The extrusion amount and speed of a screw extruder directly affect the wire spraying speed and quantity of the nozzle. On the premise that other process conditions remain unchanged, as the screw speed increases, the extrusion amount and extrusion speed also correspondingly increase, and the more fine flow is sprayed from the nozzle, resulting in a finer fiber diameter. At the same weight, there are more fibers per unit area, which increases the chances of bonding between them. After fiber mesh reinforcement, the bonding and weaving between fibers are more firm. But when the extrusion speed reaches a peak, it tends to decrease, which may be due to the insufficient stretching rate of the melt blown process itself, resulting in a decrease in the number of bonded fibers on the fabric surface and the emergence of wire merging. As the extrusion volume and speed of the screw extruder increase in production, the longitudinal and transverse strength, tear strength, elongation at break, and bending stiffness of the product all correspondingly increase.

Temperature control of each zone of screw extruder

The screw extruder is the key to forming a uniform melt. According to the different states of the slices in different areas of the extruder, the temperature setting is very important, which directly affects the smoothness of the spinning process and the physical and mechanical properties of the product. If the temperature is low, the rheological performance is poor, and the viscosity is too high, it will block the spinneret and cause the injection of yarn, resulting in an increase in fabric defects; If the temperature is too high, significant thermal oxygen degradation will occur, affecting the uniformity of the fiber mesh. Table 9-2 shows the temperature settings for each zone of screw extruders for different products.