Process flow of aluminized film

The aluminum plating process of plastic film generally adopts direct plating method, that is, the aluminum layer is directly plated on the surface of the base film. BOPET and BOPA film substrates can be evaporated directly without surface treatment before aluminizing. However, nonpolar plastic films, such as BOPP, CPP, PE, etc. Before evaporation, corona treatment or adhesive coating is needed to make its surface tension reach 38-42 dynes/cm or have good adhesion. In the vapor deposition process, the rolled film is placed in a vacuum chamber, and the vacuum chamber is closed for vacuumizing. When the vacuum degree reaches a certain level (above 4× 10-4 MBA), the evaporation boat is heated to 1300℃ ~ 1400℃, and then the aluminum wire with purity of 99.9% is continuously fed into the evaporation boat. Adjust the unwinding speed, winding speed, wire feeding speed and evaporation rate, turn on the cooling source, make the aluminum wire melt and evaporate continuously on the evaporation boat, and form a bright aluminum layer on the surface of the moving film after cooling.

Vacuum evaporation principle

Put the coated film substrate (cylindrical) into a vacuum vapor deposition machine, vacuumize with a vacuum pump to make the vacuum degree in the coating reach1.3x10-2 ~1.3x10-3pa, and heat the crucible to13 pa. Gaseous aluminum particles are deposited on the surface of the moving film substrate and cooled and reduced to form a continuous and bright aluminum layer. The thickness of aluminum plating layer is controlled by controlling the evaporation speed of aluminum, the moving speed of thin film substrate and the vacuum degree of coating room. Generally, the thickness of aluminized layer is 25 ~ 500 nm, and the width of aluminized film is 800 ~ 2000 mm ..

Evaporation method: There are two methods to evaporate aluminum on the substrate surface: direct evaporation method and transfer method.

(1) direct evaporation method. Aluminized film is formed by evaporating aluminum directly on the surface of substrate by vacuum coater. Direct evaporation requires a higher substrate, especially to form a metal film with a bright surface, which requires a better surface finish. If the paper surface is rough, direct evaporation method should be adopted to coat the surface before aluminizing. In addition, there are less volatiles in the substrate during evaporation. Therefore, the direct evaporation method has great restrictions on the substrate. It is mainly suitable for the evaporation of plastic film and paper, but it requires high quality of paper and has certain restrictions on the number of paper.

(2) Transfer method. The aluminized film is formed by transferring the aluminum layer to the surface of the substrate with the help of a carrier film (vacuum aluminized film). Transfer method is a new technology developed on the basis of direct evaporation method, which overcomes the limitations of direct evaporation method on substrate requirements, and is especially suitable for aluminizing all kinds of paper and cardboard, and can also be used for aluminizing plastic films. Transfer method has been applied to aluminizing products of cloth, fiber, leather and other substrates abroad. In China, aluminized paper is mainly produced by transfer method.

Production technology of aluminized film;

Unwinding substrate → vacuumizing → heating evaporation boat → feeding aluminum wire → evaporation → cooling → thickness measurement → flattening → winding.