Durable Hydrophilic Coating for Absorbent Articles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing disposable absorbent articles face challenges with hydrophilic nonwoven fabrics, as current methods for rendering them hydrophilic result in coatings that are not durable, prone to wash-off, and lead to increased liquid strike-through time and urine leakage due to reduced surface tension.
Innovation Solution
A durable hydrophilic coating composition comprising a film-forming polymer, a wetting agent, and nanoparticles (alumina or silica) is applied to the nonwoven core wrap, providing long-lasting hydrophilicity and fast liquid strike-through without surface tension reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If nonwoven fabric is coated with hydrophilic surfactants, then liquid strike-through time is reduced, but coating durability is poor and surfactant is washed off during use
Solution Approach 1:
The patent combines hydrophilic surfactants with hydrophobic polymers to form a composite coating composition. The hydrophobic polymer provides a durable matrix that adheres to the nonwoven fabric, while the hydrophilic surfactant dispersed within it provides the desired wetting and strike-through properties. This composite structure prevents the surfactant from being washed off while maintaining fast liquid passage.
Solution Approach 2:
The patent modifies the coating composition by controlling the ratio of hydrophilic surfactant to hydrophobic polymer, as well as the molecular weight and concentration of these components. By adjusting these parameters, the coating achieves optimal balance between hydrophilicity (for fast strike-through) and adhesion durability (to prevent wash-off during use).
2Speed
If add-on levels of surfactants are increased to improve hydrophilicity, then liquid strike-through time decreases, but surface tension reduction increases causing urine leakage
Solution Approach 1:
The patent carefully controls the concentration and type of surfactant in the coating composition to achieve the desired strike-through performance while limiting surface tension reduction. By using specific surfactant molecules with appropriate hydrophilic-lipophilic balance and controlling their add-on level, the coating provides fast liquid passage without excessively lowering surface tension, thus preventing urine leakage.
3Strength
If corona or plasma treatment is applied to render nonwoven hydrophilic, then adhesion is improved, but hydrophilicity decreases over time during storage
Solution Approach 1:
The patent applies corona or plasma treatment to the nonwoven fabric before coating with the hydrophilic composition. This preliminary treatment creates a surface that is more receptive to coating adhesion, ensuring strong bonding. The subsequent hydrophilic coating then provides long-lasting hydrophilic properties that do not diminish over storage time, combining the adhesion benefits of plasma treatment with the durable hydrophilicity of the coating.
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 coating composition ensures a consistent and rapid liquid strike-through time, maintains hydrophilicity during storage and use, and prevents surface tension reduction, thereby reducing urine leakage and improving the performance of absorbent articles.
Implementation Method 1
A durable hydrophilic coating composition comprising a film-forming polymer, a wetting agent, and from about 0.001% to about 40%, by weight of the composition, of nanoparticles
Implementation Method 2
nanoparticles are selected from the group consisting of alumina, silica and combinations thereof
Implementation Method 3
a film forming polymer
Implementation Method 4
coating the surface of the nonwoven with hydrophilic surfactants
Implementation Method 5
a wetting agent
Implementation Method 6
wetting agent
Data Source
AI summary
A durable hydrophilic coating composition is provided comprising a film forming polymer, a wetting agent and from about 0.001% to about 40%, by weight of the composition, of nanoparticles. The nanoparticles are selected from the group consisting of alumina, silica and combinations thereof and have a particle size of from about 1 to about 750 nanometers. The weight ratio of the film forming polymer to the nanoparticles is from about 1:1 to about 1:30. A disposable absorbent article is also disclosed.