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What are the factors affecting the surface tension of the drawn film?Date:【2020-07-15】 Read【86】Times 【Print】 【Back

The surface tension of the stretched film depends on the surface free energy of the plastic film, and the surface energy of the stretched film depends on the molecular structure of the film material itself. So, what are the factors that affect the surface tension of the stretched film? Next, I introduce to you:


Affecting factor 1: Non-polar polymer, small surface free energy, low surface wet tension, generally about 30 dynes/cm. In theory, if the surface tension of the object is less than 33 dynes/cm, ordinary ink or adhesive will not adhere firmly, so surface treatment must be performed;


Influencing factor 2: Polyester (PET, PBT, PEN, PETG) is a polar polymer with a high surface free energy and a surface wet tension greater than 40 dynes/cm. However, for high-speed color printing or in order to increase the bonding force between the vacuum aluminum plating layer and the BOPET film surface, it is also necessary to perform surface treatment on the BOPET film to further increase its surface wet tension;


Three influencing factors: the aluminum layer transfer occurs during the aluminum plating process, and the glue transfer occurs during the glue coating process. The main measure to prevent the corona on the opposite side of the film is to adjust the pressure of the rubber roller in front of the corona treatment roller. The pressure at both ends of the roller should be consistent and appropriate.


When testing the surface tension of a stretched film, a strict dynamic and static equilibrium test must be performed. The radial runout requirement is less than 0.05mm. The purpose is to ensure that the plastic film can smoothly enter the corona roller, prevent air entrainment, and avoid the phenomenon of anti-corona.


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