Stretchable Sheet Welding Segmentation for Tear Resistance

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Solution Overview

Problem

Existing stretchable sheets with elastic members sandwiched between two sheets tend to have attached portions that easily tear, leading to potential breaks along these areas due to melting, which compromises the tear strength and integrity of the sheets.

Innovation Solution

A stretchable sheet design featuring a pair of sheets with elastic members secured by a welding construction, where strongly-attached and weakly-attached portions are strategically arranged to prevent tearing, with the weakly-attached areas preventing melting and maintaining sheet integrity, and a manufacturing apparatus using an anvil roll with ridges to differentiate attachment strengths and pressures for reliable securing of elastic members.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the sheets are welded together at attached portions to secure elastic members, then the elastic members are firmly secured to the sheets, but the attached portions become prone to tearing due to melting

Engineering Contradiction:

Improvesecuring reliability of elastic membersVSAvoidtear strength of sheets at attached portions

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The attached portions are segmented into strongly-attached portions (for securing elastic members) and weakly-attached portions (for preventing sheet tearing). This segmentation allows different functional requirements to be met in different regions of the attached portions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different attachment strengths are applied locally: strong attachment at portions where elastic members are secured, and weak attachment at portions between elastic members. This local differentiation resolves the contradiction by providing strong securing where needed while maintaining sheet integrity elsewhere.

Inventive Principle:

Principle #3Local quality

2Shape

If the attached portions extend long continuously to clearly form folds, then the folds are clearly formed between adjacent attached portions, but the sheets may break along the long attached portions

Engineering Contradiction:

Improveclarity of fold formationVSAvoidbreak resistance of sheets along attached portions

Core Design Contradiction:

ShapeVSStrength

Solution Approach 1:

The continuous attached portions are segmented into strongly-attached and weakly-attached sections. The weakly-attached portions create controlled interruption points that prevent continuous tear propagation while still allowing clear fold formation at the strongly-attached portions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The weakly-attached portions act as intermediary elements between strongly-attached portions, serving as stress relief zones that prevent sheet breakage while maintaining the overall fold structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If the sheets are heated and melted at attached portions to weld them together, then the sheets are secured together, but the melted positions tear more easily than un-melted positions

Engineering Contradiction:

Improvewelding capability of sheetsVSAvoidtear strength at welded positions

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The welding process is segmented into strong welding at portions requiring secure attachment and weak or no welding at portions where sheet integrity must be maintained. This selective welding approach prevents tear propagation while ensuring adequate securing at critical locations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different welding intensities are applied locally: strong welding at attached portions for securing elastic members, and weak or no welding at portions between elastic members. This local differentiation maintains sheet tear strength while providing adequate welding where required.

Inventive Principle:

Principle #3Local quality

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

The solution effectively secures elastic members to the sheets with high reliability, prevents sheet melting at weakly-attached areas, maintains intrinsic tear strength, and allows for clear fold formation, resulting in a flexible and soft stretchable sheet with enhanced surface pressure for secure attachment.

Implementation Method 1

the first surfaces 1f and 2f of the pair of sheets 1 and 2 are attached to each other by a welding construction (a welded structure) without using an adhesive

Methodology Applied

Scientific EffectWelding: Welding

Data Source

PatentUS11890174B2Stretchable sheet, worn article using the same, and stretchable sheet manufacturing apparatus

Publication Date: 2024.02.06 ZUIKO CORP

AI summary

A stretchable sheet 10 includes: a plurality of attached portions 3 spaced apart from each other in the direction of stretch Df, wherein the first surfaces 1f and 2f of a pair of sheets 1 and 2 are attached to each other by being welded without using an adhesive, at the attached portions 3, the attached portions 3 hold elastic members F, and the attached portions 3 extend in a direction Dp crossing the direction of stretch Df of the elastic members F; and a plurality of folds P that appear between the attached portions 3 while the elastic members F are shrunk, wherein the attached portions 3 include: a plurality of strongly-attached portions 3s arranged on opposite sides of each elastic member F in the crossing direction Dp; and a plurality of weakly-attached portions 3w arranged between adjacent elastic members F and between adjacent strongly-attached portions 3s.