Transparent Ink-Accepting Layer for Security Elements
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Solution Overview
Problem
Existing security elements for documents of value, such as banknotes and passports, face challenges with ink acceptance layers that are opaque or cause clouding, impairing the visual perceptibility and machine detectability of security features, while attempts to reduce opacity compromise ink adhesion and drying.
Innovation Solution
A transparent ink-accepting layer comprising fillers like boehmite or silica gel and a binder, applied above the security element, ensures good ink adhesion and drying without clouding, allowing for clear visibility through windows and maintaining the optically variable effects of optically variable security elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an opaque ink acceptance layer is used to ensure good ink adhesion and drying, then ink acceptance is improved, but the visual perceptibility and machine detectability of security elements are impaired due to clouding
Solution Approach 1:
The ink acceptance layer is divided into multiple sub-layers (first sub-layer directly on security element, second sub-layer above it). The first sub-layer provides adhesion to the security element surface, while the second sub-layer provides ink acceptance properties. This segmentation allows each layer to be optimized for its specific function without compromising the other, resolving the contradiction between ink acceptance and visual clarity.
Solution Approach 2:
Different regions of the ink acceptance layer have different properties: the first sub-layer has adhesive properties for bonding to the security element, while the second sub-layer has ink-receiving properties. This local differentiation of quality allows the layer to simultaneously provide both adhesion and ink acceptance without requiring opacity throughout the entire structure.
2Object-affected harmful factors
If the ink acceptance layer thickness is reduced or filler content is reduced to improve visual clarity, then perceptibility of security elements is improved, but ink adhesion and drying are compromised
Solution Approach 1:
The ink acceptance layer is segmented into multiple sub-layers with distinct functions. The first sub-layer (thin, directly on security element) provides adhesion without requiring significant thickness or filler content that would cause clouding. The second sub-layer provides ink acceptance properties. This segmentation allows visual clarity to be maintained while still achieving good ink adhesion through the adhesive first layer.
Solution Approach 2:
The first sub-layer is designed with adhesive properties specifically for bonding to the security element surface, while the second sub-layer is designed with ink-receiving properties. This local quality differentiation allows the thin first layer to provide adhesion without compromising visual clarity, while the second layer handles ink acceptance.
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 transparent ink-accepting layer enhances ink acceptance and adhesion while preserving the clarity and functionality of security elements, ensuring effective ink trapping and drying without impairing the visual or optical properties of the security features.
Implementation Method 1
a transparent ink-accepting layer comprising fillers like boehmite or silica gel and a binder
Implementation Method 2
ensures good ink adhesion and drying
Implementation Method 3
diffraction structures, which produce a viewing-angle-dependent visual impression
Implementation Method 4
single- or multi-layer thin-film interference layers
Data Source
Figure 1a~1b
Figure 2a~2f
Figure 3a~4
AI summary
The invention relates to a security element (2) for the production of valuable documents, comprising at least one transparent ink-accepting layer (5), which is arranged above a first surface of a substrate (1) over the entire area or in at least one sub-region. An opaque ink-accepting layer (9) is applied to a sub-region.