Water-Based Ink Formulation for High Optical Density
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Solution Overview
Problem
Water-based pigment inks for ink-jet recording often suffer from strike-through, where the ink is visible from the backside due to low optical density, especially when high pigment solid content is used.
Innovation Solution
A water-based ink formulation incorporating a pigment, water, a nonionic surfactant with an ethylene oxide chain, an anionic surfactant with an ethylene oxide chain, and a glycol ether penetrant, where the average number of ethylene oxide groups in these components satisfy specific conditions to prevent strike-through while achieving high optical density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high pigment solid content is used to achieve high optical density, then the optical density increases, but strike-through occurs where ink becomes visible from the backside
Solution Approach 1:
The patent changes the chemical parameters of the ink formulation by specifying precise relationships between the average numbers of ethylene oxide groups in nonionic surfactant (X), anionic surfactant (Y), and penetrant (Z), where |X-Y|≤1, |Y-Z|≤1, and |Z-X|≤1. This parameter control optimizes surfactant effectiveness and penetrant action to prevent strike-through while maintaining high optical density.
Solution Approach 2:
The patent uses a composite surfactant system combining both nonionic and anionic surfactants with ethylene oxide chains, along with a penetrant containing ethylene oxide groups. This composite approach creates synergistic effects where the surfactants work together to control ink behavior and the penetrant moderates penetration, resolving the contradiction between optical density and strike-through prevention.
2Reliability
If high pigment solid content is used, then the ink remains on the recording sheet better, but the ink penetrates vertically through the sheet causing strike-through
Solution Approach 1:
The patent controls the penetrant's ethylene oxide group count (Z) within specific ranges and maintains |Y-Z|≤1 and |Z-X|≤1, where Y and X are the ethylene oxide group counts of anionic and nonionic surfactants. This parameter optimization ensures the penetrant sufficiently moderates vertical penetration while the surfactants maintain ink retention on the recording sheet surface.
Solution Approach 2:
The penetrant containing ethylene oxide groups acts as an intermediary substance that moderates the ink's penetration into the recording sheet. By selecting a penetrant with controlled ethylene oxide content that matches the surfactants (|Y-Z|≤1, |Z-X|≤1), the patent creates a balanced system where penetration is sufficiently reduced without compromising ink retention or optical density.
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 achieves high optical density while preventing strike-through, even with high pigment solid content, and exhibits better quick-drying properties, ensuring the ink remains on the recording sheet without penetrating vertically.
Implementation Method 1
a nonionic surfactant having an ethylene oxide chain; an anionic surfactant having an ethylene oxide chain; and a penetrant having an ethylene oxide chain
Implementation Method 2
the nonionic surfactant, the anionic surfactant, and the penetrant satisfy the following conditions (I) to (III)
Data Source
Figure 1
AI summary
A water-based ink for ink-jet recording includes: a pigment; water; a nonionic surfactant having an ethylene oxide chain; an anionic surfactant having an ethylene oxide chain; and a penetrant having an ethylene oxide chain, wherein the nonionic surfactant, the anionic surfactant, and the penetrant satisfy the following conditions (I) to (III). condition (I): -1 ≤ X - Y ≤ 1 condition (II): -1 ≤ Y - Z ≤ 1 condition (III) :-1 ≤ Z - X ≤ 1 X: an average value of the number of ethylene oxide groups in the ethylene oxide chain of the nonionic surfactant Y: an average value of the number of ethylene oxide groups in the ethylene oxide chain of the anionic surfactant Z: an average value of the number of ethylene oxide groups in the ethylene oxide chain of the penetrant