Lithographic Plate Precursor Absorber Mix for Stable Exposure Visibility
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Solution Overview
Problem
Existing on-press development type lithographic printing plate precursors face challenges in maintaining visibility of exposed portions over time and ensuring storage stability, particularly in negative tone lithographic printing plate precursors.
Innovation Solution
Incorporating two or more infrared absorbers with different maximum absorption wavelengths in the range of 760 nm to 900 nm, and using a combination of decomposition-type and non-decomposition-type infrared absorbers in the image-recording layer, which enhances the visibility and storage stability of the exposed portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single type of infrared absorber is used in the image-recording layer, then the structure is simple, but the temporal visibility and storage stability are insufficient
Solution Approach 1:
The patent employs a composite infrared absorber system comprising at least two different infrared absorbers with distinct maximum absorption wavelengths within the 760-900 nm range. This composite approach leverages the complementary absorption characteristics of each component to achieve superior temporal visibility and storage stability throughout the infrared region, resolving the contradiction between reliability improvement and structural complexity.
Solution Approach 2:
The infrared absorption function is segmented into multiple specialized components, each optimized for specific wavelength ranges. By dividing the absorption task among multiple infrared absorbers with different maximum wavelengths, the system achieves comprehensive coverage and enhanced stability without requiring a single complex material.
2Illumination intensity
If decomposition-type infrared absorbers are used, then color development is enhanced, but dark polymerization occurs reducing visibility over time
Solution Approach 1:
Non-decomposition-type infrared absorbers serve as intermediaries that absorb infrared energy without undergoing chemical decomposition. These stabilizing components mitigate the dark polymerization effect caused by decomposition-type absorbers, thereby maintaining temporal visibility while allowing color development to proceed through controlled mechanisms.
Solution Approach 2:
The patent converts the potentially harmful dark polymerization effect into a beneficial outcome by using non-decomposition-type infrared absorbers to suppress unwanted side reactions. The controlled decomposition of specific infrared absorbers is harnessed to generate necessary color development while the stabilizing components prevent excessive or uncontrolled polymerization.
Data Source
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Figure 3
AI summary
Provided is an on-press development type lithographic printing plate precursor having two or more maximal absorption wavelengths in a wavelength range of 760 nm to 900 nm, in which in a case where the on-press development type lithographic printing plate precursor is subjected to exposure to infrared having a wavelength of 830 nm at an energy density of 110 mJ/cm2, in a portion subjected to the exposure, a brightness change ΔL before the exposure and after storage subsequent to the exposure for 24 hours under conditions of 25°C and 70% RH is 3.0 or more. Also provided are 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.