Negative-Working Lithographic Printing Plate Precursors with Wax Overcoat
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Solution Overview
Problem
Conventional negative-working lithographic printing plate precursors suffer from inadequate scratch resistance and processor sludge formation during handling and processing, despite the use of large organic particles in the topcoat, which are ineffective in improving scratch resistance.
Innovation Solution
A negative-working lithographic printing plate precursor with a water-soluble overcoat layer comprising film-forming polymeric binders and hydrocarbon wax particles, where the wax particles are dispersed in an amount of at least 1.3 weight % and have an average largest dimension of 0.05 µm to 0.7 µm, providing enhanced scratch resistance and reduced processor sludge formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If large organic particles are used in the topcoat, then the topcoat provides some protective function, but scratch resistance remains inadequate
Solution Approach 1:
The patent changes the particle size parameter of the organic wax particles from conventional large sizes (typically >1 µm) to a specific range of 0.1-10 µm, with preference for 0.5-5 µm. This parameter change optimizes both scratch resistance and processor sludge formation, resolving the contradiction between protective function and scratch resistance.
Solution Approach 2:
The topcoat is formulated as a composite material containing organic wax particles dispersed in a water-soluble binder polymer. This composite structure combines the protective properties of the binder with the scratch-resistant properties of the wax particles, while the specific particle size range optimizes performance in both scratch resistance and processor sludge reduction.
2Reliability
If conventional topcoat formulations are used, then the precursor maintains basic functionality, but processor sludge formation occurs
Solution Approach 1:
The patent changes the particle size parameter of organic wax particles to 0.1-10 µm (preferably 0.5-5 µm), which is a critical parameter change that prevents processor sludge formation while maintaining topcoat functionality. This specific size range allows the particles to be effectively removed during processing without forming sludge, resolving the contradiction between processor cleanliness and sludge formation.
3Ease of operation
If the outermost layer is made water-soluble for easy removal, then processing becomes easier, but scratch resistance during handling deteriorates
Solution Approach 1:
The water-soluble outermost layer is formulated as a composite containing organic wax particles (0.1-10 µm) dispersed in a water-soluble binder polymer. The binder polymer provides water solubility for easy removal during processing, while the wax particles provide scratch resistance during handling. This composite structure resolves the contradiction between processing ease and scratch resistance.
Solution Approach 2:
The patent optimizes the particle size parameter of wax particles to 0.1-10 µm, which ensures that the particles remain embedded in the water-soluble matrix during handling (providing scratch resistance) but can be effectively removed during processing (maintaining ease of operation).
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 improved scratch resistance and cleaner processor conditions by using small hydrocarbon wax particles in the overcoat layer, surprising given their size, while maintaining precursor sensitivity and printing performance.
Implementation Method 1
organic wax particles dispersed within the one or more film-forming water-soluble polymeric binders
Implementation Method 2
the negative-working imageable layer comprising a free radically polymerizable component, an initiator composition that is capable of generating free radicals upon exposure to imaging radiation
Data Source
AI summary
Negative-working lithographic printing plate precursor a negative- working imageable layer and an outermost water-soluble overcoat layer that is disposed directly on the negative-working imageable layer. The outermost water-soluble overcoat layer comprises: (1) one or more film-forming water-soluble polymeric binders, and (2) organic wax particles dispersed therein. The organic wax particles have an average largest dimension of at least 0.05 μm and up to and including 0.7 μm, as determined from a scanning electron micrographic of the dried outermost water-soluble overcoat layer. Useful organic wax particles include fluorinated or non-fluorinated hydrocarbon wax particles.