Hydrophobic Toplayer for Lithographic Printing Plate Robustness
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Solution Overview
Problem
Prior art lithographic printing plates are susceptible to damage during automatic transport and mechanical/manual handling, leading to reduced printing quality due to surface damage and contamination.
Innovation Solution
A negative-working photopolymer printing plate precursor with a hydrophobic binder in the top layer, which enhances the robustness and clean-out behavior, and includes a leuco dye for high contrast print-out images, formed by exposure to low energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional toplayer with water-soluble or water-swellable polymers is used, then the toplayer acts as an oxygen barrier and is easily removable during processing, but the printing plate precursor is susceptible to damage during handling and transport
Solution Approach 1:
The patent changes the chemical composition parameter of the toplayer from water-soluble/swellable polymers to hydrophobic binder polymers. This parameter change fundamentally alters the toplayer's properties: it becomes resistant to water and mechanical damage while maintaining oxygen barrier functionality, thereby improving handling robustness without complicating the manufacturing process
Solution Approach 2:
The patent creates a composite toplayer structure by combining hydrophobic binder polymers with optional functional additives such as leuco dyes, infrared dyes, and photoinitiators. This composite approach allows the toplayer to simultaneously provide mechanical protection, oxygen barrier, and imaging functionality, resolving the contradiction between durability and functional performance
2Manufacturing precision
If exposure energy is increased to improve image formation, then polymerization is enhanced, but the risk of damage to the coating increases
Solution Approach 1:
The patent applies beforehand cushioning by incorporating a hydrophobic binder in the toplayer that provides mechanical protection to the underlying photopolymerizable coating. This protective layer absorbs and distributes mechanical stresses during handling and exposure, cushioning the coating against damage while allowing the exposure process to proceed with sufficient energy for complete polymerization
Solution Approach 2:
The patent implements preliminary action by forming a robust, damage-resistant toplayer structure before the exposure and development processes. This pre-formed protective layer ensures that subsequent handling and high-energy exposure do not compromise the coating integrity, allowing optimal imaging conditions to be achieved
3Measurement precision
If a leuco dye is added to the toplayer for high contrast print-out images, then image visibility is improved, but the toplayer composition becomes more complex
Solution Approach 1:
The patent applies universality by selecting a hydrophobic binder polymer that can simultaneously serve as the primary binder and as a compatible matrix for leuco dyes and other functional additives. This multi-functional approach allows the toplayer to provide mechanical protection, oxygen barrier, and high-contrast imaging capabilities without requiring separate layers or complex composite structures
Solution Approach 2:
The patent merges multiple functions into a single toplayer layer by combining the hydrophobic binder with leuco dyes, infrared dyes, and photoinitiators in the same matrix. This consolidation achieves high contrast print-out images and other functional benefits while simplifying the overall structure compared to using separate layers for each function
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 hydrophobic binder improves resistance to handling-induced damage and reduces toning on prints, while the leuco dye provides high contrast and stability to print-out images, ensuring better image quality and handling resistance.
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
The coating further includes a leuco dye which changes colour upon exposure to heat or light wherein the exposed areas of the coating define a print-out image
Data Source
AI summary
A lithographic printing plate precursor is disclosed including a support and a coating comprising (i) a photopolymerisable layer including a polymerisable compound and a photoinitiator, and a toplayer provided above the photopolymerisable layer; characterized in that the toplayer includes a hydrophobic binder.