How much do you know about the filter layer of face mask?

In just one month, many companies have switched to masks. Although the price of melt-blown fabrics has increased a lot, the shortage of melt-blown fabrics nationwide is scarce, and there are not so many melt-blown fabric supply markets. Cloth link. Cut out a used medical mask, you will find that the mask has three layers, (inner layer) moisture absorption layer, (middle layer) core filter layer, and (outer layer) water blocking layer.

Because according to the national production regulations, medical masks contain at least 3 layers of non-woven fabrics (N95 grade masks, structurally optimized: (middle layer) core filter layers are more and thicker)

S layer: polypropylene resin

M layer: polypropylene resin with high melt index

 

Meltblown cloth(PP Meltblown Fabrıcs Wholesale), commonly known as the "heart" of the mask, is the filter layer in the middle of the mask, which can filter bacteria and prevent the spread of germs. Meltblown cloth is a film made of polypropylene with high melt index. It is a film composed of many crisscross fibers stacked in random directions. The fiber diameter ranges from 0.5 to 10 microns. one.

So, how does melt-blown cloth filter viruses in the environment? Although the size of the new coronavirus is very small, about 100 nanometers (0.1 micrometers), the virus cannot exist independently. The main transmission routes are secretions and droplets when sneezing. The size of the droplets is about 5 micrometers. One, second, the meltblown cloth is essentially a fiber filter. When the droplets containing the virus are close to the meltblown cloth, they will also be electrostatically adsorbed on the surface and cannot penetrate.

Although the raw materials of the S layer and M layer of the mask are polypropylene-specific resins, the special materials for melt-blown fabrics and other non-woven fabric materials differ greatly in production process and performance. The special material for meltblown cloth is polypropylene with high melt index. The higher the melt index of polypropylene, the finer the melt-blown fibers, and the better the filterability of the melt-blown cloth.

It is reported that through process optimization, Shanghai Petrochemical is expected to increase production by about 2 tons per day in the short term, reaching a daily production of 8 tons of special materials for meltblown cloth. It should be known that domestic melt-blown non-woven fabrics(Non Woven Meltblown Fabric Manufacturer) were relatively niche, with an annual production capacity of 53,500 tons, accounting for 1% of non-woven fabric production capacity. They are mainly used to produce masks, environmentally friendly materials, clothing, battery separators and other products.

It is said that the melting index of Shanghai Petrochemical's previous products is only one-thirtieth of the special materials for mask melt-blown cloth(Polypropylene Meltblown Fabrıcs Supplier). Faced with the challenges of insufficient hardware such as slow pelletizing speed of the extruder, short cooling distance, and insufficient screw length, the company tried to find ways to make use of the existing equipment by modifying the electronic control system and transmission system, calling other production line sinks, and optimizing the die head. Carry out emergency transformation and adjustment to meet production needs.

Comparing the cross-sectional views of N95 masks and medical surgical masks, the scanning electron microscope pictures can clearly see that the thickness of the meltblown cloth of the surgical mask is 156 microns, and the thickness of the meltblown cloth layer of the N95 grade mask is 521 microns, which is 3 Times.