Control Of Viscosity Of Wrapping Film

Good adhesion ensures that the packaging film and layers on the outside of the goods are firmly attached, and there are two main methods to obtain adhesion: one is to add PIB or its masterbatch to the polymer; Another method is to blend VLDPE. PIB is a semi transparent viscous liquid, and direct addition requires specialized equipment or modification of the equipment. Generally, PIB masterbatch is used.
The migration of PIB has a process that usually takes three days, and is also affected by temperature. When the temperature is high, the viscosity is strong; When the temperature is low, it is not very sticky, but after stretching, the viscosity is greatly reduced. Therefore, it is best to store the finished film within a certain temperature range (recommended storage temperature is between 15 ℃ and 25 ℃). Blended with VLDPE, the viscosity is slightly poor, but there are no special requirements for the equipment. The viscosity is relatively stable and not controlled by time, but it is also affected by temperature. When the temperature is above 30 ℃, the viscosity is relatively high, and when it is below 15 ℃, the viscosity is slightly poor. The desired viscosity can be achieved by adjusting the amount of LLDPE in the adhesive layer. This method is commonly used for three-layer co extrusion.