Aluminum is a metal second only to steel production, but the history of aluminum as a packaging material has only been more than 30 years. In recent years, aluminum has been used more and more in packaging because of its excellent performance. Its density is small, only 1/3 of steel, lighter weight; excellent processing, easy to stamp into a variety of complex shapes; strong corrosion resistance, no rust; barrier properties, shading, and fragrance protection Excellent, can effectively protect the product; high thermal conductivity, easy to sterilize aluminum cans; silvery white, beautiful color, and high reflectivity to light, easy to print, good printing effect; non-toxic and tasteless, will not be due to aluminum Ion escaping creates an odor in the interior of the food; scrap aluminum containers can be re-melted without environmental pollution. Its main disadvantages are: softer material, lower strength, easily deformed by collision, poor welding performance, joints can not be welded, poor corrosion resistance to acid and alkali, unsuitable for holding fruit foods, and high cost.
Aluminum packaging materials are mainly pure aluminum, aluminum alloy and aluminum foil.
(1) pure aluminum plate and alloy aluminum plate
Pure aluminum plate containing more than 99.9% aluminum, the thickness is generally between 0.25 ~ 0.3mm. It is soft and has low strength, so it is less used as a packaging material, but it is also useful as a wine container.
Alloy aluminum plate is made by adding a small amount of alloy composed of magnesium, manganese and copper to aluminum. Aluminum alloys commonly used in packaging are aluminum-magnesium alloys and aluminum-manganese alloys, also known as rust-proof aluminum alloys. The strength and hardness of the aluminum alloy plate are obviously improved, the corrosion resistance is strong, the polishing property is good, and the appearance is kept bright for a long time.
Aluminum alloy plates are mostly used for making canned containers. When used in fish and meat cans, they do not produce the phenomenon of blackening and vulcanization like tin plating cans; more are packaged beverages, and do not cause the phenomenon of hair blisters and flavor changes in beverages.
(2) Aluminum foil
Aluminum foil is made of pure aluminum with a purity of 99.5% or more and is rolled to a thickness of 0.005~0.2mm. It is light and lustrous, with strong reflection ability, and can be used as heat-proof insulation packaging; good barrier property, gas-impermeable body and water vapor; easy to process, easy to process into various shapes; easy to print, gluing, painting, coloring, Embossing, printing, etc.; adaptable to temperature, stable in shape at high or low temperatures; excellent shading, excellent fragrance protection, etc. The major disadvantage of aluminum foil is that it is not resistant to acids and alkalis, it cannot be welded, and it has low tear strength.
Aluminum foil is widely used in packaging, it can be individually packaged items; more is made of composite materials with paper, plastic film, etc., used for packaging of food, cigarettes, cosmetics, pharmaceuticals, chemicals, etc., can be made into cooking bags , packaging convenience foods and cooking foods.