Multi-Layer Polyamide Tube for Fuel Permeation and Adhesion
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Solution Overview
Problem
Multi-layer tubes used for automobile lines face challenges with inadequate heat resistance, chemical resistance, and durability of interlayer adhesion, particularly when exposed to fuels and heat treatments, which affects their ability to prevent chemical permeation and maintain low-temperature impact resistance.
Innovation Solution
A multi-layer tube structure comprising an aliphatic polyamide composition with an elastomer polymer containing unsaturated compounds and a semi-aromatic polyamide composition, where the aliphatic polyamide contains 70-95% aliphatic polyamide and 5-30% elastomer polymer, and the semi-aromatic polyamide has a specific diamine and dicarboxylic acid unit composition, enhancing interlayer adhesion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single-layer tube using conventional polyamide-based resins is used, then strength and flexibility are improved, but chemical resistance and heat resistance become inadequate
Solution Approach 1:
The patent employs a multi-layer composite structure where an aliphatic polyamide layer provides strength and flexibility, while a semi-aromatic polyamide layer (containing 60 mol% or more of 1,9-nonanediamine unit and/or 2-methyl-1,8-octanediamine unit) provides superior chemical resistance and heat resistance. This composite approach allows both requirements to be satisfied simultaneously.
2Reliability
If a multi-layer structure incorporating semi-aromatic polyamide is used, then chemical permeation resistance is improved, but interlayer adhesion durability deteriorates when exposed to fuel and heat
Solution Approach 1:
The patent optimizes specific parameters of the semi-aromatic polyamide composition, requiring it to contain 60 mol% or more of 1,9-nonanediamine unit and/or 2-methyl-1,8-octanediamine unit based on all diamine units. This specific compositional parameter ensures both chemical permeation resistance and maintains interlayer adhesion durability even when exposed to fuel and heat treatments.
3Ease of manufacture
If conventional polyamide-based resins are used, then manufacturing ease is maintained, but ability to prevent chemical permeation becomes inadequate
Solution Approach 1:
The patent combines conventional aliphatic polyamide (easy to manufacture) with semi-aromatic polyamide (superior chemical permeation resistance) in a multi-layer structure. This allows the manufacturing process to remain relatively simple while achieving the required chemical permeation resistance for alcohol-containing gasoline.
Data Source
AI summary
The present invention is a multi-layer tube comprising at least two layers having an (a) layer containing an aliphatic polyamide composition (A) and a (b) layer containing a semi-aromatic polyamide composition (B) containing a specific semi-aromatic polyamide (B1), wherein the aliphatic polyamide composition (A) contains a specific amount of an aliphatic polyamide (A1) and a specific amount of an elastomer polymer (A2) containing an unsaturated compound having a carboxyl group and/or acid anhydride group, and the product of the terminal amino group concentration [X] of the aliphatic polyamide (A1) per g of the aliphatic polyamide composition (A) and the total concentration [Y] of the carboxyl group and acid anhydride group of the elastomer polymer (A2) per g of the aliphatic polyamide composition (A) is a specific amount.