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Excellent Water or Static Electricity, Read This Article to Understand

Pulished on Nov. 12, 2020


BOGDA all products support free sample delivery, please bear the freight! BOGDA all products are factory direct, high quality and low price, welcome to inquire! 0513-88837932 melt blown non-woven fabric is widely used in the field of air filter materials at present. Filtration efficiency and resistance are two key factors. Melt blown non-woven fabric is characterized by high efficiency and low resistance, electrostatic adsorption on the cloth surface, which plays a filtering role. Which electret is the best? See below.


The main raw material of meltblown cloth is melt blown masterbatch. The most commonly used melt blown masterbatch is PP with high fluidity, and the melt index is 1200g / 10min or 1500g / 10min.The main parameters of meltblown cloth include filtration efficiency and flow resistance (including inspiratory and expiratory resistance in the use of mask). High quality meltblown cloth has higher filtration efficiency and lower resistance. Conventional meltblown cloth is mainly mechanical barrier. Due to the problems of pore size structure and distribution, the filtration efficiency of fine particles including air dust, aerosol, bacteria and virus is not high. In order to improve the filtration efficiency, the pore size must be reduced. By increasing the gram weight, the fiber diameter is difficult to be less than 1 um for meltblown cloth, which will lead to the decrease of porosity and increase the air flow resistance.


What is electret?


Electret means to charge, which means electricity. With electret, it can be charged. The common electrets include electret, thermal electret, optical electret, magnetic electret, radiative electret and mechanical electret. The melt blown non-woven fabric can become a high-efficiency air filter material when charged with electricity.How to improve the performance of the melt spray cloth to meet the requirements?One is to rely on raw materials electret masterbatch, the other is electret process. At present, electrets are divided into electrostatic electret and water electret.


(一)Static electret process of melt blown


One of the important factors for the melt blown fabric to meet the standard is to add tourmaline, silicon dioxide, zirconium carbonate and other inorganic materials into PP polypropylene polymer in advance, and then charge the melt blown material by one or more groups of corona discharge methods with needle electrode voltage of 35-50kv before rolling cloth. When high voltage is applied, the air under the needle tip will produce corona ionization In the process of partial breakdown discharge, the carriers are deposited on the surface of melt blown cloth by the action of electric field. Some carriers will go deep into the surface layer and be trapped by the electret masterbatch, which makes the meltblown cloth become electret filter material. The voltage of this corona process is a little smaller than that of high voltage about 200kV, and there is not so much ozone produced. The effect of charging distance and charging voltage makes the return effect. The further the charging distance is, the less charge the material will capture.


The requirements of electret melt blown cloth are as follows: 1. A set of melt blown equipment; 2. Electret masterbatch; 3. Four sets of high-voltage electrostatic discharge device; 4. Under normal temperature and humidity conditions, PP melt blown electret material has good charge storage stability, but when the sample is in high humidity environment, due to water The polar group in the molecule and the foreign particles in the atmosphere can compensate for the charge on the fiber, resulting in a large amount of charge loss. The charge decreases with increasing humidity and becomes faster and faster. Therefore, in the process of transportation and storage, the melt blown cloth must be kept away from moisture and avoid contact with high humidity environment. If the melt blown cloth is not purchased in time, it will be difficult for the mask to meet the standard if it is not well preserved. This is one of the reasons why the cloth made by many manufacturers is up to the standard at that time and is not qualified after a period of time.


Excellent Water or Static Electricity, Read This Article to Understand

(二)Electret process of melting and spraying water


Originated from the United States, it differs from the traditional melt blown cloth electret process in that the corona electret is used in the traditional melt blown cloth, and its surface electret is obvious, but the filtering effect cannot reach the peak value and the storage will decrease with time, and the static electricity attenuation on the material surface is obvious Electret melt blown cloth is a kind of high-pressure water pump that delivers the prepared pure water to the spunlace device. The fan-shaped nozzle sprays the melt blown cloth, and the friction between the two results in static electricity generation. The performance of water electret melt blown cloth is that the electrostatic quantity is saturated, and the water electret charging method is feasible The detection of oil and salt can effectively solve the problem that the filter efficiency of melt blown cloth in mask industry is reduced after storage.


Process steps:


1. Melt blown cloth generation: electret polypropylene with high fluidity is selected and a small amount of water electret masterbatch is added


2. Pure water equipment: tap water is selected as the water source. The water source is filtered by sand and gravel tank and activated carbon. Reverse osmosis agent and hydrochloric acid are added to the filtered water source, and the water source is filtered by reverse osmosis membrane. The basic industrial reagent is added to the filtered water source automatically to complete the preparation of pure water.


3. Water electret process: the prepared pure water is transported to the fan-shaped nozzle through the high-pressure water pump. The fan-shaped nozzle spurs the melt blown cloth, and generates electric charge through the friction between water and melt blown fiber to complete the spunlaced electret.


4.Drying process: the melt blown cloth after the spunlaced electret is sent into the drying box through the transmission network, which is dried by hot air, and then cut and wound after drying.


Summary


After reading this article, you must have a better understanding of melt blown nonwoven fabric electret process. No matter the manufacturer is electrostatic electret or water electret, in the process of transportation and storage, it must be moisture-proof and avoid contact with high humidity environment. Otherwise, if you buy the melt blown fabric which meets the standard in time, the finished product is still difficult to meet the standard.


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