Corona treatment is an electrical treatment that enhances the surface adhesion of the substrate.

The principle involves utilizing corona discharge through high-frequency high-voltage on the surface of the plastic being treated, which generates low-temperature plasma. This plasma causes free radical reactions on the plastic surface, leading to cross-linking of polymers. The surface becomes rougher and increases its wettability with polar solvents. These plasmas, resulting from electrical discharge and penetration, break down the molecular structure of the surface, further oxidizing and polarizing the treated surface molecules. The ionic discharge erodes the surface, thereby enhancing the adhesion capability of the printed material.

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After corona treatment, the cross-linking structure of the plastic surface layer is reduced compared to the inner layer, resulting in higher mobility of the surface functional groups. Therefore, during storage, many plastics exhibit a decline in the corona treatment effect, with additives migrating from the interior to the surface. This migration contributes to a decrease in surface energy, affecting adhesion, and this negative impact cannot be fully suppressed.

2. The purpose of corona treatment is to alter the surface energy of many substrates, making them more receptive to adhesion with printing inks, coating materials, and adhesives. After some processing during the manufacturing process, all substrates possess enhanced adhesion properties.

Curing is a post-processing technique, it should be noted that curing is not a method that can be used to alter the surface energy of the substrate during the production of printing materials. Other processing methods include flame treatment and coating techniques. The specific processing method to be used largely depends on the structure of the substrate.