Factors Affecting Uniformity of Spunbonded Nonwovens

Spunbond nonwovens' uniformity can be affected by various factors, the first of which is the accuracy of the spinning box installation, which involves ensuring proper centering, levelness, and precision in the installation of the drafting channel. It is crucial to align the centerline of the channel with that of the spinning box. Furthermore, any mechanisms that require sealing must be sealed securely to maintain uniformity.

To ensure effective spinning of the polymer melt, it is essential that the raw material is with good spinnability. This means that the melt flow extruded by the spinning assembly must be uniform across the entire width. Several factors influence this uniformity, including the temperature of the spinning box, the melt pressure within the spinning box, and the technical condition of the spinneret.

The uniformity of the quenching and drawing airflow also places a significant role. Its uniformity refers to temperature consistency, flow uniformity, speed, and flow symmetry on both sides. These factors are influenced by the net cleanliness of the side-blowing air chamber outlet and the guide honeycomb, as well as the flatness and symmetry of the channel surface. Additionally, improper suction flow from the monomer exhaust fan—whether too large or too small—can negatively impact product uniformity.

The uniformity of web formation is closely linked to the consistency of the suction airflow used to deposit the web. It is essential that the flow rate of this suction airflow is uniform and steady across its entire width, with all air current parallel to one another and travelling in the same direction. Besides, the air permeability uniformity of the mesh belt can impact the evenness of web laying, particularly when the mesh belt becomes contaminated.

The technical condition of filament separation and swinging devices, which are utilized on some spinning systems, can impact the uniformity of the final product. The cooling draft airflow can disrupt the web formation process. As the drafting speed increases, the level of interference also rises, which can prevent the fiber web from securely and consistently adhering to the surface of the mesh belt. Furthermore, the distance between the stretcher and the web former markedly affects the uniformity of the web. Therefore, it is essential to optimize this distance based on different drafting speeds.