Vacuum vapor deposition of metal film is a new process to form composite film by vapor deposition of metal on the surface of film substrate under vacuum conditions.
The metal material can be gold, silver, copper, zinc, chromium, aluminum, etc. Among them, aluminum is the most used. Plastic film or paper surface (single side or double side)
Coating a thin layer of metallic aluminum becomes an aluminized film, which is widely used to replace aluminum foil/plastic, aluminum foil/paper and other aluminum foil composite materials.
Compared with aluminum foil composite materials, aluminized film has the following characteristics:
(1) greatly reduces the amount of aluminum, saves energy and materials, and reduces the cost. The thickness of composite aluminum foil is mostly.
7 ~ gpm, and aluminized film
The thickness of the aluminum layer is about.
About 0.05 n, the amount of aluminum used is about aluminum foil.
1140 ~1180, and the production speed can be as high as.
450 meters/minute.
(2) It has excellent folding resistance and good toughness, few pinholes and cracks, and no warping and cracking, so it is harmful to gas, water vapor,
An obstacle to smell, light, etc. It's improved.
(3) It has excellent metallic luster and the light reflectivity can reach.
97%; Color film can be formed by paint treatment, and the decorative effect is aluminum foil.
Out of reach.
(4) Local aluminum plating can be carried out through shielding to obtain any pattern or transparent window with visible contents.
(5) The aluminized layer has good conductivity, which can eliminate the electrostatic effect; Its sealing performance is good, especially when packing powdery products, it will not pollute the sealing parts.
Point to ensure the sealing performance of the package.
(6) Good adaptability to post-processing such as printing and compounding.
Due to the above characteristics, aluminized film has become a new composite film with excellent performance, economy and beauty, which has replaced aluminum foil in many aspects.
Composite materials are mainly used for vacuum packaging of flavor foods and agricultural products, as well as packaging of medicines, cosmetics and cigarettes. In addition, there are a lot of aluminized films.
Used as bronzing material and trademark label material in printing.
Secondly, coating the substrate.
The substrate of aluminized film is mainly plastic film and paper.
The vacuum evaporation process has the following requirements for the substrate to be plated:
(1) has good heat resistance, and the substrate must be able to withstand the radiant heat of evaporation source and the latent heat of condensation of evaporation.
(2) less volatile substances are generated from the membrane substrate; For the substrate with high hygroscopicity, it should be treated before coating.
(3) The substrate should have certain strength and surface smoothness.
(4) Good adhesion to evaporation coating; about
Non-polar materials such as PP and PE should be surface treated before evaporation to improve the adhesion to the coating.
Connectivity
Commonly used film substrates are: BOPET, BONY, BOPP, PE, PVC and other plastic films and paper. In a plastic film substrate,
BOPET，
The aluminized film formed by BONY and BOPP has excellent luster and adhesion, which is an excellent aluminized film and widely used as packaging materials.
Materials and hot stamping materials in printing. Aluminum plating.
PE film has poor gloss, but low cost and wide application. Aluminized paper formed from paper substrate
The cost is lower than that of aluminized plastic film; Thinner and cheaper than aluminum foil/paper composite; Its processability is good, and it is not easy to curl and leave no wrinkles when printing.
Mark and so on. Therefore, it has largely replaced the aluminum foil/paper composite as the inner packaging material and packaging trademark material of cigarettes and foods.
1. Vacuum evaporation principle. Put the coated substrate (cylindrical) into a vacuum evaporation machine, and vacuumize with a vacuum pump to make the vacuum degree in the coating reach.
reach
1.3x10-2 ~1.3x10-3pa, heating the crucible to make high-purity aluminum wire enter.
Melted and evaporated into gaseous aluminum gas at1200℃ ~1400℃.
Aluminum particles are deposited on the surface of moving film substrate, and a continuous and bright aluminum layer is formed after cooling and reduction. Schematic diagram of metal vacuum evaporation
See figure
14-9.
Figure 14-9 Schematic diagram of metal vacuum evaporation.
1- pump 2- unwinding 3- cooling roller 4- heat shield 5- material source 6- winding
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, aluminum plating
The thickness of the aluminum layer is inches.
25-500 nm, and the width of the aluminized film is
800mm~2000mm。
2. Evaporation method. There are two methods to evaporate aluminum on the substrate surface: direct evaporation and transfer.
(1) direct evaporation method. The substrate is directly evaporated on the surface of the substrate by a vacuum coater to form an aluminum-plated film. direct expansion
Electroplating requires high substrate, especially to form a bright metal film, which requires a good surface finish.
