The surface wetting tension of PET film

Surface Wetting Tension and Its Significance

Surface wetting tension refers to the ability of a liquid to spread across a solid surface, typically expressed in mN/m (milliNewtons per meter). PET films generally have a low surface wetting tension, implying that some liquids, especially water-based solutions, do not spread easily on its surface, resulting in the formation of small droplets.

To enhance the surface wetting properties of PET films, surface pre-treatment processes such as corona discharge, plasma treatment, and chemical treatment are commonly employed. These treatments increase the film’s surface polarity, subsequently improving its surface wetting tension and, therefore, its adhesive properties with materials like coatings, inks, and adhesives.

Specifics on Surface Treatment

Untreated PET films usually have a surface tension in the range of 40-50 mN/m. However, after surface pre-treatment, the surface tension can be increased to 50-70 mN/m or even higher. This is crucial for improving the print quality, adhesive performance, and coating properties of the PET film.

It is important to note that the measurement of surface wetting tension requires specialized equipment and may be influenced by various factors, including the cleanliness of the film’s surface and the testing conditions. Therefore, the selection and adjustment of the surface treatment method should be made based on the specific application requirements.

Reorganizing the Content

Polyethylene Terephthalate (PET) films, extensively applied in packaging, bottle-making, and numerous other domains, boast impressive mechanical strength, heat resistance, transparency, and chemical stability. However, their low surface wetting tension, usually ranging from 40-50 mN/m, poses challenges, especially with the spread of water-based solutions.

Surface treatments such as corona discharge, plasma treatment, and chemical treatment play a pivotal role in addressing this issue. These processes enhance the surface polarity of the PET films, elevating their surface wetting tension to a more favorable range of 50-70 mN/m or higher. This modification is crucial for ensuring a better adhesion with inks, coatings, and adhesives, consequently improving the print quality and overall performance of the PET films.

To learn about the surface treatment of PET films, you can read the article “Enhancing Adhesion: The Essential Guide to Surface Pre-treatment of PET Films“.