Latent-Reactive Adhesive Bonding for TPU/PC Security Documents
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Solution Overview
Problem
Existing methods for laminating security and/or valuable documents with electronic components and diffractive elements often result in premature damage to components due to thermal and mechanical overload, and risk delamination, especially when using polycarbonate films with components like chip modules and volume holograms, leading to potential counterfeiting and manipulation risks.
Innovation Solution
The use of latent-reactive adhesives between protective layers and polymer layers, formed from different base polymers, to create a secure and durable bond during lamination, reducing the risk of component damage and delamination, while allowing for a substance-to-substance connection that prevents easy separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If self-adhesive or elastic protective layers are applied on electronic components to avoid mechanical destruction during lamination, then component damage is reduced, but delamination risk increases due to water vapor and air diffusion through card edges
Solution Approach 1:
A protective layer made of thermoplastic polyurethane (TPU) is introduced as an intermediary between the PC card structure and the electronic component. This protective layer has different mechanical properties than PC, providing cushioning during lamination while its chemical structure enables strong substance-to-substance bonding with PC through latent-reactive adhesives, preventing both mechanical damage and delamination
Solution Approach 2:
The protective layer material (TPU) is selected with specific material parameters including lower glass transition temperature and different heat transfer coefficient compared to PC. These parameter changes allow the protective layer to be softer during lamination (reducing mechanical stress on chips) while maintaining structural integrity and bonding capability
2Strength
If PC films are pressed onto soft photopolymer of holograms during lamination, then bonding is achieved, but Bragg planes are shifted causing wavelength shifts and reduced 3D impression
Solution Approach 1:
The TPU protective layer is positioned beforehand between the PC film and the hologram photopolymer. This protective layer acts as a cushion that distributes and reduces the mechanical pressure during lamination, preventing direct contact between the hard PC film and soft photopolymer, thereby avoiding Bragg plane shifts while still enabling bonding through the latent-reactive adhesive system
3Reliability
If latent-reactive adhesives are used between protective layers and polymer layers, then substance-to-substance connection is achieved preventing delamination, but manufacturing complexity increases
Solution Approach 1:
The latent-reactive adhesive system utilizes phase transition or state change principles where the adhesive remains inactive during lamination and only activates under specific conditions (heat, moisture, or time) after lamination is complete. This allows the adhesive to perform its bonding function without interfering with the lamination process, achieving strong substance-to-substance connection while maintaining 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
This approach effectively protects electronic components and diffractive security elements during lamination, integrates protective layers safely within the document, and reduces the risk of delamination and counterfeiting, ensuring the integrity and functionality of the security and/or valuable documents.
Implementation Method 1
adhesive layers with a latent-reactive adhesive being arranged at least between the polymer layers and the protective layers
Implementation Method 2
protective layers being formed of a first base polymer, polymer layers being formed of a second base polymer being different from the first base polymer
Data Source
AI summary
A document (2) containing:electronic components (14) and/or diffractive security elements;at least one protective layer (4, 5) being arranged on one side or two protective layers (4, 5) being arranged on both sides of the electronic components (14) and/or of the diffractive security element, said protective layers being formed of a first base polymer,polymer layers (8, 9, 12, 13), being formed of a second base polymer being different from the first base polymer, into which the electronic components (14) and/or the diffractive security element with the protective layers (4, 5) are laminated; andadhesive layers with a latent-reactive adhesive (10, 11) being arranged at least between the polymer layers (8, 9, 12, 13) and the protective layers (4, 5), and wherein the core layer or protective layers are formed of a thermoplastic elastomer.