Ink Composition Surface Tension Control for Uniform Solid Printing
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Solution Overview
Problem
Ink compositions applied on non- or low-absorbable media tend to spread 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 and controlled surface tension differences is used to apply an ink composition, where the pretreatment liquid includes a cationic polymer with a concentration of 6.0 Eq/L or more, and the ink composition has a static surface tension of 25.2 to 29.3 mN/m, with a controlled difference of 3.5 mN/m or less before and after drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a pretreatment liquid with cationic flocculant is applied to suppress ink spread, then ink composition spread is reduced, but solid uniformity decreases due to Marangoni convection during drying
Solution Approach 1:
The patent applies a pretreatment liquid containing cationic flocculant before ink composition application. The cationic flocculant pre-reacts with anionic components in the ink, forming precipitates that reduce surface tension gradients and prevent Marangoni convection during drying, thus simultaneously suppressing ink spread and maintaining solid uniformity
Solution Approach 2:
The pretreatment liquid acts as an intermediary substance between the medium and ink composition. It modifies the surface properties and chemical environment, enabling the ink to dry uniformly without spread by mediating the interaction between ink components and the medium surface
2Adaptability or versatility
If ink composition with low surface tension is used to improve wettability, then ink spread increases on non-absorbable media, but coverage is improved
Solution Approach 1:
The patent modifies the surface tension parameter of the ink composition by adding surfactants and using low-surface-tension organic solvents. This allows the ink to wet non-absorbable media effectively while the pretreatment liquid's flocculation action prevents excessive spread by reducing surface tension gradients during drying
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
This method effectively suppresses ink spread and maintains solid uniformity by flocculating anionic components and stabilizing surface tension gradients, preventing the coffee ring phenomenon and ensuring consistent image formation on non- 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
the ink composition to form the solid area on the medium is gradually dried on the medium
Implementation Method 3
Marangoni convection may be generated due to a surface tension gradient associated with unevenly distributed components of the ink composition
Implementation Method 4
the method of applying the ink composition described above adjusts the surface tensions of the ink composition before and after the drying such that the difference therebetween becomes 3.5 mN/m or less
Data Source
AI summary
A method may comprise: applying a pretreatment liquid onto a medium and drying the same; and thereafter applying an ink composition onto the medium and drying the same. 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 may be 25.2-29.3 mN/m. A difference between this static surface tension and a static surface tension of remaining component(s) of the ink composition after drying is 3.5 mN/m or less. The organic solvent(s) may comprise at least one organic solvent having a static surface tension of 28.0-34.0 mN/m. A content of the at least one organic solvent relative to an overall amount of the ink composition is 7.5-24.0 weight %.