Overview and process of the hottest vacuum alumini

Overview and process of vacuum aluminum plating film 1. Overview

vacuum evaporation of metal film is a process that must be managed according to standard materials. Under high vacuum (above 10-4mba), the metal is melted and gasified by resistance, high frequency or electron beam heating, and attached to the surface of the film substrate to form a composite film. The metallized materials can be gold, silver, copper, zinc, chromium, aluminum, etc., of which aluminum is the most used. Aluminized film or paper is formed by coating a very thin layer of metal aluminum on the surface of plastic film or paper

the vacuum aluminum plating film used on packaging has the following characteristics:

(1) compared with aluminum foil, it greatly reduces the amount of aluminum, saves energy and materials, and reduces the cost. The thickness of composite aluminum foil is mostly 7 ~ 9um, while the thickness of aluminum layer of aluminum plated film is about 400 (0.04um). Its aluminum consumption is about 1/200 of that of aluminum foil, and the production speed can be as high as 700m/min

(2) it has excellent folding resistance and good toughness, with few pinholes and cracks, no kneading and multi curve control bending and cracking, and improved barrier to gas, water vapor, odor, light, etc

(3) it has excellent metallic luster, and the light reflectivity can reach 97%; And it can form a color film through coating treatment, and its decoration effect is inferior to that of aluminum foil

(4) partial aluminum plating can be carried out by shielding or elution to obtain any pattern or transparent window, and the contents of the package can be seen

(5) the aluminized layer has good conductivity and can eliminate electrostatic effect. Especially when packaging powdered products, it will not pollute the sealing part, ensuring the sealing performance of the packaging

(6) it has good adaptability to post-processing such as printing and compounding

due to the above characteristics, aluminized film has become a new type of composite film with excellent performance, economy and beauty, which has replaced aluminum foil composite material in many aspects. It is mainly used for packaging flavor food, daily necessities, agricultural products, drugs, cosmetics and cigarettes

Huangshan Yongxin Co., Ltd. has produced vacuum aluminized film for more than 10 years. Its main products include VMPET, VMCPP, vmbopp, vmbopa, vmpe, vmpvc, rainbow film, laser anti-counterfeiting film, cloth, etc. In 2002, the company carried out technical cooperation with Rexam company in the UK, and applied its camplus technology to the aluminum plating process, which greatly improved the fastness and barrier performance of the aluminum layer of vacuum aluminum plating film. Now it has been widely used in the packaging fields of milk powder and drugs instead of aluminum foil

II. Principle of vacuum evaporation

install the reel shaped 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 rewinding station, and vacuum it with a vacuum pump to make the vacuum degree in the evaporation room reach 4 × Above 10-4mba, heat the evaporation boat to melt and evaporate the high-purity aluminum wire into gaseous aluminum at the temperature of 1300 ℃ ~ 1400 ℃. Start the film winding system. When the film speed reaches a certain value, open the baffle to deposit and cool the gaseous aluminum particles on the surface of the moving film substrate, forming a continuous and bright metal aluminum layer. See Figure 1 for the schematic diagram of vacuum aluminizing. The thickness of aluminum coating is controlled by controlling the evaporation speed of metal aluminum, the moving speed of base film and the vacuum degree in the evaporation room. Generally, the thickness of aluminum coating is 250 ~ 500

III. coating substrate

due to the particularity of the vacuum evaporation process, it has the following requirements for the coated film substrate:

1. Good heat resistance, and the substrate must be able to withstand the radiant heat of the evaporation source and the condensation latent heat of the evaporation

2. Less volatile substances are produced from the film substrate; The substrate with high hygroscopicity shall be dried before evaporation

3. The base material should have a certain strength

4. Good adhesion to evaporated coating; For PP, PE and other non-polar materials, surface treatment should be carried out before evaporation to improve the adhesion fastness of the coating

commonly used aluminized substrates include: BOPET, BOPA, BOPP, CPP, improving the effective supply capacity and level of medium and high-end PE, PVC and other plastic films and paper. Among the plastic film substrates, the aluminized film produced by BOPET, BOPA and BOPP has excellent gloss and adhesion. It is an aluminized film with excellent performance, which is widely used as packaging materials and bronzing materials. The gloss of aluminized PE film is poor, but the cost is low and it is widely used. Aluminized paper formed from paper substrate is thinner and cheaper than aluminum foil/paper composite; Its processing performance is good, and it is not easy to curl and leave creases in printing. It is mainly used as inner packaging materials such as cigarettes and food, as well as trademark materials

changes in water vapor transmission rate of various substrates before and after aluminizing the market capacity of plastic extruders will be further expanded

normal> substrate

normal align=center> thickness

normal align=center> μ M

normal align=center> transmittance without aluminum plating

normal>g/(m2.24h) value= "40" hasspace= "false" negative= "false" numbertype= "1" tcsc= "0">40 ℃

normal align=center> transmittance after aluminum plating

normal align=center>g/(m2.24h) value= "40" hasspace= "false" negative= "false" numbertype= "1" tcsc= "0">40 ℃