Nonwoven Elastomer Laminate Activation for Edge Bond Integrity
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Solution Overview
Problem
Existing methods for imparting elasticity to laminates comprising elastic films and nonwoven layers are complex and prone to delamination at the outer edges, requiring additional gluing or welding, which complicates the process and increases costs.
Innovation Solution
Applying a longitudinal tension to the laminate during unwinding between toothed rollers simplifies the activation process and enhances the bond strength between the elastic film and nonwoven, reducing the likelihood of detachment at the edges, thus eliminating the need for ultrasonic welding lines or high-tack glues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the laminate is activated by passing between toothed rollers without longitudinal tension, then the activation process is simpler, but the bond between elastomer and nonwoven detaches at the outer edges
Solution Approach 1:
The invention changes the physical parameter of applying longitudinal tension during activation. By introducing a tensioning roller that applies controlled tension (e.g., 1-10 N) to the laminate in the machine direction during the toothed roller activation process, the bond strength at the edges is significantly improved without requiring additional gluing or welding operations.
2Reliability
If additional gluing or welding is applied to prevent edge detachment, then the bond strength improves, but the process complexity and cost increase
Solution Approach 1:
The invention extracts and eliminates the need for additional gluing or welding operations by introducing a simple tensioning mechanism. The tensioning roller applies longitudinal tension during activation, which inherently prevents edge detachment, thereby removing the requirement for separate gluing or welding steps and their associated equipment and costs.
3Manufacturing precision
If the laminate is stretched during activation, then elasticity is imparted to the laminate, but the outer edges are prone to delamination
Solution Approach 1:
The invention changes the activation process by introducing longitudinal tension as an additional controlled parameter. The tensioning roller applies a specific tension range (1-10 N) in the machine direction while the toothed rollers stretch the laminate in the transverse direction. This combined parameter control ensures uniform stretching and elasticity activation while maintaining bond integrity at the edges through the stabilizing effect of longitudinal tension.
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 method results in a laminate with a gradient of elasticity, where the center has greater elasticity than the edges, reducing the propensity for detachment during use and allowing for the use of less expensive adhesives or no weld lines at the edges.
Implementation Method 1
The mutual engagement of the teeth while the laminate is between the two teeth has the effect of stretching the laminate. On leaving the two rollers, the laminate substantially resumes the shape it had before entering it. However, the deformation that has taken place causes the laminate as a whole to now have elasticity, namely a transverse elasticity
Implementation Method 2
a tension is imparted to the ribbon in the longitudinal direction or in the machine direction during its unwinding between the teeth, in particular by providing a tensioning roller, in particular downstream of the teeth
Data Source
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AI summary
The laminate useful as the shaped nappies or the devices for the incontinence of the adults and babies, comprises two non-woven layers (301, 401), and left and right elastic films (201, 202) engaged between the two non-woven layers by interposition of an adhesive. The laminate has an activated width lower or equal to the cross section width. The activated width has a left side and a right side. The elasticity increases over the left edge on a part of left side of the activated width and decreases on a part of the right side. The laminate useful as the shaped nappies or the devices for the incontinence of the adults and babies, comprises two non-woven layers (301, 401), and left and right elastic films (201, 202) engaged between the two non-woven layers by interposition of an adhesive. The laminate has an activated width lower or equal to the cross section width. The activated width has a left side and a right side. The elasticity increases over the left edge on a part of left side of the activated width and decreases on a part of the right side towards the straight edge of the activated width. The elasticity curve of the laminate is measured by a test of stretching to 10 Newton (in percentage of lengthening) in function of the distance in mm of the point of measure at the left edge of the activated width presented in each point of measure of the increasing part, or left side. A slope of the elasticity curve is lower than 15%/mm, and comprises between 15 and 5. The two elastic films have a left and a right activated length. The elasticity curve of the right activated length is symmetric as in a mirror of the elasticity curve of the left activated length. The slope in absolute value of the curve in the right part of decrease of the left activated width is lower than 7 of the left part of increase of the left activated width. The curve presents a maximum for a point of measurement at middle of the activated width of the laminate. Independent claims are included for: (1) a process of assigning elasticity with a laminate; and (2) a device for assigning elasticity with a laminate.