Multilayer Biofuel Tube Structure With Low-Plasticizer Inner Polyamide
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Solution Overview
Problem
Current multilayer tube structures used for transporting alcohol-containing petrol fail to meet the stringent requirements of car manufacturers, particularly in terms of low extractable matter, which can lead to clogging of vehicle engines, and existing structures are unsuitable for the new extractables test where the proportion of extractables must be less than or equal to 6 g/m2 of tube inner surface area.
Innovation Solution
A multilayer tubular structure is designed with a specific arrangement of layers, including a barrier layer and inner layers containing polyamides with low carbon content and minimal plasticizer, where the inner layers have a plasticizer content of 0 to 1.5% by weight, and the outer layers can have up to 15% plasticizer, to reduce extractable matter and enhance barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional multilayer tube structures are used for transporting alcohol-containing petrol, then the tubes can provide basic barrier properties and mechanical strength, but the proportion of extractable matter exceeds the stringent requirement of 6 g/m2, leading to potential engine clogging
Solution Approach 1:
The patent applies local quality by differentiating the plasticizer content across different layers of the multilayer tube structure. The inner layer (in contact with fuel) contains 0-1.5% plasticizer to minimize extractables, while outer layers can contain up to 15% plasticizer for mechanical flexibility. This localized variation in composition resolves the contradiction by reducing harmful extractables where they contact the fuel system while maintaining structural integrity elsewhere.
Solution Approach 2:
The patent uses composite materials by combining multiple polymer layers with different plasticizer contents and compositions. The multilayer structure includes at least an inner layer and an outer layer with distinct material properties, creating a composite tube that simultaneously achieves low extractable matter release and adequate mechanical performance for fuel transport applications.
2Reliability
If the inner layers contain minimal plasticizer (0-1.5% by weight) to reduce extractables, then the extractable matter proportion decreases below 6 g/m2, but the flexibility and ease of assembly may be compromised
Solution Approach 1:
The patent resolves this contradiction by applying local quality through spatial differentiation of plasticizer content. The inner layer has minimal plasticizer (0-1.5%) to ensure low extractables, while the outer layer contains higher plasticizer (up to 15%) to provide the necessary flexibility for assembly and installation. This localized approach allows each layer to optimize for its specific functional requirement.
Solution Approach 2:
The patent applies segmentation by dividing the tube into functionally distinct layers with different plasticizer contents. The inner layer and outer layer are segmented as separate functional units, each optimized for its specific role: the inner layer minimizes chemical interaction with fuel, while the outer layer provides mechanical flexibility. This segmentation allows the tube to meet both low extractable matter and flexibility requirements simultaneously.
3Strength
If outer layers contain up to 15% plasticizer to maintain mechanical integrity and flexibility, then the tube maintains adequate strength and flexibility, but the overall extractable matter proportion increases
Solution Approach 1:
The patent applies local quality by concentrating higher plasticizer content (up to 15%) in the outer layers that are not in direct contact with fuel, while keeping the inner layer plasticizer content minimal (0-1.5%). This spatial differentiation allows the outer layers to provide mechanical integrity and flexibility without significantly contributing to extractable matter release into the fuel system.
Solution Approach 2:
The patent uses segmentation to separate the mechanical support function (handled by outer layers with higher plasticizer) from the fuel contact function (handled by inner layers with minimal plasticizer). This functional segmentation allows each layer to be optimized independently, enabling the outer layers to contain sufficient plasticizer for mechanical integrity while the inner layers minimize extractable matter release.
4Reliability
If the inner layer contains polyamides with low carbon content and minimal plasticizer, then the barrier properties against petrol and degradation products improve, but the manufacturing complexity increases due to precise composition control requirements
Solution Approach 1:
The patent applies parameter changes by specifying precise ranges for plasticizer content (0-1.5% in inner layer, up to 15% in outer layers) and polyamide carbon content. These defined parameter ranges provide clear manufacturing targets that balance barrier performance requirements with manufacturability, allowing producers to achieve the desired low extractable matter levels through controlled compositional parameters rather than overly complex processing requirements.
Data Source
AI summary
The present invention relates to a multilayer tubular structure (MLT) intended for the transport of fluids, in particular of petrol, especially alcohol-containing petrol, comprising, from the outside inwards, at least one barrier layer (1) and at least one inner layer (2) located below the barrier layer,said inner layer (2), or all the layers (2) and the other optional layers located below the barrier layer, containing on average from 0 to 1.5% by weight of plasticizer relative to the total weight of the composition of the layer (2) or to the total weight of all the compositions of the layers (2) and the other optional layers located below the barrier layer, respectively,said inner layer (2) predominantly comprising at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units, said aliphatic polyamide being chosen from:a polyamide denoted A, having a mean number of carbon atoms per nitrogen atom, denoted CA, of from 4 to 8.5, advantageously from 4 to 7;a polyamide denoted B, having a mean number of carbon atoms per nitrogen atom, denoted CB, of from 7 to 10, advantageously from 7.5 to 9.5;a polyamide denoted C, having a mean number of carbon atoms per nitrogen atom, denoted CC, of from 9 to 18, advantageously from 10 to 18;with the proviso that when said inner layer (2) comprises at least three polyamides, at least one of said polyamides A, B and C is excluded.