Good viscosity makes the packaging film layer on the outside of the goods stick together with the layer to make the goods firm, and there are two main ways to obtain the viscosity: one is to add PIB or its masterbatch to the polymer; The other is blended VLDPE. PIB is a translucent viscous liquid, which requires special equipment or modification of the equipment for direct addition, and PIB masterbatch is generally used. There is a process of PIB moving out, which generally takes three days, and it is also affected by temperature, and it is highly viscous when the temperature is high; It is not too sticky when the temperature is low, and the viscosity is greatly reduced after stretching. Therefore, it is best to store the finished film within a certain temperature range (the recommended storage temperature is 15°C~25°C). Blended VLDPE, the viscosity is slightly worse, but there are no special requirements for the equipment, the viscosity is relatively stable, not controlled by time, but also affected by temperature, the temperature is higher than 30 °C, the viscosity is slightly worse when it is lower than 15 °C, and the amount of LLDPE in the adhesive layer can be adjusted to achieve the desired viscosity. Three-layer co-extrusion mostly adopts this method.
