Commonly used high-temperature engineering plastics in hot runner systems mainly include polyetheretherketone (PEEK), polyimide (PI), polyphenylene sulfide (PPS), and liquid crystal polymer (LCP). These materials can operate stably for extended periods above 150℃ and are suitable for high-temperature, high-load injection molding environments.
1. Polyetheretherketone (PEEK)
Heat resistance: Long-term operating temperature up to 250℃, short-term withstand temperature above 300℃
Advantages: High strength, wear resistance, chemical corrosion resistance, suitable for high-precision mold components
Applications: Hot runner nozzle seals, manifold insulating sleeves
Processing requirements: Requires high-temperature injection molding equipment; mold temperature is recommended to be controlled between 170 and 200℃.
2. Polyimide (PI)
Heat Resistance: Thermal decomposition temperature up to 600℃, stable performance within the range of -269℃ to 300℃
Advantages: Excellent electrical insulation, dimensional stability, and radiation resistance
Subclasses include:
PMMI (Polypyroxene Tetramethylimide): HDT up to 360℃, used for precision high-temperature parts
PEI (Polyetherimide): HDT approximately 217℃, good flowability, suitable for complex structural parts
PAI (Polyamide-Iimide): Tensile strength 190MPa, HDT up to 274℃, excellent abrasion resistance
Applications: Hot runner heating coil supports, high-temperature sensor sleeves
3. Polyphenylene Sulfide (PPS)
Heat Resistance: Long-term operating temperature above 200℃; HDT can reach 260℃ after glass fiber reinforcement.
Advantages: Self-flame retardant, low moisture absorption, extremely strong chemical resistance, good dimensional stability.
Applications: Insulating terminals and connector housings in hot runner systems.
Caution: Prevent chloride ion corrosion at high temperatures; avoid sharing recycled materials with PVC.
4. Liquid Crystal Polymer (LCP)
Heat Resistance: Ultra-heat resistant LCP can withstand reflow soldering temperatures above 300℃.
Advantages: High modulus, low creep, excellent melt flowability, suitable for thin-walled structures.
Applications: Signal transmission components and precision connectors in micro hot runner systems.
Advantages: Low molding shrinkage, reducing loosening of fit due to thermal expansion and contraction.
Practical Tips: When selecting high-temperature engineering plastics, a comprehensive evaluation should be conducted considering the operating temperature of the hot runner system, mechanical load, electrical insulation requirements, and cost control. For example, PEI or PAI (good biocompatibility) are preferred for medical-grade injection molding, while PPS or PEEK can be selected for automotive parts production to cope with high-temperature oil environments.
