Electro-aluminum hot stamping process principle and process conditions

Electro-aluminum hot stamping is the use of special foils to transfer text and graphics to the surface of plastic products at a certain temperature. The advantage of this method is that the method does not need to process the surface, and a simple device can be used for color printing. In addition, products with metallic luster such as gold and silver can also be printed. This article will introduce some of the materials used in hot stamping, processes, and problems that are easily encountered in the hot stamping process.
Aluminium hot stamping material

The main material for hot stamping of aluminum foil is anodized aluminum, also called hot stamping aluminum. It consists of a polyester film substrate and a transfer layer.

Types of hot stamping foil: Can be divided into roll foil and leaf foil. Can also be divided according to the type of substrate: the more commonly used 1 #; 8 #; 12 #; 15 #; 18 # universal sign. In accordance with the color points, more commonly used are: gold and silver foil, brown and red foil, light blue foil, black, red, green and so on.
1# Anodized aluminum: Suitable for hot stamping on the surface of paper, leather, linoleum, silk and organic glass or plastic surface with light color ink and soft texture.

8 # Anodized aluminum: suitable for hot stamping on paper, varnished cloth, leather.
12 # Anodized aluminum: suitable for hot stamping plexiglass, hard plastic and some glossy paper surface.
15 # Anodized aluminum: can escape on the surface of plastic film and soft plastic products. BR> 18# Anodized aluminum: Anodized aluminum is suitable for hot stamping paper products and leather with dark ink and thick lines at the background.

Hot stamping process quality and influencing factors

Electro-aluminum hot stamping actually uses the principle of hot-press transfer. Under certain temperature and pressure, the hot-melt silicone resin shedding layer and adhesive are heated to melt. After the silicone resin is melted, the adhesive force is reduced. The aluminum layer is peeled from the base film, and the heat-sensitive adhesive adheres the aluminum layer to the hot stamping material. The aluminum layer with the color material is present on the surface of the stamping material.

The hot stamping step has the following steps: (1) The hot stamping foil is in contact with the substrate. (2) Apply heat and pressure. (3) Remove the pressure and remove the polyester film. (4) Feed the hot stamp foil and replace the stamped stamp.

Quality: Comprehensive factors such as stamping compatibility, speed, temperature, pressure and the quality of the printing plate, the quality of the plate, plate loading and hot plate technology, the degree of tension of the aluminum foil and the condition of the stamping machine. Impact, the quality of hot stamping will also be different. Perfect stamping depends on temperature, pressure, and time.

Hot Stamping Temperature: When the stamping temperature is too high, it will cause the hot stamping to lose the metallic luster, blistering, unclear edges, stencil and other faults. When the stamping temperature is too low, hot stamping, writing hairiness, or even hot stamping may occur.

Temperature applicable standard: 1# 80°C - 90°C; 8# 75°C- 90°C; 12# 75°C- 90°C; 15# 60°C- 70°C; Pure Gold 80°C-130°C; Color foil, gold and silver foil 70°C-120°C.

Pressure: Over pressure causes thickening of the paste or print. When the pressure is too low, the hot foil and the substrate cannot adhere, and the hot stamping area cannot be cut.

Hot stamping speed: It actually reflects the contact time between the stamping material and the substrate, directly affecting the fastness of the stamping.

Fast: Hot stamping or blotting will occur.
Slow: It will not only affect the quality of hot stamping but also affect the production speed.

The suitable hot stamping speed for 8# and 12# aluminum foils is 18-30 sheets/minute; the suitable hot stamping speed for 15# is 18-22 sheets/minute; the suitable speed for 1# anodized aluminum is 40 sheets/minute.

Under normal circumstances, the speed is generally not changed when hot stamping is performed. That is, the speed is a constant, and when the conditions change, the conditions are usually adapted by changing the temperature and pressure.

Several hot stamping solutions

Hot stamping of copperplate paper products:

1. For the waxy field version, use five layers of gauze wrapped in rosin to wipe in the hot stamping area, the number of use; light ink plus 390 adhesive and 390 white dry mime once.

2. In the hot stamping process, pullback sometimes occurs. The reasons may be the following two points:

a) The underlying ink layer of the print is not dry enough.

b) Too much white ink is used on light-colored inks. Since the pigment particles of white ink are relatively coarse, the binding force between the connecting materials is relatively poor. On the other hand, it may also be due to the chalking of the printed surface (due to the excessive penetration of the binder on the surface of the substrate, the pigment particles are deposited on the surface of the ink film). Use a bright lighter and dry oil again. It is also possible to use electro-aluminum hot stamping with a small separation force.

Gold card paper stamping:

Characteristic is that the surface coating is equivalent to a layer of metallic color pre-printed, smooth surface, poor permeability, ink is not easy to adhere, the best use of special ink for printing synthetic paper, ink volume should be small, as thin as possible, and can not spray too much More, the print can only be hot stamped after it is completely dry. Another way to solve the hot stamping is to print a thin layer of background color before hot stamping.

Hot Stamping Sticky Material

Hot Stamping Adhesion Promoting Material is an adhesion promoting material that is used when hot stamping material does not have adhesive ability or adhesive ability, and hot stamping does not adhere to the imprint. The use of adhesion-promoting materials allows the hot stamping material to bond firmly to the adherends in the absence of sufficient bonding power to form a good hot stamping effect. There are two main types of hot stamping adhesion aids:

1. Adhesive powder (adhesive powder refers to powdered adhesion aid)

There are mainly three kinds of rosin powder, protein powder and bronzing powder. The application of these three kinds of small and uniform materials on the surface of the stamped material can effectively assist hot stamping. The disadvantage is that it cannot be attached on an overly smooth surface.

2. Adhesive liquid (adhesive liquid refers to liquid adhesion aid)

There are two kinds of shellac and protein liquid.

In actual work, when foils (such as red gold foil, etc.) and color chips are used for hot stamping, adhesion aids must be used, because such stamping materials do not have any bonding ability, or have poor bonding ability. In the case of hot stamping of anodized aluminum or colored foils, when hot stamping is not possible, the adhesion aids can also be used under normal conditions, so that the purpose of hot stamping can be achieved.