Multilayer Fuel Line Composition for Low Additive Migration
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Solution Overview
Problem
Existing fuel lines face issues with additive migration and leaching, leading to embrittlement and insufficient resistance to chemicals like zinc chloride, particularly when used in automotive applications where mechanical strength and chemical resistance are critical.
Innovation Solution
A multi-layer plastic pipe design featuring an inner layer of polyamide 6, a middle EVOH barrier layer, and an outer layer of polyamide 616, with specific impact modifiers and plasticizers, such as acid-modified ethylene-α olefin copolymers and hydroxybenzoic acid esters, to minimize additive migration and enhance mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional multi-layer fuel lines with polyamide and EVOH layers are used, then chemical resistance and barrier properties are improved, but additive migration and leaching occur leading to embrittlement
Solution Approach 1:
The patent changes the chemical composition parameters of the polyamide layers by incorporating specific stabilizer packages and controlling plasticizer types and concentrations. The outer layer uses a polyamide blend with specific stabilizers that prevent additive migration, while maintaining the necessary chemical resistance properties through controlled composition parameters.
Solution Approach 2:
The patent employs a multi-layer composite structure where the outer layer is a specially formulated polyamide blend containing stabilizers and plasticizers that work synergistically. This composite material approach allows the outer layer to protect the inner layers from fuel contact while preventing additive migration, thus resolving the contradiction between chemical resistance and additive stability.
2Strength
If impact modifiers are added to improve mechanical strength, then cold impact resistance is improved, but resistance to zinc chloride and chemical stability deteriorate
Solution Approach 1:
The patent applies local quality by concentrating impact modifiers specifically in the outer layer where mechanical strength is needed for impact resistance, while the inner layers maintain higher chemical purity for zinc chloride resistance. This spatial distribution of properties allows each layer to optimize its function without compromising the other.
Solution Approach 2:
The patent carefully controls the concentration and type of impact modifiers in the outer layer, using specific polyamide blends with optimized compositions. By adjusting these parameters, the patent achieves adequate cold impact strength while limiting the negative effects on zinc chloride resistance through controlled additive packages.
3Ease of operation
If plasticizers are added to maintain flexibility, then mechanical flexibility is improved, but additive washout increases
Solution Approach 1:
The patent uses stabilizer packages as intermediary substances that bind to plasticizers and prevent their migration and washout. These stabilizers act as mediators between the plasticizer and the fuel environment, allowing the plasticizer to maintain flexibility while preventing its extraction by fuel or washing processes.
Solution Approach 2:
The patent formulates the outer layer as a composite material containing plasticizers combined with specific stabilizer systems. This composite approach allows the plasticizer to provide necessary flexibility while the stabilizer matrix prevents excessive washout, resolving the contradiction between maintaining flexibility and minimizing additive loss.
Data Source
AI summary
A plastics line (1) is described with at least one layer (5) consisting of the following components:(A) 70-94 weight percent of a polyamide selected from the following group: polyamide 516, polyamide 616, polyamide 1016 or mixtures thereof;(B) 4-20 weight percent impact modifier;(C) 2-15 weight percent of plasticiser;(D) 0-5 weight percent of additives different from (B) and (C),wherein the sum of (A)-(D) is 100 weight percent, and with the proviso that layer (5) does not contain polyamide 6,as well as a method of manufacturing such a plastic pipe and uses of such a plastic pipe.