Ink Set Dynamic Surface Tension Control for Bleeding Suppression
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Solution Overview
Problem
Existing ink jet recording methods face challenges in achieving high image quality on recording media with ink gradation and color uniformity, particularly due to issues like blurring and bleeding, which are not effectively addressed by previous proposals focusing on static and dynamic surface tension adjustments.
Innovation Solution
An ink set with specific dynamic surface tension characteristics is developed, where the difference between the dynamic surface tension at 50 milliseconds and 500 milliseconds is controlled, along with the lightness relationship between inks, to suppress bleeding and improve gradation and color uniformity on plain paper and ink-receiving layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the area of one dot is reduced to improve gradation, then gradation is improved, but a plurality of dots are apt to link with each other causing blurring
Solution Approach 1:
The invention changes the surface tension parameter of the ink from static to dynamic control. By controlling the dynamic surface tension at specific lifetimes (0.2 sec or less: 40 mN/m or more; 1 sec or more: less than 50 mN/m), the ink maintains proper dot formation without excessive spreading, preventing dot linking and blurring while preserving gradation quality.
Solution Approach 2:
The invention introduces dynamic surface tension control that changes over time (lifetime). The surface tension is not fixed but varies according to the lifetime parameter, allowing different tension values at different time points during ink deposition and drying, thereby controlling both dot formation and prevention of blurring.
2Object-affected harmful factors
If the surface tension of ink is increased to suppress blurring, then blurring is suppressed, but the ink is unable to wet the surface uniformly reducing color uniformity
Solution Approach 1:
The invention uses dynamic surface tension that varies with lifetime to resolve the contradiction. At early stages (short lifetime), higher surface tension prevents blurring, while at later stages (longer lifetime), the surface tension adjusts to allow uniform wetting and color distribution, achieving both anti-blurring and color uniformity.
Solution Approach 2:
The surface tension parameter is changed over time through dynamic control. By specifying surface tension values at different lifetime points (0.2 sec and 1 sec), the invention enables the ink to exhibit different wetting behaviors at different time points, suppressing blurring initially while ensuring uniform color distribution subsequently.
3Object-affected harmful factors
If the surface tension of ink is increased to suppress blurring, then blurring is suppressed, but the permeability of ink into the recording medium is reduced causing ink migration
Solution Approach 1:
The invention changes the surface tension parameter dynamically over lifetime. By controlling surface tension at specific lifetime points, the ink achieves optimal balance between preventing surface blurring and enabling controlled permeation into the recording medium, thereby preventing ink migration while suppressing blurring.
Solution Approach 2:
The dynamic surface tension characteristic allows the ink to exhibit time-dependent behavior. At short lifetime, high surface tension prevents blurring; at longer lifetime, the surface tension evolution enables proper permeation control, preventing ink migration issues that occur with statically high surface tension inks.
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 ink set effectively suppresses bleeding and enhances image gradation while maintaining color uniformity, even on media with ink-receiving layers, by optimizing the dynamic surface tension and lightness relationships between inks, ensuring proper wetting and permeation.
Implementation Method 1
the blurring of ink is suppressed by setting the surface tension of the ink in a bubble period T (second/bubble) of 0.2 or less to be 40 mN/m or more, and the ejection reliability of the ink is improved by setting the surface tension of the ink in a bubble period T (second/bubble) of more than 1 to be less than 50 mN/m
Implementation Method 2
the permeability of the ink into the recording medium is reduced, so it takes a long time for the ink to finish permeating into the recording medium
Data Source
AI summary
An ink set is provided which can suppress bleeding irrespective of the type of recording medium. The ink set includes a plurality of aqueous inks each containing a dye, and has at least a first aqueous ink containing a dye, wherein the difference between the dynamic surface tension of the first aqueous ink at a lifetime of 50 milliseconds and the dynamic surface tension of the first aqueous ink at a lifetime of 500 milliseconds is 7 mN/m or more; and, between the first aqueous ink and at least one type of aqueous ink except the first aqueous ink included in the ink set, dynamic surface tension γa (mN/m) of an ink A having relatively higher lightness at a lifetime of 500 milliseconds and dynamic surface tension γb (mN/m) of an ink B having relatively lower lightness at a lifetime of 500 milliseconds satisfy −5≦(γa−γb)≦3.