Meltspinning

Melt spinning is a polymer fiber spinning process in which a thermoplastic polymer is melted and extruded through a spinneret to form continuous filaments. As the molten polymer exits the spinneret, it is rapidly cooled (quenched) to solidify the filaments. The filaments are then drawn to increase molecular orientation and strength and are wound onto collection packages. Because no solvents are used, melt spinning is widely employed for thermoplastics such as polyesters, nylons, and polyolefins.

Process overview: Polymer pellets are fed to an extrusion equipment where they are melted above their melting point. The melt is forced through spinneret capillaries to form filaments, which are exposed to a cooling medium, typically air. The quenched filaments are collected on take-up rollers and often passed through a drawing stage to improve strength and modulus. Filaments can be produced as multifilament bundles, which may later be assembled into tow or cut into staple fibers.

Materials and variants: Melt spinning is suitable for a range of thermoplastics, including polyethylene terephthalate (PET), nylon, and polypropylene. Variations exist in quenching methods (air or gas), and drawing can occur in air, hot gas, or on heated rollers. The process is generally solvent-free, unlike solution-based spinning methods.

Advantages and limitations: Melt spinning offers high production rates and solvent-free operation, good process control, and compatibility with high molecular weight polymers. Limitations include the need for polymers with adequate thermal stability and processability, potential thermal degradation at high temperatures, and control of fiber diameter and orientation.

Applications: Widely used for textile fibers, nonwovens, and industrial fibers made from PET, nylon, and other thermoplastics.