Multilayer Fuel Tube Structure With Low-Extractable Polyamide Layers
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Solution Overview
Problem
Current multilayer tube structures used for transporting petrol, especially alcohol-containing petrol, fail to meet stringent criteria set by car manufacturers due to high extractable matter levels, leading to potential clogging of vehicle engines, and existing structures are unsuitable for biofuels with high alcohol content.
Innovation Solution
A multilayer tubular structure with a barrier layer and outer layers containing minimal plasticizer, predominantly comprising aliphatic polyamides with specific carbon-to-nitrogen atom ratios, reducing extractable matter and enhancing barrier properties against petrol and its components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional multilayer tube structures are used for transporting petrol, then the tubes can provide basic barrier properties and mechanical strength, but they exhibit high extractable matter levels that lead to engine clogging
Solution Approach 1:
The patent changes the chemical composition parameters of the outer layers by specifying polyamides with particular carbon-to-nitrogen atom ratios (CA between 4-8.5, CB between 7-10, CC between 9-18) and limiting plasticizer content to 0-5% by weight. These parameter modifications reduce extractable matter to ≤6 g/m² while preserving barrier properties against petrol and its components.
Solution Approach 2:
The patent employs a composite multilayer structure consisting of an inner barrier layer (PPA or fluoropolymer) combined with outer layers made from specific polyamide compositions. This composite approach leverages the low permeability of the barrier layer and the controlled extractables profile of the engineered polyamide outer layers to simultaneously achieve excellent barrier performance and low extractable matter.
2Object-generated harmful factors
If the tube structure is modified to reduce extractable matter, then engine compatibility improves, but the mechanical integrity and flexibility of the tube may be compromised
Solution Approach 1:
The patent carefully selects polyamide parameters (carbon-to-nitrogen ratios, molecular weight, plasticizer content) that simultaneously satisfy both low extractables requirements and mechanical performance criteria. The specified ranges for CA (4-8.5), CB (7-10), and CC (9-18) are optimized to maintain tensile strength, elongation, and impact resistance while reducing extractable matter to ≤6 g/m².
Solution Approach 2:
The multilayer composite structure distributes mechanical loads across different layers, allowing the outer polyamide layers to provide tensile strength and flexibility while the inner barrier layer provides chemical resistance. This division of functional responsibilities enables each layer to be optimized for its specific role without compromising overall tube integrity.
3Ease of operation
If plasticizer content is increased to improve flexibility and ease of assembly, then the tube becomes more flexible, but extractable matter levels increase leading to engine clogging
Solution Approach 1:
The patent optimizes plasticizer content to a precise range of 0-5% by weight in the outer layers, which is sufficient to provide adequate flexibility for assembly and installation while keeping extractable matter below the critical threshold of 6 g/m². This parameter optimization resolves the trade-off between flexibility and extractables.
Solution Approach 2:
The patent applies different plasticizer contents to different layers of the tube structure, with the outer layers containing 0-5% plasticizer for flexibility while the inner barrier layer maintains its specific composition for chemical resistance. This localized differentiation allows each layer to fulfill its specific functional requirements without compromising the other.
Data Source
AI summary
A multilayer tubular structure MLT intended for the transport of petrol. The MLT has at least one inner barrier layer and at least one outer layer located above the barrier layer. All the layers located above the barrier layer contain from 0 to 5% of plasticizer relative to the total weight of the composition of the layer. The outer layer is predominantly at least one aliphatic polyamide. The polyamide(s) has a number of carbon atoms per nitrogen atom selected from the following:A, from 4 to 8.5;B, from 7 to 10;C, from 9 to 18;with the proviso that when the outer layer comprises at least three polyamides, at least one of the polyamides A, B and C is excluded.