1 Aluminum foil has silvery white luster, thin and light performance

Aluminum foil has a shining silver-white beautiful luster, non-toxic, tasteless, and harmless to the human body. After coloring, embossing and printing, it can get any colorful patterns and patterns without losing its beautiful luster. At present, the minimum thickness of rolled foil can reach 4pm, and the aluminum box is light, such as aluminum foil with a thickness of 6um, which weighs only 16g per square meter.

2 Moisture-proof performance of aluminum foil

Compared with other packaging materials, aluminum foil has low moisture permeability, good moisture-proof performance, and has the advantages of safety, convenience and long shelf life, although pinholes and As the thickness of aluminum foil decreases, its moisture-proof performance still has advantages over plastic films without pinholes and other packaging materials, because the polymer chains of plastic have a large distance from each other and cannot prevent water vapor from penetrating. If the surface of the aluminum foil is coated with resin or compounded with paper or plastic film, its moisture-proof performance is better. See Table 2-1 for the moisture permeability of aluminum boxes and plastic films with different thicknesses.

Table 2-1 Moisture permeability of aluminum foil and plastic film

The thickness of aluminum foil is so small that pinholes inevitably appear to a certain extent, and the minimum thickness of pinholes is generally considered to be 0.038mm. 025mm。 Due to the improvement of rolling technology and material, this thickness has been reduced to 0. 025mm. It has also been proved by experiments that the diameter of the vent hole is critical. When the diameter is less than 5um, no oxygen and water vapor can be transmitted in the measurable range.