Cationic Modified Self-Dispersing Pigment Dispersion Stability
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Solution Overview
Problem
There is a need for stable self-dispersing pigment dispersions that can be readily formulated into inkjet inks, as existing solutions do not consistently provide optimal optical density and stability.
Innovation Solution
The development of an aqueous pigment dispersion comprising self-dispersing pigments with hydrophilic functional groups, multivalent cations (such as Mg2+, Ca2+, Cu2+, and Al3+) adsorbed via ionic bonds, and an anionic polymeric binder, which are used to enhance the stability and optical density of the ink.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-dispersing pigments are used in aqueous inkjet inks, then the ink formulation is simplified and stability is improved, but optical density is insufficient
Solution Approach 1:
The patent changes the chemical parameter of the pigment surface by introducing carboxyl groups through oxidation treatment, which enables ionic bonding with multivalent cations. This parameter change transforms the pigment surface properties to achieve both stability and enhanced optical density
Solution Approach 2:
The patent creates a composite structure by combining self-dispersing pigment particles with multivalent cations (such as Ca2+, Mg2+, Al3+) and anionic polymeric binders. This composite approach allows the system to achieve both dispersion stability and high optical density simultaneously
2Illumination intensity
If multivalent cations are added to enhance optical density, then optical density improves, but dispersion stability may be compromised
Solution Approach 1:
The anionic polymeric binder acts as an intermediary between the multivalent cations and the pigment particles. The binder adsorbs the cations and presents them to the pigment surface in a controlled manner, preventing direct aggregation that would compromise stability while maintaining optical density enhancement
Solution Approach 2:
The patent replaces simple physical mixing with a chemically driven assembly process. The ionic bonding between carboxyl groups and multivalent cations, mediated by the anionic polymer, creates a chemically stabilized structure that maintains both optical density and dispersion stability
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 solution results in stable and high-optical-density inkjet inks with improved jettability and reduced clogging, achieved by the combination of hydrophilic functional groups, multivalent cations, and anionic polymeric binders, which enhance the dispersion stability and performance.
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 self-dispersing pigment dispersions. The self-dispersing pigments are modified with a multivalent cation and an anionic polymer.