Cellulose-Free Absorbent Core for Viscous Fluid Management
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Solution Overview
Problem
Conventional absorbent cores for sanitary napkins and similar products face challenges in effectively absorbing and retaining menses and blood due to poor permeability and absorption capacity, particularly because of the viscosity and complex nature of these fluids, which leads to slower initial uptake and lower final absorption and retention.
Innovation Solution
An absorbent core structure featuring a substrate layer with a non-uniform layer of absorbent polymer material and a layer of thermoplastic material, where the thermoplastic material is in partial contact with both the substrate and the absorbent polymer layer, and the substrate layer is substantially free of cellulose fibers, enhancing immobilization and fluid management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional absorbent cores use cellulose fibers and superabsorbent materials, then absorption capacity is improved, but fluid permeability deteriorates due to viscosity and complex nature of menses and blood
Solution Approach 1:
The absorbent core is divided into multiple functional layers: a first fibrous layer for initial fluid acquisition and distribution, a second fibrous layer for additional absorption, and a superabsorbent material layer for fluid retention. This segmentation allows each layer to perform its specific function optimally, with the fibrous layers maintaining permeability for viscous fluids while the superabsorbent layer provides high-capacity retention.
Solution Approach 2:
The absorbent core uses a composite structure combining different fibrous materials (cellulose fibers and synthetic fibers) with superabsorbent materials. The cellulose fibers provide hydrophilicity and fluid wicking, while synthetic fibers provide structural integrity and bulk. The superabsorbent materials (sodium polyacrylate and/or polyacrylamide) provide high-capacity fluid retention. This composite approach balances permeability, absorption capacity, and fluid management for complex body fluids.
2Ease of operation
If the absorbent core structure is made thinner for improved comfort and discreetness, then wearing comfort is improved, but immobilization of superabsorbent material deteriorates
Solution Approach 1:
The superabsorbent material is not uniformly distributed but is instead localized in specific regions within the absorbent core, particularly within the second fibrous layer and at the interfaces between layers. This localized placement provides effective immobilization in the thin structure while maintaining the necessary fluid management properties in the regions where superabsorbent material is concentrated.
Solution Approach 2:
The superabsorbent material is nested within the fibrous matrix structure of the absorbent core layers. The fine particles of superabsorbent material are distributed and contained within the interstices of the fibrous networks, providing immobilization through the physical confinement of the fibrous structure while maintaining the thin overall profile of the absorbent core.
3Quantity of substance
If superabsorbent materials are used in high amounts, then fluid retention is improved, but initial uptake rate deteriorates due to gel blocking
Solution Approach 1:
The absorbent core segments the absorption function across different layers: the first and second fibrous layers handle initial fluid acquisition and distribution with high permeability, while the superabsorbent material layer provides subsequent fluid retention. This segmentation prevents gel blocking from immediately impeding fluid uptake by separating the high-capacity retention function from the initial acquisition function.
Solution Approach 2:
The fibrous layers are designed with porous structures that maintain open pathways for fluid penetration. The interconnected pore networks in the fibrous matrices allow viscous fluids like menses and blood to penetrate rapidly to the superabsorbent material without being blocked by gel formation, ensuring high initial uptake rates followed by effective fluid retention.
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 the absorption and retention of complex body fluids like menses and blood by optimizing fluid distribution and preventing gel blocking, maintaining a thin and flexible structure while ensuring increased wearing comfort and stability.
Implementation Method 1
a layer of a thermoplastic material wherein portions of a second surface of the layer of thermoplastic material are in direct contact with a first surface of the substrate layer and portions of the second surface of the layer of thermoplastic material are in direct contact with a first surface of the non uniform layer of absorbent material
Implementation Method 2
superabsorbent materials, such as absorbent gelling materials (AGM), usually in finely dispersed form... which are capable of absorbing large quantities of liquids and of retaining such absorbed liquids under moderate pressure
Implementation Method 3
water-insoluble, water-swellable, hydrogel-forming crosslinked absorbent polymers
Data Source
AI summary
Absorbent core for disposable absorbent articles. The core comprises a substrate layer and a non uniform layer of absorbent material comprising an absorbent polymer material and a first and second surface. The non uniform layer of absorbent material comprises a layer of a thermoplastic material comprising a layer of thermoplastic material first surface and a layer of thermoplastic material second surface. The non uniform layer of absorbent material second surface is in at least partial contact with the substrate layer. Portions of the layer of thermoplastic material second surface are in direct contact with the substrate layer first surface and portions of the layer of thermoplastic material second surface are in direct contact with the non uniform layer of absorbent material first surface. The substrate layer comprises a fibrous material substantially free of cellulose fibers, the substrate layer having a basis weight from about 25 g/m2 to 120 g/m2.