Ink Set Surface Tension Control for Transparent Substrate Bleeding
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Solution Overview
Problem
Existing recording technologies face issues with bleeding and color mixing between background and coloring ink compositions due to differences in physical properties, leading to blurring and impaired image quality, especially when using optically transparent substrates.
Innovation Solution
The proposed solution involves an ink set with a background ink composition and a coloring ink composition where the surface tension difference is set between -5 and 4 mN/m, using agents like glycol ethers, polyether siloxane-based surfactants, and fluorosurfactants to inhibit bleeding and aggregation, and a recording apparatus with controlled drying units to enhance drying times and prevent pigment sinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a white ink as a background ink composition and a coloring ink composition are recorded in a state of being adjacent to each other or superposed on each other, then an image can be formed on optically transparent substrates, but color mixing called bleeding or blurring may be caused in the boundary between the respective ink compositions
Solution Approach 1:
The patent adjusts the surface tension parameter of the background ink composition to be lower than that of the coloring ink composition (difference greater than -5 and less than 4 mN/m). This parameter change ensures that the background ink wets the substrate first and prevents the coloring ink from penetrating into it, thereby preventing bleeding and color mixing while maintaining image definition.
2Stability of the object's composition
If a background ink composition containing a background pigment is caused to be superposed on a color image, then a uniform background image can be formed, but the background pigment may sink into the color image causing color mixing or bleeding
Solution Approach 1:
The patent applies the background ink composition first to the substrate and allows it to dry completely before applying the coloring ink composition. This preliminary action ensures that the background ink forms a stable, non-porous layer that prevents subsequent pigment sinking, while maintaining uniform background coverage.
Solution Approach 2:
The patent controls the surface tension of the background ink composition to be lower than that of the coloring ink composition, creating a surface energy gradient that prevents pigment sinking. This parameter change ensures that even when superposed, the background pigment remains in its layer and does not penetrate into the color image.
3Productivity
If the background ink composition has high pigment sedimentation speed, then the ink dries faster, but the background pigment easily blurs with the underlying image
Solution Approach 1:
The patent adjusts the surface tension parameter of the background ink composition to be lower than that of the coloring ink composition. This parameter change allows the background ink to spread and wet the substrate quickly (maintaining high drying speed) while forming a stable configuration that prevents pigment sinking and blurring, thus resolving the contradiction between drying speed and image definition.
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
This approach effectively prevents bleeding and color mixing, ensuring a uniform and clear image with improved wettability and drying properties, maintaining the transparency of optically transparent substrates.
Implementation Method 1
a difference of surface tension between the background ink composition and the coloring ink composition is set to be greater than -5 and less than 4
Implementation Method 2
drying of the background ink composition is accelerated, whereby the background pigment may be prevented from sinking into the color image
Data Source
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AI summary
An ink set includes a background ink composition containing a background pigment and a coloring ink composition containing a coloring pigment. Provided that the surface tension of the background ink composition is S1 (mN/m), and the surface tension of the coloring ink composition is S2 (mN/m), S1 and S2 satisfy -5 < (S1 - S2) < 4. the ink set is used in a first mode in which the background ink composition and the coloring ink composition are recorded on a recording medium by being caused to be adjacent to each other, or in a second mode in which the background ink composition is recorded on an image which has been recorded using the coloring ink composition. A recording apparatus includes this ink set.