Lithographic Printing Plate Precursor with Zwitterionic Copolymer
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Solution Overview
Problem
Current lithographic printing plate precursors face challenges in achieving both high printing durability and stain resistance, especially after storage, due to insufficient compatibility between hydrophilic and hydrophobic surfaces, and require additional wet treatments that are environmentally costly and inefficient.
Innovation Solution
A lithographic printing plate precursor is developed with a support coated by a photosensitive layer containing a copolymer with a zwitterionic structure and a structure capable of interacting with the support, allowing for direct plate making using digital data and aqueous developers with pH 11 or less, enhancing sensitivity and durability while reducing environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the support surface is made hydrophilic to enable development with neutral dampening water, then development is possible without strong alkali, but the image area is removed by dampening water during printing causing insufficient printing durability
Solution Approach 1:
The invention applies different surface properties to different areas: the non-image area has high hydrophilicity for easy development with neutral water, while the image area maintains appropriate adhesion to prevent removal during printing. This is achieved through photopolymerization that creates distinct chemical characteristics in exposed versus unexposed regions.
Solution Approach 2:
The photopolymerizable layer uses a composite system comprising polymerizable compounds, initiators, and hydrophilic polymers with specific functional groups. This composite structure enables both the hydrophilic properties needed for neutral water development and the durability required for printing resistance.
2Reliability
If the support surface is made hydrophobic to prevent image area removal, then printing durability is improved, but ink adheres to the non-image area during printing causing printing stain
Solution Approach 1:
The invention creates locally differentiated surface properties where the non-image area exhibits high hydrophilicity to repel ink and prevent staining, while the image area maintains appropriate characteristics for ink reception. This spatial differentiation of surface properties simultaneously prevents both image removal and non-image staining.
Solution Approach 2:
The invention changes the surface energy parameters of different areas through photopolymerization. The unexposed non-image area maintains high hydrophilicity (low surface energy for ink), while the exposed image area develops appropriate adhesion properties, achieving both stain resistance and printing durability through parameter optimization.
3Reliability
If additional wet treatments (washing, rinsing, oil-desensitizing) are applied after development, then processing completeness is achieved, but environmental impact increases and process complexity increases
Solution Approach 1:
The invention extracts and eliminates the need for additional wet treatment steps by designing a photopolymerizable layer that achieves complete development with neutral water alone. The hydrophilic polymer components enable thorough removal of unexposed areas without requiring surfactant rinses or oil-desensitizing treatments, thereby reducing environmental impact.
Solution Approach 2:
The photopolymerizable layer with hydrophilic polymer components performs self-service by enabling complete development through its inherent hydrophilic properties. The neutral water is sufficient to remove unexposed areas without requiring additional chemical treatments, making the process self-sufficient and environmentally friendly.
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 lithographic printing plate with improved stain resistance and durability, including after storage, and simplifies the processing by eliminating the need for additional wet treatments, using environmentally friendly aqueous solutions and reducing waste.
Implementation Method 1
a photopolymerizable layer sensitive to laser, wherein a copolymer which contains (a1) a repeating unit having at least one ethylenically unsaturated bond and (a2) a repeating unit having at least one functional group capable of interacting with a surface of the support
Data Source
Figure 1
AI summary
A lithographic printing plate precursor includes a support and one or more layers, one of the one or more layers is a photosensitive layer containing an initiator compound, a polymerizable compound and a binder polymer, and a layer being in contact with the support of the one or more layers contains a copolymer containing a repeating unit having a zwitterionic structure and a repeating unit having a structure capable of interacting with a surface of the support.