Multilayer Laser-Markable Sheet for Electronic Passport
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Solution Overview
Problem
Existing multilayer laser-markable sheets for electronic passports face issues with maintaining high contrast and preventing forgery, as they often suffer from deterioration in image clarity due to colorants and laser light absorbing agents, leading to problems with transparency and surface smoothness.
Innovation Solution
A multilayer laser-markable sheet comprising three sheets: a transparent polycarbonate resin sheet, a colored multilayer sheet with thermoplastic polyester resin skin layers and a core layer, and a thermoplastic polyester or polyurethane resin sheet, where the sheets are laminated with a specific thickness ratio and structure to enhance transparency, thermal adhesiveness, and wear resistance, and include a protruding portion for easy binding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If colorants and laser light absorbing agents are added to the multilayer sheet to enable laser marking, then laser-markability is improved, but transparency and image clarity deteriorate
Solution Approach 1:
The patent divides the multilayer sheet into distinct functional layers: a transparent outer layer maintaining image clarity, and an inner layer containing colorants and laser absorbing agents for laser marking capability. This segmentation allows each layer to perform its specific function without compromising the other, resolving the contradiction between laser-markability and image clarity.
Solution Approach 2:
The patent applies different material compositions to different regions/layers of the multilayer sheet. The outer layer uses transparent materials for clarity, while the inner layer uses materials with colorants and laser absorbing properties. This local differentiation allows the sheet to simultaneously achieve both transparency and laser-markability.
2Ease of manufacture
If laser light absorbing agents are placed in surface layers to enable laser marking, then laser-markability is improved, but surface smoothness deteriorates due to foaming
Solution Approach 1:
The patent segments the laser absorbing function from the surface layer and places it in an inner layer. This prevents the laser absorbing agents from causing foaming and surface roughness while still enabling laser marking through the transparent outer layer, thus maintaining both laser-markability and surface smoothness.
3Productivity
If the multilayer sheet structure is simplified to improve productivity, then manufacturing efficiency is improved, but thermal resistance and durability deteriorate
Solution Approach 1:
The patent uses composite materials with specific thermal properties in the multilayer structure. Each layer is designed with materials that contribute to both manufacturability and thermal resistance, creating a composite structure that achieves both productivity and reliability requirements.
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 solution provides excellent laser-markability, high contrast between the original surface color and printed portions, improved transparency, thermal resistance, and enhanced security against forgery, while allowing for clear and durable laser markings on electronic passports.
Implementation Method 1
capable of being marked thereon by laser beam irradiation
Implementation Method 2
including a thermoplastic polycarbonate resin and a laser light energy absorbing agent
Implementation Method 3
excellent thermal adhesiveness between these multilayer sheets
Data Source
Figure 1~2A
Figure 2B
Figure 3
AI summary
A multilayer laser-markable sheet for an electronic passport includes three sheets of a sheet A/a multilayer sheet B/a sheet C as a basic constitutional unit. The sheet A includes a transparent polycarbonate resin composition including a thermoplastic polycarbonate resin and a laser light energy absorbing agent, the multilayer sheet B includes a transparent thermoplastic resin including a thermoplastic polycarbonate resin, at least one layer of the skin layers and the core layer of the multilayer sheet B including at least one selected from a dye and a pigment. The sheet C includes a sheet or a laminate sheet. The multilayer laser-markable sheet for an electronic passport has excellent laser markability and high contrast, can achieve clear letters, symbols and images, and further has excellent thermal adhesiveness, transparency, sheet conveyance property, releasability from a die after thermal press, thermal resistance, foldability and wear resistance.