Application of Aluminum Materials in Packaging Industry

Aluminum is a resource-rich white light metal, and the world’s aluminum production is second only to steel. Its application in the packaging industry ranks first in non-ferrous metals. As a packaging material, aluminum generally uses aluminum plates, aluminum blocks and aluminum foils, and aluminized films. Aluminum plates are usually used as canning materials or lidding materials; aluminum blocks are used to make extruded and thinned deep-drawn molded cans; aluminum foils are generally used for moisture-proof inner packagings or composites and flexible packaging.

The packaging plates belong to rust-proof aluminum alloys. Manganese and magnesium mainly play roles of increasing the strength of materials and improving the processing performance; copper can also increase the strength of materials, and at the same time, it can reduce the crushing performance and processing performance; adding zinc, especially in When copper and magnesium are added in the same size, the heat treatment effect becomes better, but the corrosion resistance and processability are reduced. The addition of silicon mainly reduces the melting point of aluminum, increases the strength and melt fluidity, and decreases the coefficient of thermal expansion. Aluminum foil is 0.4-4 in thickness. 7mm (more 0.5mm) industrial pure aluminum sheet made of flexible metal thin material after many times of cold rolling thinning.

one. Aluminum material characteristics

Compared to other packaging materials, aluminum materials have the following advantages:

(1) The density of aluminum is very small, 2.7 g/cm, which is only 35% of steel. This makes it easy to reduce the weight of the container. The surface of aluminum naturally produces a dense layer of Al2O3. This colorless film can prevent further oxidation.

(2) Aluminum is non-toxic and odorless, and meets the hygienic standards for packaged foods.

(3) The aluminum surface has a high gloss, is easy to be colored, and has a good printing effect.

(4) Easy open cover made of aluminum material has better opening performance than tin plate.

(5) Aluminum has excellent light and heat reflection and conduction properties, which can improve the heat sterilization and low-temperature treatment of food cans.

(6) The mechanical properties of aluminum can be kept constant at low temperatures, especially for the packaging of frozen foods.

(7) The composite film made of aluminum foil is completely airtight and opaque, and can effectively protect the interior food. Aluminum foil can also improve the strength of aluminum-plastic composite film.

(8) The waste can be recycled and reused, which can not only save energy but also prevent pollution caused by waste and meet the requirements of environmental protection.

However, there are some deficiencies in aluminum materials, including:

(1) The production of aluminum is much more energy intensive than that of tinplate and TFS, so the price is expensive.

(2) Aluminum is a non-magnetic material, so the original equipment that uses magnetic materials to absorb must be modified.

(3) Aluminum materials have poor corrosion resistance and should not be used to hold acidic, alkaline, and salty foods.

(4) The aluminum material is soft and has a lower strength than tinplate. It is easy to deform and scratch on the surface during manufacture and transportation.

(5) Aluminum welding is difficult, so it can only be made by stamping or bonding.

Currently, some of the disadvantages of aluminum can be compensated by compounding with other materials. For example, the combination of aluminum foil and paper or plastic can increase its stiffness and tensile strength; to overcome the shortcoming of low rigidity of thin-wall aluminum cans, a small amount of liquid nitrogen can be filled before the closed container, and the internal pressure generated by liquid nitrogen vaporization can be increased. Container stiffness and compressive properties; aluminum foil coated with nitrocellulose and modified polyolefin not only improves the chemical properties of the aluminum foil, maintains a good print appearance, but also provides thermal fit.

two. Application of Aluminum Materials in Packaging

1 Aluminum anti-theft cap

Currently, most of China's packaging of liquor, wine, liquor, and beverages are still based on glass bottles. About 50% of bottle caps use aluminum-made anti-theft caps. China's anti-theft caps will grow at an annual rate of 10%. By 2010, the amount of anti-theft covers will reach 15 billion, and about 60,000 tons of aluminum strips will be needed. China's aluminum cap production plant nearly 200, the annual design capacity of about 9 billion, of which the introduction of 30 production lines, production capacity of more than 5 billion, can produce nearly a hundred kinds of various types of caps. Aluminum bottle caps are often processed on a production line with a relatively high degree of automation. Therefore, the strength, elongation, and dimensional deviation of the materials are required to be very strict. Otherwise, cracks or creases may occur during deep drawing. In order to ensure that the bottle cap is easy to print after forming, the bottle cap is required to have a flat plate surface with no rolling marks, scratches, and stains. The commonly used alloy materials are 8001, HI4, 3003, and H16. Material specifications generally have a thickness of 0.20 to 43.23 mm, tolerances of ±0.1%, and widths of 449 to 796 mm. The production of aluminum bottle caps can be carried out by hot-rolled blanks or continuous casting and rolling, respectively, and cold-rolled and rolled. Production practice shows that hot rolled blanks are superior to cast blanks in the use of anti-theft caps.

2 aluminum plastic blister packaging

At present, the use of blister packs for health food and pharmaceutical tablets and capsule packaging is becoming more and more common. Aluminum plastic blister packs are also known as blister packs, or PTP (PressThrough Packaging). The aluminum foil used in the blister packaging is a sealing material that is tightly sealed on a plastic hard-plastic PVC (PVC) hard sheet, so it is also called a cover material. Almost all products in modern packaging that require opaque or high barrier composite materials use aluminum foil as the barrier layer because aluminum foil has a highly dense metal crystal structure and can completely block any gas, so it is widely used. It is expected that the packaging used for pharmaceutical blisters will account for about 60% to 70% of the future pharmaceuticals' tablets and capsules, and is currently one of the best pharmaceutical packaging materials with the most promising development prospects.

