Why does meltblown cloth become brittle?

Melt blown cloth is the core material of the mask. The melt blown cloth is mainly made of polypropylene, and the fiber diameter can reach 1 to 5 microns. There are many voids, the structure is fluffy, the ability to resist wrinkles is good, and it has good filtering, shielding, heat insulation and oil absorption. Why does meltblown cloth become brittle? The editor of Sino-Singapore Huamei Modified Plastics will answer for you.

1. The melt index is too high or too low, and the melt index is too high, such as 3000 melt index, so that the spraying process is just like catkins, and the material basically has no strength. Melt index is too low, such as S2040, sprayed at 350°C. At this time, PP has already begun to degrade by thermal oxygen, and PP is no longer PP, and physical properties cannot be enforced;

2. Generally, the screw of small melt blown equipment is relatively short and has no mixing function. The material melting basically depends on heating, so the production temperature is relatively high, and the material degradation causes the cloth to become brittle;

3. If the length-to-diameter ratio of the spinneret is relatively small, and the holes are thick and short, after the polymer is sprayed, the fibers will be thicker, the gaps will be relatively large, and the time will absorb more water, so that the cloth is not soft and brittle;

4. The winding device is too short. During the winding process, there is residual heat, and the temperature cannot be quickly cooled. After a few days, the PP material is relatively brittle after crystallization (some people add a crystallization nucleating agent as a softener);

5. Packaging. If the cloth absorbs a lot of water in the follow-up, it will become brittle. Generally, it is wrapped with stretch film and sealed.

It is worth noting that the ability to produce grade 95 and grade 99 meltblown cloth mainly depends on whether it can withstand the temptation of huge profits, strict production equipment, processing technology, electret devices, and strict use of materials.