Fuel Tank Cap Conductive Polyamide Resin Composition
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Solution Overview
Problem
Polyamide resin compositions compounded with carbon black for electric conductivity suffer from reduced impact strength and sliding characteristics due to increased carbon black content, which deteriorates fluidity and molding properties, and existing solutions fail to adequately combine electric conductivity and impact resistance for fuel tank caps.
Innovation Solution
An electrically conductive resin composition where carbon black is dispersed in polyamide resin, with an ethylene-α-olefin copolymer having reactive functional groups and high-density polyethylene, achieving a continuous phase morphology with carbon black dispersed in the polyamide resin, ensuring excellent impact strength and sliding characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compounding amount of carbon black is increased to enhance electric conductivity, then electric conductivity is improved, but fluidity and physical properties are greatly deteriorated
Solution Approach 1:
A modified ethylene copolymer with reactive functional groups serves as an intermediary substance between carbon black and polyamide resin. This modifier enables carbon black to disperse uniformly in the polyamide resin at lower compounding amounts (5-30 mass%), achieving sufficient electric conductivity (volume intrinsic resistivity ≤1×10^11 Ω·cm) while maintaining good fluidity and molding properties. The reactive functional groups on the modifier facilitate interaction with both carbon black surfaces and polyamide resin, preventing aggregation and ensuring uniform distribution.
2Reliability
If the compounding amount of carbon black is increased to enhance electric conductivity, then electric conductivity is improved, but impact strength significantly lowers
Solution Approach 1:
The modified ethylene copolymer acts as a mediator that improves the interface between carbon black and polyamide resin. By enabling uniform dispersion of carbon black at lower concentrations (5-30 mass%), the impact strength is preserved (Izod impact strength ≥300 J/m) while achieving the required electric conductivity. The modifier prevents stress concentration that would otherwise occur with aggregated carbon black particles.
Solution Approach 2:
The invention creates a composite material system consisting of polyamide resin, carbon black, and modified ethylene copolymer. This tri-component composite achieves synergistic effects where the modifier enhances the compatibility between the polymer matrix and conductive filler, resulting in a material that simultaneously possesses good mechanical properties (impact strength) and electrical properties (conductivity).
3Reliability
If a carbon black dispersing agent is compounded to improve dispersion, then electric conductivity is enhanced, but the dispersing agent soils the metal mold upon molding processing
Solution Approach 1:
The modified ethylene copolymer serves as a functional additive that performs its dispersing role during processing and then becomes part of the final product structure. Unlike traditional dispersing agents that remain as separate substances and cause mold soiling, this modifier is incorporated into the resin matrix through chemical or physical interaction, eliminating the harmful side effect of mold contamination while maintaining its dispersing function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves high impact resistance, sliding characteristics, and electric conductivity, suitable for fuel system components like fuel tank caps, ensuring effective static electricity discharge and improved processing properties.
Implementation Method 1
electrically conductive carbon black is dispersed in polyamide resin
Implementation Method 2
ethylene-α-olefin copolymer having a reactive functional group which is able to react with the polyamide resin
Data Source
AI summary
An electrically conductive resin composition of a polyamide type, characterized in that, (A) 95 to 40% by mass of polyamide resin, (B) 5 to 30% by mass of electrically conductive carbon black, (C) 10 to 40% by mass of an ethylene-α-olefin copolymer having a reactive functional group which is able to react with a terminal group of the polyamide resin and/or an amide group of the main chain and (D) 1 to 10% by mass of a high-density polyethylene resin are compounded; the polyamide resin (A) forms a continuous phase; the ethylene-α-olefin copolymer (C) in particles having an average particle diameter of not more than 2 μm is present by being dispersed in the continuous phase of the polyamide resin (A); and not less than 80% by mass of the electrically conductive carbon black (B) is present by being dispersed in the polyamide resin phase (A) which is a continuous phase, as well as a cap for fuel tank comprising it.