Permanent PMMA Security Film for Transparent Tamper Evidence
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Solution Overview
Problem
Existing security films used in documents and labels lack high transparency, good printability, and sufficient weather and UV resistance, and often require structuring to prevent non-destructive removal, while also having undesirably long tear paths and complex manufacturing processes.
Innovation Solution
The use of polymethacrylate films, produced via extrusion, with specific compositions and thicknesses, and optionally containing UV stabilizers, to achieve high transparency, good printability, and enhanced weather and UV resistance, while minimizing tear resistance and simplifying manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If state-of-the-art security films are used, then security function is provided, but transparency and printability are poor
Solution Approach 1:
The patent changes the material composition parameters by using polymethyl methacrylate as the base polymer with specific acrylate copolymers (10-40 wt%), impact modifiers (5-20 wt%), and pigments (2-20 wt%). This composition optimization achieves both security function and high transparency, resolving the contradiction between security reliability and illumination intensity.
2Reliability
If security films are structured to prevent non-destructive removal, then security function is improved, but manufacturing complexity increases
Solution Approach 1:
The patent extracts the security function from structural complexity by using material composition (polymers, impact modifiers, and pigments) rather than physical structuring. The security labels achieve peel-resistance through the intrinsic properties of the film material itself, eliminating the need for additional structuring layers or complex manufacturing processes.
3Strength
If PVC films are used for security labels, then low tear resistance is achieved, but tear path is too long allowing careful removal
Solution Approach 1:
The patent uses a composite material system combining polymethyl methacrylate with specific acrylate copolymers and impact modifiers. This composite achieves optimal tear resistance where the material breaks quickly upon tearing without being too brittle, creating a tear path that is short enough to prevent careful removal but not so short that the label becomes brittle during handling.
4Reliability
If multiple layers are used for weather protection, scratch protection, and UV protection, then protection function is improved, but device complexity increases
Solution Approach 1:
The patent achieves multi-functionality within a single security label structure. The polymethyl methacrylate base material provides inherent UV resistance, while the acrylate copolymers and impact modifiers contribute to weather resistance, tear resistance, and flexibility. The integrated pigment system provides both coloration and additional UV protection, eliminating the need for separate protective layers.
5Ease of manufacture
If impact modifiers are increased to reduce brittleness, then processability is improved, but tear resistance decreases allowing careful removal
Solution Approach 1:
The patent optimizes the impact modifier content to a specific range (5-20 wt%) and selects specific types (acrylic ester polymers with particular glass transition temperatures). This parameter optimization ensures the material has sufficient flexibility for processing and application while maintaining adequate tear resistance to prevent careful removal, resolving the contradiction between processability and security function.
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 polymethacrylate films provide secure, easily processable, and durable security labels with short tear paths, improved weather resistance, and simplified production, ensuring high-quality print images without the need for structuring.
Implementation Method 1
optionally containing UV stabilizers, to achieve high transparency, good printability, and enhanced weather and UV resistance
Data Source
AI summary
The invention relates to permanent security films made from poly(meth)acrylate, in particular from a polymethylmethacrylate, which contains a maximum 10 wt.% or no impact-resistant modifiers. Said films have a high transparency, can be easily printed and are can be applied without predetermined breaking points. The permanent security films can be used, in particular, in documents, such as passports, in security labels, such as car-related stickers or for securing products from theft, or as a price label. Said security labels are characterized by having a good resistance to weather and in particular, a particularly good UV stability. The invention relates to, in particular, the use of said security labels which have a thickness of a maximum 2 mm, contain at least 80 wt.% polymethylmethacrylate and do not contain any impact-resistant modifying particles.