Ink Composition Surface Tension Control for Print Quality
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Solution Overview
Problem
Latex ink compositions face issues with print artifacts such as streakiness, coalescence, puddling, and dewetting on media with poor water absorption properties, like machine coated or offset coated media, due to inadequate ink spreading and surface tension changes during drying.
Innovation Solution
A latex ink composition with a dynamic surface tension below 35 mN/m and a static surface tension above 21 mN/m, optimized with a mixture of surfactants including acetylene glycols, ethoxylated acetylene glycols, silicone surfactants, and fluorochemical surfactants, along with cosolvents, to enhance dotgain and prevent surface tension increases during drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional latex inks are used on poorly absorbing media, then printing speed can be maintained, but print quality deteriorates due to insufficient ink spreading and streakiness
Solution Approach 1:
The patent applies parameter changes by carefully controlling the dynamic surface tension (below 35 mN/m) and static surface tension (above 21 mN/m) of the ink composition. This specific tension range enables adequate ink spreading on poorly absorbing media during high-speed printing, resolving the contradiction between maintaining printing speed and improving print quality by preventing streakiness while ensuring sufficient dotgain.
Solution Approach 2:
The patent uses a composite surfactant system containing multiple types of surfactants (acetylene glycols, ethoxylated acetylene glycols, silicone surfactants, and fluorochemical surfactants) in specific combinations. This composite approach creates synergistic effects that maintain appropriate surface tension characteristics throughout the printing and drying process, enabling both high productivity and high print quality on challenging media.
2Duration of action of stationary object
If water evaporates during ink drying, then the ink dries faster, but surface tension increases causing puddling and dewetting
Solution Approach 1:
The patent applies preliminary action by pre-formulating the ink with a specific mixture of surfactants designed to maintain stable surface tension throughout the drying process. The surfactant composition is optimized beforehand to compensate for water evaporation effects, ensuring that surface tension remains within the target range (dynamic <35 mN/m, static >21 mN/m) even as the ink dries, thereby preventing puddling and dewetting.
Solution Approach 2:
The patent implements feedback control through the surfactant system that responds to changes in ink composition during drying. As water evaporates and the ink concentration changes, the surfactant mixture dynamically adjusts to maintain stable surface tension, preventing the increase that would otherwise cause puddling and dewetting artifacts.
3Manufacturing precision
If surfactant amount is increased to improve spreading, then dotgain improves, but print quality deteriorates due to puddling and dewetting
Solution Approach 1:
The patent applies parameter changes by precisely controlling the surfactant concentration and composition to achieve the optimal surface tension range. Rather than simply increasing surfactant amount, the invention fine-tunes the parameters of the surfactant system (types, ratios, and concentrations) to achieve adequate spreading (dotgain) while maintaining surface tension stability that prevents puddling and dewetting.
Solution Approach 2:
The patent uses a composite surfactant system with multiple types of surfactants (acetylene glycols, ethoxylated acetylene glycols, silicone surfactants, and fluorochemical surfactants) in specific ratios. This composite approach provides synergistic benefits: some surfactants promote spreading while others stabilize surface tension, achieving both high dotgain and prevention of puddling/dewetting that cannot be accomplished with single surfactants alone.
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 ink composition achieves improved print quality by ensuring adequate ink spreading and preventing puddling and dewetting on poorly absorbing media, maintaining stability and reliability in high-speed single pass printing processes.
Implementation Method 1
the ink composition has a dynamic surface tension of below 35 mN/m and a static surface tension of above 21 mN/m both determined at the operating temperature
Implementation Method 2
the spreading behavior of printed ink drops deteriorates upon drying of the ink (i.e. evaporation of water). Without wanting to be bound to any theory it is believed that this is caused by the increase of the surface tension of printed ink drops caused by the evaporation of water
Data Source
Figure 1~2
Figure 3~4A
Figure 4B~4C
AI summary
The present invention relates to an ink composition suitable for being ejected from an inkjet marking device at an operating temperature. The ink composition comprises a water-dispersible resin and has a dynamic surface tension of below 35 mN/m and a static surface tension of above 21 mN/m both determined at the operating temperature. The ink composition may comprise a mixture of water-soluble organic solvents having a difference in the relative dielectric constant of more than 5, preferably between 10 and 50. The ink composition may comprise a polymeric cosolvent, in particular a polyethylene glycol or polyethylene glycol (di)methyl ether. The ink composition may comprise a mixture of surfactants comprising at least one surfactant of a first type selected from the group consisting of acetylene glycols and ethoxylated acetylene glycols and at least one surfactant of a second type selected from the group consisting of silicone surfactants and fluorochemical surfactants.