Strand-Based Laminates for Absorbent Articles
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Solution Overview
Problem
Current stretch laminates for absorbent articles face issues such as puckering, increased material cost, inefficiency in adhesive use, and difficulty in achieving a garment-like appearance and high-speed thermal bonding due to prestrained elastic materials, which affect both performance and aesthetics.
Innovation Solution
A multilayer substrate with a first and second outer layer, where at least one layer exhibits partial elastic recovery after mechanical activation in the machine direction, and an inner layer comprising elastic strands, is used to create a uniaxially stretchable fabric that reduces gathering and enhances the appearance and feel of absorbent articles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If prestrained elastic materials are used to achieve high stretch (80-170%), then the elastic fit and stretch performance are improved, but the nonwoven layers gather and pucker, increasing basis weight and material cost
Solution Approach 1:
The patent changes the prestrain parameter from high (150-200%) to moderate (50-100%), and adjusts the elastic strand diameter accordingly (0.1-0.5mm). This parameter optimization reduces gathering while maintaining adequate stretch performance for the chassis component application
Solution Approach 2:
The patent uses a composite structure combining elastic strands with nonwoven layers, where the elastic strands provide stretch and the nonwoven provides structure. The bonding density and adhesive amount are optimized to balance stretch recovery with reduction of gathering, creating a composite material system that mitigates the drawbacks of using elastic strands alone
2Reliability
If prestrained elastic strands are bonded to nonwoven layers, then stretch recovery is achieved, but gathering causes difficult-to-control puckering that affects appearance and touch feel
Solution Approach 1:
The patent applies partial bonding rather than complete bonding across the entire nonwoven layer. By bonding only certain areas or using limited adhesive amount, the patent allows some controlled gathering while preventing excessive puckering, achieving a balance between stretch recovery and surface uniformity
Solution Approach 2:
The patent optimizes bonding parameters including adhesive amount, bonding temperature, and pressure to control the degree of gathering. By adjusting these parameters, the patent reduces puckering while maintaining adequate stretch recovery for the application
3Strength
If large amounts of adhesive are used to bond nonwovens to elastic strands, then bonding strength is improved, but adhesive diffusion into nonwoven reduces effectiveness and increases cost
Solution Approach 1:
The patent optimizes adhesive application parameters including amount, viscosity, and curing conditions to maximize bonding efficiency. By controlling these parameters, the patent reduces adhesive diffusion into the nonwoven while maintaining adequate bonding strength, thereby reducing adhesive waste and cost
4Productivity
If thermal bonding is used to bond laminates at high speed, then productivity is improved, but high melting temperature of nonwovens and strand breakage risk reduce reliability
Solution Approach 1:
The patent optimizes thermal bonding parameters including temperature, pressure, and dwell time to achieve adequate bonding at high speed while preventing strand breakage. By carefully controlling these parameters, the patent maintains strand integrity during high-speed thermal bonding processes
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 solution provides a stretchable multilayer fabric that maintains high stretch performance while minimizing material usage and adhesive requirements, improving the visual and tactile appeal of absorbent articles and enabling effective high-speed thermal bonding.
Implementation Method 1
at least one of the first or second outer layer comprises a component that exhibits at least partial elastic recovery after mechanical activation in the machine direction
Data Source
AI summary
Absorbent articles comprising a multilayer outer cover comprising a first outer layer and a second outer layer comprising a component that exhibits at least partial elastic recovery after mechanical activation in the machine direction; an inner layer, disposed between the first outer layer and the second outer layer, the inner layer comprising elastic strands; and wherein at least one of the first outer layer and second outer layer is laminated to the inner layer.