How is Polypropylene POY filament produced? The article "Spinning Process" explains it thoroughly.

Melt preparation, with proper pre-preparation

Polypropylene POY filament is made from polypropylene pellets as the basic raw material, combined with the required color masterbatches and functional masterbatches, and fully mixed according to the ratio before being sent to the extruder. The material is heated and gradually melted and plasticized in the extruder, continuously transported under the push of the screw, and impurities and gel particles are filtered out by the filter component to ensure the purity and uniformity of the melt, avoiding defects and breaks in the subsequent filament. Temperature control during the melt transportation is very crucial; temperature fluctuations will directly affect the fluidity of the melt, causing a deterioration in the uniformity of the filament.

Spinning formation, stretching and cooling to form filament

Clean melt is precisely delivered by a metering pump to the spinning box, and is extruded from the micro holes of the spinneret to form a fine stream. The extruded melt stream enters the side blowing air area, where uniform cold air rapidly cools and solidifies the filament flow, initially forming fibers. Polypropylene has a special heat conductivity property, and the cooling air speed, temperature, and stability need to be matched and adjusted. The cooled filament strand is uniformly applied with spinning oil by the oiling device to enhance the smoothness and anti-static ability of the filament bundle, reducing frictional hairiness between the filament strands.

Subsequently, the filament strand passes through the pre-network nozzle for mild network entanglement, allowing the single filaments to slightly entangle with each other, preventing splitting and scattering during subsequent winding. Different from FDY, POY only undergoes low-speed pre-stretching and does not complete full stretching and shaping, retaining a certain potential stretching space.

Winding formation, semi-finished product winding

The filament strand after oiling and pre-networking enters the winding machine to form a tube. The winding tension needs to be controlled stably; unstable tension is likely to cause poor tube formation and uneven internal stress in the filament. The POY obtained from winding is a semi-finished product, with internal unreleased internal stress, and generally undergoes the leveling process for DTY processing, used for fabricating fabrics, straps, etc.

In the entire process, melt filtration, cooling conditions, oil application, and winding tension are the key control points. During production, the supporting parameters need to be adjusted according to the target fineness to reduce unevenness in the yarn, fuzz, and breakage. When purchasing raw materials, one can also focus on evaluating filament tube formation, yarn smoothness stability, and network uniformity.

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