ratio, maximizing light interaction per unit thickness. This allows effective masking with minimal layer thickness, preserving text visibility under transmitted light while maintaining UV transparency for luminescence
3Object-affected harmful factors
If a masking layer is applied to mask the security thread, then the metallic aspect is reduced, but the UV radiation is blocked, hampering luminescent properties
Solution Approach 1:
The patent changes the optical parameters of the masking layer by selecting nanoscale fillers with refractive indices (1.4-1.6) close to that of the binder, creating a composition that is transparent to UV radiation wavelengths (200-400 nm) while scattering visible light. This parameter selection allows the masking layer to reduce metallic appearance without blocking UV-induced luminescence
Solution Approach 2:
The patent applies local quality by making the masking layer selectively transparent to UV radiation while opaque to visible light in the reflected direction. The nanoscale filler composition creates different optical properties for different wavelength ranges, allowing UV transmission for luminescence activation and visible light scattering for masking, thus resolving the contradiction between aesthetic masking and functional luminescence
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 effectively reduces the visibility of security threads under reflected light without degrading their legibility under transmitted light, enabling the use of low optical density metal layers and preserving luminescent properties, thus enhancing document security without manufacturing complexities.
Implementation Method 1
A security element with a masking structure comprising a mixture of at least two nanoscale fillers, preferably including colloidal silica and titanium dioxide, which scatters light to reduce visibility under reflection while maintaining transparency under transmitted light
Data Source
AI summary
A security element, preferably a security wire, for a secure document, may include a masking structure for reducing the visibility of a surface of the element when the latter is located inside the document or on the surface thereof, the masking structure comprising a mixture of at least two nanometric fillers.