Disposable Diaper Waist Air Permeability via Segmented Crotch Sheet
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Solution Overview
Problem
Conventional two-separated disposable diapers exhibit lower air permeability at the waist portion compared to those with a single-piece outer sheet, primarily due to unnecessary coverage by nonwoven fabric on the absorber's overlap sections.
Innovation Solution
The design eliminates the crotch outer sheet from the absorber's underside at specific sections near the waist, reducing its proportion at overlap areas and incorporating resilient and elastic members to enhance fit and prevent bending, while maintaining or improving air permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the crotch outer sheet is laminated on the underside of the liquid impervious sheet across the entire absorber area, then the diaper structure is simplified and materials are easier to select, but air permeability at the waist portion is reduced due to unnecessary coverage on overlap sections
Solution Approach 1:
The crotch outer sheet is segmented into different coverage zones: it covers the intermediate portion of the absorber but is removed from the front-side and back-side outer overlap sections. This segmentation allows the diaper to maintain structural simplicity while restoring air permeability at the waist portion by eliminating unnecessary material coverage in specific areas.
Solution Approach 2:
The crotch outer sheet is selectively positioned to provide local coverage where needed (intermediate portion) while being absent where it hinders performance (overlap sections). This local quality approach ensures that the sheet performs its protective function in the crotch area while allowing air circulation at the waist overlap sections.
2Reliability
If the crotch outer sheet covers the entire absorber underside, then liquid imperviousness is improved, but the diaper becomes thicker and less breathable at the waist portion
Solution Approach 1:
The liquid impervious protection is segmented into two layers: the liquid impervious sheet provides base coverage across the entire absorber underside, while the crotch outer sheet provides additional localized protection only at the intermediate portion. This segmentation maintains reliable liquid imperviousness while improving breathability at the waist overlap sections.
Solution Approach 2:
Enhanced liquid imperviousness is applied locally at the intermediate portion where the crotch outer sheet is laminated, while the overlap sections maintain only the basic liquid impervious sheet coverage. This local quality differentiation ensures adequate protection where needed while preserving breathability where the sheets overlap at the waist.
3Strength
If multiple sheets are laminated at the overlap sections, then structural strength is increased, but air permeability is reduced due to the additional material layers
Solution Approach 1:
The multi-layer lamination structure is segmented to appear only at the intermediate portion and not at the front-side and back-side outer overlap sections. This segmentation maintains structural strength where the absorber is thickest and most vulnerable, while eliminating unnecessary layers at the waist overlap sections to restore air permeability.
Solution Approach 2:
Enhanced structural strength through multi-sheet lamination is applied locally at the intermediate portion where the crotch outer sheet is present, while the overlap sections maintain a simpler single-sheet structure. This local quality approach ensures adequate strength at critical areas without compromising breathability at the waist.
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 increases air permeability at the waist, enhances the diaper's strength, and improves fit by efficiently transferring elastic forces, reducing the likelihood of absorber shifting and bending phenomena.
Implementation Method 1
an absorbent element interposed between the foregoing sheets to absorb and retain a liquid
Implementation Method 2
resilient and elastic members are fixed in an extended state along the front-back direction on the underside of the absorbent element
Data Source
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AI summary
[Means for Solving Problems] In an underpants type disposable diaper, including: a ventral-side outer sheet 12F and a back-side outer sheet 12B which are not connected but separated at a crotch portion; an absorber 20 having a liquid impervious sheet and a crotch outer sheet 12M laminated on an underside of the liquid impervious sheet in the absorber so as to be exposed on an external surface of a product, assuming that the number of sheets disposed on the underside of the liquid impervious sheet is B1 at the intermediate portion 23, A1 at front- and back-side outer overlap sections X and Z, and C1 at the front- and back-side outer nonoverlap sections 20F and 20B, there is established a relationship of B1<C1<A1.