The production process of meltblown cloth
Meltblown cloth does not seem to be anything special, but the production process is very complicated. Its production process can be summarized into three major steps: first, naphtha is extracted from petroleum, then chemically processed into polypropylene, and finally the cloth is made by meltblown process. The general process is shown in Figure 4.
Production process of meltblown cloth
The production process of meltblown cloth is mainly divided into three steps: melt extrusion, meltblown process and electret treatment. The specific flow chart is shown in Figure 5. Here we focus on electret processing.
Electret refers to a dielectric material with long-term charge storage function. It has the advantages of high efficiency, low flow resistance, antibacterial, and energy saving. On the basis of ensuring the physical collision barrier effect of conventional filter materials, electrostatic adsorption is added. The electret treatment makes the fibers of the filter material charged, combined with the dense characteristics of the melt-blown microfiber material, so a large number of electrodes are formed between the charged fibers. The charged fibers can not only attract most of the charged particles in the environment like a magnet, but also Part of the uncharged particles can be polarized, and then some pollutants with smaller particle sizes can be adsorbed, and even nano-scale substances such as viruses can perform electrostatic adsorption or charge repulsion blocking.
The meltblown cloth used in medical masks must be electret treated. Sterile medical masks are sterilized with ethylene oxide. After sterilization, there will be ethylene oxide residues on the masks, which not only irritate the respiratory tract, but also cause carcinogens. The residual ethylene oxide must be released through analytical methods to meet the safe content standard. The entire standard process of analytical disinfection takes 7 days to half a month.
Detection basis of meltblown cloth
According to the standard FZ/T 64034-2014 Spunbond/meltblown/spunbond (SMS) nonwovens.
Test items：
1. Appearance quality inspection: cloth surface appearance, holes, impurities, odor, micropores, crystal points, frit, stiff wire, unreinforced area, thin mesh, width deviation, color difference, joint quality
2. Internal quality inspection: mass deviation rate per unit area, longitudinal breaking strength, transverse breaking strength, longitudinal and transverse breaking elongation, hydrostatic pressure, air permeability
3. Detection of microbial indicators: total number of bacterial colonies, total number of fungal colonies, coliform bacteria, and announcement of pathogenic purulent bacteria.
