Principle of polyester film online coating technology
1. The function of online coating
By using different coating liquid, such as polyester, polyurethane, acrylic, silicon solution, etc., online coating can enhance the specific surface properties of the film, such as enhancing the printing performance of the film, enhancing the aluminum layer stripping force of the film after aluminum plating, providing the potting resistance of the film after aluminum plating, and improving the surface smoothness of the film. When using each coating solution, the production process should be adjusted accordingly to meet the technical requirements such as curing time and temperature of the coating solution, and ensure the stability of production.
2. Prepare the main components of the coating solution
The coating liquid prepared for online coating is generally water-based, and the basic components are water, leveling agent (to make the coating liquid evenly dispersed), functional coating liquid (to provide the main function of the coating liquid), curing agent (also known as crosslinking agent, through the drying process and the cross-linking reaction with the resin, so that the resin and the surface of the film firmly combined) and catalyst.
3. Online coating and other surface treatment methods compared
Compared with the off-line coating method, there is no need for off-line rewinding, and the horizontal drawing section is used as the oven to dry the coating liquid between the longitudinal drawing and the transverse drawing, which has high production efficiency. And because of uniform coating, the coating is thinner than off-line coating, and the coating effect is better, which can significantly reduce the coating cost. The surface tension of the film treated by corona will gradually decay with the passage of time, and there is no corona attenuation problem on the surface of the film treated by coating.
4. Online coating process
The production process of online coating mainly consists of coating liquid preparation, coating liquid supply, film corona treatment, concave roll coating, drying system and so on.
The coating solution needs to be stirred in the supply tank for a period of time to make a coating solution that can be used for online coating. The finished coating liquid is driven into the intermediate tank through the liquid supply pump. After the polyester film is lengthwise stretched by the longitudinal drawing equipment, the corona equipment is required to the surface of the film
