Effects of the Extrusion Temperature of Co-extruded PP Films on the Extrusion Flow Rate
The tandem extrusion system of single screw and melt pump is usually used in the production of multilayer co-extruded films.The stability control of film thickness is an important technical problem to determine the qualities of film products.In order to determine the extrusion temperature with higher longitudinal thickness stability,this paper analyzed the factors related to the longitudinal thickness fluctuation of co-extruded polypropylene films,found that the longitudinal thickness fluctuation was caused by the fluctuations of extrusion flow rate,and investigated the effects of extrusion temperature change on the fluctuation of melt pump outlet pressure and extrusion flow rate.To analyze the fluctuations of melt pump outlet pressure and extrusion flow rate caused by the changes of material viscosity,the existing multi-layer co-extrusion test line was used to adjust and monitor parameters.The extrusion temperature was set as the variable,and the melt pump inlet pressure and rotational speed were set as the fixed values.The experiment results show that with the increase of extrusion temperature,the viscosity of the material decreases and the fluidity of melt increases.The fluctuation trend of screw speed is basically the same as that of melt pump outlet pressure,and the fluctuation amplitude of screw speed is 2.75 times that of the melt pump outlet pressure.At the same time,when the melt pump outlet pressure decreases,the melt pump pressure difference between the inlet and outlet decreases,the volume efficiency increases,and the extrusion flow rate increases slightly.Compared the fluctuations of extrusion flow rate at different temperatures,it could be concluded that the fluctuation value is the smallest when the extrusion temperature is set at 220℃.The film has a high longitudinal thickness stability which has certain guidance for the film productions.
Tandem Extrusion SystemMelt PumpExtrusion TemperatureExtrusion Flow RateSingle Screw ExtruderPolypropylene
万方数据
维普
