The strips discharged from the pelletizing template by the water ring pelletizer are immediately cut into pellets by the rotating cutter, so the PP plastic melt must be cuttable, so that the extruder temperature, extrusion speed, connection body The temperature, the melt pressure, the temperature of the discharge template, the number of holes in the discharge template, the temperature of the cooling water, the pressure of the cooling water, and the uniformity of the mixing ratio of the raw materials are all put forward. In these nine conditions, the conditions are suitable. It can ensure that when the water ring pelletizer makes high melt index PP, the equipment operates normally and makes qualified PP plastic particles.
Polypropylene (PP) is a general-purpose thermoplastic resin with excellent mechanical properties, heat resistance, chemical resistance, and low price, which has been widely used. PP granulation can adopt the process of drawing pellets, hot pelletizing of water ring die surface and so on. The hot die cutting of the water ring die surface has the characteristics of high pelletizing efficiency, small footprint, smooth and beautiful particles, but the high melt index PP has low viscosity and easy adhesion, which has always been a problem in the granulation process.
Because PP is in a molten state and the temperature difference is small, the melt index will change greatly. Therefore, when the process is not well-controlled, the water ring pelletizer is used to cut the pellets, which may easily cause the quality of the plastic particles to run out of control. Adhesion and agglomeration will seriously block the water ring and cut the pellet cover, causing production interruption. Therefore, using the correct water ring pelletizer pelletizing process is the key to the normal operation of the PP water ring pelletizer.
The strips discharged from the pelletizing template by the water ring pelletizer are immediately cut into pellets by the rotating cutter, so the plastic melt must be cuttable, which is the most basic requirement to ensure the normal granulation process. However, in order to ensure this most basic requirement, the temperature of the extruder, the speed of extrusion, the temperature of the connecting body, the pressure of the melt, the temperature of the discharge template, the temperature of the cooling water, the pressure of the cooling water and the mixing ratio of the raw materials Uniformity has put forward requirements, and under suitable conditions, it can ensure that the water ring pelletizer performs high melt index PP, and the equipment operates normally.
1. Extruder temperature When the temperature of the extruder is too high, it will cause the melt index to increase and the melt viscosity to decrease. The extruded melt is easy to stick, which is not conducive to pelletizing. When the temperature of the extruder is low, PP plastic If it is not good, the viscosity increases, the die expansion rate increases, and there is no problem with pelletizing, but the outer diameter of the particles becomes larger, the shape is rough, and the appearance quality of the particles becomes worse. Therefore, it is important to first find out the appropriate temperature. Through experiments, it is known that the extruder adopts the process of high temperature in the feeding section and gradually decreasing temperature at the discharge end, which can be well compatible with the problems of raw material plasticization and excessive temperature of the discharge port. The specific actual temperature is adjusted according to the actual situation according to the difference of the extruder and the material formula.
2. Extruder extrusion speed Plastic extruder is an important part of these links. Different extruder screw design will affect the plasticization of raw materials. At different speeds, the friction heat of the screw is different. It affects the temperature of the raw material at the outlet of the extruder, which affects the melt index of the raw material. Higher temperature will cause the pellet to stick, so the appropriate extrusion speed is also the influencing factor of the normal pelletizing of the PP water ring pelletizer.