Ink Composition Stabilizing Pigments with Dispersant
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Solution Overview
Problem
Pigment-based inkjet inks are difficult to formulate due to challenges in suspending pigments, leading to aggregation and print defects, while dye-based inks lack light and water resistance.
Innovation Solution
An ink composition comprising a dispersion medium, at least one pigment, a dispersant, a durable polymer, and a dispersion additive, such as a quinacridone derivative, which stabilizes the pigments and enhances dispersibility and dispersion stability, preventing aggregation and improving print quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pigment-based inks are used, then light and water resistance is improved, but pigment aggregation occurs leading to formulation difficulty
Solution Approach 1:
The patent introduces a dispersant as an intermediary substance between the pigment particles and the ink vehicle. The dispersant molecules adsorb onto the pigment surface, providing steric or electrostatic stabilization that prevents pigment aggregation while maintaining compatibility with the ink matrix, thereby resolving the formulation difficulty of pigment-based inks
Solution Approach 2:
The patent creates a composite system combining pigment particles, dispersant molecules, and ink vehicle components. This composite approach allows the pigment to maintain its light and water resistance properties while the dispersant and vehicle work together to prevent aggregation, achieving both durability and ease of formulation
2Reliability
If pigment particles are suspended in ink matrix, then light and water resistance is improved, but pigment aggregation occurs
Solution Approach 1:
The dispersant acts as a mediator between pigment particles and the ink vehicle, adsorbing onto pigment surfaces to provide repulsive forces that prevent aggregation. This maintains stable suspension of pigment particles in the ink matrix while preserving the light and water resistance properties
Solution Approach 2:
The patent modifies the surface properties of pigment particles through dispersant adsorption, changing parameters such as surface charge (zeta potential) or surface hydrophobicity. These parameter changes create repulsive interactions between particles, preventing aggregation and maintaining stable suspension
3Ease of manufacture
If dyes are used in inkjet inks, then ease of formulation is improved, but light and water resistance deteriorates
Solution Approach 1:
The patent fundamentally changes the chemical nature of the coloring agent from soluble dyes to insoluble pigment particles. This parameter change (from molecular to particulate form) provides inherent light and water resistance, while the use of dispersants and optimized ink vehicles maintains ease of formulation through controlled dispersion processes
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 ink composition achieves high print quality with enhanced pigment dispersibility and stability, reducing print defects and improving the durability of printed images against light and water exposure.
Implementation Method 1
a dispersant... which stabilizes the pigments and enhances dispersibility and dispersion stability
Implementation Method 2
a dispersion additive, such as a quinacridone derivative, which stabilizes the pigments and enhances dispersibility and dispersion stability, preventing aggregation
Data Source
AI summary
An ink composition is described herein. In one example, an ink includes at least one pigment, at least one dispersant, and at least one durable polymer in a water-based dispersion medium including at least one hydrophilic solvent. The dispersant is present at from about 0.05 wt% to about 15 wt% of the ink composition. Further, the ink composition includes at least one dispersion additive.