Double-sided corona treatment is a technology that applies a high-frequency and high-voltage electric field on both sides of the PET film to ionize the air and produce low-temperature plasma. The high-energy particles (such as electrons, ions, etc.) in these plasmas bombard the surface of the film, causing the surface molecular chains to break and recombine, thereby increasing the surface roughness and polarity. This treatment process not only changes the chemical composition of the film surface, but also has a significant impact on its physical form.
During the double-sided corona treatment process, the bombardment of high-energy particles causes a tiny concave-convex structure on the surface of the PET film, that is, the surface roughness is increased. This increase in roughness provides more attachment points for the deposition of aluminum atoms, allowing aluminum atoms to better embed into the concave-convex structure on the surface of the film during the deposition process, thereby enhancing the bonding between the aluminum coating and the PET film.
Double-sided corona treatment significantly improves the adhesion of the aluminum coating by increasing the surface roughness of the PET film. This improvement in adhesion is mainly reflected in the following aspects:
Physical intercalation: The rough surface provides more physical intercalation points for aluminum atoms, allowing aluminum atoms to be firmly embedded in the concave-convex structure of the film surface during the deposition process. This physical intercalation enhances the bonding force between the aluminum layer and the PET film, making the aluminum layer more difficult to fall off during use.
Forming of chemical bonds: Although the increase in surface roughness mainly provides physical intercalation, the rough surface is also more conducive to the formation of chemical bonds. During the double-sided corona treatment process, the number of polar groups on the film surface increases, and these polar groups can form strong chemical bonds with aluminum atoms, such as the coordination bond between the carbonyl group and the aluminum atom, and the hydrogen bond between the hydroxyl group and the aluminum atom. The formation of these chemical bonds further enhances the adhesion of the aluminum layer.
Reducing stress concentration: The rough surface can disperse the stress generated by the aluminum layer during the deposition process and reduce the phenomenon of stress concentration. This helps prevent the aluminum layer from falling off or cracking when subjected to external forces, thereby improving the service life and performance of the product.
In addition to improving the adhesion of the aluminized layer, the effect of double-sided corona treatment on increasing the surface roughness of PET film also has a positive impact on its printing adaptability. The rough surface is more conducive to the adhesion of printing ink and improves the bonding force between ink and film.
Enhanced ink permeability: The rough surface increases the contact area between ink and film, allowing the ink to more fully penetrate into the concave and convex structure of the film surface. This penetration enhances the bonding force between ink and film, making the printed pattern clearer and brighter.
Faster ink drying: Strong oxidants such as ozone generated during double-sided corona treatment can oxidize the surface of the film, making it more oleophilic. This increase in oleophilicity is conducive to the drying and curing of ink, thereby speeding up printing and improving production efficiency.
Improved durability of printed patterns: Due to the enhanced bonding force between ink and film, the printed pattern is more difficult to fall off or fade during use. This helps to improve the overall quality and aesthetics of the product and extend the service life of the product.
Double-sided corona treated aluminized PET film has significant application advantages in many fields such as packaging, printing and electronics. Its excellent barrier properties, metallic luster and bright appearance make the product unique in the market competitiveness. At the same time, no harmful substances are produced during the double-sided corona treatment process, which meets environmental protection requirements, making the product have significant advantages in green packaging and sustainable development.
