Absorbent Core Channels with Varying Bond Strength for Fluid Handling

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Solution Overview

Problem

Channels in absorbent cores of personal hygiene articles can compromise liquid spreading and wet fit, leading to reduced absorbent capacity and slower absorption kinetics, particularly in the crotch region where superabsorbent polymer (SAP) is concentrated.

Innovation Solution

The absorbent core features elongated, absorbent material-free channels with varying bond strengths along their length, with higher strengths in the front and crotch sections and a weaker bond in the intermediate section, allowing preferential delamination to release swelling pressure and improve fluid handling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If channels are made with uniform high bond strength throughout, then channel durability is improved, but fluid absorption speed is reduced due to constrained core flexibility

Engineering Contradiction:

Improvechannel durabilityVSAvoidfluid absorption speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The channel bond strength is made non-uniform along its length, with different sections having different bond strengths. The front section (near urine entry) has lower bond strength to allow early delamination and rapid fluid distribution, while the back section has higher bond strength to maintain structural integrity and durability. This local differentiation resolves the contradiction by optimizing each section's bond strength for its specific functional requirement.

Inventive Principle:

Principle #3Local quality

2Speed

If channels are made with uniform low bond strength throughout, then fluid absorption speed is improved due to better core flexibility, but channel durability is reduced

Engineering Contradiction:

Improvefluid absorption speedVSAvoidchannel durability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

Different sections of the channel have different bond strengths tailored to their specific functions. The front section uses lower bond strength to facilitate rapid delamination and fluid absorption, while the back section uses higher bond strength to ensure durability and prevent premature failure. This localized optimization allows the channel to achieve both speed and reliability in different locations.

Inventive Principle:

Principle #3Local quality

3Strength

If channels are made completely bonded (no delamination), then channel structural integrity is maintained, but swelling pressure is not released and fluid handling is compromised

Engineering Contradiction:

Improvechannel structural integrityVSAvoidswelling pressure buildup

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The channel bond is segmented into different sections with different bond strengths. The front section is designed to delaminate preferentially under swelling pressure, releasing stress and enabling fluid distribution. The back section remains strongly bonded to maintain overall structural integrity. This segmentation allows controlled delamination that balances pressure release with structural stability.

Inventive Principle:

Principle #1Segmentation

4Object-generated harmful factors

If channels are made with preferential delamination in the intermediate section, then swelling pressure release is improved, but uniform liquid spreading is compromised

Engineering Contradiction:

Improveswelling pressure releaseVSAvoidliquid spreading uniformity

Core Design Contradiction:

Object-generated harmful factorsVSStability of the object's composition

Solution Approach 1:

The channel bond strength distribution is made asymmetric along its length, with the intermediate section having lower bond strength to facilitate preferential delamination. This asymmetric bond pattern creates a controlled weak point that releases swelling pressure while the stronger front and back sections maintain structural integrity and promote uniform liquid spreading through the absorbent core.

Inventive Principle:

Principle #4Asymmetry

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 design enhances fluid distribution and retention, reducing leakage and absorbent material usage while maintaining core integrity, as demonstrated by improved urine handling and reduced run-off in testing.

Implementation Method 1

an absorbent material layer between the core wrap top layer and bottom layer

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

superabsorbent polymer particles... capable of absorbing and retaining fluid

Methodology Applied

Scientific EffectOsmosis: Osmosis

Implementation Method 3

The channel bond can be achieved through adhesive bonding, thermo bonding, mechanical bonding, ultrasonic bonding

Methodology Applied

Scientific EffectAdhesive bonding: Adhesive

Implementation Method 4

preferential delamination to release swelling pressure

Methodology Applied

Scientific EffectStress relaxation: Stress Relaxation

Data Source

PatentUS20250228716A1Absorbent article comprising a channel with varying bond strength

Publication Date: 2025.07.17 PROCTER & GAMBLE CO

AI summary

A personal hygiene absorbent article (20) having at least one elongated, absorbent material-free channel (26) having a front end (62) and a back end (66) and a middle point (64). The channel includes a channel bond (27) between the core wrap top layer (45) and the core wrap bottom layer (46). The channel bond strength varies along the length of the channel so that the bond strength in an intermediate section (102) is weaker than the bond strength in a front section (100) and a crotch section (104). The bond strength is measured in minutes for each section according to the Static Peel Force Time Test disclosed herein.