Meltblown Nonwoven Fabric: The "Heart" of Masks and Key to High-Efficiency Filtration

Meltblown nonwoven fabric is a type of ultra-fine fiber nonwoven fabric produced from polymeric raw materials using the meltblown process. Due to its unique microstructure and outstanding filtration performance, it's hailed as the "heart" of face masks and plays an indispensable role in air filtration, liquid filtration, oil absorbent materials, and more.

Meltblown Process Principle

The meltblown process is an efficient method for producing ultra-fine fiber nonwoven fabrics. Its basic principle is:

• Polymer Melting: The polymer (most commonly high melt flow index polypropylene, PP) is fed into an extruder, where it's heated and melted into a homogeneous melt.
• High-Velocity Air Stretching: The molten polymer is extruded through a spinneret (a device with hundreds to thousands of tiny orifices), forming very fine polymer streams.
• Fiber Formation and Cooling: Below the spinneret, a high-velocity stream of hot air (usually parallel to or at an angle to the polymer streams) is ejected, intensely stretching and attenuating these freshly extruded polymer streams. During this stretching, the polymer streams rapidly thin down, forming ultra-fine fibers with diameters typically between 0.5 and 10 micrometers. Simultaneously, the air stream rapidly cools and solidifies them.
• Random Web Formation: These ultra-fine fibers are blown onto a collecting screen by the air stream, where they randomly accumulate and intertwine, forming a fluffy, dense web with a complex porous structure. Because the fibers are extremely fine and randomly arranged, the meltblown nonwoven fabric forms a vast number of micro-pores internally, which are crucial for its high-efficiency filtration performance.
• Self-Bonding: The fibers on the collecting screen spontaneously bond due to their residual heat and natural adhesion between fibers, forming a nonwoven fabric with a certain degree of strength, usually without the need for additional binders.

Characteristics of Meltblown Nonwoven Fabric

• Ultra-fine Fiber Diameter: Fiber diameters are typically between 0.5 and 10 micrometers, much finer than human hair. This significantly increases the number of fibers and surface area per unit area.
• High Filtration Efficiency: Due to its fine fibers and dense, complex porous structure, meltblown nonwoven fabric exhibits excellent mechanical blocking and adsorptive filtration capabilities against tiny particulates (such as bacteria, virus-carrying droplets, dust, PM2.5).
• Unique Capillary Structure: The large number of micro-pores and capillary structures inside give it good adsorption properties, especially strong adsorption capacity for oily substances.
• Good Uniformity: The random arrangement of fibers leads to relatively uniform properties in all directions of the fabric.
• Softness and Bulkiness: Fine fibers and a fluffy structure make the fabric soft to the touch.
• Hydrophobic/Water Repellent: Most meltblown nonwovens use polypropylene as a raw material, which is inherently hydrophobic and can effectively block the penetration of water-based liquids.
• Enhanced Filtration through Electret Treatment: Meltblown fabric treated with electrostatic electret technology can carry electrostatic charges, further improving the filtration efficiency of ultra-fine particles through electrostatic adsorption while maintaining low breathing resistance.

Functions and Applications

Due to its exceptional filtration and barrier properties, meltblown nonwoven fabric is widely used in various fields that demand high levels of protection and cleanliness:

• Medical and Health Protection:
  • Medical Face Masks (Core Filter Layer): This is the most well-known application of meltblown nonwoven fabric, particularly in N95 and surgical masks, where the meltblown layer is crucial for achieving high filtration efficiency.
  • Medical Protective Clothing and Isolation Gowns: Provides an effective barrier against blood, bodily fluids, bacteria, and viruses.
  • Surgical Drapes, Sterilization Wraps: Used in operating rooms to ensure a sterile environment.
• Filtration Materials:
  • Air Filters: Used in HVAC systems, air purifiers, car cabin air filters, HEPA filters, etc., for efficient filtration of airborne particulates, bacteria, and viruses.
  • Liquid Filtration: Used in water treatment, beverage filtration, industrial liquid filtration, etc.
• Oil Absorbent Materials:
  • Oil Booms, Oil Absorbent Pads: Possess strong oil absorption capacity, used for cleaning up oil spills on water surfaces, industrial oil leaks, etc.
• Thermal Insulation Materials:
  • Apparel Linings, Fillings: Their unique micro-pore structure can trap a large amount of air, providing excellent thermal insulation properties.
• Wiping Materials:
  • Precision Instrument Wipes, Industrial Wipes: Known for good absorbency and lint-free characteristics.

Meltblown nonwoven fabric, with its precise microstructure and excellent performance, plays a critical role in addressing public health challenges, improving environmental quality, and enhancing industrial production efficiency.