Diaper Absorber Vertical Stretchable Part Dynamic Fit
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Solution Overview
Problem
The crotch portion of underpants-type disposable diapers experiences inadequate dynamic fit due to the rigidity of absorbers, which limits stretchability and can cause stiff feelings and liquid leakage, as conventional elastic members are insufficient in addressing dynamic changes from wearer motion and absorber volume variations.
Innovation Solution
Incorporating a vertical stretchable part in the absorber with lifting elastic members that extend and contract to maintain fit, utilizing leg opening and waist lower portion elastic members with different contraction forces to enhance fit and reduce absorber contraction, and providing curved elastic members along leg openings to support the vertical stretchable part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If elastic members are provided in the absorber existence region to improve fit, then the fit would be improved, but the absorber would develop irregular asperities causing stiff feeling and liquid leakage
Solution Approach 1:
The absorber is divided into a rigid portion (for stable absorption) and a flexible portion (for fit adaptation). The flexible portion is positioned to overlap with elastic members, allowing localized deformation without affecting the entire absorber structure, thus preventing asperity formation while maintaining liquid leakage prevention.
Solution Approach 2:
Different regions of the absorber are assigned different mechanical properties: the rigid portion maintains structural integrity for reliable absorption, while the flexible portion (with lower basis weight) allows elastic deformation to accommodate wearer motion and absorber volume changes, preventing stiff feeling and leakage.
2Reliability
If the absorber is made rigid to maintain absorption function, then liquid leakage prevention is improved, but dynamic fit during wearer motion deteriorates
Solution Approach 1:
The absorber structure is segmented into rigid and flexible portions along the width direction. The rigid portion ensures reliable liquid leakage prevention, while the flexible portion (positioned at edges or specific regions) adapts to dynamic changes during wearer motion, providing excellent dynamic fit without compromising absorption function.
Solution Approach 2:
The absorber exhibits spatially varying mechanical properties: rigid in core regions for reliable containment, and flexible (lower basis weight) in peripheral regions for dynamic adaptation. This local differentiation allows the absorber to maintain both reliability and adaptability simultaneously.
3Ease of operation
If elastic members are positioned closer to lateral sides to improve fit, then the fit is improved, but the absorber contraction is reduced
Solution Approach 1:
The elastic members are extracted from the central absorber region and repositioned closer to the lateral sides. This positioning allows the elastic members to act on the outer body without directly contracting the absorber, reducing harmful absorber contraction while still providing fit improvement through outer body deformation.
Solution Approach 2:
The outer body serves as an intermediary between the elastic members and the absorber. The elastic members contract the outer body, which then indirectly affects the absorber through the flexible portion, reducing direct absorber contraction while maintaining fit improvement benefits.
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 provides a more excellent dynamic fit by allowing the vertical stretchable part to extend and contract with wearer motion and absorber volume changes, preventing large absorber contraction and ensuring a firm fit without the need for dedicated elastic members in the absorber region.
Implementation Method 1
lifting elastic members capable of exerting a contraction force lifting a portion of the vertical stretchable part... the vertical stretchable part vertically extending and contracting in length by elastic extension and contraction of the lifting elastic members
Implementation Method 2
an absorber provided on the inner side of the outer body ranging from the front body to the back body... changes in the volume of the absorber between before and after absorption
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
The present invention is intended to improve the dynamic fit of a crotch portion. The foregoing issue is solved in such a manner that a vertical stretchable part (17) vertically extending and contracting in length is provided in a vertical intermediate portion of an absorber (13) in a front body (F), an outer body (20) of the front body (F) has a portion overlapping at least the vertical stretchable part (17), width-direction both side sections of the portion, and a waist opening-side area of the portion and the sections, lifting elastic members (30) having a contraction force of lifting a portion of the vertical stretchable part (17) on a rear side of a front end toward width-direction both sides and an obliquely upward side at least when the diaper is worn are provided in the outer body (20) of the front body (F) on closer to lateral sides than to a width-direction intermediate portion of the absorber (13), and the vertical stretchable part (17) vertically extends and contracts in length by elastic extension and contraction of the lifting elastic member (30).