The functional layer of protective mask is melt blown nonwoven fabrics. In order to meet the requirements of high efficiency and low resistance

it needs to be treated with corona charging and hydro charging. However

there are few reports on electret mechanism

especially hydro charging. In this paper

the filtration efficiency and surface charge distribution of corona charging and hydro charging nonwoven fabrics were compared at first. Then the hydro charging experiment was simulated and the influences of the conductivity of water was explored. The results showed that compared with corona charging

hydro charging can significantly improve the filtration efficiency of the melt blown nonwoven material

especially low areal density melt blown materials. The filtration efficiency of meltblown nonwoven fabric decreased with the increase of the conductivity of water significantly. It is believed that meltblown nonwoven fabrics can be negatively and positively charged simultaneously by the hydro charging process according to the surface charge potential measurement.The review also indicated that the surface of hydro charging and corona electret melt blown nonwoven materials can generate positive and negative charges

and they are randomly distributed.