Thermosensitive Lithographic Plate Double Coating
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Solution Overview
Problem
Conventional positive thermosensitive lithographic printing plates face issues with ink adhesion and 'pull erosion' due to incomplete removal of the photosensitive layer, leading to reduced sensitivity and developing latitude, as well as compromised chemical resistance and resolving power.
Innovation Solution
A double-coated positive image thermosensitive lithographic plate material is developed, featuring a hydrophilic lower layer with an alkali-soluble copolymer resin and a top layer with novolac phenolic resins, utilizing near-infrared dyes for heat-induced solubility differences and a dissolution inhibitor to enhance solubility contrast between exposed and unexposed regions, along with a development accelerator to improve image formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer positive thermosensitive lithographic printing plate is used, then the structure is simple, but ink adhesion and pull erosion occur due to incomplete removal of the photosensitive layer
Solution Approach 1:
The printing plate is divided into two distinct layers: a base layer containing phenolic resin and a top layer containing alkali-soluble copolymer resin with dissolution inhibitor. This segmentation allows each layer to perform its specific function - the base layer provides structural stability and ink receptivity, while the top layer enables complete removal in exposed areas without causing pull erosion, thereby resolving the contradiction between structural simplicity and printing reliability.
Solution Approach 2:
The invention uses composite material composition with phenolic resin as the base and alkali-soluble copolymer resin with dissolution inhibitor as the top layer. This composite structure combines the advantages of both materials - phenolic resin provides good ink adhesion and chemical resistance, while the alkali-soluble copolymer enables complete removal in exposed areas, eliminating pull erosion and improving printing quality.
2Device complexity
If conventional photosensitive layer composition is used, then the formulation is simple, but sensitivity and developing latitude are reduced
Solution Approach 1:
The invention modifies the chemical composition parameters of the photosensitive layer by incorporating alkali-soluble copolymer resin with specific functional groups and controlled dissolution inhibitors. This parameter change in the formulation - specifically the inclusion of resins with different solubility characteristics and the controlled addition of dissolution inhibitors - significantly improves sensitivity and developing latitude while maintaining formulation simplicity through the use of commercially available polymer components.
3Manufacturing precision
If the photosensitive layer is completely removed in exposed regions, then sensitivity is improved, but chemical resistance and resolving power are compromised
Solution Approach 1:
The invention applies local quality by using dissolution inhibitors specifically in the top layer where complete removal is needed, while the base layer maintains phenolic resin for chemical resistance. This localized application of different material properties allows the exposed top layer to be completely removed for high sensitivity, while the unexposed areas and base layer maintain chemical resistance and resolving power, thus resolving the contradiction between sensitivity and chemical resistance.
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 achieves high sensitivity, excellent development latitude, and good chemical resistance, effectively preventing ink adhesion and 'pull erosion' while maintaining high resolving power and image quality.
Implementation Method 1
By beam irradiation of an infrared laser, absorbing dyes in the coating material which is coated to the aluminum substrate convert light energy into heat energy
Implementation Method 2
Under the influence of heat, transient phase change or decomposing occurs to coating component, so that the hydrogen bonds originally present between the components are damaged
Implementation Method 3
the dissolving ability of the coating components of the exposure regions in alkaline developing liquid is increased, so that the coating components are cleared by alkaline developing liquid
Data Source
AI summary
The present invention relates to a thermosensitive lithographic printing plate material, and more particularly to a thermosensitive lithographic printing plate material applying to computer-to-plate. A positive image thermosensitive lithographic plate material includes a hydrophilic layer. The hydrophilic layer is coated with a lower layer and a top layer in turn. The hydrophilic layer is sensitive to infrared radiation. The lower layer of the hydrophilic layer is consisting of alkali-soluble copolymers, near infrared absorbing dyes, dissolution inhibitors, development accelerators and background coloring dye. The positive image thermosensitive lithographic plate material containing the above alkali-soluble resin have a high sensitivity, good developing latitude, good chemical resistance and good resolving ability.