Multilayer Polymer Structure for Fuel Tanks
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Solution Overview
Problem
Existing multilayer polyolefin structures for applications like fuel tanks and food packaging face challenges with poor barrier properties, dimensional stability, mechanical strength, and high production costs due to complex five or six layer constructions, which are prone to delamination and polymer degradation.
Innovation Solution
A bilayer or multilayer structure comprising a semi-aromatic polyamide layer with an impact modifier and a functionalized un-functionalized polyolefin layer, providing improved chemical resistance, dimensional stability, and mechanical strength, while being more cost-effective and suitable for complex shapes like fuel tanks and hoses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If five or six layer constructions incorporating barrier layers are used, then barrier properties are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent uses a composite material approach by combining semi-aromatic polyamide (providing barrier properties) with polyolefin (providing mechanical strength and processability) in a bilayer structure. This composite construction achieves the required barrier performance without needing complex five or six layer constructions, thereby reducing device complexity while maintaining reliability.
2Reliability
If five or six layer co-extrusion processes are used, then barrier properties are improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent segments the multilayer structure into two distinct functional layers: an inner semi-aromatic polyamide layer for barrier properties and an outer polyolefin layer for mechanical strength and processability. This segmentation allows each layer to be optimized independently and simplifies the co-extrusion process compared to managing five or six layers, making the manufacturing process more manageable while maintaining required barrier behavior.
3Reliability
If poly(ethylene-vinyl alcohol) is used as barrier layer, then barrier properties are improved, but material stability and cost increase due to degradation
Solution Approach 1:
The patent changes the material parameter by selecting semi-aromatic polyamide instead of poly(ethylene-vinyl alcohol) as the barrier layer. This parameter change results in a material with superior thermal and chemical stability, resistance to degradation over time, and better long-term performance. The semi-aromatic polyamide maintains its barrier properties without the degradation issues associated with poly(ethylene-vinyl alcohol), thereby improving both stability and cost-effectiveness.
4Stability of the object's composition
If aliphatic polyamide is used as barrier layer, then manufacturing stability is improved, but barrier performance for demanding applications is inadequate
Solution Approach 1:
The patent changes the polyamide parameter from aliphatic to semi-aromatic structure. This parameter change fundamentally improves the barrier performance while maintaining manufacturing stability. The semi-aromatic polyamide provides enhanced chemical resistance and barrier properties against fuels, hydrocarbons, and gases, while still allowing for stable co-extrusion processing. This resolves the contradiction by achieving both manufacturing stability and superior barrier performance simultaneously.
5Reliability
If complex multilayer structures are used, then barrier properties are improved, but mechanical strength and dimensional stability decrease
Solution Approach 1:
The patent employs a composite material strategy where the outer polyolefin layer provides high mechanical strength and dimensional stability, while the inner semi-aromatic polyamide layer provides barrier properties. This composite bilayer structure achieves the required barrier performance without compromising mechanical strength, as each layer performs its specialized function optimally. The synergistic combination resolves the contradiction between barrier properties and mechanical strength.
Data Source
AI summary
Multilayer structure comprising at least one couple (L1-L2) of adjacent layers (L1) and (L2), wherein:the layer (L1) comprises at least one polymer composition (C1) comprising: (i) at least one semi-aromatic polyamide, and (ii) at least one impact modifier (I1);the layer (L2) comprises at least one polymer composition (C2) comprising: (i) at least one un-functionalized polyolefin (PO2); (ii) at least one functionalized polyolefin (FPO2), the functionalized polyolefin comprising functional groups chosen from carboxylic groups, their esters, their anhydrides and their salts.Process for manufacturing such multilayer structure, which comprises co-extruding or co-blowmolding polymer compositions (C1) and (C2) so as to obtain one couple (L1-L2) of adjacent layers (L1) and (L2).Shaped article comprising such multilayer structure and process for manufacturing the shaped article.