What are the factors that affect the quality of meltblown cloth?

MFI of polymer raw materials
Meltblown cloth is a better barrier layer for face masks. It is an extremely fine material. The interior is made up of many superfine fibers criss-crossed in random directions. Taking PP as an example, the higher the MFI, the finer the wire drawn during melt-blown processing, and the better the filtration performance.

Hot air jet angle
The hot air jet angle mainly affects the drawing effect and fiber morphology. The smaller angle will cause the fine flow to form parallel fiber bundles, resulting in poor uniformity of the nonwoven fabric. If the angle tends to 90 °, a highly dispersed and turbulent air flow will be generated, which is conducive to the random distribution of fibers on the screen curtain, and the resulting melt-blown cloth has good anisotropy.


Screw extrusion speed
Under the condition of constant temperature, the screw extrusion rate should be kept in a certain range: before a certain critical point, the faster the extrusion speed, the higher the melt-blown cloth quantitative, the greater the strength; to exceed the critical value, the melt-blown cloth Instead, the strength decreases, especially when MFI> 1000, which may be because the extrusion rate is too high, which leads to insufficient wire drawing and serious wire, so that the bonding fiber on the cloth surface is reduced, and the strength of the meltblown cloth is reduced.


Hot air velocity
Under the same temperature, screw speed and receiving distance (DCD) and other conditions, the faster the hot air speed, the smaller the fiber diameter, the non-woven fabric feels softer, and the more fibers are entangled, resulting in a denser and smoother web. Strength increased.

Receive distance (DCD)
Too long acceptance distance will lead to a decrease in the vertical and horizontal strength and bending strength, the non-woven fabric feels fluffy, and in the melt-blown process will lead to a reduction in filtration efficiency and filtration resistance.


Meltblown die head

Many of the spinneret mold materials on the market are not standard materials, and some low-end mold steels are used instead. There will be some micro-cracks that are invisible to the eyes during use. The hole diameter is rough, and the accuracy is poor. . As a result, the spinneret is uneven, the toughness is poor, and the thickness of the spinneret is different, which is easy to produce crystals.

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