Lithographic Printing Plate Precursor White Light Stability
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Solution Overview
Problem
Existing on-press developable lithographic printing plate precursors suffer from low contrast and reduced readability of printout images due to increased sensitivity to white light, which affects the stability of the printout image over time.
Innovation Solution
The use of a lithographic printing plate precursor comprising an aluminum-containing substrate and an infrared radiation-sensitive image-recording layer, which includes free radically polymerizable components, infrared radiation absorbers, an initiator composition, color-forming compounds, and compounds represented by Structure (P), achieving a high contrast printout image with stability under white light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acid-sensitive leuco dyes are used to generate printout in on-press developable precursors, then color difference between exposed and non-exposed regions is achieved, but the contrast is much lower than wet processed plates and printout stability under white light is poor
Solution Approach 1:
The patent changes the chemical parameters of the color-forming system by introducing specific compounds (Formula 1 with sultone or vinyl sultone groups, Formula 2 with carbonyl groups, and Formula 3 with heterocyclic rings) that have different reactivity and stability characteristics compared to conventional leuco dyes, achieving both high contrast and white light stability
Solution Approach 2:
The patent creates a composite chromogenic system combining multiple components: the specific compound of Formula 1, color-forming compounds of Formula 2, and compounds of Formula 3, where each component contributes different properties (contrast, stability, color intensity) to achieve overall superior performance
2Manufacturing precision
If more sensitive color forming compositions are used to improve printout, then color difference between exposed and non-exposed regions increases, but sensitivity to white light increases causing increased color formation in non-image areas
Solution Approach 1:
The patent introduces compounds with specific local chemical structures (Formula 1 with sultone/vinyl sultone groups at specific positions, Formula 2 with carbonyl groups, Formula 3 with heterocyclic rings) that create localized reactive sites only activated by infrared radiation, preventing unwanted activation by white light while maintaining high contrast in exposed regions
Solution Approach 2:
The patent converts the potential harm of white light exposure by designing a system where white light actually helps complete the development process in exposed regions through the action of compounds of Formula 3 on the intermediate products formed by infrared exposure, turning a harmful factor into a beneficial one
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 solution achieves a strong initial printout image with a color contrast of ΔE greater than 8 between exposed and non-exposed regions, and maintains a ΔE of at least 5 after storage under white light for one hour, enhancing readability and stability.
Implementation Method 1
one or more infrared radiation absorbers
Implementation Method 2
one or more free radically polymerizable components; an initiator composition
Implementation Method 3
one or more color-forming compounds; a strong printout image with a color contrast of ΔE greater than 8 between exposed and non-exposed regions
Data Source
AI summary
IR-sensitive lithographic printing plate precursors provide a high contrast and stable printout image using an IR radi ati on- sensitive composition. This composition includes: a free radically polymerizable component, an IR absorber, an initiator composition, color-forming compound(s) such as a specific leuco dye, and compound(s) represented by the following Structure (P): wherein X is -0-, -S-, -NH-, or -CH2-, Y is >N- or >CH-, R1 is hydrogen or an alkyl, R2 and R3 are independently halo, thioalkyl, thiophenyl, alkoxy, phenoxy, alkyl, phenyl, thioacetyl, or acetyl, and m and n are independently 0 or an integer of 1 to 4. The printout image exhibits a color contrast between the exposed and non-exposed regions of a ΔΕ greater than 8. A ΔΕ of at least 5 is maintained between the exposed and the non-exposed regions with exposure to white light for at least one hour. These precursors, when IR-exposed, can be developed on-press.