The Science of Spunbond Extrusion Technology

In Spunbond extrusion, virgin homopolymer polypropylene (PP) with a tailored melt flow index (MFI 25–40) is melted in continuous twin-screw extruders and metered through precision spinneret plates containing thousands of micro-capillary orifices. As the molten filaments emerge, they enter a controlled quenching chamber.

High-velocity laminar cool air streams draw and accelerate the filaments downward at speeds exceeding 3,000 m/min. This aerodynamic drafting stretches the polymer chains, aligning crystalline structures along the filament axis. This molecular orientation is the fundamental source of Spunbond's high tensile strength, tear toughness, and minimal elongation under load.

The continuous filaments are deposited by vacuum suction onto a moving wire conveyor belt, forming a uniform random fibrous web. Finally, heated calender rollers with precision relief patterns thermally fuse filament intersections, consolidating the web into a dimensionally stable, breathable, and lint-free fabric roll without any chemical binders or adhesives.