Back Coat Layer Surface Roughness for Lithographic Printing Plate Adhesion
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Solution Overview
Problem
Existing planographic printing plate precursors face challenges in eliminating interleaving paper without causing scratches, adhesion, or particle contamination, particularly due to high glass transition temperatures and the falling of fine particles, which affect image formability and lead to printing troubles.
Innovation Solution
A planographic printing plate precursor with a back coat layer having a surface roughness structure characterized by an arithmetic average height of 0.5 µm or greater, formed by continuous thin and thick film portions, and a Bekk smoothness of 200 seconds or less, using a non-alkali-soluble resin and specific coating methods to prevent horn-like protrusions and ensure effective lamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a back coat layer with high glass transition temperature is used to prevent adhesion between precursors, then adhesion prevention is improved, but scratches and particle contamination occur affecting image formability
Solution Approach 1:
The back coat layer is designed with non-uniform surface roughness featuring both thin film portions and thick film portions. The thick film portions provide high glass transition temperature for adhesion prevention, while the thin film portions reduce scratches and particle contamination. This local quality variation resolves the contradiction between adhesion prevention and harmful factor reduction.
Solution Approach 2:
The back coat layer uses a composite structure combining resin fine particles with specific surface roughness characteristics. This composite material approach allows simultaneous achievement of high adhesion prevention (through the resin matrix with appropriate Tg) and low scratch/particulate generation (through the controlled roughness structure with Sa ≤ 0.4 μm).
2Reliability
If resin fine particles are added to the back coat layer to prevent adhesion, then adhesion prevention is improved, but image formability deteriorates due to particle falling
Solution Approach 1:
The resin fine particles are distributed non-uniformly within the back coat layer, with higher concentration in thick film portions and lower concentration in thin film portions. This local quality variation prevents particle falling onto the recording layer while maintaining adhesion prevention in the thick film regions.
Solution Approach 2:
The surface roughness arithmetic average height Sa is controlled within a specific range (≤ 0.4 μm) to prevent particle falling. This parameter control ensures that particles remain embedded in the back coat layer rather than detaching and contaminating the recording layer, thus maintaining image formability.
3Ease of manufacture
If interleaving paper is removed manually to eliminate cost and disposal issues, then cost and environmental issues are improved, but plate-making step load increases and peeling failure may occur
Solution Approach 1:
The invention extracts and eliminates the interleaving paper component from the laminate structure by providing the back coat layer with adhesion-preventing properties. This allows precursors to be laminated directly without interleaving paper, reducing cost and disposal issues while maintaining productivity.
4Productivity
If automatic removal of interleaving paper is implemented to avoid manual labor, then labor efficiency is improved, but removal mistakes cause printing troubles
Solution Approach 1:
The invention extracts and eliminates the interleving paper component entirely by providing the back coat layer with inherent adhesion prevention. This eliminates the need for any removal process (manual or automatic), thus maintaining high productivity while ensuring printing quality through consistent adhesion prevention.
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 prevents scraping, peeling, adhesion, and scratches between precursors, while maintaining image formability and preventing particle contamination, thus enabling the reliable elimination of interleaving paper.
Implementation Method 1
a back coat layer having a surface roughness structure characterized by an arithmetic average height of 0.5 µm or greater, formed by continuous thin and thick film portions
Implementation Method 2
formed by continuous thin and thick film portions
Implementation Method 3
using a non-alkali-soluble resin
Data Source
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AI summary
Provided are a planographic printing plate precursor, a laminate thereof, and a method of producing a planographic printing plate precursor capable of satisfying all purposes for eliminating interleaving paper used for preventing scraping and peeling, preventing adhesion, imparting a plate-separating property for preventing multiple-plate feeding, and preventing scratches. The planographic printing plate precursor which includes a polymer layer on a surface of a belt-like support 12 includes a back coat layer 70 having an arithmetic average surface roughness Sa of 0.5 µm or greater due to a surface roughness structure in which thin film portions 60 and thick film portions 62 are continuously formed on a rear surface of the belt-like support 12.