Elastic Diaper Laminate with Pre-Stretched Hydroentangled Nonwoven
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Solution Overview
Problem
Existing elastic laminates for diaper fastening elements, particularly those with nonwoven and elastic film layers, face limitations in stretching properties, requiring enhancement to achieve consistent and efficient elongation characteristics.
Innovation Solution
The laminate incorporates hydroentangled nonwoven outer layers with loop-shaped fiber structures, which are stretched transversely using a ring-rolling process with profiled rollers, and an elastic film laminated between these layers, allowing for adjustable stretching and maintaining a consistent stretching force over a wide range by pre-stretching less than the yield point, and incorporating a non-stretchable reinforcement layer between elastic film strips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the nonwoven fabric is stretched beyond 100% elongation, then the stretching force increases progressively, but the bond structure of the hydroentangled nonwoven is compromised and the yield point is reached
Solution Approach 1:
The nonwoven fabric is pre-stretched to a specific elongation range (100-200%) before lamination with the elastic film. This preliminary stretching action modifies the fiber structure in advance, allowing the laminate to achieve consistent stretching characteristics without compromising bond structure integrity during subsequent use.
Solution Approach 2:
The patent changes the physical parameters of the nonwoven fabric by controlling the stretching elongation within specific ranges (100-200% for hydroentangled nonwoven, 50-150% for other types). This parameter control optimizes the balance between stretching capability and bond structure preservation.
2Adaptability or versatility
If the laminate is stretched in the transverse direction after lamination, then the stretching properties are improved, but the manufacturing process complexity increases
Solution Approach 1:
The transverse stretching is performed on the nonwoven fabric before lamination with the elastic film, rather than after. This preliminary action simplifies the overall manufacturing process by consolidating the stretching operation into the preparation stage, avoiding additional complex equipment requirements in the lamination stage.
Solution Approach 2:
The patent employs dynamic stretching processes where the nonwoven fabric is stretched to specific elongation ranges (100-200% for hydroentangled, 50-150% for others) and then fixed in that state before lamination. This dynamic approach allows the material to be adapted to different application requirements while maintaining a controlled manufacturing process.
3Device complexity
If the elastic film is laminated over the entire width, then the laminate structure is simplified, but the stretching force distribution becomes less controlled
Solution Approach 1:
The elastic film is applied in strips that are spaced apart from one another in the transverse direction, rather than as a continuous layer. This segmentation allows for better control of stretching force distribution across the laminate, while the spacing between strips is optimized to maintain structural integrity.
Solution Approach 2:
The patent applies different stretching characteristics to different regions of the laminate. The elastic film strips provide localized elasticity where needed, while the spaced arrangement allows the nonwoven fabric to provide structural support in between strips, creating a laminate with optimized local properties.
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 significantly attenuates the progressive increase in extension force, maintaining a relatively constant stretching force and elongation characteristics, effectively improving the stretch properties of the laminate while retaining the bond structure of the nonwoven fabric.
Implementation Method 1
The hydroentangled nonwoven (spunlace nonwoven), which forms at least one of the two outer layers, contains loop-shaped fiber structures that have formed as a result of the hydrojet treatment. Due to these loop-shaped structures, which are characteristic of hydroentanglement, the nonwoven can be stretched by up to 100% with little force.
Implementation Method 2
The laminate is expediently stretched in the transverse direction by a ring-rolling process, in which the laminate consisting of outer nonwoven layers and a laminated elastic film is passed through a profiled roller arrangement.
Implementation Method 3
an elastic film laminated at least in regions between the outer layers
Implementation Method 4
In the profile roller arrangement, the laminate is locally overstretched transversely to the running direction. The degree of stretching can be adjusted by the depth of engagement of the profile rollers.
Implementation Method 5
The nonwoven fabric bonded by water jets can be stretched by up to 100% with little force. With further elongation, the elongation force increases progressively until the elongation limit is reached at approximately 200% elongation.
Data Source
AI summary
The invention relates to an elastic laminate, in particular for elastic diaper fastening elements, comprising external layers of non-woven fabric and an elastic foil, laminated at least in areas between the external layers. At least one of the two external layers consists of a water jet compacted non-woven fabric, which can be stretched in transverse direction. According to the invention, the water jet compacted non-woven fabric is stretched in the area of the elastic foil in at least one axial direction.