To talk about the production process of medical face masks, we must first speak of the core raw material of face masks: non-woven fabric composed of artificial synthetic fibers. Some people may wonder that if cotton is fiber and if it is feasible to use cotton as a material. The answer is no. We choose synthetic fiber to produce masks.
The non-woven fabric uses pp polypropylene, and the molten pp polypropylene is blown into fabulous fibers through high-speed hot air. Fly onto a roller, the fibers are randomly bonded to each other at a high temperature, and as the roller continues to roll, they are superimposed into a cloth. Here is a key quality indicator of non-woven fabrics, that is the weight per unit area of the non-woven fabric, which represents the density and thickness of the non-woven fabric structure.
This fiber can be as thin as 0.25 microns, and there must be gaps between the fibers. And the layers are extruded and bonded together to form a labyrinth-like channel so that the non-woven fabric has its natural filtering properties. For example, the droplets produced by our sneeze have a diameter of 0.5 to 12 microns, which is larger than the gap between the fibres of the non-woven fabric, so that the non-woven fabric can be very dust-proof and anti-droplet. But this does not reach the medical-grade level. At most, it is a dust mask. In order to achieve the medical grade, the next important step is to add static electricity to the fiber, thereby increasing the electrostatic adsorption effect and further improving the filtration efficiency. This is the electrostatic electret process of the 3 layer face mask filter material.
In this way, 95% filtration efficiency is achieved. However, it still can not prevent viruses and germs. Because medical face masks need to be sterilized with ethylene oxide before they leave the factory, and they have to be allowed to stand for analysis for a while. The residual amount of disinfected substances should reach the residual standard before putting on the market.