Sears Company has done in-depth research on nano-meltblown fibers, and it is said that it has reached the stage of industrialization. Other enterprises, such as Nonwoven Technology (NTI), have also developed processes and technologies for producing nano-melt-blown fibers and obtained patents.
In order to spin nanofibers, the spinneret holes are much thinner than those on ordinary melt-blowing equipment. NTI can be as small as 0.0635 mm (63.5 micron) or 0.0025 inch, and the spinnerets with modular structure can be combined into a total width of more than 3 meters. The diameter of meltblown fiber spun in this way is about 500 nanometers. The diameter of the thinnest single fiber can reach 200 nanometers.
Because of the small nozzle hole in the melt-blown equipment for spinning nanofibers, the output will be greatly reduced if no measures are taken. Therefore, NTI increases the number of spinnerets, and each spinneret plate has 3 or more rows of spinnerets. By combining many unit components (depending on the width), the output can be greatly improved in the spinning process. In fact, when 63.5 micron holes are used, the number of holes per meter of a single row spinneret is 2880, and if three rows are used, the number of holes per meter of spinneret can reach 8640, so its output can be equivalent to that of spinning ordinary meltblown fibers.
Because the thin spinneret with high-density holes is expensive and easy to break (broken by heat under high pressure), companies have developed new bonding technology to enhance the firmness of spinneret so as not to leak under high pressure.
At present, nano-meltblown fibers can be used as filtration media, which can significantly improve filtration efficiency. Some data also show that because the fibers in nano-scale meltblown nonwovens are finer, the meltblown nonwovens with lighter gram weight can be combined with spunbonding and still bear the pressure of the same head, and SMS products made of it can reduce the proportion of meltblown fibers.