Water-Based Ink Viscosity Control via Humectant Ratio
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Solution Overview
Problem
Water-based inks for ink-jet recording face challenges in suppressing viscosity increase during both short-term and long-term drying, as existing humectants like glycerol and diethylene glycol have insufficient effects, leading to instability in ink jetting.
Innovation Solution
A water-based ink formulation incorporating a sulfonic acid group-modified self-dispersible pigment, glycerol, diethylene glycol, and a penetrant, with a specific blending ratio of glycerol and diethylene glycol (0.01≦DEG/(Gly+DEG)≦0.11, to effectively suppress viscosity increase after drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If diethylene glycol is used as humectant, then viscosity is low and jetting is smooth, but volatility is high causing insufficient viscosity suppression after drying
Solution Approach 1:
The patent combines diethylene glycol (low viscosity) with glycerol (low volatility) in a specific ratio to create a humectant system that achieves both smooth jetting during operation and stable viscosity after drying. The synergistic combination allows the ink to benefit from the low viscosity of diethylene glycol while the glycerol component suppresses volatility and maintains viscosity stability during storage.
2Reliability
If glycerol is used as humectant, then solidification is suppressed due to low volatility, but viscosity is high reducing jetting stability
Solution Approach 1:
The patent merges glycerol (low volatility, solidification suppression) with diethylene glycol (low viscosity) in a controlled ratio. The glycerol component effectively prevents solidification during storage, while the diethylene glycol component keeps the overall viscosity low for smooth jetting, resolving the contradiction between solidification suppression and viscosity control.
3Ease of operation
If conventional humectants are used, then ink can be discharged, but viscosity increases after short-term and long-term drying causing jetting instability
Solution Approach 1:
The patent changes the key parameter of humectant composition by using a specific combination of diethylene glycol and glycerol in a controlled ratio (0.05 ≤ Gly/(Gly+DEG) ≤ 0.45). This parameter change optimizes the balance between initial jetting performance and long-term viscosity stability, preventing excessive viscosity increase after both short-term and long-term drying periods.
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 formulation achieves superior jetting stability by maintaining lower viscosity after both short-term and long-term drying, ensuring stable ink discharge and improved re-dispersion properties.
Implementation Method 1
a penetrant
Implementation Method 2
a water-based ink for ink-jet recording in which glycerol is used as the humectant (antidrying agent)
Data Source
AI summary
There is provided a water-based ink for ink-jet recording, including: a self-dispersible pigment modified by sulfonic acid group; glycerol; diethylene glycol; a penetrant; and water, wherein the glycerol and the diethylene glycol satisfy the following condition (i):0.01≦DEG/(Gly+DEG)≦0.11 (i)in the condition (i), Gly represents an amount of the glycerol in the water-based ink (% by weight); and DEG represents an amount of the diethylene glycol in the water-based ink (% by weight).