Lithographic Printing Plate Precursor with Leuco Dye Toplayer
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Solution Overview
Problem
Current lithographic printing plates face challenges in achieving high contrast between image and non-image areas before processing, especially in direct on-press development, where existing solutions often require high exposure energies or high dye concentrations, leading to contamination risks and reduced image quality.
Innovation Solution
A negative-working photopolymer printing plate precursor with a coating comprising a leuco dye and a hydrophobic binder derived from a vinylidene monomer, which changes color upon UV light or IR exposure, allowing for high visual contrast at low energy levels, enabling efficient plate detection and registration without additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high dye concentrations are used to achieve high visual contrast, then image quality improves, but contamination risks increase
Solution Approach 1:
The patent changes the chemical parameters of the dye system by using a leuco dye that undergoes a chemical transformation upon exposure. Instead of relying on high concentrations of conventional dyes, the invention uses a low concentration of leuco dye that transforms into a highly contrasting colored form when exposed to UV or IR light, thereby achieving high visual contrast without the contamination risks associated with high dye concentrations
Solution Approach 2:
The patent applies color change principles by using a leuco dye that exists in a colorless or pale form before exposure and transforms into a intensely colored form after exposure to UV or IR light. This color transformation mechanism enables high visual contrast between exposed and unexposed areas without requiring high dye concentrations, thus avoiding contamination issues
2Productivity
If high exposure energies are used to achieve high visual contrast, then plate detection efficiency improves, but image quality deteriorates
Solution Approach 1:
The patent changes the energy absorption parameters by selecting a leuco dye with high absorption coefficient at specific wavelengths (UV or IR). This allows the system to achieve the same or better visual contrast effect at much lower exposure energies, thereby improving plate detection efficiency without compromising image quality
Solution Approach 2:
The patent applies partial action by using minimal exposure energy sufficient to trigger the leuco dye transformation. Since the leuco dye has high sensitivity and produces intense color change, only a small portion of the total energy spectrum (specific UV or IR wavelengths) is needed to achieve complete contrast, avoiding the excessive energy that would degrade image quality
3Measurement precision
If additional processing steps are added to improve plate detection, then detection accuracy improves, but process complexity increases
Solution Approach 1:
The patent applies preliminary action by incorporating the leuco dye color change mechanism directly into the exposure step. The visual contrast is generated during the imaging process itself, before any separate detection or processing steps. This eliminates the need for additional processing steps while maintaining high detection accuracy
Solution Approach 2:
The patent makes the exposure system multi-functional by using the leuco dye transformation to simultaneously achieve both the lithographic image formation and the visual contrast for plate detection. The same exposure step that creates the functional printing plate also generates the visual contrast, eliminating the need for separate detection mechanisms or processing steps
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 a high visual contrast of at least 2 CIE 1976 color difference ΔE at low exposure energies, facilitating efficient plate detection and registration, reducing the need for additional processing steps and minimizing contamination risks, while maintaining image quality and stability.
Implementation Method 1
A negative-working photopolymer printing plate precursor with a coating comprising a leuco dye and a hydrophobic binder derived from a vinylidene monomer, which changes color upon UV light or IR exposure
Implementation Method 2
changes color upon UV light or IR exposure, allowing for high visual contrast at low energy levels
Implementation Method 3
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.
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 an leuco dye and a hydrophobic binder.