How to Improve the Filtration Efficiency of Meltblown Nonwoven Fabric

Meltblown Nonwoven Fabric is the core material of medical masks, and its filtration efficiency directly affects the protective effect of masks. There are many factors that affect the filtration performance of Melt Blown Nonwoven fabric, such as fiber linear density, fiber web structure, thickness and density. If the material is too tight, the pores are too small, and the breathing resistance is too large, the user cannot breathe air smoothly, and the mask will lose its use value. This requires the filter material not only to improve its filtration efficiency, but also to reduce its breathing resistance as much as possible, and the breathing resistance and filtration efficiency are contradictory. Electrostatic electret treatment is an effective way to solve the contradiction between breathing resistance and filtration efficiency.

Filtration mechanism of Meltblown Nonwoven: Among the filtration mechanisms of melt - blown filter materials, the five recognized filtration mechanisms are Brownian diffusion, interception, inertial collision, gravity sedimentation and electrostatic adsorption. The first four principles are all mechanical barriers, and the filtration mechanism of meltblown cloth can be simply summarized as mechanical barriers and electrostatic adsorption.

How to Improve the Filtration Efficiency of Melt Blown Nonwoven
1. Mechanical barriers
The average fiber diameter of meltblown polypropylene cloth is 2 ~ 5 μm. For particles larger than 5 μm in the air, it can be blocked with Meltblown Nonwoven Polypropylene. When the dust diameter is less than 3 μM, the fibers in the meltblown cloth are randomly arranged with the interlayer, forming a fiber filter layer with multiple curved channels. Mechanical filtration van der Waals forces are used to adsorb the particles on the fiber surface as they pass through various tortuous channels or paths. When the particle size and wind speed are large, the airflow is close to the filter material and flows around due to resistance, while the particles are streamlined due to inertia and collide directly with the fibers. When the particle size is small and the flow rate is low, the particles hit the fibers and are trapped due to the diffusion caused by Brownian motion.
2. Electrostatic adsorption
Electrostatic adsorption means that when the fibers of the filter material are charged, the particles are captured by the coulomb force of the charged fibers ( electret ). When dust, bacteria, viruses and other particles pass through the filter material, the electrostatic force can not only effectively attract charged particles, but also capture and induce polarization neutral particles, which has an electrostatic induction effect. As the electrostatic potential increases, the electrostatic adsorption increases.