Meltblown Microfiber Technology

Meltblown process—producing ultra-fine fibers: (1) Polymer extrusion (PP primary, PET, PA melted 230-300°C), (2) Extrusion through die (0.2-0.4 mm capillaries, 20-40 holes per cm width), (3) Attenuation via converging hot air streams (300-400°C, velocity 0.3-0.6 Mach) stretching polymer to 0.5-10 μm diameter (100-1000× extrusion diameter, true microfibers), (4) Deposition onto collector forming self-bonded web (thermal bonding during deposition from residual heat). Fiber diameter distribution: 0.5-5 μm typical (100× finer than spunbond 20-50 μm), log-normal distribution, controlled via air velocity, polymer viscosity, temperature. Properties: ultra-high surface area (5-20 m²/g fiber vs. 0.05-0.2 m²/g conventional), low strength (tensile 10-40 N/5cm, fine fibers weak individually but numerous), excellent filtration (sub-micron particle capture), fluid barrier (hydrophobic PP repelling liquid), and softness (fine fibers). Applications: filtration (face masks N95/FFP2 achieving 95% filtration of 0.3 μm particles via mechanical and electrostatic mechanisms, HEPA filters, cabin air filters, vacuum bags), medical barriers (fluid-resistant surgical gowns, drapes—SMS middle layer), absorbent products (oil spill cleanup, absorbent pads—high surface area), and battery separators. Limitations: high energy consumption (300-400°C air), low production speeds (10-50 m/min vs. spunbond 300-800 m/min), higher cost ($3-8/kg vs. spunbond $1.50-3/kg) limiting to applications requiring microfiber properties. Recent developments: nanofibres via electrospinning (0.01-1 μm), ultra-fine meltblown (<1 μm average), and bicomponent meltblown (improving strength).