Dual-Layer Pigment Ink Method for Optical Density and Scratch Resistance
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Solution Overview
Problem
Existing image recording methods using anionic and cationic pigment black inks achieve high optical density but suffer from low highlighter resistance, as the pigments either remain on the surface and are easily scratched or penetrate inside the medium, leading to a trade-off between optical density and highlighter resistance.
Innovation Solution
An image recording method involving a first black ink containing a salt with specific ions and anions, which promotes pigment aggregation near the surface, and a second black ink that reacts with the salt to enhance dispersion stability, ensuring both high optical density and highlighter resistance by controlling the aggregation reaction and surface tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If anionic pigment black ink is caused to react with cationic pigment black ink, then the optical density of the image improves, but the highlighter resistance of the image becomes low
Solution Approach 1:
The invention divides the ink application into two separate processes: first applying a black ink containing a salt (without or with minimal pigment), then applying a second black ink containing pigment. This segmentation allows the salt to remain in the surface layer to provide highlighter resistance, while the pigment from the second ink provides optical density, resolving the contradiction between the two properties.
Solution Approach 2:
The salt is applied in advance through the first ink layer before the pigment-containing second ink is applied. This preliminary action ensures that the salt is already positioned in the surface layer to prevent highlighter penetration, while the subsequent pigment application ensures high optical density without disrupting the salt's protective function.
2Illumination intensity
If pigments remain on the surface of the record medium, then the optical density improves, but the pigments are easily scratched away reducing highlighter resistance
Solution Approach 1:
The salt acts as an intermediary substance between the pigment and the record medium surface. The salt forms a stable layer that anchors the pigment particles, preventing them from being easily scratched away while still allowing the pigment to provide high optical density. This intermediary layer resolves the contradiction between surface pigment retention and scratch resistance.
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 method achieves a balance between high optical density and highlighter resistance by promoting pigment aggregation near the surface, preventing penetration and enhancing dispersion stability, thus overcoming the trade-off in previous methods.
Implementation Method 1
promotes pigment aggregation near the surface
Implementation Method 2
enhance dispersion stability
Implementation Method 3
the static surface tension of the first black ink is higher than the static surface tension of the second black ink
Data Source
AI summary
The image recording method includes a first process of applying a first black ink containing a pigment to a record medium; and, after the first process, a second process of applying a second black ink containing a pigment to the record medium such that the second ink at least partly overlaps the first black ink, in which the first black ink contains a salt containing at least one kind of cation selected from the group consisting of an alkali metal ion, an ammonium ion, and an organic ammonium ion and at least one kind of anion, and the static surface tension of the first black ink is higher than the static surface tension of the second black ink.