Multivalent Cation Modified Self-Dispersing Pigment Inkjet Inks
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Solution Overview
Problem
Current inkjet ink formulations do not adequately address the need for improved bleed properties and optical density in printing quality, particularly in aqueous inkjet inks containing self-dispersing pigments.
Innovation Solution
An aqueous pigment dispersion is created with self-dispersing pigments having hydrophilic functional groups, such as carboxyl groups, and multivalent cations like Mg2+, Ca2+, Cu2+, Al3+, which are adsorbed onto the pigment via ionic bonds, enhancing the ink's stability and optical density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If monovalent salts are added to improve optical density, then optical density increases, but bleed properties deteriorate
Solution Approach 1:
The patent changes the ionic parameter from monovalent to multivalent cations, fundamentally altering the electrostatic interaction mechanism with pigment particles. This parameter change enables simultaneous improvement of optical density and bleed resistance by creating stronger ionic bonds that prevent both excessive pigment aggregation (improving OD) and pigment migration (improving bleed resistance).
Solution Approach 2:
The invention creates a composite system combining self-dispersing pigments with multivalent cations, where the synergistic interaction between the carboxyl-functionalized pigment surface and multivalent cations produces enhanced performance. The composite effect generates improved optical density through controlled aggregation while maintaining bleed resistance through strong ionic attachment.
2Illumination intensity
If multivalent cations are added at ink formulation stage, then optical density improves, but pigment dispersion stability worsens
Solution Approach 1:
The patent applies preliminary action by pre-functionalizing the pigment surface with carboxyl groups before adding multivalent cations. This preliminary modification ensures that when multivalent cations are introduced, they bind to predetermined sites on the pigment surface, creating stable ionic complexes that enhance optical density without compromising dispersion stability.
Solution Approach 2:
The carboxyl functional groups act as intermediaries between the pigment particles and multivalent cations. These intermediary groups facilitate controlled ionic bonding, allowing the multivalent cations to enhance optical density while the carboxyl groups maintain dispersion stability by providing uniform distribution and preventing uncontrolled aggregation.
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 solution results in inkjet inks with improved bleed properties and increased optical density, ensuring better printing quality by stabilizing the pigment dispersion and optimizing the interaction between the pigment and multivalent cations.
Implementation Method 1
a multivalent cation selected from the group consisting of Mg2+, Ca2+, Cu2+, Al3+, Fe3+, and mixtures thereof, wherein said cation is adsorbed onto said self-dispersing pigment via ionic bonds between the cation and surface acid group on the self-dispersing pigment
Data Source
AI summary
This invention pertains to aqueous inkjet inks containing self-dispersing pigments. The self-dispersing pigments are modified with multivalent cations.