Expanded Polyamide Resin Molding via Supercritical Gas Injection
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Solution Overview
Problem
Current methods for producing expanded polyamide resin moldings fail to achieve sufficient weight reduction while maintaining high heat resistance and load resistance, particularly in automotive components, due to limitations in expansion ratio and complexity of existing processes.
Innovation Solution
A polyamide resin composition combining a glycidyl group-containing styrene copolymer with a crystalline and noncrystalline polyamide resin, along with an inorganic reinforcing material, is used in a molding process that includes injecting a chemical foaming agent or supercritical inert gas into a cavity, followed by mold enlargement to achieve a uniform expanded structure with high expansion ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a chemical foaming agent is used to produce expanded polyamide molding, then the molding can be obtained with some expansion, but the expansion ratio is low and weight reduction is insufficient
Solution Approach 1:
The patent changes the physical state parameter of the foaming agent from solid (chemical foaming) to supercritical fluid, enabling much higher expansion ratios (2.5-3.5 times) while maintaining uniform cell structure and achieving sufficient weight reduction
Solution Approach 2:
The patent uses a composite system combining polyamide resin with supercritical carbon dioxide or nitrogen, creating an expanded molding that achieves both high expansion ratio and uniform cellular structure for optimal weight reduction
2Manufacturing precision
If carbon dioxide is absorbed beforehand and heating is performed in a post step, then an expanded molding with expansion ratio of 2 can be obtained, but the process is complicated and productivity is low
Solution Approach 1:
The patent merges the molding and expanding steps into a single integrated process by injecting supercritical foaming agent during injection molding, eliminating the separate post-step heating process and significantly improving productivity
Solution Approach 2:
The patent incorporates the foaming agent into the resin before molding, so that expansion occurs automatically during the molding process itself, eliminating the need for subsequent separate expanding operations
3Ease of manufacture
If a supercritical fluid of nitrogen or carbon dioxide is dissolved in molten resin followed by injection molding, then molding can be achieved, but the expansion ratio is only 1.25 and weight reduction is insufficient
Solution Approach 1:
The patent optimizes the injection parameters (pressure, temperature, timing) of the supercritical foaming agent to achieve maximum expansion ratio of 2.5-3.5 times, transforming the insufficient expansion (1.25x) into sufficient weight reduction
4Manufacturing precision
If a core-side mold is moved and critical inert gas is injected directly into the resin, then expanded molding can be obtained, but uniform foam cells cannot be formed due to rapid solidification of crystalline polyamide
Solution Approach 1:
The patent pre-dissolves the supercritical foaming agent into the molten resin before injection, ensuring uniform distribution throughout the material, which enables uniform nucleation and foam cell formation even during rapid cooling
Solution Approach 2:
The patent uses supercritical carbon dioxide or nitrogen which maintains solubility and enables controlled expansion even during rapid solidification, overcoming the limitation of conventional inert gases that cannot form uniform cells in quickly solidifying polyamides
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 approach results in an expanded polyamide resin molding that is lightweight, has high heat resistance, and exhibits superior load resistance, making it suitable for automotive applications by enhancing both heat insulating properties and oscillation resistance.
Implementation Method 1
a method that comprises mixing a raw material resin and an organic foaming agent that decomposes on heating to generate gas
Implementation Method 2
a method for producing an expanded polyamide molding by dissolving a supercritical fluid of nitrogen or carbon dioxide in a molten resin
Implementation Method 3
a core-side mold is moved in the mold opening direction and simultaneously a critical inert gas is injected directly into the resin in the mold, so that an expanded molding is obtained
Data Source
Figure 1(A)~1(B)
Figure 2~3
Figure 4
AI summary
Provided is a polyamide resin composition which can provide an expanded molding being superior in heat resistance and sufficiently reduced in weight and having high load resistance by a simple molding process. The polyamide resin composition is characterized by comprising a polyamide resin (A), a glycidyl-group-containing styrene copolymer (B) having two or more glycidyl groups per molecule, a weight average molecular weight of 4000 to 25000 and an epoxy value of 400 to 2500 Eq/1×106 g and an inorganic reinforcing material (C) in a proportion such that the content of the glycidyl-group-containing styrene copolymer (B) is 0.2 to 25 parts by mass and the content of the inorganic reinforcing material (C) is 0 to 350 parts by mass relative to 100 parts by mass of the polyamide resin (A).