Meltblown Nonwoven Fabric
September 19, 2022
The process of melt blown nonwoven fabric: polymer feeding --- melt extrusion --- fiber formation --- fiber cooling --- netting --- reinforcement into cloth.
Development of Meltblown Nonwoven Technology —— Since the two - component meltblown technology entered the 21st century, the development of melt blown nonwoven technology in the world has advanced by leaps and bounds.
American Hills and Nordson have developed two - component melt - blown technology earlier, including sheath - core, side - by - side, triangle, etc., usually the fiber fineness is close to 2 µ. And the number of holes of melt - blown spinneret components can reach 100 per inch holes, the amount of extrusion per hole can reach 0.5 g / min.
Skin - core type: It can make the nonwoven fabric feel soft and can be made into concentric, eccentric and irregular products. Generally, cheap materials are used as the core, and the expensive polymer with special or required properties is the outer layer. For example, the core is polypropylene and the outer layer is nylon to make the fiber hygroscopic. The core is polypropylene and the outer layer is low for bonding Melting point polyethylene or modified polypropylene, modified polyester, etc. For carbon black type conductive fibers, the conductive core is wrapped inside.
Side - by - side type: It can make the nonwoven fabric have good elasticity. It is usually made of two different polymers, or the same polymer with different viscosity to form side-by-side two-component fibers. It can be made by using different thermal shrinkage of different polymers. Spiral crimped fibers. For example, 3M has developed a nonwoven fabric of melt - blown PET / PP bicomponent fibers. Due to the different shrinkage, it forms a spiral crimp, which makes the non woven fabric have excellent elasticity.
Tip type: This is a compound of another polymer in the trilobal type, cross type and tip type, such as antistatic, moisture - conducting.
Micro - denier type: You can use orange petal - shaped, strip - shaped peeling type components, or island - type components. Two incompatible polymers are peeled to make ultrafine fiber webs, or even nanofiber webs, such as the split bicomponent fiber developed by Kimberly - Clark, which is made of two incompatible polymers. When the component fibers are in hot water for less than one second, the two polymers can be completely peeled off to make an ultra - fine fiber web. The island type needs to dissolve the sea to obtain a fine island fiber web.
Mixed type: It is a fiber web that combines different materials, different colors, different fibers, different cross - sectional shapes, and even fibers in parallel with the core - sheath, which has both co - spinning and bicomponent fibers, so that the fibers have various properties required . Compared with general melt - blown fiber products, this type of melt - blown bicomponent fiber nonwoven fabric or mixed fiber non woven fabric can further improve the filterability of the filter medium and make the filter medium antistatic, conductive, hygroscopic, and enhanced barrier properties, etc .; or to improve the adhesion, bulkiness and breathability of the fiber web.
Two - component meltblown fibers can supplement the deficiencies of a single polymer, such as polypropylene is cheaper, but if used in medical materials, it is not resistant to radiation, so polypropylene can be the core The problem of radiation resistance can be solved by wrapping the radiation - resistant polymer on the outside. Therefore, the product can be made cheap and can fulfill the functional requirements. For example, the heat and humidity exchanger that can be used in the respiratory system in the medical field can provide suitable natural heat and humidity. It has the advantages of light weight, disposable or convenient disinfection, low price, and the additional function of removing pollutant filters. It can be composed of two uniformly mixed two - component meltblown fiber webs. It uses sheath - core type bicomponent fiber, the core is polypropylene and the sheath is nylon. Bicomponent fibers can also be shaped cross - sections, such as trilobal and multilobal, to make their surface area larger. At the same time, they can also use polymers that can improve the filtration performance on the surface layer or blade tip. The olefin or polyester melt - blown two - component fiber web can be made into cylindrical liquid and gas filters. Melt - blown two - component fiber web can also be used in cigarette filters; using the wicking effect to make high - end ink - absorbing wicks; wicking sticks for liquid retention and infusion, etc.
Development of Meltblown Nonwoven Fabric Technology - Meltblown Nanofibers In the past, meltblown fibers were based on Exxon 's patented technology. However, in recent years, many international companies have broken through Exxon technology to develop finer nanometer fibers.
Hills has done a lot of research on nano - meltblown fibers, which is said to have reached the stage of industrialization. Other companies such as Nonwoven Technologies ( NTI ) have also developed processes and technologies for nanomelt blown fibers that can be produced, and have obtained patents.
In order to spin nanofibers, the spinneret holes are much thinner than those on ordinary melt - blown equipment. NTI can be as small as 0.0635 mm ( ie 63.5 microns ) or 0.0025 inch. The spinnerets with modular structure can be combined Into a total width of more than 3 meters. The diameter of the melt - blown fiber thus spun is about 500 nm. The finest single fiber diameter can reach 200 nanometers.
Due to the small orifice of the melt-blown equipment for spinning nanofibers, if no measures are taken, the output will inevitably be greatly reduced, so NTI adopts an increase in the number of orifices of each spinneret, each spinneret has 3 or more rows of spinnerets hole. By combining many unit components ( depending on the width ), the output can be greatly increased during spinning. The actual situation is that when 63.5 micron holes are used, the number of holes in a single row of spinneret per meter is 2880.
Because the thin spinnerets with high - density holes are expensive and fragile ( cracked by heat under high pressure ), companies have developed new bonding techniques to enhance the spinneret ’s fastness, making it unaffected.
At present, nano - meltblown fibers can be used as filter media, which can significantly improve the filtration efficiency. Information also shows that because the fibers in nanometer meltblown nonwoven fabrics are thinner, lighter weight meltblown fabrics and spunbond composites can be used, which can still withstand the pressure of the same head, and the SMS products they make reduce the proportion of meltblown fibers.
