Spunbond Technology and SMS Fabrics

Spunbond process—polymer to fabric in single step: (1) Polymer extrusion (PP, PET, PA granules melted 220-290°C), (2) Spinning through spinneret (500-10,000 holes/m width, 0.3-0.6 mm diameter), (3) Quenching (cooling air solidifying filaments), (4) Drawing (pneumatic or mechanical stretching filaments 1.5-4× achieving 2.5-4.0 g/den tenacity), (5) Web formation (filaments deposited onto moving conveyor forming uniform web, controlled turbulence creating random orientation), (6) Bonding (calendar, through-air, or point bonding), speeds 300-800 m/min, 15-200 GSM. Advantages: continuous filaments providing high strength (tensile 100-400 N/5cm), uniformity, integration of spinning-web formation-bonding eliminating intermediate processes reducing cost 30-50% vs. staple-based nonwovens. SMS (Spunbond-Meltblown-Spunbond) composite—outer spunbond layers (strength, 15-30 GSM each) with meltblown core layer (barrier, filtration, 5-20 GSM), achieving strength + barrier properties, dominant in medical textiles (surgical gowns, drapes, face masks), hygiene (diaper covers), and filtration. Bicomponent spunbond—side-by-side or sheath-core fibers enabling self-bonding (low-melt component), improved softness, or special properties, growing application in hygiene, medical. Production capacity: individual lines 20,000-100,000 tonnes/year (largest fabric production capacities), economies of scale critical, capital investment $20-50 million per line.