Polyamide 6 Resin Composition for High-Pressure Hydrogen Extrusion
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Solution Overview
Problem
Conventional resin tank materials for high-pressure hydrogen gas storage in fuel cell electric vehicles suffer from hydrogen permeation, deformation, and defects due to low melt tension and poor drawdown resistance during extrusion molding, leading to thickness deviations and cracks when exposed to repeated charging and discharging of hydrogen.
Innovation Solution
A polyamide resin composition comprising 70-99 parts by weight of polyamide 6 resin, 1-30 parts by weight of an ethylene/α-olefin copolymer impact modifier modified with unsaturated carboxylic acid, and 0.005-1 parts by weight of a metal halide, with a melt tension of 20 mN or more and a take-up speed at strand break of 30 m/min or more, enhancing extrusion moldability and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyamide resin composition is used for extrusion molding, then gas barrier properties are improved, but extrusion moldability deteriorates due to low melt tension and poor drawdown resistance
Solution Approach 1:
The patent changes the chemical composition parameters by introducing a specific copolymerized polyamide component with controlled composition ratio and molecular weight distribution. This modifies the melt tension and drawdown resistance parameters while maintaining the gas barrier properties of the polyamide resin system.
Solution Approach 2:
The patent creates a composite resin composition by combining polyamide 6, copolymerized polyamide, and impact modifier in specific ratios. This composite structure achieves both excellent gas barrier properties and improved extrusion moldability through synergistic effects of the different polymer components.
2Productivity
If extrusion molding is used for long tank liner production, then productivity is improved, but thickness uniformity deteriorates due to drawdown occurrence
Solution Approach 1:
The patent modifies the rheological parameters of the resin composition by controlling the copolymerized polyamide composition ratio and molecular weight distribution. These parameter changes improve drawdown resistance, enabling stable extrusion molding with uniform thickness throughout the production process.
3Reliability
If polyamide resin composition with excellent gas barrier properties is used, then hydrogen permeation resistance is improved, but melt tension decreases leading to poor extrusion moldability
Solution Approach 1:
The patent develops a composite polyamide system combining polyamide 6 with copolymerized polyamide in specific ratios. This composite maintains the hydrogen permeation resistance of polyamide while the copolymerized component contributes to higher melt tension and better extrusion moldability.
Solution Approach 2:
The patent applies different functional components in specific regions of the resin composition: polyamide 6 provides gas barrier properties, while copolymerized polyamide with specific molecular weight distribution provides melt strength. This local quality differentiation resolves the contradiction between permeation resistance and melt tension.
4Reliability
If resin composition is optimized for gas barrier properties, then hydrogen gas accumulation resistance is improved, but drawdown resistance decreases causing thickness deviation
Solution Approach 1:
The patent optimizes the molecular weight distribution parameter of the copolymerized polyamide component. This parameter change enhances both the hydrogen gas accumulation resistance through improved polymer packing and the drawdown resistance through increased melt elasticity and strength.
Data Source
AI summary
A polyamide resin composition for an extrusion-molded article exposed to high-pressure hydrogen gas contains: 70 to 99 parts by weight of a polyamide 6 resin (A); 1 to 30 parts by weight of an impact modifier (B); and 0.005 to 1 parts by weight of a metal halide (C) with respect to a total of 100 parts by weight of the polyamide 6 resin (A) and the impact modifier (B). The polyamide resin composition has a melt tension of 20 mN or more when measured at 260° C. and a take-up speed at strand break of 30 m/min or more when measured at 260° C.