Self-Dispersible Aqueous Ink for Color Density and Storage Stability
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Solution Overview
Problem
Existing aqueous inks using self-dispersible pigments face challenges in achieving both high color developability and storage stability, particularly on recording media with low color developability, due to pigment sinking into the medium and aggregation during long-term use, which affects image quality and ink stability.
Innovation Solution
The use of a self-dispersible pigment with specific functional groups bonded to its surface, where the molar ratio of anionic groups is controlled between 0.20 to 0.97, enhancing adsorption to cellulose for improved color developability and electrostatic repulsion for stability, without accelerating pigment aggregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If self-dispersible pigments with high reactivity functional groups are used to improve color developability, then color developability is improved, but storage stability deteriorates due to pigment aggregation
Solution Approach 1:
The patent changes the chemical parameters of the pigment surface by introducing two types of functional groups with different reactivities. The first functional group provides high reactivity for color developability, while the second functional group with lower reactivity prevents excessive aggregation. The molar ratio of these functional groups is controlled to optimize both color developability and storage stability.
Solution Approach 2:
The patent creates a composite functional structure on the pigment surface by combining two different functional groups. This composite approach allows the pigment to exhibit both high reactivity (for color developability) and controlled stability (for storage), resolving the contradiction between these two properties.
2Manufacturing precision
If functional groups with high reactivity are bonded to pigment surface to enhance color developability, then color developability is improved, but pigment aggregation accelerates during storage
Solution Approach 1:
The patent modifies the surface chemistry parameters of the pigment by introducing functional groups with specific reactivity levels. The first functional group enhances color developability through high reactivity, while the second functional group controls aggregation by providing moderate reactivity, thus maintaining particle diameter stability during storage.
Solution Approach 2:
The patent applies different functional groups to different locations on the pigment surface, creating local variations in reactivity. The first functional group is positioned to provide high reactivity for color development, while the second functional group is distributed to prevent aggregation, achieving both color developability and particle stability.
3Manufacturing precision
If aqueous ink is used to achieve good image quality, then color developability is improved on some media, but storage stability deteriorates due to pigment aggregation
Solution Approach 1:
The patent changes the chemical composition parameters of the ink by incorporating pigments with dual functional groups. This allows the ink to achieve good color developability on various recording media while maintaining storage stability, as the functional groups control both reactivity and aggregation behavior.
Solution Approach 2:
The patent uses a composite pigment structure with two types of functional groups to create an aqueous ink that balances color developability and storage stability. The first functional group ensures good color development, while the second functional group prevents aggregation during storage, resolving the contradiction in aqueous ink performance.
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 achieves both satisfactory color developability and storage stability of the ink by optimizing the molar ratio of functional groups, ensuring effective interaction with cellulose and preventing pigment aggregation.
Implementation Method 1
enhancing adsorption to cellulose for improved color developability
Implementation Method 2
electrostatic repulsion for stability
Data Source
AI summary
The aqueous ink for ink jet includes a self-dispersible pigment in which functional groups are bonded to a surface of a particle of a pigment and include a first functional group represented by the formula (1) and a second functional group including at least one kind of group represented by the formula (2). A molar ratio of an anionic group amount of the first functional group to a total anionic group amount of the first functional group and the second functional group in the self-dispersible pigment is 0.20 times or more to 0.97 times or less. In the formula (2), two of R1 to R5 each represent COOM2 and three thereof represent hydrogen atoms, and the two COOM2s are adjacent to each other or are present at positions sandwiching one carbon atom for forming a benzene ring.