However, the quality of pharmaceutical aluminum foil in China is far from the import of aluminum foil. From the actual situation reflected by several domestic companies that produce PTP pharmaceutical packaging, there are mainly the following two problems.

(1) The number of pin holes in medicinal aluminum foil is far from the requirement. The pinhole of aluminum foil is a defect of penetrating performance, which affects the barrier performance of aluminum foil. Especially for pharmaceutical packaging, it is easy to make oxygen, water vapor, and light penetrate to reduce the efficacy of drugs. Pharmaceutical aluminum foils in national standards require that the pinhole diameter be no more than 0.3mm, and that the diameter should be no more than 1/m2 in the range of 0.1 to 0.3mm. At present, domestic aluminum foil rarely meets this standard.

(2) The thickness of pharmaceutical aluminum foil is uneven and its tensile strength is low. Due to the uneven thickness of the aluminum foil, it is easy to cause the amount of the adhesive coating in the mechanical coating process of the PTP aluminum foil to be difficult to reach the standard coating amount range, thereby affecting the enthalpy strength of the aluminum foil and the polyvinyl chloride hard sheet. Due to uneven thickness, low tensile strength leads to breakage of the foil after tension is applied in the actual processing, which is not conducive to the normal production. These problems require the attention of raw material manufacturers.

3 aluminum beverage cans

Currently. The development of aluminum beverage cans has three major features, namely easy-pull lids, special-shaped cans, and self-heating/self-cooling beverage cans. For a long time, although metal packagings such as aluminum beverage cans have been challenged by tinplates and PET materials, due to their light weight and recyclable advantages, they are still one of the major beverage packaging formats and have not only achieved stable development. And it is also constantly developing and innovating.

Recently, coins packaging company developed EPOL (easy opening cover). This can lid is coated with a polymer-coated steel ring and a corrosion-resistant aluminum foil enthalpy that can be used in existing filling equipment. The aluminum foil lid can be safely opened and is more suitable for use by the elderly and children. Due to the competition of PET bottles, the demand for aluminum cans for beverages in the Japanese market has gradually decreased in recent years. However, with the development of new types of aluminum cans, the demand for aluminum cans has started to rise again. At present, companies such as Takeuchi Stamping Industry, Daiwa Manufacturing, and Mitsubishi Materials have entered the production of aluminum cans, and aluminum can lids developed by the Caisaki Manufacturing Plant have also been put on the market.

In order to complement each other's advantages, Daiwa Corporation has focused on the advantages and disadvantages of two kinds of beverage packaging containers, namely PET bottles and aluminum cans, and has been able to avoid weaknesses. In the world, it has successfully developed a new container for beverage packaging that can impart re-tightness to metal cans. "New bottle metal cans (new cans).

The new bottle is a new packaging container developed beyond the existing two-piece can and three-piece can structural frame. It not only applied the current three-piece metal can's composite technology, crimping technology, but also applied Two-piece can deep-drawing forming technology cans, and then use the existing canned contents and processing technology with screw caps to achieve the use of metal aluminum, processed to form a bottle with a 28mm diameter and drink The new metal bottle packaging container. The new container combines the advantages of metal cans and PET bottles while overcoming the inherent disadvantages of both. Taking into account the environmental issues, the new bottle is made of a single-metal aluminum alloy material. The surface of the material, that is, the inner and outer surfaces of the can body are composited with PET film material; the inner surface of the bottom cover is also compounded with PET. The film is coated with PET on the outer surface; the bottle cap is coated with low-density PET and the outer surface is subjected to printing. In this way, the inner layer of the new bottle can avoid contact with the contents and does not need to use various paints traditionally used in metal cans. After successful trial production of new bottles and cans, it was exhibited at the Australian can-making industry exhibition in 2000, and won the award presented by the exhibition in the name of a Japanese company. This technology is also very eye-catching in the international community. The demand for aluminum-PET cans may further increase in the future.

According to a survey conducted by the Japan Aluminum Can Recycling Association, since these four companies entered the production field of aluminum cans, the sales volume of aluminum cans alone reached 1.5 billion in 2002, which is 2.5 times that of the previous year, and this was the basis for 2003. Increased by about 20%.

The beverage packaging market is one of the largest markets for the metal packaging market. In order to improve the brand effect, in addition to using the silver-white properties of aluminum, the shape of aluminum cans is becoming more and more important. Therefore, manufacturers of metal forming equipment are also discussing aluminum can forming and embossing technology. Because aluminum is easier to shape and achieve the desired shape, researchers are exploring aluminum can roll reel forming, spin forming and rheology techniques that will be used first in beer cans in the near future.

Beverages such as beer and soda use aluminum cans to increase the use of aluminum products, and other industries are currently considering the use of aluminum cans. According to the information provided by U.S. Industrial Information Resources, over a year ago, Japan’s largest aluminum can manufacturer, Dahe Aluminum Can, began producing aluminum cans for beer and tea companies. This company has produced 480 million aluminum cans last year. With the addition of two other Japanese aluminum can makers, it is expected that the output of aluminum cans in Japan will double in the next two to three years. Aluminum cans are favored by the beverage industry due to their light weight and easy recycling. Recently, they have continued to spread to other industries and have the tendency to replace glass bottles and metal bottles.

three. in conclusion

Experts believe that the new market share of aluminum materials will make new progress along with the promotion of so-called active packaging. Due to the application of new technologies for the development of aluminum products, the demand for aluminum materials will be further expanded in the future.