Viscoelastic Ink Phase Angle Control for High-Speed Printing
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Solution Overview
Problem
Conventional inks used in high-speed flexographic and rotogravure printing suffer from print defects such as pinholing due to their viscoelastic properties, which are not adequately controlled, leading to irregular ink transfer and substrate interaction issues at elevated speeds.
Innovation Solution
Formulating inks with controlled viscoelastic properties by adjusting the phase angle to less than 60°, 50°, or 45° at 10 Hz, achieved by selecting specific resins, solvents, and additives, and modifying solvent affinity and hydrogen bonding, to enhance ink stability and substrate interaction at speeds over 1200 ft/min.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If linear printing speed is increased to improve productivity, then printing speed increases, but print defects such as pinholing occur due to inadequate ink viscoelastic control
Solution Approach 1:
The patent applies parameter changes by controlling the viscoelastic properties of the ink through phase angle measurement and adjustment. Specifically, the ink formulation is modified to achieve a phase angle between 0-60 degrees at 10 Hz oscillation frequency, which optimizes the ink's flow and transfer characteristics at high printing speeds, thereby preventing pinholing defects while maintaining productivity
Solution Approach 2:
The patent inverts the conventional approach by not merely increasing speed but by fundamentally changing the ink's viscoelastic parameters to enable high-speed printing. Instead of accepting pinholing as an inevitable consequence of high speed, the solution reverses the problem by adjusting the phase angle to negative or near-zero values, which inverts the ink's response to rapid substrate movement and prevents defect formation
2Ease of manufacture
If ink viscoelasticity is not controlled, then conventional ink formulations can be used, but irregular ink transfer and substrate interaction issues occur at elevated speeds
Solution Approach 1:
The patent replaces mechanical control methods with a fundamental change in ink rheology. Instead of relying on mechanical adjustments to achieve uniform ink transfer, the solution substitutes by controlling the molecular-level viscoelastic properties through phase angle adjustment, which inherently ensures uniform ink transfer and substrate interaction at high speeds
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 viscoelasticity results in reduced pinholing defects, improving print quality with less than 1% pinholes by area, enabling high-speed printing without print defects.
Implementation Method 1
measuring the phase angle of the ink and controlling the phase angle of the ink to less than 60°, 50°, or 45° at a frequency of 10 Hz
Data Source
AI summary
An ink for high-speed printing is formulated by controlling the phase angle of the ink to less than 60° at a frequency of 10 Hz 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 to 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. The ink is applied to a substrate, which moves at a speed of greater than 1200 feet/min.