Ink Composition Surface Tension Control for Uniform Printing
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Solution Overview
Problem
Ink compositions applied on non-absorbable or low-absorbable media tend to spread excessively and experience a decrease in solid uniformity due to surface tension gradients and Marangoni convection during drying, especially when forming solid images.
Innovation Solution
A method involving a pretreatment liquid with a cationic flocculant is applied to the medium, followed by precise control of surface tension differences before and after drying to suppress ink spread and maintain uniformity, using a line head for ink ejection and drying devices to manage the drying process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ink composition is applied onto non-absorbable or low-absorbable medium, then ink coverage is improved, but ink spread increases and solid uniformity decreases
Solution Approach 1:
A pretreatment liquid containing a cationic flocculant is applied to the medium before applying the ink composition. The cationic flocculant adsorbs onto the medium surface and neutralizes negative charges, creating a preliminary layer that prevents excessive ink spread and maintains solid uniformity when ink is subsequently applied.
Solution Approach 2:
The surface tension of the ink composition is precisely controlled to be within a specific range (25.2-29.3 mN/m). Additionally, the difference in surface tension between the ink composition and the remaining components after drying is limited to 3.5 mN/m or less. These parameter controls prevent Marangoni convection and maintain solid uniformity.
2Ease of operation
If ink composition with low surface tension is used to improve wetting, then ink spread increases on non-absorbable medium
Solution Approach 1:
The surface tension of the ink composition is optimized to a specific range (25.2-29.3 mN/m) that provides adequate wetting on non-absorbable media without causing excessive spread. This precise parameter control allows the ink to adhere properly while maintaining edge definition and solid uniformity.
3Reliability
If ink composition is dried on medium, then ink fixation is improved, but Marangoni convection occurs due to surface tension gradient
Solution Approach 1:
The surface tension of the ink composition is controlled to be within 25.2-29.3 mN/m, and the difference in surface tension between the ink composition and the remaining components after drying is limited to 3.5 mN/m or less. This minimizes surface tension gradients during drying, preventing Marangoni convection and the coffee ring effect while ensuring proper ink fixation.
Solution Approach 2:
The ink composition is formulated as a composite system containing anionic solid components, organic solvents with specific surface tensions (28.0-34.0 mN/m), surfactants, and water. This composite formulation ensures that the surface tension remains stable during drying, preventing convective flows that would compromise solid uniformity.
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 method effectively prevents ink spread and maintains solid uniformity by flocculating anionic components and managing surface tension gradients, ensuring consistent image quality on non-absorbable or low-absorbable media.
Implementation Method 1
the cationic flocculant in the pretreatment liquid can flocculate the anionic solid component of the ink composition, thereby suppressing spread of the ink composition
Implementation Method 2
drying the ink composition on the medium after the applying of the ink composition
Implementation Method 3
Marangoni convection may be generated due to a surface tension gradient associated with unevenly distributed components of the ink composition. The Marangoni convection may unexpectedly contract the ink composition and/or cause a coffee ring phenomenon
Data Source
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AI summary
A method of applying an ink composition may comprise: applying a pretreatment liquid onto a medium (2) and drying the same; and thereafter applying an ink composition onto the medium (2) and drying the same. The medium (2) may be a non-absorbable or low-absorbable medium. The pretreatment liquid may comprise a flocculant of cationic polymer of which cation concentration is 6.0 Eq/L or more. A drying rate of the pretreatment liquid after its drying may be 50% or more. A static surface tension of all components of the ink composition, including organic solvent(s), may be 25.2 mN/m or more and 29.3 mN/m or less. A difference between this static surface tension and a static surface tension of remaining component(s) of the ink composition after its drying of the ink composition is 3.5 mN/m or less. The organic solvent(s) may comprise at least one organic solvent having a static surface tension of 28.0 mN/m or more and 34.0 mN/m or less. A content of the at least one organic solvent relative to an overall amount of the ink composition is 7.5 weight% or more and 24.0 weight% or less.