Infrared Dye Wavelength Shift for Laser Marking
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Solution Overview
Problem
Current infrared dyes used in laser markable security documents face challenges with absorption in the visual spectrum, limiting the achievable colour gamut and causing background coloration, and there is a lack of dyes with absorption maxima above 1100 nm that have minimal visual spectrum absorption.
Innovation Solution
Development of an infrared dye with a chemical structure that has minor absorption in the visual spectrum and a maximum absorption above 1130 nm, allowing for greater spacing of absorption peaks and reduced background coloration, enabling high colour gamut and multicolour imaging without contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If infrared dyes with absorption maxima below 830 nm are used, then laser marking sensitivity is improved, but background coloration increases due to absorption in the visual spectrum
Solution Approach 1:
The patent applies parameter changes by shifting the absorption maximum wavelength parameter of the infrared dye from below 830 nm to above 1100 nm. This wavelength shift fundamentally changes the dye's interaction with light, allowing it to absorb infrared radiation effectively while remaining transparent to visible light, thus eliminating background coloration while maintaining laser marking sensitivity.
Solution Approach 2:
The invention transitions from using dyes that operate in the near-infrared region (700-830 nm) to dyes operating in the short-wavelength infrared region (above 1100 nm). This dimensional shift in the electromagnetic spectrum allows separation of the infrared absorption function from the visible spectrum, enabling independent optimization of laser sensitivity without visual interference.
2Quantity of substance
If infrared dyes with absorption maxima closer together are used, then material efficiency is improved, but colour gamut decreases due to spectral overlap
Solution Approach 1:
The patent applies segmentation by dividing the infrared spectrum into distinct, non-overlapping regions for different dyes. By using dyes with absorption maxima above 1100 nm and spaced at least 60 nm apart, each dye can be independently activated by specific laser wavelengths, enabling precise control over which color layer is activated and achieving full color gamut without spectral contamination.
Solution Approach 2:
The invention changes the wavelength parameter spacing between multiple infrared dyes from potentially overlapping values to values that are at least 60 nm apart, with all absorption maxima above 1100 nm. This parameter optimization allows each dye to respond to distinct laser wavelengths, enabling independent control of multiple color layers and achieving high color gamut in laser-marked images.
3Object-generated harmful factors
If dyes with absorption maxima above 1100 nm are used, then background coloration is reduced, but availability of suitable dyes decreases
Solution Approach 1:
The patent employs composite materials by combining specific infrared dyes (CI 1100-1150) with leuco dyes and acid generators in a layered structure. This composite approach allows the infrared dye to provide the optical filtering function (reducing background coloration) while the leuco dye provides the color development function upon laser activation, creating a synergistic system that overcomes the limited availability of single-component dyes with all required properties.
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 new infrared dye achieves a high colour gamut with minimal background coloration, enabling the creation of multicolour laser markable articles with improved imaging quality and security features in documents.
Implementation Method 1
an infrared dye which absorbs the IR radiation and converts it into heat
Data Source
Figure 1~2
AI summary
Infrared dyes having an infrared absorption maximum above 1130 nm are disclosed which have minor colouration in the visual spectrum. The infrared dyes are especially useful for producing multicolour laser marked security documents having reduced background coloration and enhanced colour gamut.