Lithographic Plate Precursor with Silane-Functional Particles for Clean-Out
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Solution Overview
Problem
Existing lithographic printing plates face challenges in achieving a balance between press durability and clean-out behavior, particularly under non-aggressive processing conditions, with contamination of fountain solutions being a significant concern during on-press processing.
Innovation Solution
A lithographic printing plate precursor containing a coating with discrete particles comprising silane groups, silanol groups, and/or siloxane reaction products, which enhances clean-out behavior and resistance of imaged areas during on-press processing by facilitating removal of non-image areas with dampening liquid and/or ink.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithographic printing plates are used with hydrophobic coating on hydrophilic support, then the ink-accepting areas are well-defined, but the clean-out behavior is insufficient and fountain solution contamination occurs during on-press processing
Solution Approach 1:
The patent applies local quality by creating distinct surface properties in different areas of the printing plate. The coating contains particles with specific surface treatments that provide different wettability characteristics: hydrophilic particles in non-image areas facilitate clean-out by dampening liquid, while hydrophobic particles in image areas maintain ink acceptance. This spatial differentiation of surface properties resolves the contradiction between clean-out behavior and fountain solution contamination.
Solution Approach 2:
The patent employs composite materials by formulating a coating that combines multiple particle types with different surface properties. The coating comprises a mixture of hydrophilic particles (such as silica, alumina, or titania) and hydrophobic particles (such as organic polymer particles), creating a composite structure that simultaneously provides good clean-out behavior in non-image areas and maintains ink-accepting properties in image areas, thereby preventing fountain solution contamination while ensuring reliable printing performance.
2Reliability
If aggressive processing conditions are used to improve clean-out behavior, then non-image areas are completely removed, but press durability of imaged areas deteriorates
Solution Approach 1:
The patent uses local quality to differentiate the properties of particles in different regions. Hydrophilic particles are strategically positioned or activated in non-image areas to enhance clean-out behavior with mild processing, while hydrophobic particles are maintained in image areas to preserve press durability. This localized property distribution allows gentle processing conditions that protect imaged areas while ensuring complete removal of non-image areas.
Solution Approach 2:
The patent applies parameter changes by modifying the surface treatment of particles within the coating to alter their wettability characteristics. By controlling the surface chemistry of particles (e.g., through silane treatment or polymer coating), the coating achieves optimal clean-out behavior under non-aggressive processing conditions while maintaining the structural integrity and press durability of the imaged areas. The particle surface parameters are tuned to respond differently to dampening liquid versus printing ink.
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 improved clean-out performance and press durability by ensuring complete removal of non-image areas, reducing fountain solution contamination and maintaining ink-water balance, thereby preventing printing defects like image blinding or scumming.
Implementation Method 1
Photopolymer printing plates rely on a working-mechanism whereby the coating - which typically includes free radically polymerisable compounds - hardens upon exposure. 'Hardens' means that the coating becomes insoluble or non-dispersible in the developing solution and may be achieved through polymerization and/or crosslinking of the photosensitive coating upon exposure to light and/or heat.
Implementation Method 2
discrete particles comprising a plurality of silane groups, and/or silanol groups and/or siloxane reaction products of said silane and/or silanol groups
Implementation Method 3
discrete particles comprising a plurality of silane groups, and/or silanol groups and/or siloxane reaction products of said silane and/or silanol groups
Data Source
AI summary
A lithographic printing plate precursor including a support and a coating comprising a photopolymerizable layer including a polymerisable compound, optionally a sensitizer, a photoinitiator and discrete particles which comprise a plurality of silane groups, and/or silanol groups and/or siloxane reaction products of said silane and/or silanol groups.