PET film is a kind of thermoplastic film with high transparency, good gloss and good air tightness, which is widely used in packaging, optics, building materials, medicine and other industries.

PET film is a kind of film with strong polarity. The surface tension of PET film without any treatment can reach more than 40 dynes. However, some inks are directly covered, and the adhesion is not ideal. A special treatment on PET film is required to achieve better adhesion.

Adhesion is the basis of most properties of coatings, such as scratch resistance, water resistance, abrasion resistance and chemical resistance. At present, there is no clear scientific explanation for the fundamental mechanism of adhesion. It is generally believed that the substrate with high surface tension can form good adhesion. However, this theory is applied to PET film. Among the commonly used plastic film substrates, PET film is the third most difficult substrate to adhere after PE and PP.

Corona treatment is a physical treatment method to form fine cracks and effective functional groups on the film surface by high-voltage discharge. This treatment method is more effective on PET film and is the most commonly used treatment method. After corona treatment, not only the surface tension of PET film is greatly improved for wetting, but also the surface roughness is greatly improved. For scenes with general requirements on adhesion, corona treatment is already very good. However, if customers have particularly high requirements for adhesion, corona treatment can not meet the requirements of high quality.

UV hardening coating solution is a kind of hardening coating cured by ultraviolet lamp. After coating a layer of UV hardening coating solution on PET film and curing by ultraviolet lamp, a layer of high hardness, transparent and scratch resistant coating will be formed on PET film. The hardness of PET film after UV hardening treatment will be greatly improved, thus extending its application scenario.