Layered Absorbent Core Structure for Fluid Permeability

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Solution Overview

Problem

Conventional absorbent articles, including sanitary napkins, face challenges in effectively absorbing and retaining menses and blood due to poor permeability of superabsorbent materials, which are hindered by the viscosity and complex nature of these fluids, leading to slower absorption and lower retention capacity.

Innovation Solution

A sanitary napkin with an absorbent core comprising a layered structure of cellulose fibers and superabsorbent materials, where the first layer is free of absorbent gelling materials and the second layer is free of cellulose fibers, allowing for improved absorption and distribution of complex body fluids without significant thickness increase.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If superabsorbent materials are used in the absorbent core, then absorption capacity for aqueous fluids is improved, but permeability towards menses and blood deteriorates due to viscosity and complex nature of these fluids

Engineering Contradiction:
Improveabsorption capacityVSAvoidpermeability
Core Design Contradiction:
Quantity of substanceVSSpeed

Solution Approach 1:

The absorbent core is divided into multiple layers with different compositions: a first layer comprising cellulose fibers for rapid absorption of corpuscular components, and a second layer comprising superabsorbent materials for absorption of aqueous fluids. This segmentation allows each layer to optimize its function for different fluid components, resolving the contradiction between overall absorption capacity and initial permeability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The absorbent core uses a composite structure combining cellulose fibers and superabsorbent materials in specific layers. The cellulose layer provides high permeability for initial fluid uptake, while the superabsorbent layer provides high absorption capacity for aqueous portions, creating a composite system that achieves both rapid permeability and high retention capacity.

Inventive Principle:
Principle #40Composite materials

2Quantity of substance

If absorbent gelling materials are dispersed in fibrous layers, then absorption characteristics are improved, but thickness of the absorbent core increases

Engineering Contradiction:
Improveabsorption capacityVSAvoidthickness
Core Design Contradiction:
Quantity of substanceVSLength of stationary object

Solution Approach 1:

Superabsorbent materials are localized in specific regions (second layer) rather than being uniformly distributed throughout the entire absorbent core. This local concentration allows high absorption capacity in the superabsorbent layer while keeping the overall core thickness minimized, as the cellulose layer provides structural support and initial absorption without requiring superabsorbent materials.

Inventive Principle:
Principle #3Local quality

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 absorbent core achieves enhanced absorption and handling capacity for menses and blood, maintaining a stable thickness and density, thereby improving comfort and performance.

Implementation Method 1

cellulose fibres, such as for example wood pulp fibres, show a greater absorption and diffusion capacity towards the water fraction of menses and blood, which may be very rapidly acquired and may be transported within the fibrous structure

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 2

superabsorbent materials, such as absorbent gelling materials (AGM), usually in finely dispersed form... water-insoluble, water-swellable, hydrogel-forming crosslinked absorbent polymers which are capable of absorbing large quantities of liquids and of retaining such absorbed liquids under moderate pressure

Methodology Applied
Scientific EffectHydrogel formation: Hydrogel

Data Source

PatentEP1943992B1Absorbent core having improved structure
Publication Date: 2012.02.22 PROCTER & GAMBLE CO
  • EP1943992B1 patent drawingFigure 1~2

AI summary

Absorbent core for disposable absorbent articles, particularly for the absorption of menses or blood.