Foldable duct comprising laminated foil on inside and outside
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Solution Overview
Problem
Existing foils used for laminating ducts, typically made of metal and polymer layers, exhibit low mechanical properties and are prone to rupture under bending, stretching, and pressure, which is a concern for ducts in ventilation systems requiring flexibility and fire protection.
Innovation Solution
Incorporating a polyethylene terephthalate (PET) layer between an outer aluminium layer and an inner polyethylene (PE) layer, with an additional intermediate PE layer for adhesion, enhances the foil's mechanical properties and flexibility, allowing it to withstand repeated folding and pressure without breaking, while also providing fire resistance and air-tightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a foil made of metal layer (aluminium) and polymer layer (polyethylene) is used for laminating ducts, then the foil provides basic protection, but it has low mechanical properties and breaks easily when bent, stretched or exposed to pressures
Solution Approach 1:
The patent applies composite materials by creating a multi-layer foil structure consisting of an outer aluminium layer, an intermediate PET layer, and an inner PE layer. This composite structure combines the fire resistance of aluminium, the mechanical strength and flexibility of PET, and the adhesion properties of PE, thereby resolving the contradiction between basic protection and mechanical strength.
Solution Approach 2:
The patent changes the material parameters by replacing the single-layer or simple multi-layer structure with a specific three-layer composite having defined thicknesses (0.03-0.05 mm total). The intermediate PET layer with specific mechanical properties transforms the overall foil performance, improving strength while maintaining flexibility and resistance to breaking.
2Ease of operation
If the foil is made to be flexible for repeated folding, then it can be folded and unfolded repeatedly, but it may rupture due to folding and stretching
Solution Approach 1:
The intermediate PET layer acts as a flexible reinforcement that allows the foil to be folded and unfolded repeatedly without rupturing. PET provides the necessary flexibility and elastic recovery, while the composite structure distributes stress across all layers, preventing rupture at fold lines.
Solution Approach 2:
The patent uses thin film technology with a total thickness of 0.03-0.05 mm to create a flexible yet strong foil. The thin film structure allows repeated folding while the multi-layer composite design prevents rupture by distributing mechanical stresses across different material layers.
3Reliability
If the foil needs to withstand concentrated pressures without puncturing, then it maintains integrity for fire protection, but existing foils with low mechanical properties fail under such pressures
Solution Approach 1:
The outer aluminium layer provides fire protection and pressure resistance, while the intermediate PET layer adds mechanical strength to withstand concentrated pressures without puncturing. The composite structure distributes pressure loads across layers, maintaining integrity for fire protection while resisting puncture forces.
4Strength
If additional layers are added to enhance mechanical properties, then the foil becomes stronger and more flexible, but the structure becomes more complex
Solution Approach 1:
The patent uses a three-layer composite structure that enhances mechanical strength while keeping the design relatively simple. Each layer has a specific function: outer aluminium for fire protection, intermediate PET for mechanical strength and flexibility, and inner PE for adhesion. This functional distribution achieves high performance without excessive complexity.
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
The solution results in a foil that maintains integrity under mechanical stress and repeated folding, meeting stringent fire protection and air-tightness criteria, ensuring the duct's functionality and safety in ventilation systems.
Implementation Method 1
An additional layer of polyethylene (PE), having melting point below PET, is intermediate the outer aluminium layer and the layer of PET in order to adhere the aluminium layer to the PET layer. The adhesion arises when the polymer is melted.
Implementation Method 2
The inner layer of polyethylene (PE) having a melting point below PET, also functions as an adhesive between the PET layer and the duct or the outer layer of aluminium, when wrapped around or inside a duct.
Implementation Method 3
This layer of PET brings a flexibility to the foil at the same time as it does not break easily when it is exposed to mechanical forces, such as bending, stretching and pressure.
Data Source
Figure 1~3
AI summary
The present invention concerns a foldable duct (4) made of glass or stone fibres and binder agent having a foil (1) laminated thereon, on the inside and outside of the duct, wherein the foil (1) at least comprises: -an outer layer of aluminium (5), -an intermediate layer of a thermoplastic polymer (6) having a lower melt point than polyethylene, positioned closest to the outer layer of aluminium (5), -an intermediate layer of polyethylene (7), positioned between the intermediate layer of thermoplastic polymer (6), and -an inner layer of a thermoplastic polymer (8) having a lower melt point than polyethylene.