Multilayer Nonwoven Core Structure to Prevent SAP Rewet
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Solution Overview
Problem
Conventional disposable absorbent articles face challenges in maintaining liquid holding capacity and distribution without increasing complexity or cost, particularly due to gel-blocking effects caused by superabsorbent polymer (SAP) particles, which can lead to liquid reflux and re-wetting issues when pressure is applied.
Innovation Solution
A multilayer nonwoven acquisition and distribution sheet comprising a first layer for fluid acquisition, a second layer with smaller void volumes to act as a non-return valve, and a third layer with SAP particles, where the void volumes in the second layer are smaller than those in the third layer, preventing fluid reflux and enhancing fluid distribution and absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the amount of fluff is reduced to make the article thinner, then the article thinness is improved, but the liquid holding capacity deteriorates and rewet effect increases
Solution Approach 1:
The acquisition and distribution layer is divided into three distinct layers with different functions: first layer for rapid liquid acquisition, second layer for liquid distribution, and third layer for liquid retention. This segmentation allows each layer to be optimized for its specific function, enabling thinness while maintaining liquid holding capacity through the coordinated action of all layers.
Solution Approach 2:
Each layer is given different local properties: the first layer has high porosity for rapid acquisition, the second layer has controlled void volumes for distribution, and the third layer contains SAP particles for retention. This local quality differentiation enables the thin structure to perform multiple functions simultaneously without requiring excessive material thickness.
2Speed
If pressure is applied to the article by body movements, then the liquid transmission speed is improved, but gel-blocking occurs causing liquid reflux and re-wetting
Solution Approach 1:
The second layer acts as an intermediary between the first and third layers, with void volumes specifically designed to be smaller than SAP particles. This intermediary structure prevents direct compression of SAP particles during body movements, eliminating gel-blocking while maintaining rapid liquid transmission through the controlled void network.
Solution Approach 2:
The second layer utilizes a porous structure with controlled void volumes that are smaller than SAP particles but sufficient for liquid flow. This porous material allows rapid liquid transmission under pressure while physically preventing SAP particle compression and gel formation, solving the reliability issue during dynamic use.
3Productivity
If SAP particles are placed close together to increase absorption capacity, then the absorption efficiency is improved, but gel-blocking effect increases blocking liquid transmission
Solution Approach 1:
SAP particles are segregated into the third layer only, separated from the liquid acquisition and distribution pathways in the first and second layers. This spatial segmentation allows high SAP concentration for efficient absorption while preventing gel-blocking in the liquid transmission paths, as the SAP particles remain isolated in their dedicated layer.
Solution Approach 2:
The problem is solved by adding the vertical dimension with a three-layer structure. SAP particles are concentrated in the third layer (vertical separation), allowing high absorption capacity without blocking liquid transmission in the first and second layers. This dimensional arrangement decouples absorption efficiency from liquid transmission reliability.
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 configuration improves fluid intake and retention capacity, reduces gel-blocking, and maintains article thinness without using expensive SAP particles, achieving efficient fluid management with minimal re-wetting, as demonstrated by reduced rewet values.
Implementation Method 1
The void volumes in the second layer are smaller than the void volumes in the third layer, thereby the body fluids are forwarded to the third layer in an irreversible way
Implementation Method 2
A third layer comprising superabsorbent polymer (SAP) particles, for receiving the body fluids from the second layer
Implementation Method 3
the first layer for acquiring and transferring body fluids to the second layer
Data Source
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AI summary
The present invention relates to multi-layered non-woven structures being useful as components of disposable absorbent articles and garments comprising super absorbent particles and thereby acts as a core. The invention thereby ensures that the body fluids can penetrate from a first layer, which acts as an acquisition layer, up to a third layer comprising SAP particles, the second non-woven layer serving to decrease the fluid volume per surface unit, as a conventional dispersion layer. However the second layer of the invention additionally acts like a non-return valve, preventing, or at least strongly limiting, any fluid transfer from the third layer to the first layer. Channels free of SAP can additionally be design to improve the inlet and rewet properties of the multilayer acquisition and distribution sheet non-woven material.