Quinacridone Pigment Composition for Stable Inkjet Ink Dispersion
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Solution Overview
Problem
Quinacridone pigments used in inkjet inks exhibit low initial viscosity but undergo thickening after storage, leading to insufficient dispersion stability and dispersion stability issues.
Innovation Solution
A pigment composition containing quinacridone pigment and a compound represented by formula (I), where some hydrogen atoms in the benzene rings are substituted with sulfonic acid aluminum salts, interacting with a binder resin to enhance dispersion stability and storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If quinacridone pigments are used in inkjet inks, then initial dispersibility is achieved, but dispersion stability deteriorates due to thickening after storage
Solution Approach 1:
The patent changes the chemical structure of the quinacridone pigment by introducing specific substituents (sulfonic acid groups, hydroxyl groups, or carboxylic acid groups) at positions 1, 5, 6, or 8 of the quinacridone ring system. This structural modification alters the pigment's interaction with the binder resin, preventing excessive thickening during storage while maintaining good initial dispersibility in inkjet inks.
Solution Approach 2:
The patent creates a composite pigment structure by combining quinacridone core with specific functional groups (sulfonic acid, hydroxyl, or carboxylic acid) at defined positions. This composite structure enables simultaneous achievement of good dispersibility and storage stability by balancing hydrophilic and hydrophobic interactions with the binder resin.
2Ease of operation
If conventional quinacridone pigments are used, then initial viscosity is low, but storage stability worsens due to thickening
Solution Approach 1:
The patent modifies the quinacridone pigment structure by adding specific functional groups that control the pigment-resin interaction. These structural parameter changes ensure the pigment maintains appropriate viscosity characteristics during storage without excessive thickening, while keeping initial viscosity low for good inkjet printability.
3Object-affected harmful factors
If dehalogenation is pursued for environmental safety, then use of dichloroquinacridone-sulfonic acid metal salts is reduced, but dispersion stability may deteriorate
Solution Approach 1:
The patent replaces conventional dichloroquinacridone-sulfonic acid metal salts with alternative quinacridone pigment structures containing sulfonic acid groups, hydroxyl groups, or carboxylic acid groups. These alternative structures achieve dehalogenation (removing harmful chlorine atoms) while maintaining or improving dispersion stability through the strategically positioned functional groups that enhance interaction with binder resin.
Solution Approach 2:
The patent changes the chemical composition parameters of the quinacridone pigment by introducing environmentally friendly functional groups (sulfonic acid, hydroxyl, or carboxylic acid) at specific positions, replacing the harmful dichloro groups. This parameter change eliminates environmental hazards while maintaining dispersion stability through the new functional groups' interaction with the binder resin.
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 pigment composition achieves high dispersion stability and excellent storage stability, making it suitable for inkjet inks.
Implementation Method 1
a compound represented by formula (I), in which some hydrogen atoms in the benzene rings are substituted with sulfonic acid aluminum salts, interacting with a binder resin
Data Source
AI summary
An object of the present invention is to provide a pigment composition that is suitable as an IJ ink and has high dispersion stability and excellent storage stability, a coloring agent containing the pigment composition, and, in particular, an IJ ink. The pigment composition of the present invention contains a quinacridone pigment and a compound represented by formula (I) below. In formula (I), n represents an integer of 1 to 8. At least C.I. Pigment Red 122 is preferably contained as the quinacridone pigment.