Transparent Ink-Receptive Layer for Banknote Security Elements
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Solution Overview
Problem
Existing substrates for documents of value suffer from unsatisfactory ink acceptance and adhesion due to opaque ink acceptance layers, which impair the visual and machine detectability of security elements, especially when overprinted with additional imprints, and fail to maintain clarity in optically variable security elements.
Innovation Solution
A substrate with a thin, free-radically curing ink-receptive layer based on unsaturated urethane acrylates, which can be post-crosslinked by high-energy radiation, ensuring good ink acceptance and adhesion without clouding, and is suitable for high-energy radiation-curable printing inks, allowing for reduced layer thickness and improved transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an opaque ink acceptance layer is used to ensure good ink acceptance and adhesion, then ink adhesion is improved, but the visual and machine detectability of security elements is impaired
Solution Approach 1:
The patent applies parameter changes by transitioning the ink acceptance layer from opaque to transparent through chemical composition modification. The layer is formulated with specific transparent polymers and curing agents that allow it to maintain ink acceptance properties while becoming optically transparent, thus resolving the contradiction between adhesion and detectability.
Solution Approach 2:
The patent uses composite materials by creating an ink acceptance layer composed of multiple transparent components including polymers, curing agents, and transparent fillers. This composite structure enables the layer to simultaneously provide good ink acceptance, adhesion, and optical transparency for security element detectability.
2Quantity of substance
If the layer thickness of the ink acceptance layer is reduced to improve transparency, then visual perceptibility is improved, but ink acceptance and drying performance deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition and curing mechanism of the ink acceptance layer. The layer is formulated with high-reactivity curing agents and optimized polymer matrices that enable effective ink acceptance and curing even at reduced thicknesses, thus improving transparency without sacrificing manufacturing performance.
Solution Approach 2:
The patent replaces the traditional drying mechanism with a radiation-curing mechanism. Instead of relying on evaporation and drying processes that require sufficient layer thickness, the ink acceptance layer is designed to cure rapidly upon exposure to UV or electron beam radiation, enabling thin layer application while maintaining effective ink fixation.
3Ease of manufacture
If conventional drying processes are used for the ink acceptance layer, then processing is simplified, but the layer remains opaque and impairs security element visibility
Solution Approach 1:
The patent replaces conventional thermal drying processes with radiation curing using UV light or electron beams. This substitution transforms the curing mechanism from evaporation-based to photochemical or radiative crosslinking, enabling the ink acceptance layer to become transparent while maintaining processing efficiency and effectiveness.
Solution Approach 2:
The patent applies parameter changes by introducing radiation-curable chemical components into the ink acceptance layer formulation. The layer contains photoinitiators or radiation-sensitive groups that enable crosslinking upon radiation exposure, fundamentally changing the curing parameters from thermal to radiative, thus achieving transparency without compromising manufacturing simplicity.
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 provides excellent ink adhesion and transparency, maintaining the optically variable effects of security elements and enabling clear perception through see-through windows, while ensuring effective curing and processing of high-energy radiation-curable inks, thus enhancing the production and authenticity verification of documents of value.
Implementation Method 1
The ink-receptive layer (5) that can be post-crosslinked by the action of high-energy radiation is a free-radically curing ink-receptive layer or a cationically curing ink-receptive layer
Implementation Method 2
subjecting the substrate to high-energy radiation so that the printing ink is cured and the ink-receptive layer is post-crosslinked
Data Source
Figure 1a~1b
Figure 2a~2b
AI summary
The invention relates to a storable substrate (1) for producing documents of value, said substrate comprising an ink-receiving layer (5) which is crosslinkable subsequently by exposure to high-energy radiation. The invention further relates to a method for producing a document of value, said method comprising the following steps: providing a substrate (1) which comprises an ink-receiving layer (5); applying a printing ink curable by high-energy radiation to the ink-receiving layer (5); and subjecting the substrate (1) to high-energy radiation, to cure the printing ink. The method may preferably involve an ink-receiving layer which is crosslinkable subsequently by exposure to high-energy radiation.