At the beginning of 2020, with the sudden COVID-19 epidemic sweeping the world, the demand for masks from all over the world surged overnight. Another word that has been mentioned repeatedly with masks is melt-blown cloth, and its quality directly determines the quality of the mask.

A common medical surgical mask has a three-layer structure. The outermost layer and the innermost layer are non-woven fabrics, and the middle layer that functions as a filter is the melt-blown fabric.The name of melt-blown fabric is called melt-blown non-woven fabric. As the name implies, it is a kind of non-woven fabric, which is different from traditional textile fabrics. Melt-blown cloth has good thermal insulation, strong filtering ability and excellent oil absorption, which is the best choice for making medical masks.

（figure 1）

The protection principle of melt-blown cloth can be simply understood as two kinds of nets, one with large holes and one with small holes.Filtration efficiency with small pores is naturally better.From the principle of production, melt-blown cloth is made of melt-blown polypropylene, which is plasticized and melted, and filaments are spouted at high temperature and high speed, and formed by natural cooling in air.The cloth sprayed in this way is equivalent to a cross-layered web of ultra-fine fibers with a diameter ranging from 0.5 to 10 microns. The density is small enough to block dust, carry viruses, bacteria and droplets.

（figure 2）

However, the non-conforming melt-blown cloth has uneven fiber thickness, which affects the air permeability and filter ability of the product.Even because of the lack of key processes, the filtration effect of 60% is difficult to achieve.Therefore, we must test the melt-blown cloth when buying masks. Such a mask can better protect our health.