Dual-Layer Anodized Aluminum Substrate for Lithographic Plates
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Solution Overview
Problem
Existing lithographic printing plate precursors face challenges in achieving optimal scratch resistance, on-press developability, and press life due to the limitations of chemical compositions and structural features, which often result in trade-offs between these properties.
Innovation Solution
A lithographic printing plate precursor is developed with a substrate having a grained and etched aluminum-containing surface, featuring a combination of inner and outer aluminum oxide layers formed through specific anodizing processes. The inner aluminum oxide layer has an average dry thickness of at least 650 nm with micropores ≤15 nm, while the outer layer has micropores ≥15 nm and ≤30 nm, with a micropore density and porosity that enhance scratch resistance and on-press developability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single anodized aluminum oxide layer is used on the substrate, then the structure is simple and manufacturing is easier, but scratch resistance and on-press developability cannot be optimized simultaneously
Solution Approach 1:
The substrate surface is segmented into two distinct aluminum oxide layers: an inner layer with micropores ≤15 nm for scratch resistance, and an outer layer with micropores ≥15 nm for on-press developability. This segmentation allows each layer to independently optimize its function without compromising the other.
Solution Approach 2:
Different regions of the substrate surface are given different properties through the two-layer structure. The inner layer provides hard, scratch-resistant properties while the outer layer provides developable, porous properties. Each layer has locally optimized characteristics suited to its specific function.
2Ease of operation
If the aluminum oxide layer has high porosity to improve on-press developability, then developability increases, but scratch resistance deteriorates
Solution Approach 1:
The porosity function is segmented between two layers: the inner layer has low porosity (micropores ≤15 nm) to maintain structural integrity and scratch resistance, while the outer layer has high porosity (micropores ≥15 nm) to enable on-press developability. This segmentation resolves the conflict between strength and ease of operation.
Solution Approach 2:
The outer aluminum oxide layer utilizes porous material structure with controlled micropore size (≥15 nm) to enhance on-press developability by allowing developer solution penetration, while the inner layer uses less porous material to maintain scratch resistance.
3Strength
If the inner aluminum oxide layer thickness is increased to improve scratch resistance, then scratch resistance improves, but press life may be affected
Solution Approach 1:
The micropore size parameter of the inner layer is optimized to ≤15 nm, providing an optimal balance where sufficient thickness can be achieved for scratch resistance while maintaining press life. The specific pore size control allows the layer to be both durable and functionally appropriate for the printing process duration.
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 combination of inner and outer aluminum oxide layers with specific structural properties improves scratch resistance and maintains high on-press developability and press life, as demonstrated by the substrates' performance in imaging and printing processes.
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
Data Source
Figure 1
AI summary
Lithographic printing plate precursors are prepared with a unique substrate and one or more radiation-sensitive imageable layers. The inventive substrate is prepared by two separate anodizing processes to provide an inner aluminum oxide layer having an average dry thickness (Ti) of 650-3,000 nm and a multiplicity of inner micropores having an average inner micropore diameter (Di) of ≤ 15 nm. A formed outer aluminum oxide layer comprises a multiplicity of outer micropores having an average outer micropore diameter (Do) of 15-30 nm; an average dry thickness (To) of 130-650 nm; and a micropore density (Co) of 500-3,000 micropores/μm2. The ratio of D0 to Di is greater than 1.1 : 1, and Do in nanometers and the outer aluminum oxide layer micropore density (Co) in micropores/μm2, are further defined by the outer aluminum oxide layer porosity (Po) according to the following equation: 0.3 ≤ Po ≤ 0.8 wherein Po is 3.14(Co)(Do 2)/4,000,000.