Lithographic Printing Plate Precursor Multi-Layer Anodic Oxide Structure
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Solution Overview
Problem
Lithographic printing plate precursors face challenges in achieving optimal scratch resistance, on-press developability, press life, and reducing re-start toning (RST) issues, particularly in negative-working on-press developable precursors, where chemical compositions or structural features that enhance one property often compromise others.
Innovation Solution
A lithographic printing plate precursor with a substrate having a grained and etched aluminum surface, featuring a multi-layer anodic oxide structure comprising an inner aluminum oxide layer with micropores less than 100 nm and an outer layer with micropores between 15-30 nm, combined with a hydrophilic layer containing a hydrophilic copolymer with amide and phosphorus-containing units, which improves the substrate's properties without sacrificing press life or on-press developability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single anodizing process is used to form aluminum oxide layer, then the manufacturing process is simple, but the scratch resistance and on-press developability cannot be optimized simultaneously
Solution Approach 1:
The single anodizing process is segmented into two sequential anodizing processes. The first anodizing forms an initial aluminum oxide layer with specific micropore structure, and the second anodizing forms a final aluminum oxide layer with different micropore structure. This segmentation allows each layer to be optimized for specific functions: the first layer provides scratch resistance while the second layer provides on-press developability, resolving the contradiction between strength and process complexity.
Solution Approach 2:
Different regions of the aluminum oxide coating are given different local qualities through the two-stage anodizing process. The first aluminum oxide layer has micropores of one size range optimized for scratch resistance, while the second aluminum oxide layer has micropores of a different size range optimized for on-press developability. This local quality differentiation allows simultaneous optimization of both properties without requiring a single complex process.
2Reliability
If chemical composition is optimized for one property, then that property improves, but other properties are compromised
Solution Approach 1:
The aluminum oxide coating is structured as a composite material system with two distinct layers, each having different chemical compositions and micropore structures. The first layer comprises aluminum oxide with specific micropore characteristics optimized for press life and scratch resistance, while the second layer comprises aluminum oxide with different micropore characteristics optimized for on-press developability. This composite structure allows each layer to independently optimize its properties without compromising the other, resolving the contradiction between reliability and adaptability.
3Object-generated harmful factors
If hydrophilic layer coverage is increased to reduce re-start toning, then RST improves, but other substrate properties may be compromised
Solution Approach 1:
The aluminum oxide layers are prepared in advance with optimized micropore structures before the hydrophilic layer is applied. The first aluminum oxide layer is formed with micropores optimized for scratch resistance, and the second aluminum oxide layer is formed with micropores that facilitate hydrophilic layer adhesion and reduce re-start toning. By performing these preparatory actions in sequence before final assembly, the patent achieves reduction of harmful RST effects while preserving the scratch resistance properties established in the first layer.
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 effectively reduces re-start toning while maintaining high scratch resistance and on-press developability, ensuring long press life and efficient printing performance.
Implementation Method 1
The substrate comprises: an aluminum-containing plate having a grained and etched planar surface; an inner aluminum oxide layer disposed on the grained and etched planar surface... an outer aluminum oxide layer disposed over the inner aluminum oxide layer
Implementation Method 2
a hydrophilic layer comprising at least one hydrophilic copolymer that comprises at least (a) recurring units, each of which has at least one amide group, and (b) recurring units, each of which has an -OM group that is directly connected to a phosphorus atom
Data Source
Figure 1
AI summary
Lithographic printing plate precursors are prepared with a unique aluminum-containing substrate prepared using two separate anodizing processes to provide an inner aluminum oxide layer of average dry thickness (Ti) of 300-3,000 nm and a multiplicity of inner micropores of average inner micropore diameter (Di) of ≤ 100 nm. An outer aluminum oxide layer is also provided to have a multiplicity of outer micropores of average outer micropore diameter (Do) of 15-30 nm and a dry thickness (To) of 30-650 nm. A hydrophilic layer disposed on the outer aluminum oxide layer at 0.0002-0.1 g/m2 has at least a hydrophilic copolymer composed of (a) recurring units having an amide group and (b) recurring units comprising an -OM group directly connected to a phosphorus atom, wherein M represents a hydrogen, sodium, potassium, or aluminum atom.