Layered Absorbent Article Structure for Longitudinal Leak Prevention

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Solution Overview

Problem

Existing absorbent articles, such as disposable diapers, suffer from longitudinal leakage of excrements, particularly when a wearer excretes multiple times, as conventional designs fail to effectively prevent leakage in this direction.

Innovation Solution

The absorbent article is designed with a longitudinal direction corresponding to the front-rear direction of the wearer, featuring a crotch, front, and rear portions, and includes an absorbent assembly with leak-proof cuffs and a layered absorbent member where the second layer has a longitudinal extension in the rear portion, providing enhanced elasticity and absorbent polymer density to prevent longitudinal leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a stacked absorbent member is used, then cushioning properties are improved, but appearance becomes poor due to bulkiness

Engineering Contradiction:
Improvecushioning propertiesVSAvoidappearance
Core Design Contradiction:
StrengthVSShape

Solution Approach 1:

The absorbent member is divided into multiple layers: a first layer (stacked absorbent member with fiber material and absorbent polymer particles for cushioning), a second layer (sheet-type absorbent member with absorbent polymer particles for thin profile), and an intermediate layer. This segmentation allows each layer to contribute different functions, resolving the contradiction between cushioning and appearance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure combining stacked absorbent member (fiber material + absorbent polymer) and sheet-type absorbent member (absorbent polymer between sheets). This composite approach allows the product to simultaneously achieve the cushioning properties of stacked members and the thin appearance of sheet-type members.

Inventive Principle:
Principle #40Composite materials

2Quantity of substance

If conventional absorbent articles are used, then basic absorption is provided, but longitudinal leakage prevention is poor

Engineering Contradiction:
Improveabsorption capacityVSAvoidlongitudinal leakage prevention
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The second layer is designed with a longitudinal extension only in the rear portion of the absorbent member, creating local quality differentiation. This extension has higher absorbent polymer density and forms a pocket structure specifically in the rear portion, providing enhanced longitudinal leakage prevention where it is most needed while maintaining overall absorption capacity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The second layer extends in the longitudinal direction at the rear portion, creating a three-dimensional pocket structure that protrudes into the crotch portion. This dimensional change creates a reservoir for storing excrements, preventing longitudinal leakage by providing an additional spatial dimension for containment.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Reliability

If the second layer has a longitudinal extension in the rear portion, then longitudinal leakage prevention is improved, but structural complexity increases

Engineering Contradiction:
Improvelongitudinal leakage preventionVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The absorbent member is segmented into distinct layers with the second layer having a specific longitudinal extension only in the rear portion. This segmentation allows the complex pocket structure to be achieved through layer design rather than complex assembly, reducing manufacturing complexity while maintaining the leakage prevention function.

Inventive Principle:
Principle #1Segmentation

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 design effectively prevents longitudinal leakage by forming a pocket structure that temporarily stores excrements, ensuring excellent leakage prevention performance and comfort through the use of a flexible second layer with higher absorbent polymer density and elasticity.

Implementation Method 1

an absorbent member to absorb and retain a body fluid

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

an absorbent member mainly including an absorbent polymer layer

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 3

a portion of the leak-proof cuff between the end portion fixing part in the front portion and the end portion fixing part in the rear portion is a stretch portion that is not fixed to other members and has elasticity in the longitudinal direction

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4201386B1Absorbent article
Publication Date: 2026.01.21 KAO CORP
  • EP4201386B1 patent drawingFigure 1
  • EP4201386B1 patent drawingFigure 2~3
  • EP4201386B1 patent drawingFigure 4(a)~4(b)

AI summary

An absorbent member (5) includes a first layer (6) and a second layer (7) placed on the non-skin-facing surface side of the first layer (6) and containing an absorbent polymer (P). The second layer (7) has, in at least one of a front portion (A) and a rear portion (C), a longitudinal extension (7F) extending outward in the longitudinal direction X from a tangent (65L) that extends in the lateral direction (Y), to a longitudinal end (65) of the first layer (6). In at least one of the front portion (A) and the rear portion (C), an end portion fixing part (120) of each leak-proof cuff (12) overlaps with the longitudinal extension (7F) of the second layer (7) in plan view, and the longitudinal end (65) of the first layer (6) is located longitudinally inward from the end portion fixing part (120) and is located a space (S) apart from the end portion fixing part (120). The longitudinal extension (7F) of the second layer (7) has a smaller bending rigidity than the first layer (6) and has a larger density of the absorbent polymer (P) than the first layer (6).