Diaper Waist Elastic Gradient Force Design
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Solution Overview
Problem
Pants-type disposable diapers often cause discomfort due to the upper end portions of strip projecting parts cutting into the wearer's body, despite efforts to reduce contractile force in the waist region to prevent slipping off.
Innovation Solution
A pants-type absorbent article design with a waist region divided into first and second waist regions, where the first waist region has a smaller unit contractile force than the second waist region, and a folded portion forming the upper end of the strip projecting parts, reducing stiffness and discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the contractile force in the waist region is reduced to prevent slipping off, then the comfort is improved, but the diaper may slip off the wearer
Solution Approach 1:
The waist region is divided into a first waist region and a second waist region with different contractile force characteristics. The first waist region has lower contractile force for comfort, while the second waist region has higher contractile force to prevent slipping off. This segmentation allows simultaneous optimization of both comfort and reliability.
Solution Approach 2:
Different regions of the waist are assigned different mechanical properties: the first waist region (upper part) has smaller unit contractile force for comfort, while the second waist region (lower part) has greater unit contractile force for preventing slip-off. This local differentiation of properties resolves the contradiction between comfort and reliability.
2Reliability
If the contractile force in the waist region is increased to prevent slipping off, then the reliability is improved, but the upper end portions of strip projecting parts cut into the wearer's body
Solution Approach 1:
The waist region is segmented into first and second waist regions with different contractile forces. The first waist region has lower contractile force that prevents the strip projecting parts from cutting into the wearer's body, while the second waist region provides higher contractile force for slip prevention.
Solution Approach 2:
The upper waist region (first waist region) is designed with smaller unit contractile force to avoid cutting discomfort, while the lower waist region (second waist region) has greater unit contractile force for reliability. This local quality differentiation simultaneously addresses both harmful effects.
3Ease of operation
If a folded portion is added to form the upper end of strip projecting parts, then the stiffness is reduced and comfort is improved, but the device complexity increases
Solution Approach 1:
A folded portion is formed in advance in the outer covering sheet at the upper end of the strip projecting parts. This preliminary folding structure reduces stiffness and prevents cutting into the wearer's body before the diaper is put on, while adding minimal complexity to the overall structure.
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 design effectively suppresses the cutting in of the upper end portions of the strip projecting parts into the wearer's body while maintaining sufficient contractile force to prevent the diaper from slipping off, enhancing comfort and fit.
Implementation Method 1
a first waist elastic member disposed approximately in parallel with the edge of the waist opening in a first waist region that is an upper part of the waist region, and a second waist elastic member disposed approximately in parallel with the first waist elastic member in a second waist region that is a region of the waist region below the first waist region
Data Source
AI summary
A pants-type disposable diaper includes a pair of strip projecting parts projecting laterally from a line of connection between front and rear parts located respectively on the belly and back sides of a wearer, a first waist elastic member joined to a first waist region that is an upper part of a waist region extending along a waist opening, and a second waist elastic member joined to a second waist region that is a lower part of the waist region. In a state in which an outer covering sheet is elongated in a right-left direction, a first unit contractile force that is a contractile force in the right-left direction per unit width of the first waist region in an up-down direction is smaller than a second unit contractile force in the second waist region.