Table of Contents
Metal packaging material refers to a material used for packaging goods by rolling metal into thin sheets. Compared with other packaging materials, metal packaging materials have high strength, stiffness, toughness, dense organizational structure, and good processability.
In addition, metal packaging materials are easy to print, have excellent decoration performance, and are also an excellent recyclable material with good environmental performance.
Therefore, metal materials are still widely used in modern commodity packaging.
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Performance characteristics of metal packaging materials
Has excellent barrier performance
Metal packaging materials have excellent barrier properties, including gas resistance, moisture resistance, light resistance, aroma retention, etc., which can maintain the quality and flavor of food for a long time. Therefore, the application in food packaging can provide food with a longer shelf life and better maintain its original flavor.
Excellent mechanical properties
Metal packaging materials have high compressive strength and are not easily damaged even when the walls are thin. They also exhibit high temperature and humidity resistance, insect resistance, and corrosion resistance.
These characteristics make it easy to transport, store, and load and unload goods packaged in metal containers, greatly increasing the sales radius of the goods.
Excellent processing performance
Metal materials have good ductility, good processing performance, and mature processing technology. They can be rolled into various thicknesses of plates, sheets, and foils.
Plates can also be processed into various shapes of packaging containers through stamping, rolling, stretching, welding, and other methods.
Foils can also be composite with packaging materials such as plastic and paper, and are suitable for mechanized continuous automatic production.
Good surface decoration
Due to the good glossiness of metal materials themselves and their ease of printing and decoration, they can provide an ideal and beautiful packaging image through surface design, printing, and decoration. At the same time, they have a strong texture, which can attract consumers and promote sales.
Metal packaging containers are usually reusable after use due to their durability, such as being used as containers for storage.
Metal packaging containers discarded by consumers can generally be recycled and reused, which not only saves resources but also reduces environmental pollution, making them green and environmentally friendly packaging materials.
Rich raw material resources
Iron and aluminum, as the main metal packaging materials, are extremely abundant in nature and have been industrialized and produced on a large scale.
Poor chemical stability
It is manifested as being prone to corrosion in the natural environment, with weak acid and alkali resistance, and less corrosion resistance than glass and plastic.
Therefore, metal packaging materials usually need to be covered with a layer of protective substances on the surface to prevent corrosion and damage from the outside world and the packaging material.
At the same time, it is also necessary to prevent the migration of harmful substances in the metal from polluting the product.
Relatively high cost
Compared to paper, glass, and composite packaging materials, metal packaging containers are more expensive, so they are usually not used for packaging low-priced goods.
Classification of metal packaging materials
There are many types of metal materials, but there are not many types of metal materials used for packaging, mainly including steel, aluminum, copper, tin, zinc, etc. The most commonly used materials are steel, aluminum, and their alloys.
The main forms of metal materials used for packaging include metal plates, strips, wire, foil, etc. Plate and foil can be distinguished by thickness, generally referring to those with a thickness less than 0.2mm as foil; Plates larger than 0.2mm are called plates. Metal plates and strips are mostly thin sheet materials with a thickness of 0.2-1mm.
Metal sheets are mainly used for manufacturing packaging containers such as cans, boxes, cans, and barrels; Metal thin tape is mainly used for packaging and sealing; Metal wire is used for bundling or making packaging nails; Metal foil has specific properties such as high density of metal tissue, mainly aluminum foil. Foil is mainly used to make composite packaging materials with special properties with materials such as paper and plastic.
Steel and aluminum can be further divided into the following categories based on coating and thickness.
The steel used for packaging is mainly low-carbon thin steel plate, which has good plasticity and ductility, good can making process, and excellent comprehensive protective performance. However, the punching and drawing performance is not as good as aluminum.
The biggest disadvantage of steel packaging materials is poor corrosion resistance and easy rusting, and they must be used through surface coating and coating methods. According to the composition and purpose of the surface coating, there are mainly several types of steel packaging materials:
Low carbon thin steel plate. It refers to a thin steel plate with a thickness of no more than 3mm and a carbon content of less than 0.25%, which can be directly made into metal containers. After surface coating treatment, it can be used to make food and beverage cans.
Tinned steel sheet. It is a low-carbon thin steel plate coated with pure tin on both sides, which can be divided into hot-dip tinplate and electroplated tinplate according to different tin plating processes.
Galvanized steel sheet. It is a zinc protective layer with a thickness of 002mm or more coated on low-carbon steel plates. The dense zinc layer greatly enhances the corrosion resistance of the board.
Chromium plated steel sheet. It is a low-carbon thin steel plate coated with chromium and chromium oxide on both sides.
Steel for transportation packaging. Mainly used for manufacturing large containers for transportation packaging, such as containers, steel cans, steel drums, and bundling materials.
The main characteristics of aluminum materials are light weight, non-toxic, odorless, good plasticity, good ductility, excellent drawing performance, stable chemical properties in the atmosphere and water vapor, non rusting, and clean and glossy surface.
However, it is not resistant to corrosion in acid, alkali, or salt media, so the surface also requires coatings or coatings to be used as food containers. Aluminum materials for packaging are mainly used in the following forms.
Aluminum plate. It is a pure aluminum or aluminum alloy sheet, which is one of the materials for making cans and can partially replace tinplate.
Aluminum foil. Electrolytic aluminum plates with a purity of over 99.5% are used, which are made by rolling and have a thickness of less than 0.2mm.
Aluminum coated film. The vacuum deposition method is used to coat the plastic film or paper surface with an extremely thin aluminum layer with a thickness of about 30mm. Because it is coated with an extremely thin aluminum layer on plastic film and paper, its insulation performance is worse than that of aluminum foil, but its puncture resistance is excellent.
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