Absorbent Article Welding Strength via Elastic Release
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Solution Overview
Problem
Existing absorbent articles, such as pull-on disposable diapers, face issues with the separation of side seal portions when force is applied due to inadequate welding between the front and back sheet members, leading to reduced bonding strength.
Innovation Solution
A method and apparatus for manufacturing absorbent articles that involves stretching elastic members between sheet members, overlapping them, releasing the stretch, and welding in the released state to increase the basis weight of nonwoven fabrics in the weld regions, thereby strengthening the bonding between the members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is performed while elastic members are stretched, then the welding process can be completed, but the basis weight of nonwoven fabric in the weld portion is reduced, resulting in insufficient welding strength
Solution Approach 1:
The elastic member is placed in a stretched state before the welding process, allowing the nonwoven fabric to be positioned and secured. The stretching is then released before welding, ensuring adequate basis weight is present at the weld portion. This preliminary positioning action resolves the contradiction by separating the placement function from the welding function in time.
Solution Approach 2:
The patent employs a dynamic process where the elastic member transitions from a stretched state to a released state. During the stretched state, the elastic member is positioned between sheet members; during the released state, the basis weight increases at the weld portion. This dynamic state change allows the system to optimize both placement accuracy and welding strength at different stages.
2Strength
If adhesive bonding is used to strengthen welding, then bonding strength increases, but the product becomes less soft and more complex
Solution Approach 1:
The patent replaces chemical bonding (adhesive) with a mechanical process (welding) to achieve bonding strength. By controlling the timing of the welding process to occur after elastic member placement but before final assembly, the invention achieves strong bonding without requiring additional adhesive materials or complex bonding equipment, thus maintaining product simplicity and softness.
3Ease of manufacture
If welding is performed in stretched state, then manufacturing process is simplified, but welding strength is insufficient due to reduced basis weight
Solution Approach 1:
The elastic member is preliminarily positioned in the stretched state between the sheet members, which simplifies the overall manufacturing process by enabling easy placement. The stretching is then released before welding to ensure adequate basis weight, maintaining welding strength. This preliminary positioning action resolves the contradiction between manufacturing simplicity and welding strength.
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 approach enhances the welding strength between the front and back sheet members, reducing the likelihood of separation during wear or application, and allows for a softer product without the need for adhesive bonding.
Implementation Method 1
an elastic member (elastic string) stretchably contractible in a left-right direction
Implementation Method 2
a welding process of welding one end portion in the left-right direction of the first member and one end portion in the left-right direction of the second member to each other, to form the weld portion
Data Source
AI summary
A method for manufacturing an absorbent article that includes: a first sheet body that includes two first sheets and a first elastic string that is stretchable and contractible in a left-right direction; a second sheet body; and a first weld portion. The method includes: (a) placing the first elastic string in a stretched state where the first elastic string is stretched in the left-right direction between the first sheets disposed in a thickness direction intersecting the left-right direction; (b) causing the second sheet body to overlap with the first sheet body in the thickness direction; (c) releasing the stretched state to bring about a released state; and (d) welding one end portion of the first sheet body in the left-right direction and one end portion of the second sheet body in the left-right direction to each other, to form the first weld portion.