基于非连续超临界N_2注气系统的聚丙烯发泡注塑工艺参数

The Processing Factors of Polypropylene Foam Injection based on Intermittent Supercritical N_2 Gas Injection System

将聚丙烯与1%的滑石粉混合造粒,使用N2作为物理发泡剂,通过自行搭建的非连续超临界N2注气系统,研究发泡注塑工艺过程中注射行程、注射速度、螺杆转速、熔体温度对制品表面质量、减重和泡孔结构的影响。结果表明:注射行程引起的熔体填充量变化是影响制品减重的首要因素,随着填充量的增加,减重下降明显;高压力降速率能够得到均匀泡孔分布且泡孔密度较高的制品;螺杆转速导致停留时间改变对制品表面质量影响较大;熔体温度影响到发泡剂在聚合物熔体中的溶解,螺杆转速130～150 r/min、熔体温度200℃时,能够得到减重、制品表面质量和泡孔结构俱佳的制品。

Polypropylene mixed with 1% talc and then palletized by twin-screw extruder. Nitrogen was used as a physical blowing agent. By the use of self-buih intermittent supercritical N2 gas injection system, the impact of injection molding process including injection stroke, injection speed, screw speed and melt temperature on product surface quality, weight reduction and cell structure were studied. It showed that the injection stroke was the primary factor that affected weight reduction. As the plasticizing length increased, the weight reduction decreased obviously. High pressure drop rate could improve the foaming performance. Screw speed had an obvious impact on the product surface quality;melt temperature impacted the solubility of the blowing agent. When the screw speed 130 -150 r/min, melt temperature 200 ℃ , the PP product was obvious improvement of weight reduction, surface quality and foaming performance.