Absorbent Article With Front-to-Rear Density Gradient for Leakage Control

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Solution Overview

Problem

Existing absorbent articles transfer biofluid too rapidly when a large amount is discharged, leading to uneven absorption and potential leakage, as the absorbent body is not utilized effectively in the front-rear direction.

Innovation Solution

The absorbent article features a variable-density portion with low, medium, and high-density regions that increase stepwise or gradually from the front to the rear, incorporating grooves to facilitate controlled biofluid transfer, ensuring balanced absorption across the crotch and rear regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a groove is provided to facilitate biofluid transfer, then biofluid transfer capability is improved, but when large amount of biofluid is discharged, the transfer becomes too rapid causing uneven absorption

Engineering Contradiction:
Improvebiofluid transfer speedVSAvoidabsorption uniformity
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The absorbent body is divided into regions with different densities: a first region with lower density and a second region with higher density. This local quality variation allows the front portion to rapidly absorb and transfer biofluid while the rear portion with higher density provides controlled absorption, preventing uneven distribution and leakage.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The density parameter of the absorbent body is changed along the front-rear direction, creating a gradient from lower density at the front to higher density at the rear. This parameter change enables different absorption rates in different regions, controlling the overall biofluid transfer speed while maintaining uniform absorption.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If density increases from front to rear, then absorption control is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveabsorption controlVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Instead of creating a continuously varying complex structure, the patent divides the absorbent body into distinct regions with different densities. This approach achieves absorption control through simple regional differentiation rather than complex continuous variation, reducing manufacturing complexity while maintaining functionality.

Inventive Principle:
Principle #3Local quality

3Quantity of substance

If the entire absorbent body is utilized, then absorption capacity is improved, but rapid rearward transfer hinders effective use of the whole body

Engineering Contradiction:
Improveabsorption capacityVSAvoidbiofluid transfer speed
Core Design Contradiction:
Quantity of substanceVSSpeed

Solution Approach 1:

By changing the density parameter from front to rear, the patent creates a gradient that slows down biofluid transfer as it moves rearward. This allows the biofluid to be progressively absorbed throughout the entire absorbent body, maximizing absorption capacity while preventing rapid uncontrolled transfer that would leave the rear regions underutilized.

Inventive Principle:
Principle #35Parameter changes

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 allows for appropriate biofluid transfer and absorption, preventing leakage and maximizing the utilization of the absorbent body, particularly in the rear region, even with large fluid discharge.

Implementation Method 1

the absorbent body includes a variable-density portion in which a density increases stepwise or gradually from a front toward a rear

Methodology Applied
Scientific EffectDensity gradient: Density Gradient

Implementation Method 2

the variable-density portion includes a low-density portion, a medium-density portion, and a high-density portion from the front toward the rear

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 3

the absorbent body includes a crotch-corresponding region corresponding to the wearer's crotch when worn

Methodology Applied
Scientific EffectCapillary absorption: Capillary Action

Implementation Method 4

an absorbent body provided between the topsheet and the backsheet

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentEP3777806B1Absorbent article
Publication Date: 2025.07.16 DAIO PAPER CORP
  • EP3777806B1 patent drawingFigure 1
  • EP3777806B1 patent drawingFigure 2
  • EP3777806B1 patent drawingFigure 3

AI summary

An absorbent article includes a liquid-permeable topsheet, a liquid-impermeable backsheet, and an absorbent body provided between the topsheet and the backsheet, wherein the absorbent body includes a crotch-corresponding region corresponding to the wearer's crotch when worn, and a front region being adjacent to and forward of the crotch-corresponding region, and a rear region being adjacent to and rearward of the crotch-corresponding region, and has a variable-density portion with a density increasing stepwise or gradually from a front toward a rear, the variable-density portion being located in a region extending at least from the crotch-corresponding region to the rear region.