Aqueous Laser-Sensitive Coating Composition for High-Contrast Marking
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Solution Overview
Problem
Existing laser-sensitive compositions for marking substrates face challenges such as low sensitivity, poor image stability, background discoloration, smoke emission, lack of transparency, and potential toxicity, while maintaining high laser sensitivity and marking quality.
Innovation Solution
An aqueous coating composition comprising a colour former, developer, and binder with a specific weight ratio, where the binder includes an acrylate binder with acrylic acid and styrene, and additional monomers like α-methyl styrene, ethyl acrylate, and 2-ethylhexyl acrylate, with the colour former and developer in un-encapsulated form, enhancing sensitivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional laser-sensitive compositions are used, then laser marking can be achieved, but sensitivity is low and image stability is poor
Solution Approach 1:
The patent changes the chemical parameters of the laser-sensitive composition by using specific colour formers (e.g., fluoran derivatives) and developers (e.g., sulfonyl ureas) in controlled weight ratios, and by adjusting the glass transition temperature of the polymer matrix (120-190°C), thereby achieving both high laser sensitivity and good image stability
Solution Approach 2:
The patent creates a composite material system combining colour forming compounds, developers, and polymer matrices with specific properties (glass transition temperature range), where the synergistic interaction of components achieves enhanced sensitivity and stability simultaneously
2Manufacturing precision
If high laser sensitivity is achieved, then marking quality improves, but background discoloration and smoke emission increase
Solution Approach 1:
The patent converts the potentially harmful smoke emission into a beneficial effect by using char-forming compounds that undergo controlled thermal decomposition to form protective carbon layers, thereby reducing smoke while enhancing marking quality
Solution Approach 2:
The patent adjusts the composition parameters including the weight ratio of developer to colour former (1:0.1 to 1:5), the glass transition temperature of the polymer (120-190°C), and the presence of char-forming compounds to control the thermal decomposition behavior, thereby reducing smoke emission while maintaining high marking quality
3Reliability
If conventional compositions are used, then marking can be performed, but transparency is compromised
Solution Approach 1:
The patent changes the optical parameters of the composition by selecting specific colour formers and developers that form colored complexes with appropriate light absorption characteristics, and by controlling the polymer matrix properties, thereby achieving transparent markings that maintain reliability
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 composition achieves higher sensitivity and improved image stability with minimal background discoloration and smoke emission, allowing for high contrast, transparent markings without compromising transparency or safety.
Implementation Method 1
A possible laser-sensitive composition, for example, comprises a colour forming compound and a colour developer, which upon laser treatment react to form a coloured image
Implementation Method 2
The electron donor dye precursor is separated from said electron acceptor compound in the mark formation layer by either encapsulating the dye precursor within a polymer having a glass transition temperature of from about 120-190° C.
Implementation Method 3
laser marking as laser marking is cheaper in terms of overall economics and shows performance benefits such as high speed and contact free marking
Data Source
AI summary
Aqueous composition comprising a color former, a developer, and a binder, wherein (a) the weight ratio between the developer and the color former is in the range of from 1 to 5; (b) the binder comprises an acrylate binder, comprising acrylic acid and styrene, and at least one additional monomer selected from the group consisting of α-methyl styrene, ethyl acrylate and 2-ethylhexyl acrylate; and (c) the color former and/or the developer are present in an un-encapsulated form; a process for the preparation of these compositions, substrates coated with this composition and a process for its preparation, and a process for preparing a marked substrate using this composition.