When processing flame retardant PA, what unique processes can improve the quality of products?
Publish Time: 2025-02-17
Flame retardant PA (polyamide) is widely used in many fields such as electronics, automobile manufacturing, etc. due to its high strength, wear resistance, and easy processing.Raw material pretreatmentDrying: Flame retardant PA is hygroscopic. Moisture will cause hydrolysis during processing, reduce material performance, and may also form defects such as bubbles and silver wires on the surface of the product. Therefore, the raw materials need to be fully dried. Vacuum drying or hot air circulation drying can be used, and the drying temperature can be controlled at 80-120℃, and the drying time is about 4-8 hours to reduce the water content to less than 0.1%.Additive premixing: The uniformity of dispersion of additives such as flame retardants, plasticizers, and antioxidants is crucial to the quality of the product. A high-speed mixer can be used to premix additives and PA resin to ensure that the additives are evenly coated on the surface of the resin particles, laying the foundation for the full dispersion of additives in subsequent processing.Processing technology optimizationScrew combination design: In extrusion processing, a reasonable screw combination can promote the plasticization and mixing of materials. Screw elements with strong shearing and dispersing capabilities, such as kneading blocks, reverse thread elements, etc., can be used. By adjusting the arrangement order and quantity of these elements, the flame retardant and other additives can be fully dispersed in the PA matrix to improve the flame retardant and mechanical properties of the material.Injection molding process parameter adjustment:Temperature control: Properly increasing the barrel temperature is conducive to the plasticization of PA resin and the dispersion of additives, but too high a temperature will cause the decomposition of flame retardants and degradation of materials. Generally, the temperature of the front section of the barrel is controlled at 240-260℃, the temperature of the middle section is 250-270℃, and the temperature of the rear section is 230-250℃.Injection pressure and speed: Higher injection pressure and speed can ensure that the material fills the mold cavity, but too high pressure and speed may cause flash, internal stress and other problems in the product. The injection pressure and speed should be reasonably adjusted according to the shape, size and complexity of the product. For example, for thin-walled products, the injection speed can be appropriately increased; for thick-walled products, the injection speed can be appropriately reduced to reduce the generation of shrinkage marks and pores.Holding time: Sufficient holding time can compensate for the cooling shrinkage of the product and improve the density and dimensional stability of the product. Generally, the holding time is controlled at 10-30 seconds, and the specific time can be adjusted according to the thickness of the product and the shrinkage rate of the material.Post-processing processHeat treatment: Heat treatment of the flame retardant PA product after molding can eliminate internal stress and improve crystallinity, thereby improving the mechanical properties and dimensional stability of the product. Put the product in an oven and treat it at 120-150℃ for 2-4 hours, and then slowly cool it to room temperature.Surface treatment: In order to improve the appearance quality and environmental resistance of the product, it can be surface treated. For example, by using methods such as coating and electroplating, a protective film is formed on the surface of the product, which can not only improve the beauty of the product, but also enhance its chemical corrosion resistance and wear resistance.Quality inspection and controlOnline monitoring: During the processing, online monitoring technologies such as melt pressure sensors and temperature sensors are used to monitor the changes in processing parameters in real time. Once abnormal parameters are found, the processing technology is adjusted in time to ensure the stability of product quality.Finished product inspection: Comprehensive inspection of finished products, including mechanical property testing, flame retardant performance testing, appearance inspection, etc. Through strict quality inspection, unqualified products are screened out, the causes are analyzed and corresponding improvement measures are taken to continuously improve the quality level of products.
