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Lamination and printed films are usually made of multiple layers of polymer films of different materials through coextrusion, coating or lamination. These materials may include polyethylene (PE), polypropylene (PP), polyester (PET), nylon (PA), etc. Each material has its own unique performance characteristics, such as barrier properties, mechanical strength, transparency, etc. The printed layer is used to provide product information, brand logo and aesthetic effects, and is usually formed by printing ink on the surface of the film.
In order to meet the high requirements of packaging materials in the food, pharmaceutical, daily chemical and other industries, composite and printed films need to have excellent barrier properties to prevent external factors such as oxygen, moisture, light and other factors from affecting the contents of the package. The mechanical strength and tear resistance of the film material and the adhesion and color vividness of the printing ink are also important performance indicators.
The scientific principle of plasma treatment and corona treatment
Plasma treatment: Plasma is a highly ionized gas that contains a large number of active particles such as electrons, ions, and free radicals. When these active particles come into contact with the surface of the film material, they will react physically and chemically with it, thereby changing the chemical structure and polarity of the surface. Plasma treatment can remove surface pollutants, increase surface roughness, form chemical bonds, and significantly improve the bonding force of the film surface. In addition, plasma treatment can also introduce polar groups such as hydroxyl and carboxyl groups on the surface of the film material, further enhancing the polarity of the surface.
Corona treatment: Corona treatment uses a high-frequency and high-voltage electric field to produce a discharge phenomenon on the surface of the film material to form a corona discharge zone. During the discharge process, molecules such as oxygen and nitrogen in the air are ionized into free radicals and ions. These active particles react with the surface of the film material to form polar groups and increase the polarity of the surface. Corona treatment can also remove surface grease, dust and other pollutants, further improving bonding conditions. Compared with plasma treatment, corona treatment equipment is simple, easy to operate, and relatively low in cost, so it is more widely used in industrial production.
Effects of plasma and corona treatment on the performance of lamination and printed films
Improve surface polarity and adhesion: The surface polarity and adhesion of composite and printed films treated with plasma or corona are significantly improved. This allows the layers to fit more closely together, reduces the penetration channels, and improves the barrier properties. The enhanced adhesion also helps to improve the mechanical strength and tear resistance of the film, making it more durable.
Optimize barrier properties: Barrier properties are one of the key indicators of composite and printed films. Plasma and corona treatments reduce the penetration channels by increasing the surface polarity and adhesion, thereby effectively improving the film's barrier ability to external factors such as oxygen, moisture, and light. This is of great significance for protecting the contents of the package from damage such as oxidation and deterioration.
Enhance the adhesion and color vividness of printing inks: The printing layer is an important component of the composite and printed film, and its adhesion and color vividness directly affect the aesthetics and commodity value of the packaging. Plasma and corona treatments can improve the wettability and polarity of the film surface, allowing the printing ink to better adhere to the film surface. The chemical bonds formed during the treatment process also help to improve the bonding between the ink and the film material. Therefore, the treated composite and printed films have a more solid and beautiful printed layer.
Improve mechanical strength and tear resistance: Plasma and corona treatments enhance the bonding force on the surface of the film material, making the layers more tightly bonded together. This close fit not only improves the barrier properties, but also helps to improve the mechanical strength and tear resistance of the film material. This makes the composite and printed film more durable during transportation, storage, etc., and reduces the risk of breakage and leakage.
With the continuous improvement of the performance requirements of packaging materials in the food, pharmaceutical, daily chemical and other industries, the performance optimization of lamination and printed films has become the focus of industry attention. As one of the important means to improve the performance of film materials, plasma and corona treatment have broad application prospects. In the future, with the continuous innovation and improvement of technology, these two treatment technologies will be more efficiently and environmentally friendly applied to the production of composite and printed films, providing strong support for the sustainable development of the packaging industry.
