Ink-Jet Ink Composition for High Optical Density and Stability
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Solution Overview
Problem
Ink-jet recording methods face challenges in achieving high optical density while maintaining ink stability, as increasing pigment concentration to improve optical density often leads to decreased stability.
Innovation Solution
The use of an ink composition comprising water, a water-soluble organic solvent, a self-dispersible pigment, a water-soluble N-hydroxy cyclic imide compound, and a surfactant of sulfuric acid ester salt type, which facilitates pigment aggregation and dispersion, improving optical density without compromising stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If pigment concentration in the ink is increased to improve optical density, then optical density is improved, but stability of the ink is decreased
Solution Approach 1:
A water-soluble N-hydroxy cyclic imide compound is introduced as an intermediary substance that mediates between the self-dispersible pigment particles and the aqueous medium. This compound adsorbs onto the pigment surface and provides hydrophilic groups that enhance water solubility and prevent aggregation, allowing high pigment concentration while maintaining ink stability.
Solution Approach 2:
The invention changes the chemical parameters of the ink system by introducing specific functional compounds (N-hydroxy cyclic imide compound and sulfuric acid ester salt type surfactant) that modify the surface properties of pigment particles. This enables the system to accommodate higher pigment concentrations without sacrificing stability, as the modified surface parameters prevent unwanted aggregation.
2Illumination intensity
If self-dispersible pigment is used to eliminate dispersant and improve optical density, then optical density is improved, but pigment aggregation occurs reducing ink stability
Solution Approach 1:
The water-soluble N-hydroxy cyclic imide compound acts as a mediator that bridges the hydrophobic pigment particles and the hydrophilic aqueous environment. It adsorbs onto the pigment surface through hydrophobic interactions and extends into the water phase through hydrophilic groups, preventing direct pigment-pigment aggregation while maintaining high optical density.
Solution Approach 2:
The invention creates a composite structure where the self-dispersible pigment particles are coated or associated with N-hydroxy cyclic imide compound molecules. This composite approach combines the high optical density properties of the pigment with the stabilizing properties of the imide compound, achieving both goals simultaneously.
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 effectively enhances optical density while maintaining the stability of the ink, allowing for superior image quality without the need for additional treatment solutions.
Implementation Method 1
a surfactant of sulfuric acid ester salt type
Implementation Method 2
a self-dispersible pigment; a water-soluble N-hydroxy cyclic imide compound
Data Source
AI summary
There is provided an ink for ink-jet recording including: water; a water-soluble organic solvent; a water-soluble N-hydroxy cyclic imide compound; a self-dispersible pigment; and a surfactant of sulfuric acid ester salt type.