Masks are non-woven materials, and non-woven fabrics are non-woven fabrics compared to woven fabrics, which are composed of directional or random fibers.

Medical masks are generally multi-layer structures, generally referred to as SMS structures (2 layers of S layers and 1 layer of M layers). At present, the highest number of layers in China is 5 layers, namely SMMMS (2 layers S layer and 3 layers M layer).

What is SMS~

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The S in it represents the spunbond layer (Spunbond), and its fiber diameter is relatively thick, about 20 microns (μm). . The most important thing in the mask is the barrier layer or the meltblown layer M (Meltblown). The fiber diameter of the meltblown layer is relatively thin, about 2 microns (μm), so it is only one-tenth of the diameter of the spunbond layer. Bacteria and blood penetration play a crucial role.

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General medical masks usually use 20 grams of meltblown cloth, and N95 cup masks use 40 grams or even higher weight of meltblown cloth.

According to the statistics of China Industrial Textiles Industry Association, as of the end of 2018, there were 1,477 domestic spunbond production lines, an increase of 65 over the previous year and a year-on-year increase of 4.6%, of which PP spunbond nonwoven production lines increased by 3.38%, SMS composite production lines An increase of nearly 13%, and PET spunbond nonwoven production lines increased by 9.32%; enterprises with an annual output of more than 50,000 tons also increased compared with 2017. Spunbond enterprises are accelerating their development towards large-scale, intensive, and high-end development, and are accelerating to meet the market demand for product upgrades and technology upgrades.

Since 2018, many domestic companies have developed products in the direction of lighter, thinner and higher performance and achieved good results. The SSMMS spunbond/meltblown composite process operates well at high speeds of more than 600 m/min; ultra-soft, lightweight and stable products of about 10 g/m2 are emerging.

Where does the SMS non-woven fabric come from~

SMS non-woven fabrics use polypropylene PP (with natural antibacterial and hydrophobic properties) as the main raw material, and the fiber diameter can reach 0.5-10 microns. These ultra-fine fibers with unique capillary structure increase the number and surface area of ​​fibers per unit area. , so that the meltblown cloth has good air filtration and is a relatively good mask material.

At present, the main processes of manufacturing SMS products (SMS non-woven fabrics) include three methods: "one-step method", "two-step method" and "one-step and half method".

The one-step method is characterized by the use of raw material slicing, the use of spunbond method and meltblown method, and the raw material is directly melted and spun into a web. As long as the spinning system engineering of different processes is reasonably arranged, the product can be For different structures, after the layers of fiber webs are laminated and compounded, they are generally consolidated into cloth by a hot rolling mill. The "one-step method" is characterized by the direct spinning of the melt into a web, the state of each spinning system can be adjusted independently, the controllability of the production process is strong, the hygienic conditions are good, the running speed is high, and the ratio of each layer of the web can be adjusted at will. , Can produce various specifications of SMS-type products, is today's mainstream technology.

Two-step method: When the two-step method is used to produce SMS products, the finished spunbond fabric and the finished melt-blown fabric are unrolled in a certain order, laminated in sequence, and then consolidated with a hot rolling mill to form an SMS product. The "two-step method" is characterized by simple equipment and low cost. In fact, the "two-step" process is a widely used lamination composite technology. It can also composite other materials, and use different other materials, and use different methods, such as ultrasonic waves, hot melt adhesives, etc. to consolidate the three layers of materials together.

One-step and one-half method: In the two-step method, the melt-blown layer fiber web produced on site can also be used to replace the melt-blown cloth product, thereby deriving the so-called "one-step and half method" composite process. The spunbond fabric is used as the bottom layer and the surface layer by two unwinding devices, and the meltblown fiber web of the middle layer is directly spun into a web by the meltblown system, laid on the spunbond fabric surface of the bottom layer, and then covered with the upper layer of spunbond fabric. Sticky cloth, preferably consolidated into SMS products with a hot rolling mill.