Aluminum Support Back Surface Roughness for Printing Plate Stacking
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Solution Overview
Problem
Current planographic printing plate precursors face inefficiencies due to scratches and adhesion issues during the exposure process, particularly when stacked without interleaf sheets, leading to reduced productivity and image quality.
Innovation Solution
A planographic printing plate precursor with a photosensitive layer on an aluminum support, where the back surface roughness is controlled to 0.13 µm or less in both longitudinal and width directions, preventing scratches and adhesion between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If planographic printing plate precursors are stacked without interleaf sheets to improve productivity, then plate-making speed increases, but scratches and adhesion issues occur between layers reducing image quality
Solution Approach 1:
The back surface of the aluminum support is given a specific roughness (Ra: 0.03 µm to 0.13 µm) that differs from the front surface, creating local quality differentiation. This controlled roughness on the back surface prevents adhesion and scratches during stacking without requiring interleaf sheets, thus maintaining both high productivity and image quality
2Reliability
If a protective layer is added to prevent polymerization inhibition by oxygen, then sensitivity and image strength improve, but the structure becomes more complex and handling becomes more difficult
Solution Approach 1:
The patent extracts the essential protective function from a separate protective layer and integrates it into the aluminum support's back surface roughness control. By controlling the back surface roughness to Ra: 0.03 µm to 0.13 µm, the support itself provides protection against adhesion and scratches, eliminating the need for an additional protective layer while maintaining image strength
3Reliability
If interleaving sheets are used to prevent adhesion between stacked plates, then image quality is maintained, but the exposing process time increases reducing productivity
Solution Approach 1:
The patent removes the interleaving sheet component entirely by transferring the protective function to the aluminum support's back surface. The controlled roughness (Ra: 0.03 µm to 0.13 µm) on the back surface provides sufficient protection against adhesion and scratches, allowing plates to be stacked directly without interleaving sheets, thus eliminating the time-consuming removal step while maintaining image quality
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 controlled surface roughness effectively reduces scratches and adhesion issues, enhancing the efficiency and quality of the printing process by allowing direct contact between layers without interleaf sheets, thereby improving productivity and image strength.
Implementation Method 1
an average surface roughness (Ra) of a back surface of the support in both of a longitudinal direction and a width direction is 0.13 µm or less
Implementation Method 2
a photosensitive layer that has sensitivity to laser light and is provided on or above a surface of a support
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention provides a planographic printing plate precursor having at least a photosensitive layer that has sensitivity to laser light and is provided on or above a surface of a support, wherein an average surface roughness (Ra) of a back surface of the support in both of a longitudinal direction and a width direction is 0.15 µm or less. The Ra is preferably from 0.13 µm or less. The support preferably comprises aluminum. A Bekk smoothness of a surface of the planographic printing plate precursor that has sensitivity to laser light is preferably 10,000 seconds or less. The invention further provides a stack having at least a plurality of the planographic printing plate precursors.