Polyamide Resin Fuel Container Crystallization Method
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Solution Overview
Problem
Polyamide resin containers used for fuel storage face challenges in ethanol resistance and fuel barrier properties due to low crystallization degrees, which are exacerbated by the direct blowing method and the limitations of existing multilayer containers in meeting regulatory standards for fuel permeation.
Innovation Solution
A production method involving a polyamide resin composition with a crystallization promoter and controlled temperature retention in the mold to increase the crystallization degree of the polyamide resin, specifically using a diamine component with 70 mol % or more m-xylylenediamine and a dicarboxylic acid component with a molar ratio of 97:3 to 90:10, and incorporating an aromatic dicarboxylic acid to enhance ethanol resistance and fuel barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyamide resin container is used for fuel storage, then the container has good mechanical strength and molding processability, but the barrier performance against fuel is poor due to low crystallization degree
Solution Approach 1:
The patent changes the crystallization temperature parameter by retaining the material in the mold at 0-60°C for a specific duration (30-70% of semi-crystallization time). This temperature parameter change promotes crystallization of the polyamide resin, increasing crystallization degree from typical low values to 40-70%, thereby improving fuel barrier performance while maintaining manufacturing feasibility
Solution Approach 2:
The patent performs preliminary crystallization promotion during the molding process itself, rather than requiring separate post-molding treatment steps. By incorporating the retention step at 0-60°C immediately after direct blowing, the crystallization action is prepared in advance during manufacturing, eliminating the need for additional processing steps
2Reliability
If the thickness of the fuel barrier layer is increased, then the fuel permeation amount decreases, but the impact absorption decreases and weight increases
Solution Approach 1:
Instead of increasing layer thickness, the patent changes the crystallization parameter of the polyamide resin itself. By controlling crystallization temperature and time during molding, the resin achieves high crystallization degree (40-70%) which inherently improves fuel barrier performance. This allows maintaining thin wall thickness while achieving required barrier performance, preserving impact absorption
3Ease of manufacture
If the molding temperature is increased, then the molding process becomes easier, but the melt viscosity decreases causing drawdown and uneven thickness
Solution Approach 1:
The patent introduces a retention temperature parameter (0-60°C) that is lower than conventional molding temperatures. This cooler retention phase after direct blowing promotes crystallization without causing drawdown, allowing the use of higher initial molding temperatures for ease of processing while maintaining thickness uniformity through the subsequent controlled crystallization phase
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 method efficiently produces containers with improved ethanol resistance and fuel barrier properties by increasing the crystallization degree of the polyamide resin, effectively meeting regulatory standards for fuel permeation while maintaining productivity.
Implementation Method 1
retaining the material in the mold whose temperature is controlled to 0 to 60° C., for a time beginning immediately after the direct blowing and lasting for 30% or more of a semi-crystallization time at cooling of the polyamide resin composition under a constant temperature of 160° C.
Data Source
AI summary
Provided is a production method for a container, including the steps of: inflating a material in a mold by direct blowing, the material including a polyamide resin composition containing 0.01 to 2 parts by mass of a crystallization promoter and 100 parts by mass of a polyamide resin obtained by polycondensation of a diamine component containing 70 mol % or more of m-xylylenediamine and a dicarboxylic acid component including an α,ω-linear aliphatic dicarboxylic acid having 4 to 12 carbon atoms and an aromatic dicarboxylic acid at a molar ratio of 97:3 to 90:10; and retaining the material in the mold whose temperature is controlled to 0 to 60° C., for a time beginning immediately after the direct blowing and lasting for 30% or more of a semi-crystallization time at cooling of the polyamide resin composition under a constant temperature of 160° C.