How to solve the problem of high MFR material being produced by polypropylene extrusion granulators?

When peroxides are used, the melt index of the product becomes very high. The extruder needs to be adapted to materials with a high melt index; first, the throttle valve should be adjusted, and the temperature of the barrel and the die temperature should be set according to the melt index required for production ； What needs to be set to a higher temperature is that of the granular water; I once adjusted it to 48 degrees. Another point concerns the cutting pressure of the pelletizer; it is advisable to replace the cutting blade. There are many adjustable factors, and the range of fusion indices is also wide; it is necessary to try making adjustments one by one based on the actual situation, in order to find the appropriate operating parameters for the fusion index!

Could the deterioration in pellet quality be due to an increase in the material’s hardness? Could it be that the addition of additives has increased the crystallinity of polypropylene?

The pyrolysis products have too good fluidity, which poses a challenge for granulation. It’s easy to cause material leakage, sheet formation, and severe filling issues; it’s just not easy to granulate! When designing the extruder, the production capacity for products with oxidized additives should be taken into account, and it should be somewhat lower than the capacity for normal products!

The extruder needs to be adapted to materials with a high melt index; first, the throttle valve should be adjusted, and the temperature of the barrel and the die plates should be adjusted according to the melt index required for production.

The throttle valve is located in the third section of the cylinder; it has already been turned down significantly – there is only 13% of its opening left before it is completely closed. Increasing the pressure at the throttle valve will rise rapidly. The typical MFR for PCW material is 60°C, but it has now dropped to 45°C. For hot oil, the typical MFR is 280°C, and it has also decreased to 245°C, which is quite low. Nevertheless, tool retraction still occurs. I believe the reason for this retraction is the low MFR of the material, which prevents proper extrusion in the die area, leading to tool retraction first. I’m not sure if other experts agree with this view. Given that the current parameters are already quite low, how should adjustments be made next? Also, is it possible that production cannot take place due to template issues? The extruder has not been run at high MFR yet, it remains the same

The MFR you mentioned isn’t too low, is it? Is the throttle valve located at the third cylinder? ? So how does the screw operate? How many sections is the cylinder you mentioned designed to have? With a high melt flow index, oxidants can be added slowly at the beginning of operating the extruder, giving the extruder time to adjust; this results in the formation of transitional material.

It’s on the high side; there was a mistake in the writing. The throttle valve is located on the attachment of the third section of the cylinder, and even when the throttle valve is fully closed, it doesn’t come into contact with the screw – it’s just used for adjusting the gap. The cylinder has 10 sections in total

So the extruder you mentioned is Japanese, right, at the third cylinder section. The throttle valve is driven by a small motor to adjust the gap at the screw, thereby changing the mixing conditions. Products with a high melting point are indeed difficult to process; more effort should be put into adjusting the temperature, and adjustments need to be made regarding the cutting blade, pressure applied by the blade, and cutting speed

Does material with a high melt index refer to that produced by hydrogen modification or by degradation methods? The production difficulty of the two in granulators is indeed different. The parameters of the adjusted granulator produced by the hydrogen adjustment method can meet production requirements, but this is not necessarily the case for the degradation method.

Generally, it refers to the production of degradation agents. Currently, few processes using the hydrogen adjustment method can achieve a melt index of over 10, but with the vapor-phase method, it is possible to reach very high melt indices using this method! !