How Are Surgical Masks Made?
Medical-surgical masks are made of non-woven fabrics, which have better bacteria filtration and breathability, and are smoother than woven fabrics. The most commonly used material is polypropylene, with a density of 20 or 25 grams per square meter. Manufacturers also use polystyrene, polycarbonate to produce medical-surgical masks.
A spun-bond process, including extruding molten plastic onto a conveyor belt, makes the 20 gsm mask material. Extradition of the material into a web, and when they cool, the wires are connected. Factories use melt-blowing technology to produce 25gsm fabric, which is a similar process. The plastic is extruded through a mold with hundreds of small nozzles and then blown into tiny fibers by hot air, cooled again, and bound to a conveyor belt.
Medical masks consist of a multilayer structure, usually covered with a layer of non-woven fabric on both sides of the mask. Non-wovens have three or four layers of material. Due to its disposable properties,non-woven fabrics have lower manufacturing costs and are cleaner. These disposable masks usually have two filter layers, which can filter out particles such as bacteria above 1 micron. However, a mask’s filtering level depends on the fiber, the manufacturing method, the cobweb structure, and the fiber’s cross-sectional shape. Masks are manufactured on a production line that will be assembled with spools of non-woven fabric. Ultrasound is obligatory to weld these layers together. A noseband, earrings, and other parts are also essential for stamping of masks. The respirator also has multiple layers. The outer layer on both sides is a protective non-woven fabric with a density between 20 and 50 grams per square meter, which can block both the external environment and the wearer’s breath. A pre-filtration layer follows this with a density of up to 250 g / m2. It is usually a needle-punched non-woven fabric produced by hot calendars. High-pressure heated rollers thermally bond plastic fibers. It makes the pre-filtration layer thicker and stiffer to form the desired shape and keeps it used as a mask. The last layer is the highly efficient electret non-woven material, which determines the filtration efficiency.
Manufacturers should disinfect the finished masks and respirators before leaving the factory.