Views: 0 Author: Site Editor Publish Time: 2022-09-21 Origin: Site
During the non-metallic coating, the higher gasification temperature and evaporation energy of the evaporation raw materials lead to the higher temperature of the evaporation zone during the evaporation process, and a large amount of radiant heat causes the substrate to absorb excessive heat energy and raise the temperature; At the same time, the heat released when the gasification molecules, ions and other particles condense on the substrate surface causes the substrate temperature to be too high and serious thermal deformation occurs. After thermal deformation, the substrate wrinkles, resulting in uneven or broken coating, which can not improve the barrier performance. Therefore, the evaporation effect of plastic films with low softening point and melting point is poor. The experiments show that only PP, pet, PA and other materials are suitable for oxide coating.
Install the rolled film substrate to be plated on the unwinding station of the vacuum evaporation machine, roll the film through the cooling roll (evaporation roll) on the winding station, and use a vacuum pump to vacuum the film so that the vacuum in the evaporation chamber reaches 4 × Above 10-4mba, heat the evaporation boat to melt the high-purity aluminum wire at a temperature of 1300 ℃ ~ 1400 ℃ and evaporate it into gaseous aluminum. Start the film winding system. When the running speed of the film reaches a certain value, open the baffle to deposit and cool the gaseous aluminum particles on the surface of the moving film substrate to form a continuous and bright metal aluminum layer. See Fig. 1 for the schematic diagram of vacuum aluminum plating. The thickness of the aluminum plating layer is controlled by controlling the evaporation speed of the metal aluminum, the moving speed of the base film, and the vacuum degree in the evaporation chamber. Generally, the thickness of the aluminum plating layer is 250 to 500 Å.
The aluminum plating process of plastic film generally adopts the direct plating method, that is, the aluminum layer is directly plated on the surface of the substrate film. BOPET and BOPA film substrates can be directly vapor deposited without surface treatment before aluminum plating. For BOPP, CPP, PE and other non-polar plastic films, corona treatment or adhesive coating shall be applied to the surface of the film before evaporation to make its surface tension reach 38-42 dynes / cm or have good adhesion. During evaporation, place the roll film in the vacuum chamber and close the vacuum chamber to vacuum. When the vacuum reaches a certain value (4 × 10-4mba or more), the evaporation boat is heated to 1300 ℃ ~ 1400 ℃, and then the aluminum wire with purity of 99.9% is continuously sent to the evaporation boat. Adjust the unwinding speed, rewinding speed, wire feeding speed and evaporation capacity, turn on the cooling source, so that the aluminum wire can be continuously melted and evaporated on the evaporation boat, so that a bright aluminum layer is formed after the moving film surface is cooled, that is, the aluminum plating film.
Production process flow of aluminized film:
Base material unwinding → vacuuming → heating evaporation boat → feeding aluminum wire → evaporation → cooling → thickness measurement → flattening → rewinding