Crosslinked Pigment Dispersion for Stable Water-Based Ink
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Solution Overview
Problem
Existing pigment dispersions in ink compositions lack sufficient temporal stability, leading to degradation over time.
Innovation Solution
A pigment dispersion comprising water, a pigment, and a polymer dispersant with a crosslinking structure containing specific structural units represented by Formulas (1) and (2), along with a hydrophilicity/hydrophobicity ratio of 8 or more and an Ar valence of 0.4 mmol/g to 2.9 mmol/g, which enhances the adsorption of the polymer dispersant to the pigment surface, preventing its release and improving dispersion stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer dispersant with crosslinking structure is used to improve dispersion stability, then temporal stability of the pigment dispersion is improved, but the complexity of the dispersant structure increases
Solution Approach 1:
The polymer dispersant is constructed as a composite structure containing multiple functional units: structural units from Formula (1) and Formula (2) that provide crosslinking capability and steric hindrance, and structural units from acid group-containing monomers that enhance pigment surface adhesion. This composite design allows the dispersant to simultaneously achieve excellent temporal stability through crosslinking while maintaining manageable structural complexity through the systematic combination of well-defined functional units.
2Reliability
If the hydrophilicity/hydrophobicity ratio is increased to improve dispersion stability, then the adsorption of polymer dispersant to pigment surface is enhanced, but the balance of hydrophilic and hydrophobic properties becomes more difficult to control
Solution Approach 1:
The patent systematically controls the hydrophilicity/hydrophobicity ratio by adjusting the proportions of hydrophilic structural units (Formula (1) and Formula (2)) and hydrophobic structural units (from acid group-containing monomers) in the polymer dispersant. By optimizing this parameter within the specified range, the dispersant achieves enhanced adsorption to the pigment surface and improved dispersion stability while maintaining controllable formulation complexity.
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 described pigment dispersion achieves excellent temporal stability by suppressing the aggregation of polymer dispersants and maintaining dispersion stability over time, thereby improving the stability of the ink composition.
Implementation Method 1
the polymer dispersant having a crosslinking structure contains a structural unit represented by Formula (1) and a structural unit represented by Formula (2)... a hydrophilicity/hydrophobicity ratio represented by the following expression is 8 or more
Implementation Method 2
the polymer dispersant having a crosslinking structure contains a structural unit represented by Formula (1) and a structural unit represented by Formula (2)... an Ar valence of the polymer dispersant having a crosslinking structure, which is represented by the following expression, is 0.4 mmol/g to 2.9 mmol/g
Implementation Method 3
the polymer dispersant having a crosslinking structure further contains a structural unit represented by Formula (1) and a structural unit represented by Formula (2)... the polymer dispersant having a crosslinking structure is formed by crosslinking an uncrosslinked polymer dispersant
Data Source
AI summary
Provided are a pigment dispersion containing water, a pigment, and a polymer dispersant having a crosslinking structure, in which the polymer dispersant having a crosslinking structure contains a structural unit represented by Formula (1) and a structural unit represented by Formula (2); and an ink composition. R1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R2 represents an alkylene group having 2 to 5 carbon atoms, R3 represents an aromatic group, X1 and X2 each independently represent -O- or -NH-, m represents an integer of 2 or more, R4 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R5 represents an alkyl group having 8 or more carbon atoms, and X3 represents -O- or -NH-.