Diaper Side Seal Tear Resistance via Continuous Bonding
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Solution Overview
Problem
The existing underpants-type disposable diapers suffer from lateral tears at the intersection of side seal portions and sheet bonding sections when the side seal portions are pulled apart, due to sheet bonding sections protruding from the side edges.
Innovation Solution
The design incorporates a stretchable region with sheet bonding sections that are continuous in the width direction, aligned at predetermined intervals, and have fixed ends that are bonded across the entire front-back direction, preventing sheet bonding sections from protruding and reducing the risk of lateral tears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sheet bonding sections are formed by intermittently bonding two sheet layers in the width direction and front-back direction, then cost is reduced and flexibility is improved, but sheet bonding sections protrude from side edges causing lateral tears
Solution Approach 1:
The patent applies different bonding configurations to different regions: in the stretchable region, sheet bonding sections are continuous in the width direction to prevent protrusion and lateral tears, while in the non-stretchable region, intermittent bonding is used to reduce cost and improve flexibility. This local differentiation resolves the contradiction between cost reduction and lateral tear resistance.
2Reliability
If sheet bonding sections are continuous in the width direction in the stretchable region, then lateral tear resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the outer body into a stretchable region and a non-stretchable region, applying different bonding strategies to each. The stretchable region uses continuous bonding for lateral tear resistance, while the non-stretchable region uses intermittent bonding for simplicity. This segmentation resolves the contradiction by localizing the complex continuous bonding only where necessary.
3Shape
If elastically stretchable members are fixed in a stretched state to provide tight fit, then fit to body is enhanced, but flexibility and cost are affected by fixing means
Solution Approach 1:
The patent fixes only the ends of elastically stretchable members to the sheet layers rather than fixing the entire length. This partial fixing action provides sufficient fit enhancement while reducing the complexity and cost of fixing means compared to full-length fixation.
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 enhances the softness and smoothness of the diaper's texture, reduces the risk of lateral tears, and allows for easier separation of side seal portions without compromising the integrity of the diaper.
Implementation Method 1
elongated elastically stretchable members, such as rubber threads, fixed in a stretched state between the sheet layers in the width direction to provide a stretchable structure for enhancement of the fit to the body
Implementation Method 2
The side seal portions are typically formed by material welding (heat sealing or ultrasonic sealing)
Implementation Method 3
The side seal portions are typically formed by material welding (heat sealing or ultrasonic sealing)
Data Source
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AI summary
An underpants-type disposable diaper includes outer members 12F and 12B having stretchable regions A2 and A3 disposed adjacent to the inner edges of the side seal portions 12A in the width direction. The stretchable regions A2 and A3 include multiple elongated elastically stretchable members 19 disposed between two sheet layers 12S and 12H at predetermined intervals in the front-back direction and extending in the width direction. The elastically stretchable members 19 each include two fixed ends 19f fixed to the two sheet layers 12S and 12H, and the section between the fixed ends 19f is unfixed to the two sheet layers 12S and 12H. The two sheet layers 12S and 12H are welded into sheet bonding sections 20, at positions between the elastically stretchable members 19 in the stretchable regions A2 and A3 adjacent in the front-back direction. No sheet bonding section protrudes from the side seal portion in the stretchable regions A2 and A3.