IR-Sensitive Lithographic Printing Plate Precursor with Borate Ions
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Solution Overview
Problem
Existing on-press developable lithographic printing plate precursors face challenges in achieving strong and stable printout images using lower exposure energy, while maintaining fast imaging speed, good on-press developability, and lithographic printing durability.
Innovation Solution
A lithographic printing plate precursor comprising a substrate with an infrared radiation-sensitive image-recording layer, which includes a free radical initiator composition with an electron-donating agent and iodonium cations, a free radically polymerizable composition, and a color-changing compound represented by Structure (I), along with borate anions, to produce a strong and stable printout image upon exposure to infrared radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional acid generators and acid-sensitive color precursors are used in infrared radiation imaging compositions, then on-press development is enabled, but the printout image is not strong enough and fades after imaging due to limited acid generation efficiency and chemical equilibration
Solution Approach 1:
The patent changes the chemical parameters of the imaging composition by replacing conventional acid generators with infrared-absorbing compounds that undergo photochemical decomposition to generate free radicals. This parameter change enables strong printout formation with lower exposure energy while maintaining on-press development capability through the free radical-mediated color development mechanism
Solution Approach 2:
The patent substitutes the acid-generation mechanism with a free radical generation mechanism. Instead of relying on acid-sensitive color precursors that require protonation, the invention uses free radical initiators that decompose upon infrared exposure to generate free radicals, which then mediate color formation through a different chemical pathway, eliminating the fading issue associated with acid equilibration
2Reliability
If higher exposure energy is used to strengthen printout, then color contrast between exposed and unexposed regions improves, but imaging speed decreases and processing time increases
Solution Approach 1:
The patent optimizes the exposure energy parameter by introducing infrared-absorbing compounds with high molar extinction coefficients in the infrared region. These compounds enable efficient energy absorption at lower exposure levels, generating sufficient free radicals for strong printout formation without requiring high exposure energy that would slow down the imaging process
Solution Approach 2:
The patent accelerates the color development process by using free radical mechanisms that proceed rapidly after infrared exposure. The free radicals generated immediately upon exposure quickly mediate color formation, allowing the process to rush through the development stage without requiring prolonged exposure or multiple processing steps, thereby maintaining high imaging speed
3Use of energy by moving object
If infrared-absorbing compounds are introduced to enable lower exposure energy imaging, then printout formation improves, but the complexity of the imaging composition increases
Solution Approach 1:
The patent achieves multi-functionality by selecting infrared-absorbing compounds that simultaneously serve as both the infrared sensitizer and the free radical initiator. These compounds absorb infrared radiation and directly decompose to generate free radicals, eliminating the need for separate acid generators and color precursors, thus reducing overall composition complexity while maintaining low exposure energy requirements
Solution Approach 2:
The patent creates a composite imaging composition that integrates the infrared-absorbing compound with the polymerizable composition and color developer in a unified system. This composite approach allows the different components to work synergistically, where the infrared-absorbing compound provides both energy absorption and radical generation functions, simplifying the overall system architecture despite the multiple functional requirements
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 and stable printout image with improved durability and shelf life, while maintaining fast imaging speed and good on-press developability, even at lower exposure energies.
Implementation Method 1
a free radical initiator composition that is capable of generating free radicals upon exposure to infrared radiation, and which comprises an electron-donating agent and one or more iodonium cations
Implementation Method 2
a free radically polymerizable composition
Implementation Method 3
the infrared radiation-sensitive image-recording layer is capable of producing a colored compound when exposed to infrared radiation
Data Source
AI summary
IR-sensitive lithographic printing plate precursors provide a stable print-out image using an IR-sensitive image-recording layer that includes: (1) a free radical initiator composition with an electron-donating agent and one or more iodonium cations; (2) a free radically polymerizable composition; and (3) a color-changing compound of Structure (I) having an indene ring in the conjugated chain between aromatic terminal groups. The IR-sensitive image-recording layer contains one or more borate ions. After IR imaging, these precursors exhibit desirable printout images both fresh and after dark storage. The precursors can be developed on-press. The infrared radiation-sensitive image-recording layer can produce a colored compound that when exposed to infrared radiation, satisfies the equation FW3>FW1 wherein FW1 is the formula weight in Daltons of the (3) color-changing compound, absent Za, and FW3 is the formula weight in Daltons of the produced colored compound, absent Za.