Semi-Aromatic Polyamide Resin Composition for Fuel Barrier and Impact Resistance
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Solution Overview
Problem
PA9T-based polyamide resin compositions face issues with impaired crystallinity, reduced moldability, and insufficient impact resistance due to the use of 2-methyl-1,8-octanediamine, leading to poor fuel barrier properties and mold releasability in injection molding.
Innovation Solution
A semi-aromatic polyamide resin composition is developed, comprising a blend of semi-aromatic polyamides with specific structural units derived from terephthalic acid, adipic acid, and 1,6-hexanediamine, along with an olefin polymer containing a heteroatom-containing functional group, and a fibrous filler, to enhance impact resistance, fuel barrier properties, and moldability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If 2-methyl-1,8-octanediamine is added to PA9T to improve fuel barrier properties, then fuel barrier properties are improved, but crystallinity and crystallization rate are impaired
Solution Approach 1:
The patent changes the chemical structure parameters of the diamine component from 2-methyl-1,8-octanediamine to straight chain aliphatic diamines (1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, or 1,10-decanediamine). This parameter change restores crystallinity while maintaining fuel barrier properties through the semi-aromatic polyamide backbone structure containing terephthalic acid units.
Solution Approach 2:
The patent creates a composite resin composition blending semi-aromatic polyamide (providing fuel barrier properties) with modified olefin polymer (providing impact resistance) and glass fiber (providing mechanical strength). This composite approach allows each component to contribute its strengths without the crystallinity impairment caused by 2-methyl-1,8-octanediamine.
2Strength
If modified olefin polymer is blended to improve impact resistance, then impact resistance is improved, but moldability and mold releasability deteriorate
Solution Approach 1:
The patent optimizes the content parameters of modified olefin polymer to 5-30 parts by mass per 100 parts of semi-aromatic polyamide, and controls the melting point of the semi-aromatic polyamide to 290-340°C. These parameter changes balance impact resistance improvement with maintenance of moldability and mold releasability.
Solution Approach 2:
The patent selects specific types of modified olefin polymers (ethylene-propylene copolymer, ethylene-butene copolymer, or propylene-1-butene copolymer) with particular properties to provide impact resistance only where needed, while the semi-aromatic polyamide matrix maintains overall moldability. The glass fiber reinforcement is also strategically used to enhance mechanical properties without compromising mold release.
3Reliability
If high crystallinity is achieved to improve fuel barrier properties, then fuel barrier properties are improved, but injection flowability deteriorates
Solution Approach 1:
The patent controls the melting point of the semi-aromatic polyamide within 290-340°C and optimizes the blend ratio with modified olefin polymer (5-30 parts per 100 parts polyamide). These parameter changes ensure sufficient crystallinity for fuel barrier properties while maintaining injection flowability through the amorphous phase provided by the modified olefin polymer and optimized processing temperature.
Data Source
AI summary
The present invention provides a semi-aromatic polyamide resin composition having exceptional impact resistance, fuel barrier properties, and injection moldability, as well as a molded article containing the same, through a semi-aromatic polyamide resin composition containing specific proportions of (A) a semi-aromatic polyamide comprising a dicarboxylic acid component comprising terephthalic acid and adipic acid and a diamine component having a linear aliphatic diamine having 4-10 carbon atoms, (B) a semi-aromatic polyamide comprising a dicarboxylic acid component having isophthalic acid and a diamine component having an aliphatic diamine having 4-15 carbon atoms, (C) an olefin polymer containing a specific amount of functional group structural units, and (D) a fibrous filler.