Why is the meltblown cloth brittle

Why is the meltblown cloth brittle? 2021-07-20

First of all, melt blown materials must be purchased through formal channels. The raw materials of meltblown cloth are generally selected special polypropylene materials with a melt index of 1500, and they have passed Rohs 2.0 non-metallic, reach-205 items, halogen, melt finger, ash, volatile matter, molecular weight distribution, and peroxide residue. Third-party testing. Only in this way can it be ensured that it achieves the excellent characteristics of environmental protection, narrow molecular weight distribution, low ash content, no other product residues, and excellent spinning performance, and meets the various standards of the number of fibers per unit area and surface area of the core of medical masks.

If you buy melt blown cloth raw materials that strictly meet the standards through formal channels, then the control of the melt blown cloth production and processing technology is particularly important, because the production process and parameter settings will directly determine the quality of the melt blown cloth, and the processing technology will not be produced. The question, then, it must be no problem to want the meltblown cloth filtration level to reach the standard.

The meltblown cloth becomes brittle the next day after it is produced. From the process analysis, there may be the following main reasons:

1. Uneven spinning and insufficient air volume of the air cooler will cause uneven heat dissipation and internal stress that can cause brittleness. This can be improved by adjusting the melt volume of the extruder, the temperature of the hot air blower, and increasing the air volume of the air cooler.

2. From the perspective of material analysis, it should be a 2040 low-melting index 38 spinneret. The filament is thick. After 24 hours to 48 hours, it will become brittle. The melt-blown material of melt finger 1500 is fine, soft and evenly distributed, so the cloth is soft. The melt index is too high, such as 3000 melt index, so that the process of spraying is like catkins, and the material basically has no strength.

3. This phenomenon is related to the excessively high temperature of raw materials and processing technology. After the fiber comes out, there is a secondary crystallization re-arrangement process inside the PP. In fact, the inside of the screw is heated, which has caused severe thermal degradation. Such problems are prone to occur in the meltblown peroxide process if the initiator residue is not well controlled. The most important thing in the meltblown peroxide process is how to complete the molecular chain scission termination before the screw extrusion is completed, to prevent the secondary residue from running to the user's non-woven screw to continue the reaction. This will test the screw equipment combination and formula control .

4. When it is just made, the melt blown cloth still has a temperature, especially the melt blown cloth machine of the large drum rewinding, even without a fan, the temperature of the melt blown cloth after winding is high, and the plastic is flexible, The greater the toughness, the more brittle after cooling.

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