Polyamide Resin Composition for Fuel Tubes
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Solution Overview
Problem
The addition of carbon black to polyamide resins to enhance conductivity results in decreased moldability due to increased melt viscosity, compromising the resin's ability to maintain low-temperature impact resistance and fuel barrier properties.
Innovation Solution
A polyamide resin composition comprising a semi-aromatic polyamide with specific terminal amino groups, a modified resin with unsaturated compounds, and a conductive filler, where the mole ratios of terminal amino groups and carboxyl/acid anhydride groups are within defined ranges, ensuring appropriate melt viscosity and improved moldability, conductivity, and fuel barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon black is added to polyamide resins to enhance conductivity, then electrical conductivity is improved, but moldability deteriorates due to increased melt viscosity
Solution Approach 1:
The patent introduces a modified resin containing carboxyl groups or acid anhydride groups as an intermediary substance between the polyamide resin and carbon black filler. This modified resin reacts with terminal amino groups of the polyamide to form a compatibilizing layer that prevents excessive viscosity increase while maintaining conductivity. The intermediary modified resin acts as a bridge that allows carbon black to be incorporated without severely degrading moldability.
Solution Approach 2:
The patent changes the chemical parameters of the resin system by introducing modified resin with specific functional groups (carboxyl or acid anhydride groups) in controlled amounts (3-30 parts by mass per 100 parts polyamide). This parameter change - the addition of reactive functional groups - transforms the system's rheological properties, allowing conductivity enhancement while controlling melt viscosity to preserve moldability.
2Reliability
If carbon black is added to polyamide resins to enhance conductivity, then electrical conductivity is improved, but low-temperature impact resistance deteriorates
Solution Approach 1:
The modified resin serves as an intermediary that protects the polyamide matrix structure from degradation by carbon black addition. By reacting with terminal amino groups, it creates a modified network that maintains the toughness and impact resistance properties of polyamide even in the presence of conductive filler, thereby preserving low-temperature impact resistance while achieving conductivity.
3Reliability
If carbon black is added to polyamide resins to enhance conductivity, then electrical conductivity is improved, but fuel barrier properties deteriorate
Solution Approach 1:
The modified resin with carboxyl or acid anhydride groups acts as a protective intermediary layer that maintains the fuel barrier properties of polyamide. This modified resin component creates a compatible matrix structure that prevents fuel permeation pathways from forming, even when carbon black is present to provide conductivity.
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 balanced melt viscosity, excellent moldability, conductivity, low-temperature impact resistance, and fuel barrier properties, making it suitable for applications like fuel tubes.
Implementation Method 1
a polyamide (A) containing: dicarboxylic acid units containing 50 to 100 mol % of terephthalic acid units and/or naphthalenedicarboxylic acid units; and diamine units containing 60 to 100 mol % of aliphatic diamine units having 4 to 18 carbon atoms, the polyamide (A) having terminal amino groups ([NH2]) in an amount of 5 to 60 μmol/g; a modified resin (B) that has been modified with an unsaturated compound having a carboxyl group and/or an acid anhydride group
Data Source
AI summary
The present invention provides a polyamide resin composition not only having an appropriate melt viscosity despite addition of a conductive filler thereto but also having excellent moldability, conductivity, low-temperature impact resistance, and fuel barrier properties. The present invention is a polyamide resin composition containing specific amounts of a polyamide, a modified resin, and a conductive filler. The polyamide contains: dicarboxylic acid units containing 50 mol % or more of terephthalic acid units and/or naphthalenedicarboxylic acid units; and diamine units containing 60 mol % or more of aliphatic diamine units having 4 to 18 carbon atoms, and has terminal amino groups in an amount of 5 to 60 μmol/g. The modified resin has been modified with an unsaturated compound having a carboxyl group and/or an acid anhydride group. In the polyamide resin composition, a difference between the number of moles (MI) of the terminal amino groups of the polyamide and the number of moles (MII) of the carboxyl groups and the acid anhydride groups of the modified resin in 1 g in total of the polyamide and the modified resin is −5.0 μmol or more and less than 4.0 μmol, and the number of moles (MII) is more than 4.0 μmol.