Wetness Indicator Composition for Disposable Absorbent Articles
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Solution Overview
Problem
Absorbent articles, such as diapers and sanitary napkins, often lack visible indicators to signal when they have become wet with liquids, making it difficult for caregivers to determine when they need to be changed, potentially leading to leaks.
Innovation Solution
A wetness indicating composition comprising a water insoluble thermoplastic polymer, superabsorbent polymer, a wetness indicator with a pH modifier, surfactant, and optionally nanoclay powder, which changes color upon exposure to liquids, providing a visible signal for timely article replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a wetness indicator is applied to an absorbent article, then the ability to detect wetness is improved, but the indicator may dissolve or lose integrity when exposed to liquids
Solution Approach 1:
The patent applies composite materials by combining the wetness indicator with a water-insoluble thermoplastic polymer matrix and superabsorbent polymer particles. This composite structure allows the indicator to maintain its integrity while exposed to liquids, as the water-insoluble polymer prevents dissolution, while still enabling the indicator to detect wetness through color change.
2Speed
If the indicator changes color quickly upon liquid contact, then wetness detection speed is improved, but the color change may be faint or hard to see
Solution Approach 1:
The patent employs parameter changes by selecting specific pH indicators and adjusting the pH of the composition to optimize both the speed and visibility of the color change. The indicator is chosen to undergo a rapid and pronounced color transition at the pH level present in body fluids, ensuring both quick detection and high visibility for the caregiver.
3Temperature
If the article is exposed to high temperature and humidity, then thermal stability is improved, but the indicator may undergo premature color change
Solution Approach 1:
The patent uses an intermediary approach by incorporating a buffer system that mediates between the environmental conditions (temperature and humidity) and the pH indicator. The buffer maintains a stable pH environment, preventing premature color change of the indicator due to thermal and humidity fluctuations, while still allowing the indicator to respond to the presence of body fluids.
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 composition ensures quick and vivid color change upon liquid contact, maintaining integrity and visibility even after exposure, offering improved thermal and humidity stability, allowing caregivers ample time to change the article.
Implementation Method 1
Absorbent articles, such as disposable diapers... are designed to absorb and hold liquids such as water and body fluids
Implementation Method 2
Often the article employs a superabsorbent polymer (SAP) to facilitate the absorption of the liquids
Implementation Method 3
a wetness indicator comprising an indicating agent and a pH modifier
Implementation Method 4
a wetness indicator comprising an indicating agent and a pH modifier... determining the presence of a color change in the wetness indicating composition
Data Source
AI summary
A wetness indicating composition is disclosed that changes color in response to a change in pH. The composition comprises a water-insoluble, thermoplastic polymer composition, a superabsorbent polymer, a wetness indicator, and surfactant. The wetness indicating composition is useful in disposable absorbent articles, e.g., disposable diapers, feminine napkins, medical dressings and beddings for humans and animals.