Elastic Laminate Transverse Stretching Method
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Solution Overview
Problem
Existing methods for creating elastic nonwoven laminates with both elastic and inelastic regions are complicated and impractical, especially when multiple elastic strips are laminated between nonwoven webs, as they require complex stretching procedures that affect bond strength and material width.
Innovation Solution
The method involves preactivating an elastic film by stretching it transversely and cutting it into strips, which are then laminated between nonwoven webs without prestretching, followed by mechanical activation of the laminate in elastic regions and winding into a roll, allowing for improved elasticity and reduced stretching force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If an elastic film is preactivated by stretching before lamination, then the stretching force required during lamination is reduced and bond strength is improved, but the lamination procedure becomes complicated when multiple elastic strips must be laminated between nonwoven webs
Solution Approach 1:
The elastic film is preactivated by stretching to 100-500% of its original width before lamination. This preliminary stretching action prepares the elastic regions to require less force during the actual lamination process, resolving the contradiction by performing the force-intensive operation beforehand when the material is more compliant.
Solution Approach 2:
The preactivated elastic film is cut into multiple parallel strips that are then laminated between nonwoven webs. This segmentation allows each strip to be independently positioned and laminated, simplifying the overall procedure compared to laminating a continuously stretched film, while still benefiting from the reduced stretching force effect of preactivation.
2Reliability
If the elastic film is stretched uniformly over its entire width during preactivation, then the stretching behavior is improved, but it becomes difficult to create adjacent elastic and inelastic regions in the final laminate
Solution Approach 1:
After uniform preactivation, the elastic film is cut into parallel strips at specific intervals. This creates local differentiation where regions between strips remain inelastic (nonwoven only) while regions with strips become elastic. The local quality principle allows the final laminate to have both elastic and inelastic adjacent regions, resolving the contradiction between uniform preactivation and regional versatility.
3Reliability
If nonwoven webs are stretched during lamination to create transverse elasticity, then CD direction elasticity is improved, but the material width is reduced and folds are formed that complicate the process
Solution Approach 1:
The nonwoven webs are preactivated by stretching them before lamination with the elastic strips. This preliminary stretching creates the necessary transverse elasticity in the final laminate without requiring complex folding operations during lamination. The preactivation prepares the nonwoven structure to accommodate the elastic regions while maintaining width stability.
4Adaptability or versatility
If multiple elastic strips are laminated between nonwoven webs, then the laminate has both elastic and inelastic regions, but the stretching forces during lamination become unmanageably high
Solution Approach 1:
The elastic film is preactivated by stretching to 100-500% of its original width before being cut into strips and laminated. This preliminary action reduces the stretching force required during lamination by up to 50%, making it feasible to laminate multiple strips between nonwoven webs without unmanageable forces.
Solution Approach 2:
The preactivated film is divided into multiple parallel strips that are laminated separately between nonwoven webs. This segmentation distributes the lamination process across multiple smaller operations, each requiring manageable stretching forces, while achieving the final configuration with multiple elastic regions.
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 laminate's stretchability and yield strength while maintaining non-elastic regions unchanged, improving the bonding and relaxation behavior of the laminate, and allows for the production of closure elements with elastic centers and less elastic ends.
Implementation Method 1
an elastic film is stretched transverse to the web direction and, after elastic relaxation, is cut into strips
Implementation Method 2
the laminate thus formed is then stretched transverse to the web direction in regions rendered elastic by the laminated strips, and after elastic relaxation
Data Source
AI summary
The invention relates to a method of making an elastic laminate. According to the invention, an elastic film (1) is stretched transverse to the web direction and, after elastic relaxation, is cut into strips (2). The strips (2) are then laminated next to one another between nonwoven material webs (4, 5) supplied without prestretching and joined to the strips (2). Last, the laminate (8) thus formed is stretched transverse to the web direction in regions (6) rendered elastic by the laminated strips (2) and, after elastic relaxation, is wound into a roll (10). - One figure