Segmented Bond Pattern for Composite Tear Resistance
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Solution Overview
Problem
Conventional mechanically bonded composites in absorbent articles face issues with stress concentration leading to fracture, inadequate tear resistance, and the need for reduced adhesive use due to cost and odor concerns, while also requiring softer and thinner designs for aesthetic and performance reasons.
Innovation Solution
A bonding design with a specific bond density and pattern that includes discrete bonds with varying sizes and orientations, interlocking patterns, and reduced adhesive use, which enhances tear resistance and stress distribution across the composite, maintaining strength without excessive adhesive reliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high pressure dynamic bonding is used to create strong bonds, then bond strength is improved, but stress concentration occurs leading to fracture at bonded locations
Solution Approach 1:
The bonding region is segmented into multiple discrete bonds arranged in a pattern rather than a continuous bond. This segmentation distributes stress across multiple discrete locations, preventing stress concentration at any single bond site and reducing the likelihood of fracture propagation.
Solution Approach 2:
Different regions of the bonding pattern have different bond characteristics (size, shape, spacing) optimized for local stress distribution. The bond pattern is designed with varying bond densities and geometries to address local stress concentrations while maintaining overall bond strength.
2Strength
If adhesive is added to improve mechanical performance, then tear resistance is improved, but cost and odor increase
Solution Approach 1:
The mechanical bond pattern itself provides the tear resistance function that would otherwise require adhesive. The discrete bond design with appropriate spacing and geometry creates inherent mechanical interlocking and stress distribution that resists tearing without needing additional adhesive materials.
Solution Approach 2:
The adhesive component is extracted or eliminated from the bonding system. The patent achieves the desired mechanical performance through optimized mechanical bonding alone, removing the need for adhesive and its associated problems of odor, cost, and potential skin irritation.
3Strength
If bond density is increased to maintain strength, then composite strength is preserved, but article thickness and stiffness increase
Solution Approach 1:
The bond pattern uses segmented discrete bonds with optimized spacing that provides sufficient strength while maintaining thinness. The segmentation allows for effective stress distribution without requiring high bond density, thus keeping the article thin and flexible.
Solution Approach 2:
The bond pattern parameters (bond size, spacing, density, geometry) are optimized to achieve the minimum necessary bond density for strength while minimizing thickness. The parameters are tuned to provide strength equivalence to higher density bonds but with reduced material usage and greater flexibility.
4Ease of manufacture
If known bond patterns are used, then manufacturing is simplified, but tear propagation is enhanced rather than inhibited
Solution Approach 1:
The bond pattern uses segmented discrete bonds with specific spacing and geometry that interrupt tear propagation paths. The segmentation creates multiple stress distribution points that stop tears from propagating across the bonded region, while the pattern remains simple enough for standard manufacturing processes.
Data Source
AI summary
A composite includes a first substrate and a second substrate joined in a bonding region, wherein the first substrate comprises a first Peak Force Tensile Strength and the second Peak Force Tensile Strength. The first Peak Force Tensile Strength is greater than or equal to the second Peak Force Tensile Strength. The bonding region has a Bond Density of about 10% to about 22%; and a Composite Tensile Strength at Peak Force that is within about 15% of the second Peak Force Tensile Strength.