Melt blowing

Melt blowing is a conventional fabrication method of micro- and nanofibers where a polymer melt is extruded through small nozzles surrounded by high speed blowing gas. The randomly deposited fibers form a nonwoven sheet product applicable for filtration, sorbents, apparels and drug delivery systems. The substantial benefits of melt blowing are simplicity, high specific productivity and solvent-free operation. Choosing an appropriate combination of polymers with optimized rheological and surface properties, scientists have been able to produce melt-blown fibers with an average diameter as small as 36 nm.[1]

Melt blowing process

History

During volcanic activity a fibrous material may be drawn by vigorous wind from molten basaltic magma called Pele's hair.[2] The same phenomenon applies for melt blowing of polymers. The first research on melt blowing was a naval attempt in the US to produce fine filtration materials for radiation measurements on drone aircraft in the 1950s.[3] Later on, Exxon Corporation developed the first industrial process based on the melt blowing principle with high throughput levels.[4] China produces 40% of the non-woven fabric in the world with the majority produced in Hebei province (2018).[5]

Polymers

Polymers with thermoplastic behavior are applicable for melt blowing. The main polymer types commonly processed with melt blowing:[6]

Process

Melt blowing is a manufacturing process used to create nonwoven fabrics and materials. It is particularly known for its ability to produce fine fibers, which can be used in various applications. Here's an overview of how melt blowing works:[7]

  • Melt Extrusion: The process begins with a polymer resin being melted and extruded through a spinneret, which is a device with tiny holes.
  • High-Speed Airflow: Simultaneously, high-speed hot air or gas is blown onto the extruded polymer streams.
  • Fiber Formation: The force of the air stretches and elongates the molten polymer into very fine fibers, which are then collected on a moving conveyor belt or drum.

Uses
Microscopic image of the outer layer of a surgical mask, made from melt blown polymer filaments

The main uses of melt-blown nonwovens and other innovative approaches are as follows.[8]

Filtration

Nonwoven melt-blown fabrics are porous. As a result, they can filter liquids and gases. Their applications include water treatment, masks, and air-conditioning filters. During the COVID-19 pandemic, the price of meltblown spiked from few thousand USD per ton to approximately 100 thousand USD per ton.

Sorbents

Nonwoven materials can retain liquids several times their own weight. Thus, those made from polypropylene are ideal for collecting oil contamination.[9][10]

Hygiene products

The high absorption of melt-blown fabrics is exploited in disposable diapers and feminine hygiene products.[11]

Apparels

Melt-blown fabrics have three qualities that help make them useful for clothing, especially in harsh environments: thermal insulation, relative moisture resistance and breathability.

Drug delivery

Melt blowing can produce drug-loaded fibers for controlled drug delivery.[12] The high drug throughput rate (extrusion feeding), solvent-free operation and increased surface area of the product make melt blowing a promising new formulation technique.

References
  1. Soltani, Iman; Macosko, Christopher W. (2018). "Influence of rheology and surface properties on morphology of nanofibers derived from islands-in-the-sea meltblown nonwovens". Polymer. 145: 21–30. doi:10.1016/j.polymer.2018.04.051. S2CID 139262140.
  2. Shimozuru, D. (1994). "Physical parameters governing the formation of Pele's hair and tears". Bulletin of Volcanology. 56 (3): 217–219. Bibcode:1994BVol...56..217S. doi:10.1007/s004450050030.
  3. Shaumbaugh, R.L. (1988). "A macroscopic view of the melt-blowing process for producing microfibers". Ind. Eng. Chem. Res. 27 (12): 2363–2372. doi:10.1021/ie00084a021.
  4. Ellison CJ, Phatak A, Giles DW, Macosko CW, Bates FS (2007). "Melt blown nanofibers: Fiber diameter distributions and onset of fiber breakup". Polymer. 48 (11): 3306–3316. doi:10.1016/j.polymer.2007.04.005.
  5. "China export credit insurance company releases domestic mask supply and demand risk analysis and outlook". Textile Net China. February 17, 2020.
  6. Dutton, Kathryn C. (2008). "Overview and analysis of the meltblown process and parameters". Journal of Textile and Apparel, Technology and Management. 6.
  7. melt blown nonwoven process Retrieved 7 June 2016.
  8. McCulloch, John G. (1999). "The history of the development of melt blowing technology". International Nonwovens Journal. 8: 1558925099OS–80. doi:10.1177/1558925099os-800123.
  9. Wei, Q. F.; Mather, R. R.; Fotheringham, A. F. & Yang, R. D. (2003). "Evaluation of nonwoven polypropylene oil sorbents in marine oil-spill recovery". Marine Pollution Bulletin. 46 (6): 780–783. doi:10.1016/s0025-326x(03)00042-0. PMID 12787586.
  10. Sarbatly R.; Kamin, Z. & Krishnaiah D. (2016). "A review of polymer nanofibres by electrospinning and their application in oil-water separation for cleaning up marine oil spills". Marine Pollution Bulletin. 106 (1–2): 8–16. doi:10.1016/j.marpolbul.2016.03.037. PMID 27016959.
  11. Wehmann, Michael; McCulloch, W. John G. (2012). "Melt blowing technology". In Karger-Kocsis, J. (ed.). Polypropylene: an A-Z reference. Polymer Science and Technology Series. Vol. 2. Springer Science & Business Media. pp. 415–420. doi:10.1007/978-94-011-4421-6_58. ISBN 978-94-010-5899-5.
  12. Balogh, A.; Farkas, B.; Faragó, K.; Farkas, A.; Wagner, I.; Van Assche, I.; et al. (2015). "Melt‐blown and electrospun drug‐loaded polymer fiber mats for dissolution enhancement: A comparative study" (PDF). Journal of Pharmaceutical Sciences. 104 (5): 1767–1776. doi:10.1002/jps.24399. PMID 25761776.
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