Due to continuous spread of global epidemic, some melt-blown fabrics that cannot meet performance requirements have been strictly investigated by state, and demand for melt-blown fabrics that can meet N95 and N99 masks is growing. Electret Masterbatch is one of important raw materials for production of meltblown fabric. In past, it has been overlooked, but in just one month, it has grown from obscurity to most sought-after meltblown fabric manufacturer in world. . What do you know about electret superconcentrate? With help of this article, you can solve many of your doubts.
1. Uncover mystery of electret masterbatch
Electret masterbatch is not as mysterious as we imagined.It is a special functional superbatch for melt blown fabric, such as flame retardant masterbatch and color masterbatch, which play a key role. For medical masks, there are three layers of structure, as shown in Figure 1. Among them, meltblown middle layer is a polypropylene material with electret masterbatch and electret high voltage processing. This layer is main part. 0.3 micron non-greasy fine particles are charged, with strong adsorption effect, which generally requires more than 95%, and aerosol filtration efficiency of Staphylococcus aureus bacteria must be below 95%, which we usually call concept of N95 masks origin.
Fig. 1. Block diagram of mask
2. Composition and classification of electret superconcentrate
When using high-flow polypropylene as base material, special plastic additives are added, which are evenly distributed in masterbatch in a high-speed mixer. charge trap density and depth in meltblown nonwoven to improve overall filtration efficiency and heat resistance of meltblown nonwoven.
There are currently three types of electret masterbatch in market, including nitrogen-containing chemical fatty acids, colloidal silicon method, and tourmaline method. Their characteristics and dosage are shown in Table 2-1 (for reference):
Table 2-1 Categories of Electret Masterbatches
Electret masterbatch model: Brother's Toughness TM ZJM010 electret masterbatch is made on basis of polypropylene with ultra-high yield strength and good toughness, through a special screw-shift mixing unit, composite imported inorganic charge enhancer. Nanoscale morphology is obtained by dispersion in a matrix. material. It can greatly improve charge storage density and filtration efficiency of meltblown polypropylene nonwovens, and can maintain long-term filterability.
Table 2-2. List of electret masterbatch parameters
Third, factors affecting efficiency of electret
Factors affecting characteristics of electret polypropylene can be analyzed from two points of view: polypropylene crystallinity and electret process conditions:
Crystallinity of polypropylene: Crystallinity is an important parameter of crystalline polymers, which has an important influence on physical and mechanical properties of materials. Factors affecting crystallinity of polypropylene include its own regularity, addition of a nucleating agent, etc. The most obvious effect is regularity of polypropylene itself. The higher regularity and crystallinity of PP, higher stability of space charge. When nucleating agent is added, nucleating agent causes polypropylene to nucleate and crystallize at a higher temperature, and when a more perfect crystal is formed, space charge stability of polypropylene will be improved to a certain extent.
Electret process conditions: Corona charging is commonly used for electret processing of meltblown polypropylene nonwovens. Charging voltage, charging time, charging distance and environmental humidity have a great influence on stability of electrostatic charge carried by air filter material, which is beneficial to a certain extent to maintain charge stability of material.
In face of huge commercial profits caused by epidemic, sellers must carefully select electret masterbatch suitable for their products, ensure product quality, meet market demand, and earn reasonable profits.
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