Multilayer Fuel Line Structure Without Adhesion-Promoter Layers
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Solution Overview
Problem
Existing multilayer fuel lines face challenges in achieving good adhesion between layers, resistance to chemicals like zinc chloride, and maintaining low permeability while ensuring high mechanical properties and impact resistance, particularly in the automotive sector.
Innovation Solution
A multilayer composite structure comprising an internal layer of fluoropolymer and an external layer made of specific polyamides, such as PA 616, with impact modifiers and plasticizers, eliminating the need for adhesion-promoter layers, and optionally further layers of polyamide, to enhance adhesion and chemical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesion-promoter layers are added between polyamide and fluoropolymer layers, then layer adhesion is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent removes the adhesion-promoter layer from the multilayer structure by directly bonding polyamide and fluoropolymer layers together. This extraction of the intermediate layer simplifies the overall structure while maintaining good layer adhesion through optimized material selection and processing parameters.
Solution Approach 2:
The patent uses composite material design by selecting specific polyamide formulations (with controlled moisture content and molecular weight) that inherently provide good adhesion to fluoropolymer layers without requiring additional adhesion-promoter layers. The composite structure achieves both simplicity and reliability.
2Reliability
If multilayer structures with high barrier properties are used, then fuel permeability is reduced, but mechanical properties and impact resistance deteriorate
Solution Approach 1:
The patent applies local quality by assigning different functions to different layers: the fluoropolymer layer provides excellent fuel barrier properties and chemical resistance, while the polyamide layer provides mechanical strength and impact resistance. Each layer is optimized for its specific function rather than requiring all layers to fulfill all requirements.
Solution Approach 2:
The multilayer composite structure combines materials with complementary properties: fluoropolymer for low permeability and chemical inertness, and polyamide for mechanical strength. The direct bonding interface between these layers creates a synergistic effect where the weak points of one material are compensated by the strengths of the other.
Data Source
AI summary
A plastic line including at least an inner layer, which directly or indirectly encloses an interior space, and an outer layer directly adjacent to the inner layer. The inner layer is based on fluoropolymer, and the outer layer consists of the following constituents: (A) 51-98% of a polyamide from the following group: PA 616, PA 516, PA 618 or mixtures thereof, and copolymers containing at least 50% of at least one of these polyamides and also mixtures of at least one of these polyamides with a further different thermoplastic material (A2), wherein the proportion of these polyamides in such mixtures makes up at least 50%; (B) 2-20% of impact modifiers or plasticizers; (C) 0-29% of additives different from (A) and (B), wherein the components (A)-(C) together make up 100% of the material of the outer layer.