Relief Printing Units for Ink Transfer in Offset Machines
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Solution Overview
Problem
Existing offset printing machines face limitations in ink transfer efficiency, leading to reduced opacity of printed images and issues like toning due to impurities on lithographic plates, with maximum water and ink retention limits hindering further improvements.
Innovation Solution
Implementing a printing method with non-lithographic printing units using relief plates or sleeves, which enhance ink transfer by allowing increased ink application without additional water, and configuring printing units to handle opaque base coats, transparent varnishes, and metallic images, while maintaining a continuous gap-less image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of water feed to the lithographic plate is increased to increase the amount of ink feed, then the ink transfer is improved, but it produces emulsion and increases water transferred to the web, affecting subsequent printing units
Solution Approach 1:
The patent changes the fundamental printing parameter from offset printing to direct printing, eliminating the lithographic plate intermediate step. This allows independent control of water and ink application, enabling increased ink transfer without the emulsion problem that occurs when increasing water in offset printing
Solution Approach 2:
The patent extracts and removes the lithographic plate from the printing system, eliminating the source of the problem where water and ink interact on the plate surface to create emulsion. By printing directly from the drum, this harmful interaction is completely avoided
2Quantity of substance
If the maximum amount of water and ink retained on the lithographic plate surface is increased, then the ink transfer is improved, but improvement above certain threshold is not possible due to retention limits
Solution Approach 1:
The patent fundamentally changes the printing mechanism from offset printing with retention limits to direct printing where ink is applied directly from the ink supply to the web. This eliminates the retention threshold limitation inherent in lithographic plates, allowing continuous improvement of ink transfer by increasing ink supply
3Productivity
If aluminum lithographic plates are used, then offset printing efficiency is achieved, but a gap is produced preventing continuous gap-less image
Solution Approach 1:
The patent replaces the rigid aluminum lithographic plate mechanical system with a flexible printing drum system that can maintain continuous contact with the web throughout the printing cycle, eliminating the gap problem while preserving printing efficiency
4Productivity
If lithographic plates with impurities are used, then printing is performed, but toning is caused by small impurities transferring ink dots on non-printing regions
Solution Approach 1:
The patent removes the lithographic plate from the system entirely, eliminating the source of impurities that cause toning. By printing directly from the ink supply through the drum to the web, the intermediate plate that could contain impurities is completely extracted from the printing path
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
Improves ink transfer, resulting in thicker layers, higher opacity, reduced toning, and better application of special inks, including those with metallic flakes, by adapting existing offset printing machines to non-lithographic units.
Implementation Method 1
the image to be printed is defined by hydrophobic regions of the surface of the lithographic plate, and where the regions of the lithographic plate devoid of image to be printed are hydrophilic, so that when water is provided to the lithographic plate, said water is retained on the hydrophilic regions, preventing the adhesion thereto of a non-polar ink
Implementation Method 2
the regions of the lithographic plate devoid of image to be printed are hydrophilic, so that when water is provided to the lithographic plate, said water is retained on the hydrophilic regions, preventing the adhesion thereto of a non-polar ink
Implementation Method 3
The ink on the hydrophobic regions is then transferred to a blanket cylinder surrounded by rubber sleeve, o rubber-like sleeve, which transfers the ink to the web of laminar material to be printed
Data Source
Figure 1~2
Figure 3~5
AI summary
Printing method with improved ink transfer comprising the steps of: identifying, on a digital prepress information, at least one monochrome image as an opaque base coat, a transparent varnish coat, and/or a metallic image, configuring some of the printing units (10) of a printing machine as lithographic printing units with a rubber sleeve (40) on a first cylinder (11) and lithographic plates (41) on a second cylinder (12); and configuring at least one of the printing units (10) as a non-lithographic printing unit with improved ink transfer by including a relief plate (42) or a relief cylindrical sleeve (43) surrounding one of the first and second cylinders (11, 12) adapted to print one of the monochrome images identified as an opaque base coat and/or as a transparent varnish coat and/or as a metallic image, and by including the rubber sleeve (40) surrounding the other of the first and second cylinders (11, 12). A corresponding printing machine for printing according to the aforementioned method is also provided.