Meltblown cloth debugging method
At present, the world is actively preventing and controlling the epidemic. The most basic protective equipment for residents is Meltblown Cloth masks. Due to the high standards of viruses on masks, manufacturers need to use the material of meltblown cloth in antivirus masks Now, what kind of filter material is meltblown cloth? Let ’s take a look! Meltblown cloth debugging method
Meltblown cloth is the core material of the mask. Meltblown cloth mainly uses polypropylene as the main raw material, and the fiber diameter can reach 1 to 5 microns. There are many voids, fluffy structure, and good fold resistance. The ultrafine fibers with unique capillary structure increase the number and surface area of fibers per unit area, so that the melt-blown cloth has good filtration, shielding, heat insulation, and oil absorption. It can be used in the fields of air, liquid filtration materials, insulation materials, absorption materials, mask materials, thermal insulation materials, oil-absorbing materials and wipers.
Meltblown cloth mainly uses polypropylene as the main raw material, and the fiber diameter can reach 1 to 5 microns. With many voids, fluffy structure, and good fold resistance, these ultra-fine fibers with unique capillary structure increase the number and surface area of fibers per unit area, thus making the melt-blown cloth have good filtering, shielding, heat insulation, and oil absorption . It can be used in the fields of air, liquid filtration materials, insulation materials, absorption materials, mask materials, thermal insulation materials, oil-absorbing materials and wipers. The production process of the mask meltblown cloth is the core of the entire mask, which is the meltblown nonwoven material.
Meltblown nonwoven fabric is an ideal mask material. Due to the dense meltblown layer, the linear density of its fibers is very small, basically all are ultrafine fibers, which can reach 0.01 ~ 0.05dtex, which is about ordinary spunbond fibers. 1% of linear density. The fibers of the meltblown fiber web are very thin and the fiber web is very uniform. When the liquid comes in contact with it, the liquid is not easy to penetrate due to the surface tension; the gap formed by the connection between the ultra-fine fibers is quite small, so the dust and bacteria are blocked. The large specific surface area, combined with the irregular arrangement of nonwoven materials, solves the contradiction between the filtering effect and the suction resistance of the general filter material.
Melt spinning process introduction Melt spinning includes many types, spunbond, melt blown, electrospinning, and its composite method. The melt blown process is one of the melt spinning processes. The high-speed hot air flow is used to draw the fine flow of polymer melt extruded from the die orifice of the die, thereby forming ultra-fine fibers and collecting them on the screen or roller, and at the same time bonding themselves to become a melt-blown nonwoven cloth. The melt-blowing process is characterized by the use of a single row of spinneret holes. The high-temperature polymer melt is sprayed from the spinneret hole in the center of the spinneret, and then is drawn by the high-temperature airflow blown from both sides at a certain angle, and then collected in the collection device. It depends on the residual heat of the fiber to self-consolidate into a melt-blown cloth. Technological process melt blown: raw material conveying screw melt melt filtration melt metering spinning hot air drafting net winding. Anti-sticking: raw material conveying screw melt melt filtration melt metering spinning hot air drafting net winding
The equipment of the melt-blown production line mainly includes feeder, screw extruder, filter device, metering pump, melt-blown die head assembly, Roots blower, air heater, receiving device, winding device. Production auxiliary equipment mainly includes forging furnace, ultrasonic cleaning furnace, etc.
Roots blowers have been equipped for more than 250 meltblown fabric production lines. Customers have explored a lot of experience in the adjustment of process parameters in production, which will be popularized. The process parameters that affect the performance and structure of the melt-blown nonwoven fabric are the melt index of the raw resin, the amount of polymer melt extrusion, the airflow speed, the web structure, the number of web layers, the structure of the spinneret and the spinneret The shape, the temperature of the hot air, the distance between the spinneret and the net curtain, etc.
Due to the particularity of the melt-blown cloth production process, as a raw material for melt-blown cloth, it must meet the following requirements. The high melt index should be greater than 400g / min, leaving a narrow ash with a relatively low molecular weight distribution. The melt index of the melt blown raw material is too low, and the melt viscosity is high. It requires a large pressure from the extruder to successfully extrude it from the spinneret hole. It requires greater energy consumption and the melt blown equipment is subjected to more pressure and the melt After being extruded from the spinneret hole, it cannot be fully drawn and refined, and ultra-fine fibers cannot be formed. Therefore, only materials with a high melt index can meet the requirements of the melt-blown process, produce qualified ultra-fine fiber melt-blown cloth, and reduce energy consumption.
The extended treatment time at different temperatures of polypropylene has the same change law. The crystallinity continues to increase. When the heat treatment time is reached, it almost reaches the maximum value at that temperature. If the treatment time is extended, the crystallinity does not change much. There is not much effect on the crystallinity of polypropylene. The effect of increasing the processing temperature on the crystallinity of polypropylene during the sufficient treatment time has the same change rule. The heat treatment temperature is less than 90 ℃, and the crystallinity does not change significantly. At 90 ℃, the crystallinity rises sharply. At 140 ℃, the crystallinity is greatly improved, which can be increased by nearly 10% compared with the original sample. Through practice, it was found that the polypropylene melt-blown cloth will partially melt above 140 ° C, and the fabric structure will be destroyed.
Eternal Bliss Alloy Casting & Forging Co, Ltd.
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