On-Press Lithographic Plate Composition for Temporal Stability
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Solution Overview
Problem
Existing on-press development type lithographic printing plate precursors suffer from unsatisfactory temporal stability, particularly in negative tone lithographic printing plate precursors, leading to issues like plate missing and streak-like unevenness during printing.
Innovation Solution
The lithographic printing plate precursor is designed with an image-recording layer containing an infrared absorber and an electron-accepting polymerization initiator where the difference in LUMO (lowest unoccupied molecular orbital) between the two is 0.45 eV or more, and an outermost layer with a discoloring compound, which inhibits polymerization initiation before exposure, enhancing temporal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an on-press development type lithographic printing plate precursor is used to simplify the plate making process, then the plate making complexity is reduced, but temporal stability deteriorates leading to plate missing and streak-like unevenness
Solution Approach 1:
The patent changes the energy level parameter by specifying that the LUMO level difference between the infrared absorber and electron-accepting polymerization initiator must be 0.45 eV or more. This parameter control ensures sufficient energy absorption for polymerization while preventing premature polymerization, thereby improving temporal stability without complicating the plate making process
Solution Approach 2:
The patent uses a composite system combining infrared absorber, electron-accepting polymerization initiator, and discoloring compound in specific layers. This composite material approach enables on-press development functionality while the discoloring compound in the outermost layer provides additional stability by preventing premature polymerization initiation
2Reliability
If the LUMO level difference between infrared absorber and polymerization initiator is increased to improve temporal stability, then polymerization initiation is better controlled, but the energy absorption efficiency may be affected
Solution Approach 1:
The patent optimizes the LUMO level difference parameter to be 0.45 eV or more, which is the minimum threshold required to ensure both temporal stability and sufficient energy absorption. This parameter setting balances the conflicting requirements by providing just enough energy gap to prevent premature polymerization while maintaining adequate energy absorption for effective polymerization upon exposure
3Reliability
If a discoloring compound is added to the outermost layer to prevent premature polymerization, then temporal stability is improved, but the plate structure becomes more complex
Solution Approach 1:
The patent segments the plate structure into distinct functional layers: the image-recording layer containing the infrared absorber and polymerization initiator, and the outermost layer containing the discoloring compound. This segmentation allows each layer to perform its specific function independently, improving temporal stability through the discoloring compound without significantly complicating the overall structure
Solution Approach 2:
The discoloring compound is localized specifically in the outermost layer, providing targeted protection against premature polymerization at the surface where it is most needed. This local application of the discoloring compound ensures temporal stability improvement without requiring the entire plate structure to be modified
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
This configuration results in improved temporal stability, reduced plate missing, and better GLV suitability, resulting in higher print durability and reduced streak-like unevenness, especially when using UV ink.
Implementation Method 1
the image-recording layer contains an infrared absorber and an electron-accepting polymerization initiator, LUMO of the electron-accepting polymerization initiator-LUMO of the infrared absorber is 0.45 eV or more
Implementation Method 2
the image-recording layer contains an infrared absorber and an electron-accepting polymerization initiator, LUMO of the electron-accepting polymerization initiator-LUMO of the infrared absorber is 0.45 eV or more
Implementation Method 3
a method of preparing a lithographic printing plate and a lithographic printing method in which the on-press development type lithographic printing plate precursor is used
Data Source
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AI summary
Provided is an on-press development type lithographic printing plate precursor having a support, an image-recording layer, and an outermost layer in this order, in which the image-recording layer contains an infrared absorber, an electron-accepting polymerization initiator, and a polymerizable compound, LUMO of the electron-accepting polymerization initiator - LUMO of the infrared absorber is 0.45 eV or more, and the outermost layer contains a discoloring compound. Also provided is a method of preparing a lithographic printing plate and a lithographic printing method in which the on-press development type lithographic printing plate precursor is used.