PET protective film without surface treatment, its surface tension in more than 40mN/m, in order to enhance the binding adhesion between printing ink or vacuum aluminum plating layer and PET protective film surface, often also need to PET protective film surface treatment. Plastic film surface treatment methods are: corona treatment, chemical treatment, mechanical hair method, coating method, flame method, etc., the most commonly used is corona treatment.
Corona treatment method: by applying high frequency and high voltage power supply between metal electrode and corona treatment roller, make it discharge, ionize the air and form a lot of ozone. At the same time, high energy electric spark impact film surface. Under their combined effect, the appearance of plastic film activation, appearance can be added. The surface wet tension of PET protective film can reach more than 56 mN/m by corona treatment. The size of the wet tension on the surface of the corona treatment plastic film is related to the voltage bump applied to the electrode and the distance between the electrode and corona treatment roller. Corona treatment roller is usually high temperature resistant, ozone resistant, high insulation silicone rubber roller.
Defective Products
(1) when printing ink, there is an anti-stick scene.
(2) when the aluminum plating occurs, the aluminum plating layer is handled, and the coating layer is handled when the glue is coated. These are the last things we want to happen. The main way to avoid the film and corona is to adjust the pressure of the rubber pressing roller in front of the corona treatment roller. The pressure at both ends of the pressing roller should be common and the pressure size should be appropriate. In addition, corona roller and compression roll it is necessary to carry out.
PET protective film in high temperature and high humidity summer, corona treatment after the surface of the wet tension attenuation speed. Therefore, the plastic film should be printed or aluminized in time after corona treatment. If the PET protective film is placed for too long after corona treatment, the surface wet tension will gradually decrease, and even because the printing surface and non-printing surface wet tension tends to be the same, the printing film surface is easy to attack ink is anti-stick to the non-printing surface, the so-called "anti-stick" scene.