Stretch Laminate Bond Pattern for Stronger Absorbent Article Seams
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Solution Overview
Problem
Conventional ultrasonically bonded stretch laminates in absorbent articles lack sufficient bond strength, leading to potential tearing, delamination, and detachment, while also requiring a balance between stretchability and integrity, with a need for varied design patterns and cost-effective production.
Innovation Solution
A stretch laminate comprising a nonwoven and elastomeric layer with specific ultrasonic bond orientations and dimensions, including a majority of bonds oriented in the stretch direction and a second direction, achieving a Hysteresis Ratio of 2.5 or less and an Unload Force at 50% of 0.44 MPa or greater, along with a Low Stress Region and controlled aperture growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ultrasonic bonding is used to create stretch laminates, then the bonding process is efficient and cost-effective, but the bond strength is insufficient leading to tearing and delamination
Solution Approach 1:
The patent applies local quality by creating bonds with non-uniform characteristics - specifically, bonds with varied sizes, shapes, and spacing distributed across the laminate. This allows different regions to have different bond strengths and densities, optimizing both the overall bond strength and the stretchability of the laminate without requiring uniform high-strength bonding across the entire surface.
Solution Approach 2:
The patent utilizes parameter changes by varying multiple bond parameters simultaneously - bond size, bond spacing, bond density, and bond orientation - to achieve the desired balance between bond strength and extensibility. By adjusting these parameters, the ultrasonic bonding process can be optimized to create bonds that are strong enough to prevent delamination while remaining flexible enough to allow laminate stretching.
2Strength
If the number and positioning of bonds are increased to improve strength, then bond strength is enhanced, but stretchability is inhibited
Solution Approach 1:
The patent applies segmentation by dividing the bonding pattern into discrete, distributed bonds rather than using continuous bonding. The bonds are spaced apart at specific intervals, creating a segmented structure that allows the laminate to stretch between the bond points while maintaining strength at the bond locations. This segmentation enables the laminate to accommodate stretching movements without compromising overall bond integrity.
Solution Approach 2:
The patent implements local quality by creating regions with different bond densities and characteristics. Areas requiring higher strength have denser or larger bonds, while areas requiring greater stretchability have sparser or smaller bonds. This localized variation in bond quality allows the laminate to exhibit both high strength where needed and high extensibility where required, resolving the contradiction between these two properties.
3Ease of manufacture
If uniform bond patterns are used, then manufacturing is simplified, but design variability and aesthetic appeal are limited
Solution Approach 1:
The patent utilizes parameter changes to achieve design variability while maintaining manufacturing simplicity. By programmatically varying parameters such as bond size, bond spacing, bond shape, and bond orientation across different regions of the laminate, the system can generate diverse bond patterns that provide both aesthetic appeal and functional performance. The underlying ultrasonic bonding process remains simple and automated, but the output patterns exhibit rich variability.
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 improved bond strength, stretchability, and durability, ensuring the laminate maintains integrity during use while allowing easy application, with reduced material costs and design flexibility.
Implementation Method 1
a stretched elastomeric material is combined with a nonwoven via ultrasonic bonding
Data Source
AI summary
An absorbent article includes a first waist region, a second waist region and a crotch region disposed between the first and second waist regions; and a topsheet, a backsheet and an absorbent core disposed between the topsheet and the backsheet. The article further includes a stretch laminate having a bonding region. The bonding region has a plurality of ultrasonic bonds, a majority of the ultrasonic bonds are oriented in a stretch direction, and the bonding region has a Hysteresis Ratio of 2.5 or less and an Unload Force at 50% of 0.44 MPa or greater.