Can you explain the key steps in the production, from polymer extrusion to fabric formation?

The production of spunbonded nonwoven fabric involves several key steps, from polymer extrusion to fabric formation. Here's an overview of the process:

Polymer Preparation:

The process begins with the preparation of polymer pellets or chips. These pellets are typically made from polymers such as polypropylene (PP), polyethylene (PE), or polyester (PET).

The polymer pellets may undergo pre-processing steps, such as drying or blending with additives, to ensure uniform melting and proper extrusion.

Polymer Extrusion:

The polymer pellets are melted and extruded through a spinneret, a metal plate with numerous small holes or orifices arranged in a specific pattern.

The molten polymer is forced through the spinneret under high pressure, forming continuous filaments or fibers.

Fiber Formation:

As the extruded polymer filaments emerge from the spinneret, they are stretched and attenuated to align the molecules and orient the fibers in the desired direction.

The stretching process may involve hot air or mechanical rollers to draw out and elongate the filaments, creating thinner and more uniform fibers.

Web Formation:

The stretched polymer fibers are deposited onto a moving conveyor belt or forming wire, where they accumulate to form a loose web or mat.

The fibers are randomly distributed and entangled with each other to create a cohesive nonwoven structure.

Bonding:

The loose fiber web passes through a bonding stage where the fibers are bonded together to form a coherent fabric.

Bonding can be achieved through various methods, including thermal bonding, mechanical bonding, or chemical bonding:

Thermal Bonding: Heat is applied to the fiber web using heated rollers or calenders, causing the polymer fibers to fuse together at contact points.

Mechanical Bonding: Needles or barbed rollers mechanically entangle the fibers, interlocking them to form a stable fabric structure.

Chemical Bonding: Adhesive binders or bonding agents are applied to the fiber web, which cure or set to create bonds between the fibers.

Finishing:

The bonded nonwoven fabric may undergo additional finishing processes to enhance its properties or appearance.

This may include treatments such as calendaring (compression to improve smoothness and density), embossing (texturing for aesthetics or functionality), or surface coatings (to impart specific properties like water repellency or flame resistance).