High-Speed Printing Ink Surface Tension Control
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Solution Overview
Problem
High-speed flexographic printing faces challenges with ink printability due to ink surface tension issues, leading to defects like pinholing and irregular film leveling, which are exacerbated by the short ink travel time and dynamic conditions of high-speed presses.
Innovation Solution
Formulating inks with controlled surface tension, specifically equal to or greater than 26 mN/m, and optimizing the ratio of total non-volatiles volume fraction to maximize surface tension, using resins, solvents, and additives to ensure high surface tension and minimal surface tension gradients during drying, thereby enhancing ink leveling and spreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If printing speed is increased to improve productivity, then productivity is improved, but ink printability deteriorates due to surface tension issues causing pinholing and irregular film leveling
Solution Approach 1:
The patent applies parameter changes by modifying the surface tension of the ink formulation. Specifically, it uses inks with surface tension values between 26-35 mN/m (preferably 28-32 mN/m) to achieve proper ink flow and leveling at high speeds without pinholing or irregular film formation. This parameter adjustment resolves the contradiction by enabling high-speed printing while maintaining ink printability quality.
2Ease of operation
If ink surface tension is reduced to improve wetting and spreading, then ink spreading is improved, but pinholing and film leveling defects increase at high speeds
Solution Approach 1:
The patent challenges the conventional wisdom by using higher surface tension values (26-35 mN/m) rather than low surface tension values. This counterintuitive parameter change works because at high printing speeds, the ink has minimal time to level, so a higher surface tension maintains film integrity and prevents pinholing while still allowing adequate spreading during the brief contact window.
Solution Approach 2:
The patent applies partial action by using a moderate surface tension range (26-35 mN/m) that is higher than conventional low surface tension inks but not excessively high. This partial approach provides just enough surface tension to prevent pinholing and maintain film continuity at high speeds while still allowing sufficient wetting and spreading during the brief printing window.
3Productivity
If ink travel time is reduced to match high-speed press requirements, then productivity is improved, but ink cannot properly level and register causing print defects
Solution Approach 1:
The patent applies parameter changes by adjusting the surface tension to viscosity ratio of the ink. By formulating inks with specific surface tension (26-35 mN/m) and matching viscosity characteristics, the ink achieves rapid leveling within the reduced travel time at high speeds. The parameter adjustment ensures that surface tension-driven leveling occurs fast enough to prevent defects despite the shortened contact time.
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 approach results in improved print quality with reduced pinholing and enhanced ink film leveling, achieving pinhole-free prints even at high speeds exceeding 1800 ft/min, by maintaining high surface tension and optimizing ink composition.
Implementation Method 1
the surface tension of inks for high speeding printing... controlling the surface tension to enhance the quality of printing at high speed... the surface tension of the ink can be equal to or greater than 26 mN/m... enhanced ink leveling and spreading
Data Source
AI summary
A method of formulating ink for high-speeding printing includes controlling a surface tension of the ink to equal to or greater than 26 mN/m, equal to or greater than 28 mN/m, or equal to or greater than 30 mN/m. The surface tension is measured when the ratio of the total non-volatiles volume fraction of the ink to the maximum total non-volatiles volume fraction of the ink is a ratio between about 0.40 and about 0.90. An ink for high-speed printing includes one or more resins, one or more colorants, one or more solvents, and one or more additives. The ink can be a flexographic ink, a rotogravure ink, a heatset offset ink, or a publication gravure ink. A print of the ink includes less than 1% of pinholes by area. A method of printing includes preparing an ink and applying the ink to a substrate. The ink has a surface tension of equal to or greater than 26 mN/m, and the substrate moves at a speed of greater than 1200 feet/min.