Segmented Diaper Core Attachment Reduces Backsheet Tension

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Solution Overview

Problem

Disposable diapers with high amounts of superabsorbent polymer particles and little to no airfelt experience strain and tension lines when attached to a wearer, leading to a perceived need for replacement even when the absorbent core still has capacity for liquid absorption.

Innovation Solution

The absorbent core is attached to the backsheet in specific, limited zones rather than over the entire surface, allowing it to expand independently and reducing the formation of wrinkles and tension lines, while maintaining effective liquid distribution and absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the absorbent core is fully attached to the backsheet, then the structural stability is improved, but the backsheet develops tension lines and wrinkles when the absorbent core expands

Engineering Contradiction:

Improvestructural stabilityVSAvoidbacksheet surface smoothness

Core Design Contradiction:

Stability of the object's compositionVSShape

Solution Approach 1:

The attachment between absorbent core and backsheet is segmented into discrete attachment zones rather than continuous attachment. The absorbent core is attached at multiple separated locations including front attachment zones, back attachment zones, and side attachment zones, allowing the backsheet to remain smooth while maintaining structural stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the absorbent core have different attachment characteristics to the backsheet. Front and back regions have attachment zones for stability, while side regions have limited attachment to prevent tension lines. This local differentiation allows the absorbent core to expand without forcing the backsheet to deform.

Inventive Principle:

Principle #3Local quality

2Volume of moving object

If high amounts of superabsorbent polymer particles are used, then the absorbent core thickness is reduced, but the particles cannot be held in place without airfelt

Engineering Contradiction:

Improveabsorbent core thicknessVSAvoidparticle immobilization

Core Design Contradiction:

Volume of moving objectVSStability of the object's composition

Solution Approach 1:

A carrier substrate is introduced as an intermediary between the superabsorbent polymer particles and the backsheet. The carrier substrate provides a matrix that holds the particles in place, replacing the traditional airfelt component and enabling high particle concentration while maintaining structural integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The absorbent core uses a composite structure combining carrier substrate material with superabsorbent polymer particles. This composite approach allows the particles to be immobilized effectively without requiring airfelt, achieving both thin profile and particle stability.

Inventive Principle:

Principle #40Composite materials

3Stability of the object's composition

If the absorbent core is attached over the entire surface, then the liquid distribution is improved, but the expansion of the absorbent core forces the backsheet to expand causing strain appearance

Engineering Contradiction:

Improveliquid distribution uniformityVSAvoidbacksheet strain appearance

Core Design Contradiction:

Stability of the object's compositionVSShape

Solution Approach 1:

The attachment is segmented into specific zones rather than covering the entire surface. This segmentation allows liquid to distribute through the absorbent core while the unattached regions permit the core to expand without forcing the backsheet to deform, preventing strain appearance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of full-surface attachment, only partial attachment zones are used. This partial action is sufficient to maintain liquid distribution and structural stability while allowing enough freedom for the absorbent core to expand naturally without creating backsheet strain.

Inventive Principle:

Principle #16Partial or excessive action

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 approach reduces the appearance of strain and tension lines on the backsheet, enhancing the perceived quality and extending the usable life of the diaper by allowing the absorbent core to expand without forcing the backsheet to do so, thus preventing premature perception of capacity exhaustion.

Implementation Method 1

the superabsorbent polymer particles, upon swelling, will exert a certain force onto the nonwoven webs

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

the superabsorbent polymer particles can no longer be held in place in the interstices between the cellulose fibers

Methodology Applied

Scientific EffectOsmosis: Osmosis

Implementation Method 3

One way to facilitate immobilization is the use of adhesive, such as hot melt adhesive

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentEP2532332B2Disposable diaper having reduced attachment between absorbent core and backsheet

Publication Date: 2017.10.04 PROCTER & GAMBLE CO

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AI summary

The invention relates to disposable diaper having absorbent cores comprising superabsorbent polymer particles which are immobilized by adhesive. The absorbent core is attached to the backsheet of the disposable diaper only in certain attachment zones to reduce see-through and the formation of tension lines on the backsheet.