Special equipment for granulation production of UHF polypropylene
The mechanism of the whole production process of UHF refers to the free radical degradation reaction of polypropylene under the action of liquid peroxide, high temperature melting and screw shearing. The molecular chain is broken, the molecular weight is from large to small, the melt finger is from low to high, and the fluidity is greatly improved. Finally, UHF refers to polypropylene, the raw material of melt blown non-woven fabric, can be obtained.
Core of UHF polypropylene production line
The polypropylene raw materials are sent to the feeding bin at the top by the screw feeding machine. Two twin-screw weightlessness scales are equipped under the feeding bin, including one feeding part of PP, lubricant, antioxidant, nucleating agent and other mixtures. The other weightlessness scale is connected with the feeding bin and is responsible for feeding the remaining pp. in this way, some PP, lubricant, antioxidant, nucleating agent are mixed evenly by the high-speed mixer and the remaining PP are respectively mixed from the Different weight loss scale is added into the twin screw;
The three plunger metering pump injects liquid peroxide into the special area of the barrel into the twin-screw extruder. Under the action of liquid peroxide, high-temperature melting and screw shearing, the free radical degradation reaction of polypropylene takes place, the molecular weight changes from high to low, and the melting finger changes from low to high;
Under the action of twin-screw, the melt continues to move forward, and the melt removes ash and moisture in the molten material through the vacuum devolatilization device. After filtration, the insoluble substance and polymer gel are filtered through the mesh changer, and then extruded from the die head.
Then, the extruded strip is solidified into strips under the traction of the pelletizer, cooled and shaped by the water tank, dried by the air dryer, and sent to the pelletizer for pelletizing;
Then through the vibrating screen, after removing the cutter material, clay particles and small pieces of material, the selected particles are sent to the circulating drying silo through the air blowing;
After the particles are homogenized in the circulating drying bin, the surface moisture and low boiling point small molecule organic matter are brought out, so as to dry and reduce the odor (optional).
Select device key points:
In the process of processing, with good raw materials and mature formula design, selecting good equipment is the top priority to ensure the production of qualified ultra-high melting point polypropylene. When selecting twin-screw extruder, the following points must be taken into account.
Adopt screw feeder to reduce labor force;
Adopting weight-loss scale, high degree of automation, adopting weight-loss feeding, making the measurement more accurate, reducing the intervention of human factors, and making the quality of finished products better.
For ultra-high melting point polypropylene, special treatment is needed, such as: the specially designed die head shortens the time of strip entering water, and two water tanks are used to speed up the cooling speed of polypropylene;
Due to the high fluidity of polypropylene, resulting in the adhesion of the discharge, the optimization design of some key parts is particularly important, for example, the specially designed pelletizer can meet the needs of high-speed pelletizing.