Multilayer Polyamide Fuel Tube Structure
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Solution Overview
Problem
Conventional polyamide-based resin materials, such as PA11 and PA12, are insufficient in alcohol gasoline permeation-preventing properties, heat resistance, and interlayer adhesiveness, limiting their application in fuel tubes and hoses, and adding impact resistance modifiers like PA9T may not sufficiently address impact resistance requirements.
Innovation Solution
A multilayer structure comprising two layers of polyamide resin compositions with specific dicarboxylic acid and aliphatic diamine units, where one layer contains 70-10% impact resistance modifier and the other 50-5%, ensuring superior alcohol gasoline permeation prevention, heat resistance, and interlayer adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the walls of fuel tube, hose and tank is increased to improve the alcohol gasoline permeation-preventing property, then the alcohol gasoline permeation prevention is improved, but the flexibility of molded products decreases and the weight thereof increases
Solution Approach 1:
The invention divides the single-layer structure into a multilayer structure with an outer layer and an inner layer. The outer layer uses polyamide 11 or polyamide 12 for flexibility and processability, while the inner layer uses a resin with superior fuel barrier properties (such as EVOH, PBT, PEN, PBN, PVDF, ETFE, ECTFE, TFE/HFP, or THV) to prevent alcohol gasoline permeation. This segmentation allows each layer to optimize its function without requiring increased wall thickness.
Solution Approach 2:
The invention employs composite materials by combining polyamide 11 or polyamide 12 with resins having excellent fuel barrier properties in a multilayer configuration. This composite approach leverages the advantages of both material types: the polyamide provides flexibility and processability, while the barrier resin provides superior resistance to alcohol gasoline permeation, eliminating the need for increased wall thickness.
2Reliability
If the thickness of the walls of fuel tube, hose and tank is increased to improve the alcohol gasoline permeation-preventing property, then the alcohol gasoline permeation prevention is improved, but the cost increases due to the materials and productivity
Solution Approach 1:
The multilayer structure segments the functional requirements, allowing the use of thinner walls with comparable or superior fuel barrier performance. This reduces material consumption and manufacturing costs while meeting the alcohol gasoline permeation prevention requirements.
Solution Approach 2:
The invention changes the material composition parameters by selecting resins with high fuel barrier properties for the inner layer, enabling the use of thinner wall sections. This parameter optimization reduces material usage and manufacturing costs while achieving the required permeation prevention performance.
3Ease of operation
If conventional polyamide-based resin materials such as PA11 and PA12 are used, then the processability and flexibility are maintained, but the heat resistance and chemical resistance are insufficient
Solution Approach 1:
The multilayer structure segments the functional requirements: the outer layer of polyamide 11 or polyamide 12 provides processability and flexibility, while the inner layer of barrier resin (such as PBT, PEN, PBN, PVDF, ETFE, ECTFE, TFE/HFP, or THV) provides superior heat resistance and chemical resistance. This segmentation allows each layer to optimize its specific function.
Solution Approach 2:
The invention creates a composite material system combining polyamide 11 or polyamide 12 with resins exhibiting excellent heat and chemical resistance properties. The outer polyamide layer maintains processability and flexibility, while the inner barrier resin layer provides enhanced thermal and chemical stability, achieving both sets of properties simultaneously.
4Reliability
If a multilayer structure containing polyamide 11 or polyamide 12 as outer layer and a resin with good alcohol gasoline permeation-preventing property as innermost layer is used, then the alcohol gasoline permeation-preventing property is improved, but the interlayer adhesiveness is insufficient
Solution Approach 1:
The invention introduces a specific intermediate layer composition between the outer polyamide layer and the inner barrier resin layer. This intermediate layer acts as a mediator that ensures excellent interlayer adhesiveness while maintaining the fuel barrier properties. The intermediate layer is composed of specific resins that are compatible with both the polyamide outer layer and the barrier resin inner layer, preventing delamination and ensuring structural integrity.
Solution Approach 2:
The multilayer structure employs carefully selected composite material combinations at each interface to ensure optimal interlayer adhesion. The intermediate layer uses resins with chemical and physical properties that bridge the polyamide outer layer and the barrier resin inner layer, creating strong bonding interfaces while maintaining the overall fuel barrier performance.
Data Source
AI summary
Provision of a multilayer structure superior in the alcohol gasoline permeation-preventing property, interlayer adhesiveness, low temperature impact resistance, heat resistance and chemical resistance. A multilayer structure comprising at least two layers of layer A consisting of a polyamide resin composition (a) comprising 30 - 90 mass% of a polyamide resin (X) comprising a dicarboxylic acid unit comprising 50 - 100 mol% of a terephthalic acid unit and/or a naphthalene dicarboxylic acid unit, and a diamine unit comprising 60 - 100 mol% of an aliphatic diamine unit having 9 - 13 carbon atoms, and 70 - 10 mass% of an impact resistance modifier, and layer B consisting of a polyamide resin composition (b) comprising 50 - 95 mass% of a polyamide resin (X') comprising a dicarboxylic acid unit comprising 50 - 100 mol% of a terephthalic acid unit and/or a naphthalene dicarboxylic acid unit, and a diamine unit comprising 60 - 100 mol% of an aliphatic diamine unit having 9 - 13 carbon atoms, and 50 - 5 mass% of an impact resistance modifier, which satisfies Y≧Y'+5 wherein Y shows a content ratio (mass%) of the impact resistance modifier in layer A and Y' shows a content ratio (mass%) of the impact resistance modifier in layer B.