Melt-blown nonwovens are produced by extruding melted polymer micro- and nano fibers through a spinneret or die consisting of up to 40 holes per inch to form long thin fibers which are blown or stretched to a ultra-fine diameters typically ranging between 2-4 μm, and cooled by passing hot air over the fibers as they fall from the die as shown in Figure 3. The resultant web is collected on conveyor belt and bonded then into rolls and subsequently converted to finished products. The fibers in the web are usually self-entangled enough that additional bonding is not required. Melt-blown non-woven are used in hospital-medical uses and battery separators. The extremely fine fibers typically polypropylene differ from other extrusions particularly spun bond in that they have low intrinsic strength but much smaller size offering key properties. Often melt blown is added to spun bond to form SM or SMS webs, which are strong and offer the intrinsic benefits of fine fibers such as fine filtration, low pressure drop as used in face masks or filters and physical benefits such as acoustic insulation as used in dishwashers. One of the largest users of SM and SMS materials is the disposable diaper and feminine care industry. Melt-Blown nonwoven is applicable for filtration, absorbents, apparels and drug delivery systems. The substantial benefits of melt blowing are simplicity, high specific productivity and solvent-free operation. A typical melt blowing process consists of the following elements: extruder, metering pumps, die assembly, web formation, and winding.
Polypropylene (PP) is the key raw material used for producing Melt-Blown Non-woven fabrics owing to low cost, flexibility, moderate strength & stability, lightweight, excellent moisture resistance, high temperature resistance, and insulation properties. PP nonwoven fabrics have wide applications especially in filtration, medical, hygiene and healthcare applications.
Polymers with thermoplastic behavior are applicable for melt blowing. The main polymer types commonly processed with melt blowing include following
- Poly amides (nylons)
- Poly carbonate
Main Application Area of Melt Blown Non Woven Fabrics
The porous nonwoven melt-blown fabrics can be used in the filtration. This market segment continues to be the largest single application. The best known application is the surgical face mask filter media. The applications include both liquid filtration and gaseous filtration. Some of them are found in cartridge filters, clean room filters and others. Melt-Blown Nonwovens offer many advantages in all types of filtration. Whether a filter is designed to keep the air in your home clean, an operating room sterile, or to remove dirt and grit from the oil in your car before it reaches the engine, nonwoven fabrics get the job done. Anyone who suffers from allergies already knows that having a good heating and air conditioning filter in the home can help immeasurably in clearing the air. Air filters capture pollen, allergens, mold spores, and other microscopic particles to reduce symptoms and help everyone breathe easier. Medical filters made from nonwovens are key in any operating room to keep out pathogens, bacteria or microbes that might otherwise contaminate a sterile environment. Oil filters are an important component in your car. The nonwoven fabrics in the filters help remove contaminants from the engine oil, hydraulic oil, transmission oil and lubricating oil.
Examples of Melt-Blown Nonwoven Fabrics in Filtration
- Air, gas & dust
- Home HVAC
- Liquid, non-food