Stretch layered sheet, disposable wearing article, and method and device for manufacturing stretch layered sheet
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Solution Overview
Problem
Conventional stretchable layered sheets experience reduced air permeability in the non-stretched state, leading to dampness issues for wearers with limited stretch, as openings in the film break during thermal bonding or restretching.
Innovation Solution
A stretchable layered sheet design featuring thermally bonded non-woven fabrics and a thermoplastic film with strategically formed first and second vents, allowing air permeability in both stretched and non-stretched states through controlled thermal bonding and film breakage at boundary lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the film is thermally bonded to non-woven fabrics at attachment portions, then the sheet structure is secured, but the film breaks during thermal bonding or restretching, reducing air permeability in non-stretched state
Solution Approach 1:
The attachment portion is divided into two distinct zones: a thermal bonding area where the film is bonded to non-woven fabrics, and a non-bonding area that remains unbonded. This segmentation allows the bonded zone to provide structural integrity while the unbonded zone maintains air permeability by preventing film breakage during stretching and restretching cycles.
Solution Approach 2:
Different regions of the attachment portion are given different properties: the thermal bonding area has strong adhesion to non-woven fabrics for structural support, while the non-bonding area maintains film continuity and elasticity for air flow. This local differentiation of properties resolves the contradiction between structural integrity and air permeability.
2Adaptability or versatility
If the film is made stretchable to accommodate body movement, then comfort is improved, but openings in the film break during thermal bonding or restretching, causing dampness
Solution Approach 1:
The attachment portion is segmented into thermal bonding and non-bonding areas, allowing the film to stretch freely in the non-bonding zone without breaking. This segmentation enables the film to accommodate body movements while maintaining integrity and air permeability, preventing dampness.
Solution Approach 2:
The film is pre-stretched before thermal bonding to create a relaxed state that accommodates subsequent body movements. The non-bonding area is prepared in advance to allow elastic deformation during wear, preventing film breakage and maintaining air flow for comfort.
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
Enhances air permeability in both stretched and non-stretched states, improving comfort and reducing dampness by maintaining airflow through the sheet.
Implementation Method 1
The pair of non-woven fabrics NW and the film F are thermally bonded to each other at the attachment portion 1
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The present layered stretchable sheet includes: a plurality of attachment portions at which a pair of non-woven fabrics and a film are thermally bonded together, wherein each one of the attachment portions includes at least one thermal bonding area where the pair of non-woven fabrics and the film are thermally bonded together; at least one boundary line that defines the thermal bonding area; a first vent that is defined by a first opening of the film appearing in a stretched state of the film along the boundary line and that exerts air permeability; and a second vent that is defined by a second opening where a part of the film is absent, the second opening being adjacent to the thermal bonding area and being delimited by the boundary line, wherein the second vent exerts air permeability both in the stretched state and in a non-stretched state.