Cross-Linked Pigment Dispersion for Stable Inkjet Ejectability
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Solution Overview
Problem
Existing inkjet inks face challenges in maintaining storage stability and ink ejectability under varying temperatures, particularly when subjected to high and low temperatures, due to the trade-off between cross-linking processes that enhance storage stability but can lead to nozzle clogging.
Innovation Solution
An aqueous pigment dispersion comprising a cross-linked polymer formed from a water-soluble dispersion resin with an anionic group and a cross-linking agent having two or more epoxy groups, with a cross-linking ratio of over 80%, ensuring excellent storage stability and ink ejectability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cross-linking process is used to improve storage stability, then storage stability is improved, but ink ejectability deteriorates due to nozzle clogging
Solution Approach 1:
The patent changes the chemical parameters of the cross-linking system by specifying a cross-linking ratio of more than 80%, using a water-soluble dispersion resin with specific anionic groups, and controlling the acid value within 181-220 mgKOH/g. These parameter changes ensure that cross-linking occurs primarily on the pigment surface rather than in bulk, maintaining ink ejectability while improving storage stability
Solution Approach 2:
The cross-linking reaction is localized to the pigment particle surface through adsorption of the dispersion resin onto the pigment. This local cross-linking creates a stable coating on pigment particles without causing bulk gelation, thereby preventing nozzle clogging while achieving storage stability
2Reliability
If the cross-linking ratio is increased to improve storage stability under high temperatures, then storage stability is improved, but the risk of agglomeration and nozzle clogging increases
Solution Approach 1:
The patent specifies a cross-linking ratio of more than 80% while controlling the acid value of the dispersion resin within 181-220 mgKOH/g. This precise parameter control ensures sufficient cross-linking for thermal stability while preventing excessive cross-linking that would cause agglomeration
Solution Approach 2:
The water-soluble dispersion resin with anionic groups acts as an intermediary between the pigment and the cross-linking agent. It adsorbs onto the pigment surface and provides controlled cross-linking sites, mediating the cross-linking process to achieve high stability without agglomeration
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 dispersion provides an inkjet ink with enhanced storage stability and printability, even under temperature fluctuations, by preventing agglomeration and maintaining ink ejectability.
Implementation Method 1
a cross-linked polymer having a cross-linking ratio of more than 80%, wherein the cross-linked polymer is a reaction product of a dispersion resin having an anionic group and a cross-linking agent
Implementation Method 2
a dispersion resin having an anionic group and a water-insoluble polymer having an anionic group
Data Source
AI summary
Provided is an aqueous pigment dispersion having water, a pigment, and a cross-linked polymer, wherein the cross-linked polymer is a reaction product of a dispersion resin having an anionic group and a cross-linking agent, the dispersion resin having an anionic group is water soluble and has an acid value of 181 to 220 mgKOH/g, the cross-linking agent is a water-soluble compound having two or more epoxy groups, and the cross-linked polymer has a cross-linking ratio of more than 80%. The aqueous pigment dispersion can be used to produce an inkjet ink that maintains excellent storage stability even under high temperatures or in an environment with widely varied temperatures, and has excellent printability.