Under the influence of the new crown pneumonia, the global supply of masks is in short supply, and meltblown cloth is also rising. What are the meltblown cloth quality influencing factors as the core material of the mask? Today, through the relevant process of meltblown cloth, the five major factors affecting the quality of meltblown cloth will be introduced in detail.
MFI is the melt flow index, or melt flow index, which refers to a numerical value indicating the flow performance of plastic materials during processing. As the best barrier layer for masks, meltblown cloth is a very fine material with many crisscross microfibers stacked in random directions. Therefore, MFI is meltblown cloth quality influencing factors, that is to say, the higher MFI, the finer the filaments drawn during melt-blown processing, the better the filtration performance.
In the process of meltblown cloth production, the hot air velocity is also one of meltblown cloth quality influencing factors. 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 nonwoven fabric feels gradually softer, and the more fibers are entangled, resulting in a denser and smoother web. Strength increased.
The reason why the hot air spray angle becomes meltblown cloth quality influencing factors is because when the spray angle is small, it can promote 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, and the resulting melt-blown cloth has good anisotropy.
Too long acceptance distance will lead to the decrease of longitudinal and transverse strength and bending strength, and the fluffy hand feeling of non-woven fabrics, which will lead to the decrease of meltblown fabric filtration efficiency and filtration resistance of meltblown fabrics in the process, thus leading to the decrease of meltblown fabric quality.
Since the screw extrusion speed is also an important factor affecting the quality of meltblown cloth, under the condition of constant temperature, the screw extrusion speed should be kept within a certain range:
Before a certain critical point, the faster the extrusion speed, the higher the basis weight of meltblown cloth and the greater the strength. When the critical value is exceeded, the strength of melt-blown cloth decreases, especially when MFI is more than 1000, which may be due to insufficient drawing of filament and serious filament caused by too high extrusion rate, thus the bonding fiber on cloth surface decreases and the quality of melt-blown cloth decreases.
The above is the meltblown cloth quality influencing factors in the production process of the melt-blown cloth factory in China. Only by controlling each process point that affects the quality of the meltblown cloth, can high-quality and high-quality meltblown cloth be produced.
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