Security Document Hologram Adhesion via UV Curing
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Solution Overview
Problem
Existing security documents face challenges in maintaining strong adhesive strength for hologram security elements, which can be easily detached due to heat exposure or require excessive pressure, leading to potential damage and reduced security against forgery.
Innovation Solution
A security document with a carrier coated by a flowable layer, an adhesive layer, and a metallic layer covered by a protective lacquer, where the metallic layer is applied using an inline processing system, allowing for direct integration of the hologram structure during production and enhanced protection against detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hot-melt adhesive connection is used to attach the hologram patch, then the security element can be easily applied, but the adhesive strength is reduced and the security feature can be removed or replaced by subsequent exposure to heat
Solution Approach 1:
The patent changes the adhesive parameter from heat-sensitive hot-melt adhesive to UV-curing adhesive, which transitions from a thermally reversible bond to a chemically permanent bond that cannot be removed by heat exposure, thereby resolving the contradiction between ease of application and adhesive strength
Solution Approach 2:
The patent replaces the mechanical/thermal bonding system (hot-melt adhesive) with a photochemical bonding system (UV-curing adhesive), where the adhesive is activated by UV radiation rather than heat, eliminating the vulnerability to thermal removal while maintaining ease of application through the same lamination process
2Reliability
If one- or two-component adhesive is used to attach the security element, then adequate attachment can be achieved, but excessive pressure must be exerted which may damage or alter the hologram structure
Solution Approach 1:
The patent changes the curing mechanism parameter from pressure-dependent (one- or two-component adhesive requiring mechanical compression) to light-dependent (UV-curing adhesive activated by UV radiation), allowing adequate adhesive strength to be achieved without exerting excessive pressure that could damage the hologram structure
Solution Approach 2:
The patent replaces the mechanical pressure system with a photochemical activation system, where UV radiation initiates the curing process instead of mechanical compression, thereby achieving strong adhesive bonding without harmful pressure effects on the hologram
3Ease of manufacture
If the security element is applied separately using adhesive, then the production process is simplified, but the positioning accuracy is reduced due to standard fluctuations in exact positioning
Solution Approach 1:
The patent merges the adhesive application and hologram positioning operations into a single integrated step by incorporating the adhesive layer directly onto the carrier film during the lamination process, eliminating separate positioning operations and achieving both production simplicity and high positioning accuracy simultaneously
Solution Approach 2:
The patent performs preliminary action by pre-applying the adhesive layer to the carrier film before the hologram patch is attached, allowing the hologram to be positioned and bonded in a single operation, thereby improving positioning accuracy while maintaining production process 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
This method ensures strong adhesion and reduced risk of detachment, improving the security feature's positioning accuracy and enhancing protection against forgery by integrating the hologram structure directly during production, thereby simplifying the process and reducing energy consumption.
Implementation Method 1
a flowable layer for smoothing the surface of the carrier
Implementation Method 2
a layer of adhesive which adheres to it carries a metallic layer
Implementation Method 3
there is a layer of adhesive which adheres to it carries a metallic layer
Implementation Method 4
the metallic layer is provided with a structure that forms the security element, wherein a lacquer layer is applied as a protective layer, which extends at least over the structure
Data Source
Figure 1~3
AI summary
The invention relates to a security document and to a method for the production of a security document of this type having at least one security element (12) which comprises a structure (21) and is applied from a substrate (14) at least in the flat extent of the security element (12), wherein an adhesive layer (18) is provided thereon at least in sections and a metallic layer (20) is provided which is applied thereto with a protective layer (23) which covers the metallic layer (20), wherein the structure (21) is introduced at least into the metallic layer (20), and said structure (21) forms the security element (12).