Absorbent Core Heterogeneous Structure Fluid Acquisition
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Solution Overview
Problem
Existing absorbent cores for disposable absorbent articles face a tradeoff between permeability and capillarity, where increasing one parameter often decreases the other, making it difficult to achieve simultaneous desirable levels of acquisition rate and effective fluid movement for secure storage.
Innovation Solution
The method involves modifying absorbent web materials to create heterogeneous structures with discrete regions of high permeability and high capillarity, using processes like ring rolling, SELF, micro-SELF, and rotary knife aperturing, which disrupt fibers to create localized changes in density and basis weight, uncoupling the permeability-capillarity tradeoff.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the permeability of absorbent core layers is increased to improve fluid acquisition rate, then the capillary pressure decreases, reducing effective fluid movement and storage capacity
Solution Approach 1:
The absorbent core is divided into multiple discrete layers, each with different fiber compositions and structural properties. The topsheet-contacting layer has high permeability for rapid fluid uptake, while deeper layers have lower permeability and higher capillary pressure for secure fluid storage, creating localized functional zones within the core structure
Solution Approach 2:
The absorbent core is segmented into multiple discrete layers with progressively decreasing permeability and increasing capillary pressure from the topsheet interface toward the backsheet. This segmentation allows the fluid to encounter different functional zones sequentially, achieving both rapid acquisition and secure storage
2Stress or pressure
If the capillary pressure is increased to improve fluid movement and storage, then the permeability decreases, reducing the fluid acquisition rate
Solution Approach 1:
Different layers of the absorbent core are assigned different capillary pressure characteristics tailored to their specific functions. The layer直接接触 the topsheet has low capillary pressure to allow rapid fluid entry, while deeper layers have progressively higher capillary pressure to secure fluid storage, creating localized functional optimization
Solution Approach 2:
The absorbent core is segmented into functional zones with varying capillary pressure gradients. This segmentation enables the fluid to experience low resistance during initial uptake phases while encountering increasing retention forces as it penetrates deeper into the core structure
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
This approach results in absorbent cores with improved fluid handling properties, allowing for faster acquisition rates and greater retained capacity without a significant decrease in capillary pressure, effectively breaking the permeability-capillarity tradeoff.
Implementation Method 1
discrete regions of high permeability and high capillarity
Implementation Method 2
discrete regions of high permeability and high capillarity
Data Source
Figure 1
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AI summary
An absorbent article comprises a topsheet joined to a backsheet and has an absorbent core material disposed therebetween, the absorbent core material being a fibrous absorbent material exhibiting on one side thereof discrete raised portions or out-of-plane deformations. In one aspect, the raised portions define a continuous network of channels, the channels defining a void region adjacent the topsheet of the sanitary napkin. In another aspect, the absorbent core material comprises a fibrous airlaid nonwoven web comprising cellulosic fibers and having a first density, and a plurality of discrete out-of-plane deformations having a second density which is less than the first density. The invention further relates to a method of making an absorbent core material.