Latent Reactive Adhesive for Identification Document Lamination
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Solution Overview
Problem
The production of polycarbonate-based identification documents faces issues with the destruction of complex electronic components and diffractive structures during lamination due to mechanical stress, and existing adhesive systems are prone to delamination from environmental influences.
Innovation Solution
A multi-layer identification document with a thermoplastic layer, a storage-stable latent-reactive adhesive layer containing a di- or polyisocyanate with a melting temperature above 30°C, and a thermoplastic layer, where the adhesive layer is applied and dried before being joined to the substrate, allowing for delayed crosslinking and improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermoelastic/thermoplastic buffer layers are used to protect components during lamination, then mechanical stress is reduced, but the document security is compromised due to foreign material presence
Solution Approach 1:
The adhesive transitions from a chemically distinct foreign material state to a chemically integrated state through crosslinking. By changing the chemical parameters of the adhesive (from uncrosslinked to crosslinked state), the material becomes part of the document structure, eliminating the security issue while maintaining component protection.
Solution Approach 2:
The invention uses a composite adhesive system consisting of polyol and polyisocyanate components that form a crosslinked network. This composite material provides both the mechanical protection needed during lamination and the chemical integration required for security, resolving the contradiction between protection and security.
2Ease of manufacture
If self-adhesive films are applied to electronic components, then assembly is enabled, but delamination occurs due to water vapor and air diffusion
Solution Approach 1:
The invention replaces the mechanical adhesion mechanism of self-adhesive films with a chemical bonding mechanism. The crosslinked adhesive structure creates chemical bonds that are resistant to environmental factors like water vapor and air, eliminating delamination while maintaining ease of assembly.
Solution Approach 2:
The crosslinked adhesive structure creates a chemically inert environment that prevents diffusion of water vapor and air. The crosslinked network acts as a barrier that blocks environmental contaminants, providing long-term stability without compromising assembly capability.
3Productivity
If pressure is applied directly during lamination, then bonding is achieved, but chip destruction occurs due to mechanical stress
Solution Approach 1:
The uncrosslinked adhesive layer acts as a cushioning medium applied beforehand to the chip surface. During lamination, this soft adhesive layer absorbs and distributes mechanical stress, preventing direct pressure transmission to the chip while still enabling bonding. The layer is later crosslinked to provide permanent structural integrity.
4Ease of manufacture
If adhesive layers are used for embedding components, then assembly is enabled, but the adhesive becomes a weak point susceptible to environmental factors
Solution Approach 1:
The invention replaces the vulnerable mechanical adhesive layer with a chemically bonded crosslinked structure. The crosslinking reaction creates a three-dimensional network that is chemically resistant to environmental factors, eliminating the weak point status while maintaining the embedding function.
Solution Approach 2:
By changing the chemical state of the adhesive from uncrosslinked to crosslinked, the material transitions from being environmentally vulnerable to being chemically inert. This parameter change eliminates susceptibility to temperature fluctuations and moisture while preserving the component embedding capability.
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 solution enhances the security and durability of identification documents by preventing delamination and mechanical destruction, allowing for storage and transportation of the adhesive layer before final processing, and enabling bonding of temperature-sensitive substrates with low crosslinking temperatures.
Implementation Method 1
the adhesive comprises an aqueous dispersion containing a di- or polyisocyanate with a melting or softening temperature of > 30°C and an isocyanate-reactive polymer
Implementation Method 2
the isocyanate-reactive polymer is a polyurethane composed of crystallizing polymer chains which partially or completely decrystallize when measured by TMA at temperatures below +110°C
Implementation Method 3
allowing for delayed crosslinking and improved stability
Data Source
AI summary
The invention relates to an identification document which comprises layers A), B) and C), A) being a thermoplastic material, B) being a layer produced of a storage-stable, latent reactive adhesive, and C) being a thermoplastic material.