Split Substrate Hook Formation for Robust Laminate Bonding
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Solution Overview
Problem
Existing methods for forming protrusions on substrates, such as hooks in absorbent articles, face challenges in achieving quality, speed, and robustness, with issues like partial cavity filling, fracture, low engagement forces, and process constraints.
Innovation Solution
A method involving a first substrate with a high basis weight, such as a film, is preheated and formed with protrusions using a sonotrode, then bonded to a second substrate with a lower basis weight using a second sonotrode, allowing for optimized line speed and product quality by separating the hook formation from attachment to a larger substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If hook formation is performed on a single substrate simultaneously with attachment to a second substrate, then the process is simpler, but the quality and robustness of hook formation deteriorates due to partial cavity filling and low engagement forces
Solution Approach 1:
The patent divides the substrate processing into two separate stages: first forming hooks on a first substrate, then attaching the first substrate to a second substrate. This segmentation allows each stage to be optimized independently, ensuring complete cavity filling and high engagement forces without the constraints of simultaneous processing.
Solution Approach 2:
The patent performs hook formation as a preliminary action on the first substrate before attachment to the second substrate. This preliminary formation ensures that hooks are fully formed with complete cavity filling and high engagement forces, and only then are they attached to the final product substrate.
2Strength
If a thick film is used to increase basis weight, then the film provides structural support, but the film does not bond well with the nonwoven layer and causes wrinkling and mis-tracking
Solution Approach 1:
The patent applies different substrate types to different regions: a film substrate in the hook formation region where structural support is needed, and a nonwoven substrate in the attachment region where bonding is required. This local differentiation allows each material to perform its optimal function without the drawbacks of using a single material throughout.
Solution Approach 2:
The patent creates a composite structure by bonding a film substrate to a nonwoven substrate. This composite allows the film to provide structural support and basis weight where needed, while the nonwoven layer provides bonding capability and surface stability, eliminating the drawbacks of using either material alone.
3Adaptability or versatility
If hook formation is performed on nonwoven substrates with localized basis weight variation, then the substrate can be flexible, but hooks fail to form in low basis weight regions and burn-thru occurs
Solution Approach 1:
The patent uses a film substrate specifically in the hook formation region where consistent basis weight is critical for reliable hook formation, while allowing the nonwoven substrate to provide flexibility and adaptability in the attachment region. This local differentiation ensures consistent hook formation without burn-thru while maintaining overall substrate flexibility.
4Ease of manufacture
If rotary formation is used to form hooks, then the process can be implemented on absorbent article converting lines, but the process is constrained by machine capabilities and cannot always achieve optimal quality and speed
Solution Approach 1:
The patent segments the manufacturing process into two independent stages that can be performed on different machines: first forming hooks on a dedicated first substrate, then attaching to a second substrate on a converting line. This segmentation allows each stage to be optimized for its specific requirements, achieving both high quality and high speed without the constraints of trying to perform both operations on a single machine.
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 quality and robustness of hook formation by ensuring complete cavity filling and higher engagement forces, while reducing wrinkling and mis-tracking, enabling higher line speeds and cost-effective production.
Implementation Method 1
the first source of vibration energy may be used to alter a portion of the first substrate in the first nip to create an altered area
Implementation Method 2
the second source of vibration energy may be used to join the first substrate to the second substrate in the second nip
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
Methods of forming a laminate may include conveying a first substrate through a first nip, where a first source of vibration energy may be used to alter a portion of the first substrate in the first nip to create an altered area. The method may include conveying the first substate with the altered area and a second substrate into a second nip and using a second source of vibration energy to join the first substrate to the second substrate in the second nip.