1、 Control of physical and mechanical properties: High transparency is conducive to the identification of goods; High longitudinal elongation is beneficial for pre stretching and saves data consumption; Excellent puncture performance and lateral tear strength allow the film to withstand sharp corners or edges of the product without cracking at high tensile rates; The high yield point makes the packaged goods more secure. The film produced by casting method has high transparency, so we will not focus on comments here. With the increase of the number of C atoms in the data comonomer, the length of the branched chain increases, the crystallinity decreases, and the "entanglement or twisting" effect of the generated copolymer increases, resulting in an improvement in elongation, puncture strength, and tear strength. MPE is a highly structured and regular polymer with a narrow molecular weight distribution, which allows for precise control of the physical properties of the polymer, resulting in further improvements in performance; Due to the narrow molecular weight distribution and processing range of MPE, the processing conditions are difficult to control. Usually, 5% LDPE is added to reduce melt viscosity and increase film flatness. 2、 Sticky handling: Excellent stickiness makes the packaging film layer and layer on the outside of the product stick together to make the product strong. There are mainly two ways to obtain stickiness: one is to add PIB or its masterbatch to the polymer; Another approach is to mix VLDPE. PIB is a semi transparent viscous liquid, which requires specialized equipment or modification for direct addition. Usually, 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 greatly decreases. Therefore, it is best to store the product film within a certain temperature range (it is recommended to store it at a temperature of 15 ℃ to 25 ℃). Mixing VLDPE has slightly lower viscosity, 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 ℃, it is relatively sticky, and when it is below 15 ℃, the viscosity is slightly worse. The required viscosity can be achieved by adjusting the amount of LLDPE in the adhesive layer. This method is commonly used for three-layer co extrusion