1, mechanical properties
The mechanical properties of aluminum foil mainly include tensile strength, elongation, crack resistance and the like. The mechanical properties of aluminum foil are mainly determined by the thickness. The national standard GB/T3198-2003 "aluminum and aluminum alloy foil" has made corresponding provisions on the longitudinal mechanical properties of aluminum foil in China.
In general, the aluminum foil is light in weight, good in ductility, thin in thickness, and small in mass per unit area. However, it is low in strength, easy to tear, and easily breaks when folded, and produces perforations, so it is generally not used for packaging products alone. In many cases, it is compounded with other plastic films and papers to overcome its shortcomings.
2, high barrier properties
Aluminum foil has high barrier to water, water vapor, fiber and fragrance, and is not affected by the environment and temperature. Therefore, it is often used for perfume packaging and moisture-proof packaging to prevent moisture absorption, oxidation and volatilization of package contents. It is especially suitable for high temperature retort sterilization packaging of food.
3, corrosion resistance
The surface of the aluminum foil naturally forms an oxide film, and the formation of the oxide film can further prevent the continuation of oxidation. Therefore, the aluminum foil has certain durability and air corrosion resistance. However, it is not resistant to acid and alkali corrosion. Therefore, when the package contents have high acidity or alkalinity, the surface of the package is often coated with a protective material or coated with PE or the like to improve the corrosion resistance.
4, heat resistance, low temperature resistance
The high temperature and low temperature state of the aluminum foil is stable, the temperature does not expand and contract when the temperature is -73-371 ° C, and has good thermal conductivity, and its thermal conductivity can reach 55%. Therefore, it can be used for high temperature cooking or other hot processing, and can also be used for frozen packaging.
5, shading performance
Aluminum foil has good light-shielding performance, its reflectivity can be as high as 95%, and its appearance is silver-white metallic luster. It can show good packaging and decoration effect through surface printing decoration, so aluminum foil is also a high-grade packaging material.