Spunbonded nonwoven fabric:

Spunbonded non-woven fabric is in the polymer has been extruded, stretch and form continuous filament, filament laid into a net, the net through its own bonding, thermal bonding, chemical bonding or mechanical reinforcement method, so that the net into non-woven fabric.[10]

Its characteristic is that the fiber net is composed of continuous filament and has excellent tensile strength.

The process changes a lot, can use a variety of methods to reinforce, at the same time the filament size changes a wide range.

             Figure. 1 Manufacturing of spunbonded nonwoven fabric

After the polymer slices, masterbatch or other additive materials are added to the hopper, they are fully stirred and mixed by the hopper, and then fed into the screw for heating and melting.

After the melt is filtered through the filter screen, it is extruded from many holes in the spinneret of the spinning device by the metering pump to form many filament streams.

After the quenching chamber is cooled by lateral air blowing, the melt is cooled into filaments by trickle flow, and then spread on the mesh curtain after being drawn by high-speed air flow in the drafting area.

The fiber is laid into a net on the net laying machine and conveyed to the hot mill through the transmission screen to reinforce the cloth.

Finally, it is cut and coiled into a finished product.

The scraps produced by slitting can be conveyed to the auxiliary screw for recycling.

Polypropylene (PP) melt-blown material for masks:

The material is a non-woven fabric based on polypropylene which is prepared by melt-blown process.

Its high melt index polypropylene PP as the material, by many crisscrossed fibers in random direction laminated into the film, the fiber diameter range of 0.5-10 microns, about one thirties of the hair.

As the core material of filtration, protection and isolation products, melt-blown cloth is the filter layer in the middle of the mask, which can filter bacteria and prevent the spread of germs.

The basic process is to use an extruder to eject the melt from the spinneret head and draw the polymer melt into fibers by air flow.

The finer the fiber is, the higher the filtration efficiency is, and the stronger the ability of blocking and containing pollution is. Therefore, in order to achieve the filtration effect of the mask, there are great differences in the production process and performance between the special PP material for melt-blown cloth and other non-woven materials.

                 Fig. 2 The process principle of melt-blown method

The polymer masterbatch is put into an extruder and melted in the extruder at a temperature of about 240℃ (the main resin for the polypropylene melt-blown method). The melt passes through the metering pump and reaches the melt - blown die head. The metering pump measures the melt flow to the nozzle. Spinnerets are one-row capillaries with spacing less than 1mm and diameters ranging from 0.2 to 0.4mm. On both sides of the capillary is the intake hole, and the compressed air of 250~300℃ is added. When the newly formed polymer is extrudited from the spinneret head, the head end of the compressed air acts on the polymer, and the hot filament is drawn to the diameter of 1~10μum at an airflow higher than the speed of sound (550m/s).[11] According to its physical characteristics, this kind of net is called microfiber net. As the hot air flows downward, it mixes with the surrounding air, cooling the fibers and eventually solidifying into short, thin fibers. The main process flow of melt-blown method is as follows:

Melt preparation → filtration → metering → extrusion of melt from the spinneret hole → draft and cooling of melt flow → net formation