Color-Forming Composition for Lithographic Printing Plate Stability
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Solution Overview
Problem
Current on-press developable lithographic printing plate precursors experience rapid fading of printout images, making it difficult for operators to visually identify and attach imaged printing plates to press units, as existing chemistry does not provide stable color differentiation between exposed and unexposed regions over time.
Innovation Solution
A color-forming composition comprising an acid generator, tetraaryl borate, acid-sensitive dye precursor, and a compound with a specific structure, incorporated into a radiation-sensitive imageable layer, which enhances the printout images by maintaining optical density difference between exposed and unexposed regions, preventing rapid fading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If spirolactone or spirolactam colorant precursors with ring-opening acid are used to provide printout images, then the printout images are initially strong and visible, but the printout images fade over time and become unreadable by press operators
Solution Approach 1:
The patent changes the chemical parameters of the color-forming system by replacing spirolactone/spirolactam precursors with a new composition comprising an acid generator, tetraaryl borate, acid-sensitive dye precursor, and compound of Structure (I). This parameter change in the chemical composition resolves the fading issue while maintaining strong initial printout visibility.
Solution Approach 2:
The patent employs a composite color-forming composition integrating multiple components (acid generator, tetraaryl borate, acid-sensitive dye precursor, and compound of Structure (I)) that work synergistically. This composite approach provides both strong initial printout and sustained stability over time, overcoming the limitations of single-component systems.
2Ease of manufacture
If on-press development is used to simplify lithographic printing plate making, then processing complexity and environmental impact are reduced, but printout image stability deteriorates
Solution Approach 1:
The patent modifies the chemical parameters of the imageable layer by incorporating the specific color-forming composition, which maintains printout stability even under on-press development conditions. This parameter change enables the use of simplified on-press processing without sacrificing printout image quality.
Solution Approach 2:
The patent makes the color-forming composition inherently stable within the imageable layer, allowing the plate to be used directly on-press without intermediate processing steps. The composition acts as a self-contained, stable element that eliminates the need for separate development and stabilization processes.
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 described composition significantly improves the stability and visibility of printout images, maintaining a higher optical density difference between exposed and unexposed regions, even after 24 hours, compared to traditional chemistry, ensuring better operational efficiency and accuracy in printing.
Implementation Method 1
an acid generator... (c) an acid-sensitive dye precursor
Implementation Method 2
a tetraaryl borate... (d) a compound having the following Structure (I)... maintaining optical density difference
Data Source
Figure 1~2
Figure 3
AI summary
A color-forming composition is useful to provide a printout image in an imaged lithographic printing plate precursor. This color-forming composition includes (a) an acid generator; (b) a tetraaryl borate; (c) an acid-sensitive dye precursor; and (d) a compound having the following Structure (I): wherein n is 1, 2, 3, or 4; R independently represents a monovalent substituent or the atoms necessary to form a fused ring if n is at least 2, and at least one R substituent is an electron-withdrawing group. The color-forming composition is included within a negative-working radiation-sensitive imageable layer along with a free radically polymerizable component and a radiation absorber such as an infrared radiation absorber.