Many users may imagine the use of stretch film to be very simple, but in fact, its usage process, steps, and precautions are quite complicated. It is precisely because of this idea that the effect of the film cannot be fully manifested, such as the surface tension of the film. This performance is important for the use of the membrane and affects certain structures of the membrane itself. Below, we will mainly discuss the factors that have a significant impact on the surface tension of the film.

一、Non polar polymers have low surface free energy and low surface wet tension for stretch films, typically around 30 dynes/centimeter. In theory, if the surface tension of an object is less than 33 dynes/centimeter, ordinary ink or adhesive cannot adhere firmly, so surface treatment is necessary;

二、Polyester (PET, PBT, PEN, PETG) is a polar polymer with high surface free energy and a surface wet tension of over 40 dynes/cm. However, for high-speed color printing or to increase the adhesion between the vacuum aluminum plating layer and the surface of BOPET film, surface treatment of BOPET film is also necessary to further improve its surface wet tension;

三、During aluminum plating, there will be a transfer of the aluminum coating layer, and when applying adhesive to the stretch film, there will be a transfer of the coating layer. The main measure to prevent corona discharge on the back of the film is to adjust the pressure of the rubber pressing roller before the corona treatment roller. The pressure at both ends of the pressing roller should be consistent and appropriate.

When testing the surface tension of stretch film, we also need to conduct strict dynamic and static balance tests. The detailed test steps can be viewed through certain channels, and the precautions should be understood. When we judge the surface tension of the membrane, we first need to consider the influencing factors, so as to ensure that the use of the membrane will not be greatly affected and can play a better role.