Production process conditions
Stretch Film is a kind of packaging material used in conjunction with a winding machine, which is used to package objects for easy transportation. In the early days, LLDPE stretched films were mostly blown films, and developed from single-layer to two-layer and three-layer. With the development of social economy, LDPE stretch film has become the mainstream of the market.
The melt temperature of the stretched film is generally controlled at 250℃~280℃, the temperature of the casting cooling roll is controlled at 20℃~30℃, the winding tension should be low, generally within 10kg, in order to facilitate the viscosity agent Move out while reducing the internal stress of the finished film. This is its production process conditions.
Stickiness control
Good viscosity makes the packaging film and layers on the outside of the goods stick together to make the goods firm. There are two main ways to obtain the viscosity: one is to add PIB or its masterbatch to the polymer; the other is to blend VLDPE . PIB is a translucent viscous liquid, special equipment or modification of equipment is required for direct addition, and PIB masterbatch is generally used. There is a process for the migration of PIB, which usually takes three days, and it is also affected by temperature. When the temperature is high, the viscosity is strong; when the temperature is low, it is not too sticky, and the viscosity is greatly reduced after stretching. Therefore, the finished film is best stored in a certain temperature range (suggested storage temperature is 15℃~25℃). Blended with VLDPE, the viscosity is slightly poor, but there is no special requirement for the equipment. The viscosity is relatively stable, not controlled by time, but also affected by temperature. The temperature is relatively viscous when the temperature is higher than 30°C, and the viscosity is slightly worse when the temperature is lower than 15°C. Adjust the amount of LLDPE in the adhesive layer to achieve the desired viscosity. This method is mostly used for three-layer co-extrusion.