Tactile Security Features Using Radiation-Cured Coatings
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Solution Overview
Problem
Existing methods for creating security documents with tactile features face challenges such as reduced color strength and poor scratch resistance, limiting their effectiveness in preventing counterfeiting and illegal reproduction.
Innovation Solution
A process involving a radiation-cured basecoat and topcoat with machine-readable substances, such as cholesteric liquid crystal pigments, luminescent compounds, and infrared-absorbing compounds, applied using methods like rotogravure, screen printing, and flexo printing, to create a tactilely and machine-readable security feature with enhanced forgery-proofness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If inkjet printing is used to create tactile features, then the tactile effect is achieved, but color strength is reduced
Solution Approach 1:
The patent divides the printing process into two separate stages: first applying a radiation-curable adhesive layer that forms the tactile relief structure, then separately applying color ink on top. This segmentation allows each layer to perform its specific function optimally without compromising the other, resolving the contradiction between tactile effect and color strength.
Solution Approach 2:
The patent introduces a vertical layering dimension by building the tactile feature in the Z-direction (thickness) through the radiation-curable adhesive, while the color information resides in a separate superficial layer. This dimensional separation allows both tactile prominence and color saturation to coexist without interference.
2Strength
If screen printing or inkjet printing is used for tactile features, then tactile effect is achieved, but scratch resistance is poor
Solution Approach 1:
The patent performs the preliminary action of applying and curing the radiation-curable adhesive layer to form the tactile relief structure before applying the color ink. This preliminary formation of a durable base structure ensures that the tactile feature is established with inherent scratch resistance, and the subsequent ink application does not compromise this resistance.
Solution Approach 2:
The patent creates a composite structure consisting of a radiation-curable adhesive base layer providing mechanical strength and scratch resistance, combined with a color ink layer providing visual information. This composite material approach allows the tactile feature to maintain durability while incorporating color elements.
3Reliability
If intaglio printing is used to create tactile features, then relief features are achieved, but the process complexity increases
Solution Approach 1:
The patent replaces the complex mechanical intaglio printing system with a simpler radiation-curable adhesive application process followed by UV curing. This substitution maintains the tactile relief effect while significantly reducing equipment complexity and process steps, as the adhesive self-cures upon radiation exposure without requiring complex mechanical pressing systems.
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 combination of tactile and machine-readable features significantly improves the security of documents by attracting attention to verification, enhancing authenticity checks, and providing robust resistance against counterfeiting and reproduction.
Implementation Method 1
a radiation-curable basecoat composition and a radiation-curable topcoat composition are applied in sequence to a substrate and are radiation-cured
Implementation Method 2
machine-readable substances, such as cholesteric liquid crystal pigments
Implementation Method 3
luminescent compounds
Implementation Method 4
infrared-absorbing compounds
Data Source
AI summary
A process for manufacturing a security feature having a tactile pattern, said method including applying on a substrate a radiation-curable basecoat composition by a process selected from inkjet, offset, screen printing, flexo printing and rotogravure; at least partially or fully radiation-curing the radiation-curable basecoat composition so as to obtain a radiation-cured basecoat; applying on the radiation-cured basecoat a radiation-curable topcoat composition in a form of indicia by a process of screen printing, flexo printing or rotogravure; radiation-curing said radiation-curable topcoat composition so as to form a radiation-cured topcoat. The radiation-curable basecoat composition and/or the radiation-curable topcoat composition includes one or more machine readable feature substances independently selected from cholesteric liquid crystal pigments, luminescent compounds, infrared-absorbing compounds, magnetic compounds and mixtures thereof. The radiation-cured basecoat has a surface energy at least 15 mN/m less than the surface energy of the radiation-cured topcoat.