Security Element Adhesive Layering for Document Protection
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Solution Overview
Problem
Current security elements for documents of value, such as banknotes and passports, face challenges in providing durable and counterfeit-resistant integration with the carrier body, as existing adhesive methods can compromise the optical effects of security features and are prone to imitation.
Innovation Solution
A security element with a strip-shaped multi-layer body featuring a carrier film, decorative layer, and dual adhesive layers, where the first adhesive layer is on one surface and the second on the opposite surface, with specific surface structures and adhesive layer arrangements that enhance durability and prevent easy detachment, while maintaining optical effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a hot-melt adhesive layer is used to fix the security element to the carrier body, then the security element can be applied to the document, but the adhesive layer may compromise the optical effects of security features and is prone to imitation
Solution Approach 1:
The adhesive layer is segmented into multiple discrete adhesive points rather than a continuous layer. This segmentation prevents the adhesive from compromising the optical effects of security features while maintaining secure attachment. The discrete adhesive points are strategically positioned to avoid interfering with microlens arrays and other optical elements.
Solution Approach 2:
Different regions of the security element have different adhesive properties. The adhesive layer is applied selectively in specific areas where attachment is needed, while leaving other areas free to maintain their optical and tactile security features. This local differentiation ensures both secure fixation and preservation of security effects.
2Strength
If the adhesive layer is made thicker to ensure strong bonding, then the integration becomes more durable, but the optical effects of surface structures like microlenses are extinguished
Solution Approach 1:
The adhesive layer is divided into multiple thin discrete points rather than one thick continuous layer. Each adhesive point is thin enough to preserve optical effects in adjacent areas while collectively providing strong bonding through cumulative adhesion force across multiple attachment points.
Solution Approach 2:
The adhesive layer thickness varies locally across the security element. In areas where optical effects are critical, the adhesive is made extremely thin or absent. In areas where attachment is prioritized, the adhesive layer is thicker, creating a locally optimized structure that balances bonding strength and optical visibility.
3Ease of operation
If the security element is made easy to detach for handling, then the manufacturing and installation process is simplified, but the counterfeit security is reduced as the element can be removed and reused
Solution Approach 1:
The security element is pre-assembled with the adhesive layer already positioned and configured on the carrier body during manufacturing. This preliminary action ensures proper alignment and eliminates the need for complex field assembly, while the irreversible nature of the pre-applied adhesive prevents later removal and reuse.
Solution Approach 2:
The permanent, irreversible bonding characteristic is converted from a potential harm (difficulty of removal) into a benefit (counterfeit prevention). The very feature that makes the security element difficult to handle for repositioning is what ensures its security by preventing removal and reuse by counterfeiters.
4Strength
If dual adhesive layers are applied on both surfaces of the multi-layer body, then the integration into the document becomes extremely durable and strong, but the manufacturing process requires high precision to maintain optical imaging function
Solution Approach 1:
The dual adhesive layers are segmented into multiple discrete adhesive points on each surface rather than continuous layers. This segmentation reduces the cumulative tolerance requirements, as each discrete point can be positioned independently within a acceptable range, making the overall system more tolerant of manufacturing variations while maintaining strong bonding.
Solution Approach 2:
The adhesive layers have locally optimized properties and positions. Critical areas requiring high precision (such as regions with optical features) have adhesive points positioned and sized to maintain precise register, while less critical areas have more flexible adhesive configurations. This local differentiation allows the manufacturing process to achieve necessary precision only where required.
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 configuration achieves a strong and durable integration of the security element into the document, increases resistance to mechanical influences, and enhances counterfeit security by making the security feature more difficult to imitate, while maintaining the optical and tactile effects.
Implementation Method 1
the security element comprises a strip-shaped multi-layer body with a carrier film and at least one decorative layer and a first and a second adhesive layer, the first adhesive layer being provided on a first surface of the multi-layer body and the second adhesive layer being provided on an opposite second surface of the multi-layer body
Implementation Method 2
surface structures acting against air, such as microlens structures or microprism structures
Implementation Method 3
the optical effect of the microlenses
Data Source
Figure 1~2
Figure 3a~3b
Figure 4a~4b
AI summary
The invention relates to a security element (1) and a valuable document secured by such a security element. The security element (1) comprises a strip-shaped multilayer body (10) with a carrier film (11) and at least one decorative layer (12), as well as a first and a second adhesive layer (14, 15), wherein the first adhesive layer (14) is provided on a first surface of the multilayer body (10) and the second adhesive layer (15) is provided on an opposing second surface of the multilayer body, wherein a surface structure (97) with a plurality of structural elements in the first surface is molded in a replicating lacquer layer (91), and wherein at least in one region of the security element the first adhesive layer (95) is applied to the surface structure in a layer thickness of less than 50% of the structural depth of the structural elements of the surface structure (97).