If the paper surface is rough, direct evaporation method should be adopted to coat the surface before aluminizing. Furthermore, during evaporation, the substrate
There are fewer volatiles, so the direct evaporation method has great restrictions on the substrate. Mainly suitable for evaporation of plastic film and paper.
Evaporation plating, but the quality of paper is high, which limits the number of paper.
(2) Transfer method. It transfers the aluminum layer to the surface of the substrate through the carrier film (vacuum aluminized film) to form an aluminized film. The transfer method is direct.
The new process developed on the basis of evaporation method overcomes the limitations of direct evaporation method on substrate requirements, and is especially suitable for all kinds of paper and paperboard.
Aluminum plating on the surface can also be used for aluminum plating on plastic films.
At present, the transfer method has been applied to aluminized products of cloth, fiber, leather and other substrates abroad, and the transfer method is mainly used to produce aluminized paper in China.
Third, aluminum evaporation process
Aluminum plating process of 1. plastic film. The aluminizing process of plastic film is relatively simple. BOPET, bone and film substrates do not need surface treatment before aluminizing.
Principle, can be directly evaporated. And use
When nonpolar plastic films such as BOPP and PE are used, the surface of the film needs corona treatment before evaporation to make its surface
Tension reaching
38x 10-5n ~ 40x 10-5n。 When coating, put the film roll into the vacuum chamber, close the vacuum chamber and vacuum. When the vacuum degree reaches
At a certain time, the evaporation source is heated to
1400℃ ~ 1500℃, the purity is
99.9% aluminum wire is continuously sent to the high temperature area of evaporation source.
Save the unwinding speed, winding speed, wire feeding speed and evaporation, and turn on the cooling source to make the aluminum wire melt and evaporate continuously in the high temperature area, thus moving.
A bright aluminum layer is formed on the surface of the film, and the finished product is obtained after cooling. Aluminum-plated film can be used for printing and compounding after cutting according to specifications.
Bags and so on.
2. Paper evaporation aluminizing process. Paper aluminizing process includes direct aluminizing method and transfer method.
(1) direct aluminum plating method. Direct aluminizing method is to coat a layer of adhesive or composite layer on the surface of compacted coil substrate.
PE film, so real
Directly aluminizing with an air coater to form a metallic aluminum film on the paper surface, and then humidifying the aluminized paper to obtain the product. If necessary, you can get it.
Various colors of aluminized paper need to be colored on the surface of aluminized paper.
The direct aluminizing method has the following characteristics:
① The production process is simple and the cost is low.
② The surface quality and strength of paper substrate are required. When aluminizing, the moisture content of the paper is required to be.
When it is less than 3%, the moisture content of general paper is
6~
7%, the reduction of moisture content will make the paper brittle and easy to break. Therefore, paper is required to have high strength.
③ The product surface gloss is low and the printing filling effect is poor.
Direct aluminizing is generally only suitable for dry weight.
Thin paper and thick paper below 30g/m2 are difficult to be aluminized. Aluminizing produced by direct aluminizing method
Although the quality of paper is poor, it is widely used because of its low cost.
(2) transfer method; The technology of producing aluminized paper by transfer method is more advanced than that by direct aluminizing method. It transfers the aluminum layer on the surface of aluminized plastic film to the surface of paper base.
Aluminized paper is formed on the surface. Firstly, the coating is evenly coated on the plastic film substrate, which is the usual method.
BOPET film and
BOPP movies; Then thin the plastic.
Aluminize that film substrate in a vacuum coating cham to form a metallic aluminum film layer on the surface of the coating; Then a layer of adhesive is coated on the surface of the aluminum layer of the aluminized plastic film.
Agent; Paper, cardboard or other substrates are compounded with it as required, and then separated to separate the coating and aluminum layer from the plastic film.
The process flow is shown in the figure.
14- 10.
Figure 14- 10 transfer flow chart
The separated plastic film can be reused. The more times it is reused, the lower the cost of the product.
Production of aluminized paper by transfer method mainly has the following characteristics:
① The production process is complicated and the cost is high.
(2) wide adaptability to the base material, quantitative
30 ~ 600 g/m2 of paper or cardboard is enough, which has low requirements on the quality of the base material and does not need a surface.
Then apply paint or film.
③ Good product quality and bright surface; Because there is a coating outside the aluminized layer, it not only plays a protective role, but also improves the printing adaptability.
And the complete effect.
④ Color aluminized paper can be produced by adding pigment into the coating.
Because of the above characteristics, transfer aluminizing is widely used in the production of aluminized paper.