In order to improve the surface properties of the PET film, in order to improve the adaptability of printing and the binding force of the vacuum aluminum plating layer, a corona treatment method is generally used to increase the surface tension of the film. However, the corona method has problems such as timeliness, and especially in a high-temperature and high-humidity environment, the film tension after corona treatment is easily attenuated. However, the chemical coating method does not have such a problem, so it is favored by the printing industry and the aluminum plating industry. Some domestic companies have developed PET chemical coating products: if coated with water-soluble polymers, the surface tension of PET films can be increased; coating with acrylic emulsions can improve the adaptability of printing (water-soluble inks can be used) ; Coating with polyurethane aqueous solution can strengthen the binding force of the aluminum plating layer and the PET base film, and increase the thickness of the aluminum plating layer. In addition, the coating method can also be used to produce high-resistance films and antistatic films.