Types Of Air Filter Materials

Microporous membrane air filtration materials microporous membranes obtained by the phase inversion method or the biaxial stretching method are also used in the field of air filtration. The basic principle of the phase inversion method is to make the homogeneous polymer solution undergo mass transfer between solvent and non - solvent in the environment to form a polymer and solvent enriched phase, and then the polymer solidifies to form a film. In the phase inversion film formation, the common means to promote the phase separation of the solution can be solvent induced or thermally induced. The biaxial stretching method was invented by DuPont. When the processing temperature is between the glass transition temperature and the melting point of the polymer, micropores can be generated by biaxially stretching the polymer thick sheet in the transverse and longitudinal directions, and the tensile load is maintained. Under cooling, the shape of the micropores can be fixed. Among the biaxially oriented films that have been marketed, polytetrafluoroethylene ( PTFE ) films account for the vast majority.

Compared with traditional knitted and woven materials, nonwoven fiber Air Filter Material is isotropic in two - dimensional direction, that is, the fibers are randomly oriented in the plane. Its interior has abundant tortuous three - dimensional space. The channel not only provides a flow path for the airflow, but also increases the probability of particulate matter being trapped. Therefore, Non Woven Filter Fabric has become the mainstream development direction of Air Filter Media. The filtration mechanism of nonwoven fiber air filter materials is closely related to its two basic properties ( filtration efficiency and piezoresistance ), so it mainly focuses on the particle trapping behavior of single fibers and the movement behavior of gas molecules near single fibers. In addition, the use of air filter materials is a continuous process, and the filtration behaviors in the initial dust holding stage and the later stage of dust holding are also different. The corresponding theoretical branches are the air filtration mechanism in the steady state and the unsteady stage.