The process of melt blown non-woven fabric
The process of melt blown non-woven fabric: polymer feeding – melt extrusion – fiber formation – fiber cooling – web formation – reinforcement into fabric.
Two-component melt blown technology
Since the beginning of the 21st century, the development of melt blown nonwoven technology has made rapid progress internationally.
Hills and Nordson companies in the United States have successfully developed two-component melt blown technology earlier, including skin core, parallel, triangular and other types. The fiber fineness is usually close to 2 µ, and the number of holes in the melt blown filament component can reach 100 holes per inch, with an extrusion rate of 0.5g/min per hole.
Leather core type:
It can make non-woven fabrics feel soft and can be made into concentric, eccentric, and irregular products. Generally, inexpensive materials are used as the core, while expensive polymers with special or required properties are used as the outer layer, such as polypropylene for the core and nylon for the outer layer, making the fibers hygroscopic; The core is made of polypropylene, and the outer layer is made of low melting point polyethylene or modified polypropylene, modified polyester, etc. that can be used for bonding. For carbon black conductive fibers, the conductive core is wrapped inside.
Parallel type:
It can make non-woven fabrics have good elasticity, usually made of two different polymers or the same polymer with different viscosities to form parallel two-component fibers. By utilizing the different thermal shrinkage properties of different polymers, spiral curled fibers can be made. For example, 3M Company has developed a non-woven fabric made of melt blown PET/PP two-component fibers, which, due to different shrinkage, forms a spiral curl and gives the non-woven fabric excellent elasticity.
Terminal type:
This is another type of polymer composite used in the three leaf, cross, and terminal types. When making anti-static, moisture conductive, and conductive fibers, conductive polymers can be composite on the top, which can not only conduct moisture, but also conduct electricity, anti-static, and save the amount of conductive polymer used.
Micro Dan type:
Orange petal shaped, strip-shaped peeling components, or island shaped components can be used. Using two incompatible polymers to peel and make ultrafine fiber webs, even nanofiber webs. For example, Kimberly Clark developed a peeling type two-component fiber, which utilizes the characteristics of two-component fibers made from two incompatible polymers that can be completely peeled off in less than a second in hot water to make ultrafine fiber webs. For island type, the sea needs to be dissolved to obtain a fine island fiber network.
Hybrid type:
It is a fiber web made by mixing different materials, colors, fibers, cross-sectional shapes, and even fibers parallel to the skin core, with both co spun and two-component fibers, to give the fibers the required properties. Compared with general melt blown fiber products, this type of melt blown two-component fiber nonwoven fabric or mixed fiber nonwoven fabric can further improve the filtration performance of the filter medium, and make the filter medium have anti-static, conductive, moisture absorbing, and enhanced barrier properties; Or improve the adhesion, fluffiness, and breathability of the fiber web.
Two component meltblown fibers can supplement the shortcomings of single polymer properties. For example, polypropylene is relatively inexpensive, but when used in medical and health materials, it is not resistant to radiation exposure. Therefore, polypropylene can be used as the core, and an appropriate radiation resistant polymer can be selected on the outer layer to wrap around it, thus solving the problem of radiation resistance. This can make the product cost-effective while meeting functional requirements, such as the heat and humidity exchanger used in the respiratory system in the medical field, which can provide suitable natural heat and humidity. It is lightweight, disposable or easy to disinfect, inexpensive, and can also serve as an additional filter for removing pollutants. It can be composed of two evenly mixed two-component melt blown fiber webs. Adopting a skin core type two-component fiber, the core is made of polypropylene and the skin layer is made of nylon. Two component fibers can also adopt irregular cross-sections, such as trilobites and multilobes, to increase their surface area. At the same time, polymers that can improve filtration performance can be used on their surface or blade tip. The two-component fiber mesh of olefin or polyester melt blown method can be made into cylindrical liquid and gas filters. Melt blown two-component fiber mesh can also be used for cigarette filter tips; Utilizing the core suction effect to create high-end ink absorbing cores; Core suction rods for fluid retention and infusion.
Development of melt blown nonwoven technology – melt blown nanofibers
In the past, the development of meltblown fibers was based on Exxon’s patented technology, but in recent years, several international companies have broken through Exxon’s technology to develop finer nanoscale fibers.
Hills Company has conducted extensive research on nano meltblown fibers and is said to have reached the stage of industrialization. Other companies such as Non woven Technologies (NTI) have also developed processes and technologies for producing nano meltblown fibers and have obtained patents.
In order to spin nanofibers, the nozzle holes are much finer than those on ordinary melt blown equipment. NTI can use nozzles as small as 0.0635 millimeters (63.5 microns) or 0.0025 inches, and the modular structure of the spinneret can be combined to form a total width of more than 3 meters. The diameter of the melt blown fibers spun in this way is approximately 500 nanometers. The thinnest single fiber diameter can reach 200 nanometers.
The melt blown equipment for spinning nanofibers has small spray holes, and if no measures are taken, the yield will inevitably be greatly reduced. Therefore, NTI has increased the number of spray holes, with each spray plate having 3 or even more rows of spray holes. Combining many unit components (depending on the width) together can significantly increase the yield during spinning. The actual situation is that when using 63.5 micron holes, the number of holes per meter of the single row spinneret is 2880. If three rows are used, the number of holes per meter of the spinneret can reach 8640, which is equivalent to the production of ordinary melt blown fibers.
Due to the high cost and susceptibility to breakage (cracking under high pressure) of thin spinnerets with high-density holes, various companies have developed new bonding technologies to enhance the durability of spinnerets and prevent leakage under high pressure.
At present, nano meltblown fibers can be used as filtration media, which can significantly improve filtration efficiency. There is also data showing that due to the finer fibers in nanoscale meltblown nonwoven fabrics, lighter and heavier meltblown fabrics can be used in combination with spunbond composites, which can still withstand the same water head pressure. The SMS products made from them can reduce the proportion of meltblown fibers.
Dongguan Liansheng Non woven Technology Co., Ltd. was established in May 2020. It is a large-scale non-woven fabric production enterprise integrating research and development, production, and sales. It can produce various colors of PP spunbond non-woven fabrics with a width of less than 3.2 meters from 9 grams to 300 grams.
Post time: Oct-30-2024