Disposable Wearing Article Adhesive Tack Strength Maintenance

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Solution Overview

Problem

Disposable wearing articles face a challenge in maintaining adhesive tack strength due to body warmth being hindered by the presence of a liquid-absorbent core, leading to deterioration of peel strength between fastening and landing zones.

Innovation Solution

The design incorporates fastening zones with an adhesive layer on the inner surface of one waist region and landing zones with a plastic film strip and adhesive on the outer surface of the other waist region, allowing body warmth to transfer and soften the adhesive, maintaining tack strength and preventing deterioration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a liquid-absorbent core is placed under the fastening zones to absorb body fluid, then the absorption function is improved, but the body warmth transfer to the adhesive is hindered and peel strength deteriorates

Engineering Contradiction:

Improvebody fluid absorptionVSAvoidpeel strength of adhesive zones

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The fastening zone is divided into two functional areas: a first area with adhesive for bonding to the front waist region, and a second area without adhesive (landing zone) that allows body warmth to reach the adhesive. The liquid-absorbent core is positioned to absorb fluid while allowing thermal energy to pass through to the adhesive layer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the fastening zone are assigned different properties: the first area has adhesive material for bonding, while the second area is designed to be adhesive-free to facilitate heat transfer. The landing zone specifically lacks adhesive to allow body warmth to reach and maintain the tack strength of the adhesive in the first area.

Inventive Principle:

Principle #3Local quality

2Strength

If adhesive material is applied to fastening zones for bonding, then the bonding strength is improved, but the adhesive sets over time and tack strength decreases

Engineering Contradiction:

Improvebonding strength of adhesive zonesVSAvoidduration of tack strength

Core Design Contradiction:

StrengthVSDuration of action of moving object

Solution Approach 1:

The adhesive is positioned and configured in advance to receive body warmth from the wearer. The landing zone is prepared as an adhesive-free area that allows thermal energy to reach the adhesive, preemptively maintaining its tack strength before bonding degradation occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The physical state of the adhesive is changed from a set, rigid state to a softened, tacky state through thermal energy from the wearer's body. This temperature-induced parameter change restores and maintains the adhesive's bonding capability over time.

Inventive Principle:

Principle #35Parameter changes

3Strength

If adhesive zones are made with high initial tack strength to prevent peeling, then the initial bonding is improved, but the adhesive cannot be softened by body warmth and peel strength deteriorates over time

Engineering Contradiction:

Improveinitial tack strength of adhesive zonesVSAvoidtemperature sensitivity of adhesive material

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

The landing zone acts as an intermediary structure that facilitates heat transfer from the wearer's body to the adhesive. By being positioned between the body and the adhesive, it allows thermal energy to reach the adhesive material, softening it and maintaining its tack strength.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 ensures reliable transfer of body warmth to the adhesive layer, restoring and maintaining tack strength, thereby preventing the deterioration of peel strength between fastening and landing zones, even at low temperatures.

Implementation Method 1

the adhesive layer being softened by being warmed

Methodology Applied

Scientific EffectThermal energy transfer: Conduction (thermal)

Implementation Method 2

reliable transfer of body warmth to the adhesive layer

Methodology Applied

Scientific EffectBody warmth transfer: Conduction (thermal)

Data Source

PatentUS7758559B2Disposable wearing article

Publication Date: 2010.07.20 UNI CHARM CORP

AI summary

A disposable wearing article has longitudinally extending side edges of a front waist region. The side edges are defined by a pair of hydrophobic fibrous nonwoven fabric layers having mutually opposed surfaces tightly bonded to each other. Fastening zones are formed by an adhesive applied on longitudinally extending side edges of the rear waist region. Landing zones are formed from plastic film strip tightly bonded to the side edges of the front waist region.