Waterless Lithographic Plate Phase Separation Blister Prevention
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Solution Overview
Problem
Directly imageable waterless lithographic printing plate precursors with high sensitivity often experience a 'blister' phenomenon, where the silicone rubber layer lifts and transfers to conveyor rollers, causing exposure and development obstructions.
Innovation Solution
A directly imageable waterless lithographic printing plate precursor is developed with a heat sensitive layer containing novolac resin, polyurethane, and a light-to-heat conversion material, featuring a phase separation structure with a novolac resin phase and a polyurethane phase, where the polyurethane is obtained from a polyisocyanate and a polyhydric alcohol, and aromatic polyisocyanate accounts for at least 50 mol% of the polyisocyanate, enhancing adhesive strength and reducing blistering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high sensitivity is achieved in directly imageable waterless lithographic printing plate precursors, then exposure efficiency is improved, but the silicone rubber layer undergoes lifting (blister phenomenon) during production
Solution Approach 1:
The patent applies local quality by creating a phase separation structure where the polyurethane concentrates in specific regions to form adhesive zones. The phase separation causes polyurethane to localize at the interface between the heat sensitive layer and silicone rubber layer, providing localized high adhesion strength exactly where needed to prevent blistering, while allowing other regions to maintain high sensitivity for efficient exposure.
Solution Approach 2:
The patent uses composite materials by combining novolac resin and polyurethane in the heat sensitive layer to create a phase separation structure. This composite system leverages the different properties of each polymer: novolac resin provides sensitivity for laser exposure while polyurethane provides adhesive strength. The phase separation creates a composite structure at the micro level that simultaneously achieves both high sensitivity and high adhesion.
2Strength
If the silicone rubber layer lifts due to blister phenomenon, then adhesive strength is compromised, but the lifted layer transfers to conveyor roller causing exposure and development obstructions
Solution Approach 1:
The patent applies preliminary anti-action by incorporating the phase separation structure with concentrated polyurethane at the interface before any exposure or processing occurs. This pre-established adhesive barrier prevents the blister phenomenon from occurring in the first place, thereby stopping the chain of events that would lead to layer lifting and transfer to the conveyor roller. The adhesive strength is built-in beforehand to counteract the forces that would cause delamination.
3Strength
If phase separation structure is formed with polyurethane from aromatic polyisocyanate, then adhesive strength is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by specifying that aromatic polyisocyanate should account for at least 50 mol% of the polyisocyanate used in the polyurethane. This compositional parameter change ensures sufficient adhesive strength while providing a clear, quantifiable guideline for manufacturing. The phase separation structure forms automatically based on the thermodynamic properties of the polymer blend, so no additional complex equipment or processes are needed beyond controlling the composition parameters.
Data Source
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AI summary
Disclosed is a directly imageable waterless lithographic printing plate precursor including at least a heat sensitive layer and a silicone rubber layer formed on a substrate in this order, wherein the heat sensitive layer contains at least a novolac resin, a polyurethane and a light-to-heat conversion material, and also has a phase separation structure including at least a phase containing a novolac resin and a phase containing a polyurethane. The present invention provides a directly imageable waterless lithographic printing plate precursor which has high sensitivity and is less likely to cause blister, that is, having wide latitude.