Aqueous Ink Dynamic Surface Tension for Image Density
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Solution Overview
Problem
Ink jet recording methods using pigment inks with dispersants face issues with image density when overlapping with color inks, as the dispersant stabilizes pigment dispersion, leading to low aggregation and permeation into the recording medium, affecting scratch resistance and fixing ability.
Innovation Solution
An aqueous ink with a reactive component that destabilizes pigment dispersion, having a dynamic surface tension of 41 mN/m or more at 30 milliseconds and 28-38 mN/m at 500 milliseconds, is used to enhance image density and fixing ability without compromising ejection stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a dispersant is added to pigment ink to stabilize pigment dispersion, then pigment dispersion stability is improved, but image density is lowered when overlapping with color ink
Solution Approach 1:
The patent changes the chemical parameters of the ink system by introducing a reactive component that modifies the dispersant-pigment interaction. This allows the pigment dispersion to transition from a stable non-aggregating state to a controlled aggregating state upon contact with color ink, resolving the contradiction between dispersion stability and image density
Solution Approach 2:
The reactive component acts as an intermediary between the dispersant and the pigment. It interferes with the dispersant's stabilizing action, preventing excessive pigment aggregation while still allowing controlled aggregation when color ink is present, thus maintaining both dispersion stability and image density
2Manufacturing precision
If a component for aggregating pigment is added to color ink to enhance image density, then image density is improved, but ejection stability is lowered
Solution Approach 1:
The patent extracts the pigment aggregation function from the color ink and transfers it to the pigment ink by adding a reactive component there. This allows the color ink to remain free of aggregation-inducing components, maintaining ejection stability, while still achieving pigment aggregation through the reactive component in the pigment ink
Solution Approach 2:
Instead of adding aggregation components to the color ink as conventionally done, the patent inverts the approach by adding a reactive component to the pigment ink that induces aggregation when mixed with color ink. This reverse strategy achieves image density enhancement without compromising color ink ejection stability
3Manufacturing precision
If the surface tension of color ink is increased to prevent pigment aggregation, then image density is improved, but fixing ability is lowered
Solution Approach 1:
The patent changes the surface tension parameter of the color ink to an optimized range that balances two competing requirements: high enough to prevent premature pigment aggregation and maintain image density, but low enough to ensure proper permeation into the recording medium for adequate fixing ability
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 aqueous ink achieves high image density, excellent scratch resistance, and improved fixing ability by destabilizing pigment dispersion, ensuring effective aggregation and permeation, while maintaining ink ejection stability.
Implementation Method 1
the dispersion state of the pigment, the tendency of the pigment to aggregate is relatively low. Therefore, the color ink to be used together with such a pigment ink fails to allow an aggregated pigment to be sufficiently present on a recording medium
Implementation Method 2
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 to be used together with a pigment ink containing a pigment and a polymer, wherein the aqueous ink contains a reactive component for destabilizing the dispersion state of the 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.