Why can't filter masks be made without non-woven electret masterbatch? Today, let's talk about what you must know about mask filtering! Everyone knows that masks are divided into three layers: (inner layer) hygroscopic layer, (middle layer) core filter layer, (outer layer) water blocking layer, masks Filtration mainly includes general mechanical blocking and electrostatic adsorption.

The general mechanical blocking mechanism mainly depends on mechanical blocking effects such as Brownian diffusion, trapping, inertial collision, and direct interception. However, this mechanical blocking effect has a poor filtering effect on particles smaller than 1 μm in size and cannot be effective against viruses. Protection.

The virus protection masks mainly include medical surgical masks and N95 masks. The national YY 0469-2004 "Technical Requirements for Medical Surgical Masks" standard stipulates that important technical indicators for medical surgical masks include filtration efficiency, bacterial filtration efficiency and respiratory resistance.

1. Filtration efficiency:

Under the condition of air flow (30 ± 2) L / min, the filtration efficiency for aerodynamic median diameter (0.24 ± 0.06) μm sodium chloride aerosol is not less than 30%;

2. Bacterial filtration efficiency:

Under the specified conditions, the filtration efficiency of the S. aureus aerosol with an average particle diameter of (3 ± 0.3) μm is not less than 95%;

3. Breathing resistance:

Under the condition of filtration efficiency and flow rate, the inhalation resistance does not exceed 49Pa, and the exhalation resistance does not exceed 29.4Pa.

Among them, the second criterion to ensure the bacterial filtration effect is the staphylococcus bacterial aerosol filtration efficiency of not less than 95%, which is the origin of the N95 concept. The main material that can bring virus filtering to the mask is a very fine and static inner filter cloth-meltblown non-woven fabric.

For medical masks, the electret meltblown cloth with electret masterbatch and electret high-voltage electrical treatment is the core part. Only the charge on the meltblown cloth after the electret treatment will affect the same charged 0.3 micron. The virus particles have an efficient adsorption effect. In this process, the addition of non-woven electret masterbatches played a crucial role. Moreover, the addition of non-woven electret masterbatches will also greatly extend the surface charge decay time of the meltblown cloth!