Multilayer Fuel Line Structure Without Adhesion Promoter Layers
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Solution Overview
Problem
Existing fuel tubes for the automotive sector face challenges in achieving a balance between mechanical properties, chemical resistance, and barrier effectiveness, particularly in terms of permeability and resistance to additives, with existing multilayer structures often requiring adhesion promoter layers and not adequately addressing cold impact and elongation at break requirements.
Innovation Solution
A three-layer composite structure comprising an inner layer of polyamide 6, a middle layer of EVOH, and an outer layer based on a blend of polyamides such as polyamide 6 and polyamide 612, 614, or 616, without the need for adhesion promoter layers, which achieves excellent mechanical properties and wash-out resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multilayer structures with adhesion promoter layers are used to ensure bond between EVOH barrier layer and polyamide inner layer, then adhesion reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention removes the adhesion promoter layer from the multilayer structure by directly bonding the EVOH barrier layer to the polyamide inner layer through optimized processing conditions, thereby simplifying the layer structure while maintaining adhesion reliability
Solution Approach 2:
The invention uses a composite structure of EVOH barrier layer and polyamide inner layer with specific material compositions and ratios that enable direct bonding without adhesion promoters, achieving both simplification and reliability
2Reliability
If traditional multilayer structures are used to achieve barrier effectiveness, then permeability resistance is improved, but elongation at break and cold impact resistance deteriorate
Solution Approach 1:
The invention changes the material parameters by using specific polyamide types (PA6, PA66, PA610, PA612, PA11, or PA12) with controlled weight ratios (30-70 wt% for inner layer, 70-30 wt% for outer layer) and processing conditions to achieve both barrier effectiveness and high elongation at break (>300%),
Solution Approach 2:
The invention employs a composite structure where the inner layer contains 30-70 wt% polyamide and the outer layer contains 70-30 wt% polyamide, creating a balanced material composition that simultaneously provides barrier effectiveness and superior mechanical properties including elongation at break exceeding 300%
3Reliability
If five-layer structures with multiple functional layers are used to meet chemical resistance requirements, then chemical resistance is improved, but manufacturing complexity and production time increase
Solution Approach 1:
The invention extracts and removes unnecessary intermediate layers (adhesion promoters and other functional layers) from the traditional five-layer structure, reducing it to a simplified two-layer or three-layer structure that maintains chemical resistance while improving manufacturing efficiency
Solution Approach 2:
The invention makes the EVOH barrier layer and polyamide layers perform multiple functions simultaneously - providing both chemical resistance and adhesion without requiring separate adhesion promoter layers, thereby reducing the total number of layers and improving productivity
Data Source
AI summary
A multi-layer composite in the form of a hollow body enclosing an interior space (2) is proposed, consisting of three or four layers: an inner layer (3) adjoining the interior space (2), a middle layer (4) adjoining the latter and an outer layer (5) adjoining the middle layer (4) and closing the multi-layer composite (1) to the outside. If necessary, there is a further innermost layer (8) which directly adjoins the said inner layer (3) and is equipped with a conductive finish. The inner layer (3) is based on polyamide 6, the middle layer (4) is based on EVOH, and the outer layer (5) is based on a mixture of (A) polyamide 6 and (B) at least one other polyamide selected from the following group: polyamide 612, polyamide 614, polyamide 616 and polyamide 618.