Polyamide Foam Molding Composition for Load, Impact, and Surface Quality
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Solution Overview
Problem
Existing methods for producing polyamide resin foam molded bodies face challenges in achieving high load resistance, impact resistance, and appearance performance, particularly due to issues like low foam ratios, complex processes, and surface defects such as swirl marks and reduced glossiness.
Innovation Solution
A polyamide resin composition comprising 40 to 70 parts of crystalline polyamide resin, 5 to 15 parts of non-crystalline polyamide resin, 15 to 50 parts of inorganic reinforcing material, 0.1 to 10 parts of elastomer, and 0.5 to 15 parts of a copolymer with a functional group, which controls solidification rate and viscosity for uniform foam structure and improved appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a chemical foaming agent is used to produce polyamide foam molded body, then the foam molding process is simple, but the foam ratio is low (1.2) and weight reduction is insufficient
Solution Approach 1:
The patent changes the foaming mechanism from chemical decomposition to physical phase change. By using supercritical carbon dioxide and controlling pressure-temperature parameters during injection molding, the resin expands to achieve a foam ratio of 1.05-1.30, significantly improving weight reduction while maintaining process simplicity.
Solution Approach 2:
The patent replaces the chemical foaming agent system with a physical foaming system using supercritical fluid. The carbon dioxide undergoes phase change from supercritical state to gas state upon pressure release, generating foam cells without chemical reactions, thereby achieving weight reduction while avoiding the low foam ratio problem of chemical methods.
2Weight of moving object
If carbon dioxide absorption method is used to increase foam ratio, then weight reduction is improved, but the process becomes complicated and productivity decreases
Solution Approach 1:
The patent merges the foaming process with the injection molding process into a single integrated operation. Supercritical carbon dioxide is injected together with the molten resin, and foaming occurs during the molding cycle itself, eliminating the need for separate absorption and heating steps, thereby maintaining high productivity while achieving weight reduction.
Solution Approach 2:
The patent performs preliminary dissolution of carbon dioxide into the molten resin before injection. The resin and supercritical CO2 are mixed and pressurized in advance, so that upon injection and pressure release, foaming occurs automatically during molding, combining weight reduction benefits with efficient production.
3Ease of manufacture
If supercritical fluid injection molding is used, then the process is simplified, but the foam ratio remains low (1.25) and weight reduction is insufficient
Solution Approach 1:
The patent optimizes the supercritical fluid parameters, specifically using carbon dioxide at controlled pressure and temperature ranges. By adjusting the amount of supercritical CO2 injected and the molding conditions, the foam ratio is enhanced to 1.05-1.30, improving weight reduction while maintaining the simplicity of injection molding.
Solution Approach 2:
The patent creates a composite system combining polyamide resin with inorganic reinforcing materials (glass fibers, carbon fibers) and the supercritical carbon dioxide foaming agent. This composite approach not only improves structural properties but also enhances the foaming behavior to achieve higher foam ratios and better weight reduction.
4Strength
If glycidyl group-containing styrene-based copolymer is added to control solidification rate, then load resistance and weight reduction are improved, but surface appearance quality deteriorates
Solution Approach 1:
The patent adjusts the solidification rate by controlling the crystallization temperature and cooling conditions rather than relying solely on copolymer additives. By optimizing the molding temperature profile and using nucleating agents, the resin solidifies at appropriate rates to maintain surface quality while achieving the desired foam structure and load resistance.
Solution Approach 2:
The patent creates different properties in different regions of the molded body. The skin layer near the mold surface maintains high density and good appearance, while the interior develops the foam structure for weight reduction. This local differentiation allows surface quality to be preserved while achieving load resistance through the overall foam structure.
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 results in a foam molded body with high load resistance, excellent lightweight properties, and good glossiness, suitable for applications like automobile and home electric appliance components.
Implementation Method 1
a copolymer (E) having a functional group that reacts with a terminal group of the polyamide resin
Implementation Method 2
the inorganic reinforcing material (C)...having a specific surface area of 5 m²/g or more and an average particle diameter of 10 µm or less
Implementation Method 3
a foam molded body with high load resistance, excellent lightweight properties, and good glossiness
Data Source
AI summary
Provided is a polyamide resin composition which is used for a foam molded body and has high appearance performance, high load resistance, and high impact resistance. This polyamide resin composition for foam molding contains: 40 to 70 parts by mass of a crystalline polyamide resin (A); 5 to 15 parts by mass of a non-crystalline polyamide resin (B); 15 to 50 parts by mass of an inorganic reinforcing material (C); 0.1 to 10 parts by mass of an elastomer (D); and 0.5 to 15 parts by mass of a copolymer (E) having a functional group that reacts with a terminal group of the polyamide resin. The total amount of the crystalline polyamide resin (A), the non-crystalline polyamide resin (B), the inorganic reinforcing material (C), the elastomer (D), and the copolymer (E) having a functional group that reacts with a terminal group of the polyamide resin is 100 parts by mass.