Water-Based Wetness-Indicating Ink Composition
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Solution Overview
Problem
Current wetness-indicating inks for aqueous media are often volatile organic solvent-based, making them incompatible with cellulose-based products, environmentally unfriendly, and costly, while lacking a water-based alternative that is non-leachable and provides a clear color change visible to the unaided eye.
Innovation Solution
A water-based wetness-indicating ink composition using leuco dyes that are colorless in the presence of a desensitizer, which interacts with a developer to produce color when exposed to water, incorporating a surfactant blend with varying hydrophilic-lipophilic balance values, a binder, and a stabilizer, allowing for application on various substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If volatile organic solvent-based inks are used for wetness indication, then the ink provides color change functionality, but the ink becomes incompatible with cellulose-based products and environmentally unfriendly
Solution Approach 1:
The patent changes the fundamental parameter of the ink base from volatile organic solvent to water, making the ink environmentally friendly and compatible with cellulose-based products while maintaining the wetness indication functionality through careful selection of water-soluble leuco dyes and developers
Solution Approach 2:
The patent uses water as the ink base instead of expensive and environmentally harmful volatile organic solvents, making the ink cheaper and more environmentally friendly while achieving the same functional purpose
2Object-affected harmful factors
If water-based inks are used to replace organic solvent-based inks, then environmental friendliness improves, but the ink may leach in aqueous environments
Solution Approach 1:
The patent creates a composite ink formulation combining water-soluble leuco dyes, developers, and surfactants in a water-based medium, achieving both environmental friendliness and non-leachable properties through the synergistic interaction of components
Solution Approach 2:
The patent introduces surfactants as intermediary substances that facilitate the solubilization of hydrophobic components in the water-based ink system, preventing leaching while maintaining functionality
3Object-affected harmful factors
If water-insoluble leuco dyes are used in water-based ink, then the ink becomes environmentally friendly, but the dye solubility becomes problematic
Solution Approach 1:
The patent introduces surfactants as intermediary substances that facilitate the solubilization of hydrophobic components in the water-based ink system, preventing leaching while maintaining functionality
Solution Approach 2:
The patent changes the solubility parameter of the leuco dye by selecting water-soluble variants and adjusting the chemical environment through pH control and surfactant addition, enabling the dye to function in aqueous media
4Illumination intensity
If the ink is made visible to the unaided eye, then the color change intensity increases, but the complexity of the ink formulation increases
Solution Approach 1:
The patent utilizes the inherent color-changing properties of leuco dyes when exposed to moisture, combining this with developer substances to produce intense color changes visible to the unaided eye through carefully controlled chemical reactions
Solution Approach 2:
The patent creates a composite ink formulation combining water-soluble leuco dyes, developers, and surfactants in a water-based medium, achieving both wetness indication functionality and visible color change while maintaining environmental friendliness
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 provides a durable, environmentally friendly, and visibly distinct color change upon contact with water, suitable for diverse applications, including absorbent articles, without leaching, and can be printed at room temperature.
Implementation Method 1
preparing a solubilized active by solubilizing a water-insoluble leuco dye with the surfactant blend
Implementation Method 2
When the dried ink contacts water, the desensitizer is dissolved, allowing the leuco dye to interact with a developer to produce a color
Implementation Method 3
combining the solubilized active with a binder
Data Source
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AI summary
A color-appearing ink composition includes a surfactant blend of at least two non- ionic surfactants having hydrophilic-lipophilic balance values greater than 10, or a non-ionic surfactant having a hydrophilic-lipophilic balance value greater than 10 and a charged surfactant. The composition includes one or more water-insoluble leuco dyes, a developer and a desensitizer. The composition may be applied to a substrate to form a sensor.