Multilayer Polyamide Fuel Tube Without Adhesive Tie Layers
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Solution Overview
Problem
Existing polyamide-based multilayer tubes for fluid transfer, such as fuel tubes in vehicles, face challenges in achieving simultaneous mechanical resistance, chemical resistance, and compatibility between polymer layers, often requiring adhesive layers that complicate manufacturing and increase layer count.
Innovation Solution
A multilayer tube structure comprising an outer layer of PA-11 or PA-12, an intermediate layer of temperature-resistant PA-6,10, and an inner layer of conductive or non-conductive PA-11 or PA-12, which adhere without coextrusion ties, providing mechanical strength, chemical resistance, and conductivity, while maintaining smooth or ringed configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive layers are used to join incompatible polymer layers together, then the mechanical strength and layer adhesion are improved, but the number of layers increases and manufacturing complexity increases
Solution Approach 1:
The patent combines the functions of adhesion and structural support into the polyamide layers themselves. The outer and inner PA-11/PA-12 layers serve both as protective/functional layers and as adhesive layers that bond to the intermediate PA-6,10 layer, eliminating the need for separate adhesive layers and reducing the total layer count.
Solution Approach 2:
The polyamide layers are designed to perform multiple functions simultaneously: the outer layer provides chemical resistance and impact strength, the intermediate layer provides high-temperature pressure resistance, and the inner layer provides conductivity or chemical resistance while also serving as an adhesive layer for bonding to the intermediate layer.
2Reliability
If multiple polymer layers with different properties are used to achieve mechanical resistance and chemical resistance, then the performance requirements are met, but incompatible polymer layers require adhesive layers which complicates the structure
Solution Approach 1:
The patent uses a composite multilayer structure combining PA-11 or PA-12 with PA-6,10 polyamides. These composite materials provide both mechanical strength and chemical resistance to fuels and engine lubrication oils, while the specific polyamide combinations ensure compatibility and adhesion between layers without requiring additional adhesive layers.
3Strength
If adhesive layers are added to join incompatible polymer layers, then layer bonding is improved, but manufacturing complexity and production time increase
Solution Approach 1:
The patent merges the adhesion function into the structural polyamide layers themselves. The outer and inner PA-11/PA-12 layers are designed to bond directly to the intermediate PA-6,10 layer through their inherent adhesive properties, eliminating the need for separate adhesive layers and simplifying the coextrusion manufacturing process to a single-step operation.
Data Source
AI summary
The present invention relates to a multilayer tube comprising, in its radial direction from the outside inwards: an optional layer (1) made of nylon-11 or nylon-12 polyamide; an intermediate layer (2) comprising by weight, the total being 100%: - 50 to 100% of at least one polyamide A1 of formula X,Y/Z or 6,Y2/Z, in which X denotes residues of an aliphatic diamine having from 6 to 10 carbon atoms, Y denotes residues of an aliphatic dicarboxylic acid having from 10 to 14 carbon atoms, Y2 denotes residues of an aliphatic dicarboxylic acid having from 15 to 20 carbon atoms, Z denotes at least one unit chosen from residues of a lactam, residues of an α,Ω-aminocarboxylic acid, the unit X1, Y1, in which X1 denotes residues of a diamine and Y1 denotes residues of a diacid, the weight ratios Z/(X+Y+Z) and Z/(6+Y2+Z) being between 0 and 15%, and - 0 to 50% of nylon-11 or nylon-12 polyamide; an optional layer (3) made of nylon-11 or nylon-12 polyamide, with the condition that at least one of the layers (1) and (3) is present; the layers being successive and adhering to one another, the inner layer being the layer in contact with the fluid transported. According to one embodiment of the invention, the inner layer contains an electrically conductive material. The invention also relates to the use of these tubes for transporting fuel.