First determine the PP raw materials, there is no problem with polypropylene particles. How to determine this depends on where you purchased the polypropylene pellets. If it is confirmed that there is no problem with PP particles. Then look for the problem on the meltblown process. The phenomenon of "flying flowers" should be caused by some scattered short fibers near the receiving device during melt-blowning.
Analysis of possible causes of "flying flowers"
The wind speed and volume of the hot air jet are relatively small. The hot air jet has a low wind speed and a relatively long receiving distance (that is, the distance between the meltblown die and the receiving belt). At this time, only the middle part with a strong air flow velocity can be effectively attached to the receiving belt, and the adhesion is just right. You can adjust the receiving distance, look at the situation, and then adjust the wind speed of the airflow separately. The good combination of the two is to adjust separately first, and then according to the flying situation. Then combine and adjust.
Add a ventilation (negative pressure adsorption) equipment under the receiving net curtain. This is mainly to increase the flow rate of the cold air in the middle of the receiving distance, and to increase the adsorption capacity of the receiving mesh. In the case of insufficient suction airflow, fibers with a diameter of 1 to 2um are easily drifted away by the airflow.
The drum-type receiving device is not very good. Choose a high-end receiving drum, and its internal suction channel is divided into multiple layers to ensure that the suction volume of the drum is consistent along the axis. Another flat-net type exhaust device is more convenient. As long as the speed is uniform, the speed can be adjusted in multiple stages as much as possible.
Summary of the reasons for "flying flowers":
a. The hot air flow is too large or the temperature is too high (too many broken fibers);
b. The working temperature in each zone is too high (too many broken fibers);
c. DCD is too small (the cloth is too dense, which affects the suction efficiency);
d. The spinning environment temperature is too high (same as a);
e. When adding recycled materials, the amount of recycled materials is too large and the recycled materials are indeterminate;
f. The output is too low;
g. The suction parameters at the bottom of the net are set improperly or the net curtain is too dirty (the suction is small, and the fibers cannot be fully absorbed on the net curtain and get out of it);