Why does melt-blown cloth need static electret equipment?

Why does melt-blown cloth need static electret equipment?

01 Why does melt-blown cloth need static electret equipment?

Electret electrostatic adsorption is to capture coronavirus droplets through the coulomb force of charged fibers. The principle is to make the surface of the filter material more open, the ability to capture particles is stronger, therefore, the melt-blast non-woven filter material of the filter layer, must be processed by electret, in order to achieve 95% filtration without changing the respiratory resistance, in order to effectively prevent the virus, mask to achieve the barrier effect at the same time to ensure comfortable ventilation, The inspiratory resistance of medical masks is generally no more than 343.2 pascals (Pa), while that of civilian masks is less than 135 pascals (Pa). Electret treatment can greatly improve the filtration efficiency without changing the respiratory resistance, and the higher the electret voltage, the higher the filtration efficiency of the material. Generally requires a electret voltage of 30KV-50KV.

02 Do Masks have to be disinfected?

If they are ordinary masks, they do not need to be sterilized, but for medical purposes they need to be sterilized in the manufacturer's household ethylene oxide (E0) disinfection cabinet. Put the mask in the environment of 400mg/L ethylene oxide, and use alkylation for hydroxyl, so that the microbial macromolecules lose activity, to achieve the purpose of sterilization. However, ethylene oxide is not only flammable and explosive, but also toxic to human body, so after disinfection, it needs to stand for 7 days for analysis. After the residual amount of E0 is lower than the required value, it can be packaged and supplied to medical staff. Therefore, the manufacturer of medical masks must have the Medical Device Business License.

Ethylene oxide is also carcinogenic, so mask manufacturers need to send masks to the quality supervision Bureau for testing, must meet the national standard GB18279.1-2015, international standard IS011135:2014 requirements. Only medical masks produced in accordance with the above process, with filter materials produced from high-fusion finger melt-blown non-woven fabric, electret treatment to increase electrostatic adsorption, disinfection with ethylene oxide after production and standing for 7 days to parse the ethylene oxide, are qualified and safe medical masks that can be used to isolate the spread of the novel coronavirus.

03 Melt-blown cloth can use ultraviolet disinfection, dry steaming wet steaming method?

The polypropylene melt-blown material on the mask is very sensitive to ultraviolet radiation. After receiving ultraviolet radiation, the static electricity and fiber structure of the filter layer will be damaged, namely oxidative degradation, and the filtration performance will be significantly reduced. Even if the mask constantly absorbs the water vapor exhaled by the use of sunlight, the charge of the filter layer will be lost, the electrostatic adsorption capacity will be reduced to zero, and the filtration effect will return to about 35%. It is suggested that manufacturers planning to produce masks should conduct testing before purchasing melt-blown cloth for production to see whether the resistance test and filtration efficiency of the melt-blown cloth can meet the requirements. Only qualified melt-blown cloth can produce qualified masks. Melt-blown cloth should be tested according to GB2626-2006 standard.