Underpants-Type Diaper Display Sheet with Perforated Cover for Airflow

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Solution Overview

Problem

Existing underpants-type disposable diapers using resin film as a display sheet material face issues with appearance deterioration and reduced air permeability due to cutting processes and direct bonding of resin films, which affect the non-stretchable regions.

Innovation Solution

The diaper design interposes a perforated nonwoven fabric between the outer and inner members, allowing cutting of elastic members without a display sheet, and incorporates perforations for air permeability, using a cover nonwoven fabric to cover the inner member's back surface and extend between liquid impervious sheets, with specific bonding techniques to maintain air permeability and prevent peeling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a resin film is used as a display sheet material and elastic members are cut by pressing and heating, then the cutting process can be simplified, but the appearance of the display sheet deteriorates due to concavo-convex traces, holes, or melting

Engineering Contradiction:
Improvecutting process simplicityVSAvoiddisplay sheet appearance quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

A nonwoven fabric layer is introduced as an intermediary between the resin film display sheet and the elastic members. This nonwoven fabric absorbs the heat and pressure during the cutting process, preventing direct contact between the cutting tool and the resin film, thereby avoiding concavo-convex traces, holes, or melting on the display sheet while still enabling effective cutting of the elastic members

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If a resin film is used as a display sheet material and bonded directly to the liquid impervious sheet, then the structure is simplified, but air permeability is reduced due to direct bonding of two resin films

Engineering Contradiction:
Improvestructure simplicityVSAvoidair permeability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

A porous nonwoven fabric is used instead of a solid resin film for the display sheet. This nonwoven fabric maintains high air permeability due to its porous structure, while still providing the necessary display function and bonding capability to the liquid impervious sheet, thus resolving the contradiction between structural simplicity and air permeability

Inventive Principle:
Principle #31Porous materials

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 prevents display sheet appearance deterioration and maintains air permeability by using perforated nonwoven fabric, ensuring the diaper's appearance and functionality are preserved while avoiding direct resin film exposure and bonding issues.

Implementation Method 1

air can permeate through the inside of the perforated nonwoven fabric from the outside of the disposable diaper and to the region between the display sheet and the liquid impervious sheet

Methodology Applied
Scientific EffectAir permeation: Permeation

Implementation Method 2

the elastic member is cut by pressing and heating in a region having the display sheet to form the non-stretchable region

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentEP3530247B1Underpants-type disposable diaper
Publication Date: 2025.09.03 DAIO PAPER CORP
  • EP3530247B1 patent drawingFigure 1
  • EP3530247B1 patent drawingFigure 2
  • EP3530247B1 patent drawingFigure 3

AI summary

In an underpants-type disposable diaper including a display sheet (25) containing a resin film between an inner member (200) and at least one of a front side outer member (12F) and a back side outer member (12B), a cover nonwoven fabric (13) provided with a plurality of holes (14) having intervals and penetrating a front and a back is interposed from at least a crotch side edge of an outer member overlapping the display sheet (25) to a side of a waist opening WO between the display sheet (25) and a liquid impervious sheet (11), and an internal surface and an external surface of the cover nonwoven fabric (13) are bonded to facing surfaces, respectively, through a hot melt adhesive (25H). Compatibility between prevention of deterioration of appearance of the display sheet and prevention of a decrease in air permeability is achieved.