Aqueous Ink Dynamic Surface Tension Control for Bleeding Prevention
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Solution Overview
Problem
Ink jet recording methods face challenges in forming high-quality full-color images on various papers, particularly with bleeding and color unevenness when using black and color inks, especially during high-speed one-pass bi-directional recording.
Innovation Solution
An aqueous ink with a reactive component is used in combination with a black ink containing a self-dispersion pigment, where the dynamic surface tension of the aqueous ink is optimized to 41 mN/m or more at 30 milliseconds and between 28 mN/m and 38 mN/m at 500 milliseconds, to inhibit bleeding and color unevenness by controlling the interaction and permeation of inks on the recording medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the permeability of color inks is increased to improve fixing ability and inhibit bleeding, then the fixing ability improves, but the black ink may become unevenly mixed with color ink lowering image quality
Solution Approach 1:
The invention changes the surface tension parameters of the inks, specifically making the black ink have higher surface tension than color inks. This parameter change allows the black ink to resist permeation into the recording medium while color inks with lower surface tension can penetrate and fix properly, resolving the contradiction between fixing ability and image quality
Solution Approach 2:
Instead of making color inks have higher surface tension to prevent mixing with black ink, the invention inverts the approach by making black ink have higher surface tension. This reversal allows color inks to penetrate the recording medium for good fixing while the high surface tension black ink remains on the surface, preventing unwanted mixing
2Manufacturing precision
If the surface tension of black ink is increased to improve character quality, then character quality improves, but bleeding occurs at boundary portions between black ink and color ink images
Solution Approach 1:
The invention changes the surface tension parameter of black ink to be higher than that of color inks. This parameter change allows the black ink to maintain high surface tension for good character quality while the lower surface tension color inks can penetrate the recording medium, preventing bleeding at boundaries through proper permeation control
3Manufacturing precision
If multi-pass recording is used to achieve excellent image quality, then image quality improves, but recording time is not sufficiently shortened
Solution Approach 1:
The invention applies color inks first to the recording medium, allowing them to penetrate and fix in advance. Then black ink is applied on top, which due to its higher surface tension, remains on the surface without excessive permeation. This preliminary action sequence enables one-pass recording to achieve quality comparable to multi-pass recording while significantly reducing recording time
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 optimized ink set achieves high image quality by preventing bleeding and color unevenness, ensuring uniformity and density across images formed with both black and color inks, even at high recording speeds.
Implementation Method 1
the dynamic surface tension of the aqueous ink at a lifetime of 30 milliseconds is 41 mN/m or more, and the dynamic surface tension of the aqueous ink at a lifetime of 500 milliseconds is from 28 mN/m or more to 38 mN/m or less
Data Source
AI summary
An aqueous ink used together with a black ink containing a self-dispersion pigment, wherein the aqueous ink contains a reactive component for destabilizing the dispersion state of the self-dispersion pigment, the dynamic surface tension of the aqueous ink at a lifetime of 30 milliseconds is 41 mN/m or more, and the dynamic surface tension of the aqueous ink at a lifetime of 500 milliseconds is from 28 mN/m or more to 38 mN/m or less as determined by a maximum bubble pressure method.