High filler processing is the evenly compounding and dispersion of high percentage inorganic powder into carrier resins. During this process, the carrier should not suffer over shear to maintain its physical properties. At the same time higher output and lower wear-off of machine parts brings better cost effectiveness.
The key technologies are as follows:
1.Reasonable formula design and lubrication of raw materials, which means proper carrier MFI and percentage, uniform powder size and suitable surface treatment. The typical recipe is PE/PP+85%CaCO3+lubricant to make CaCO3 filled masterbatch. Coupling agents are generally added to get better combination of CaCO3 and carrier.
2. The raw materials can be fed to the extruder independently by loss-in-weight feeders or premixed by mixer.
Multiple feeding based on LIW feeders: resin, additives and part of CaCO3 powder are fed at the main feeding port, and the other percentage of CaCO3 powder is added by one or two side feeders. All materials are compounded by extruder.
Advantage of this technology is high automation, but it also requires better venting, compounding ability and wear resistance of extrude.
Premix based on high mixer: premix all the ingredients in high speed mixer to a certain time or temperature, and then feed mixed material into twin screw extruder for further compounding. During the premixing process, the lubricant has a strong infiltration effect on the powder, and large volume of moisture is naturally removed through high temperature, which makes it easier for feeding and brings higher output. It is also suggested to have a cooling mixer after high speed mixer to avoid the degradation of resin by high temperature stack handling.
Premix based on kneader: mix all the ingredients in the kneader for a certain time, and then feed the bulk material into twin screw extruder with force conical feeder for further compounding. Compared with high speed mixer, pre-mixing of kneader has plasticized the raw materials, which requires less for the compounding ability of extruder and helps to increase the output. Sufficient pre-mixing and lower degradation of raw material makes it applicable for film filler masterbatches, stone paper filler masterbatches etc, in which application good dispersion and high physical properties are required.
3. Maximum 900rpm screw speed, torque level up to 11N. M /cm3, 1.66 screw Do/Di ratio, and L/D up to 56 guarantee compounding effect and significantly increase the capacity.