Polyamide 6 Resin Composition for High-Pressure Hydrogen Blow-Molding
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Solution Overview
Problem
Conventional resin tank liners for high-pressure hydrogen gas face issues with hydrogen permeation, deformation, and defects due to low melt tension and poor drawdown resistance during blow-molding, leading to residual strain and cracks when exposed to repeated charging and discharging of hydrogen gas.
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 broke of 50 m/min or more, enhancing melt stability and drawdown resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polyamide resin composition is used for blow-molding, then the material has good gas barrier properties, but the melt tension is low causing drawdown and tear during blow-molding
Solution Approach 1:
The patent changes the chemical composition parameters of the polyamide resin by incorporating specific amounts of copolymerized polyamide (5-30 parts) and impact modifier (5-30 parts) per 100 parts of polyamide 6 resin. This compositional parameter change increases the melt tension to 25 mN or more while maintaining blow moldability, resolving the contradiction between strength and ease of manufacture.
Solution Approach 2:
The patent creates a composite resin composition combining polyamide 6 resin with copolymerized polyamide and impact modifier. This composite material structure provides both high melt tension (25 mN or more) and excellent blow moldability, eliminating the drawdown and tear issues of conventional single-material systems.
2Productivity
If blow-molding process is used for large molded articles, then the molding capability is improved, but the detention time is long causing resin decomposition and reduced toughness
Solution Approach 1:
The patent modifies the resin composition parameters by adding copolymerized polyamide and impact modifier, which changes the thermal and mechanical properties. This allows the resin to withstand the extended detention time of blow-molding without decomposition, maintaining toughness while enabling large article production.
3Ease of manufacture
If conventional resin composition is used for blow-molding, then the material is easy to process, but local residual strain remains causing defects and cracks under repeated hydrogen charging and discharging
Solution Approach 1:
The patent adjusts the chemical composition parameters by incorporating copolymerized polyamide (5-30 parts) and impact modifier (5-30 parts), which modifies the molecular structure to reduce local residual strain. This maintains ease of processing while preventing defects under repeated hydrogen charging and discharging cycles.
Solution Approach 2:
The composite structure of polyamide 6 resin with copolymerized polyamide and impact modifier creates a material that processes easily while resisting local residual strain. This composite approach ensures both processability and reliability under cyclic hydrogen pressure conditions.
4Stability of the object's composition
If polyamide resin composition with low melt tension is used, then the material has good flowability, but drawdown occurs during blow-molding preventing molded article production
Solution Approach 1:
The patent changes the composition parameters by adding copolymerized polyamide (5-30 parts) and impact modifier (5-30 parts), which increases melt tension to 25 mN or more while preserving flowability. This resolves the contradiction between stability and strength during blow-molding.
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 provides a blow-molded article with improved melt stability, reduced residual strain, and suppressed defects even under repeated hydrogen gas exposure, ensuring excellent blow moldability and mechanical integrity.
Implementation Method 1
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)
Data Source
AI summary
The purpose of the present invention is to provide a polyamide resin composition which has excellent blow moldability and melt stability, can suppress a local increase in a residual strain of a molded article, and can provide a blow-molded article suppressing the occurrence of defects even if charging and discharging of high-pressure hydrogen gas are repeated. Provided is a polyamide resin composition for a blow-molded article exposed to high-pressure hydrogen gas. The polyamide resin composition 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 broke of 50 m/min or more when measured at 260°C.