Development and application of the hottest aluminu

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Development and application of aluminum foil composite packaging materials

aluminum foil is not only soft in texture, good in ductility, easy to process, but also light and beautiful, easy to recycle, and beneficial to environmental protection. It is one of the most commonly used materials in modern packaging. However, because aluminum foil is easy to form pinholes in the process of packaging and use, and its barrier performance is reduced, aluminum foil is often used with paper, polymer or other metal sheets to make composite materials. Practice has proved that aluminum foil composites can greatly improve the barrier of packaging, improve the mechanical strength and mechanical properties of aluminum foil, especially suitable for making composite flexible packaging and packaging lining with a decrease of 3%, and are widely used in the packaging of food, medicine, cosmetics and other commodities

1. Aluminum foil composite processing paper

use the moisture-proof, rust proof, gas resistance and corrosion resistance of aluminum foil to make it stick with paper to become aluminum foil composite paper, or use thermoplastic film as adhesive to compound aluminum foil with paper to form multilayer composite paper. This kind of composite paper combines the high barrier property of aluminum foil with the folding and impact resistance of paper, and becomes a high-performance packaging material. Most of the composite components in the materials are non-toxic and tasteless materials, which will not cause pollution to the contents and human body, and are easy to meet the health and safety standards of packaging; At the same time, because the resin in it can be decomposed when heated to high temperature, so that paper and aluminum foil can be separated, which greatly improves the recycling and regeneration of materials, and reduces the waste of materials and the load on the environment

at present, there are many kinds of processed paper, and different papers can be used according to different needs. Kraft paper is widely used in the packaging of industrial products; The plastic can be polyethylene, polypropylene, polyester film, etc., especially the aluminum-plastic composite paper made of polyester film. When folding, the aluminum foil is not easy to break and form pinholes, which can maintain its excellent barrier performance. In order to improve the strength of composite processing paper, reinforcement can also be sandwiched in it to meet the needs of heavy product packaging. Due to the high barrier property and various packaging adaptability of aluminum-plastic composite processing paper, it is now widely used in both industrial product packaging and food packaging

2. Aluminum plastic composite can material

aluminum plastic composite can material is composed of aluminum foil, plastic film and kraft paper (paperboard), which can be made into square, cylindrical, rectangular, conical and other forms of packaging cans. Among them, cylindrical aluminum foil composite cans (hereinafter referred to as LFG cans) first appeared in the United States, and now many countries use this form of packaging

lfg cans are characterized by light weight and low price, which are about 20% lighter than aluminum cans and about 20% lower than tin cans. Of course, they are cheaper than aluminum cans; It has good moisture resistance, sealing, shading and barrier to liquid and solid contents, especially avoiding the pollution at the weld of ordinary tin cans; The stiffness and mechanical strength are moderate, and the compressive strength, axial crushing force and end cover separation force are high, which is especially suitable for the packaging of frozen food

this kind of can material is generally divided into four parts: outer surface layer, cardboard layer, inner lining layer and inner surface layer. The outer surface layer is a label layer, which is used to print trademarks and other graphics. The available paper is far beyond the range of 2.4 (6) 00kn of 600kN in Grade 6, plastic film or aluminum foil plastic composite; The cardboard layer is made of 2 ~ 3 layers of long fiber cardboard to ensure the rigidity and mechanical strength of the can body; The inner lining is the main part of the tank body. As a barrier layer, it plays the role of moisture-proof, impermeability, light blocking and so on. Therefore, aluminum foil based composite materials are used, commonly used are plastic coated aluminum foil, aluminum plastic composite materials or aluminum plastic paper composite materials. At the same time, due to its good processing performance, it can also flexibly change the number of composite layers and structure according to different packaging requirements

this composite material is also non-toxic, tasteless and does not pollute the contents. It can be reused and recycled. Using it to replace tinplate and other sheet metal cans can avoid the pollution caused by metal welds, and further reduce costs and improve economic benefits

at present, LFG cans made of this material have been widely used in the packaging of engine oil and some puffed foods such as potato chips, and will gradually occupy new fields such as pressure vessels and cooking cans with a wide variety of experimental accessories. For example, it can further improve the strength of the tank body and the structure of the end cap, continuously improve the quality of LGF tank, and also occupy a place in the liquid packaging container

3. Aluminum plastic composite flexible film

although aluminum foil is soft and foldable, it has low mechanical strength and poor sealing performance. When aluminum foil is compounded with high-strength and heat sealable plastic film, aluminum plastic composite flexible packaging materials with excellent barrier, mechanical properties and heat sealing performance can be obtained, which are widely used in food packaging, cooking bags, chemical and industrial product packaging, military product packaging, etc

for example, aluminum foil bags used as packaging materials for soft canned food are composite materials with three or four layers of aluminum foil in the middle layer. The inner substrate is non-toxic polyolefins, with a thickness of about 9 μ m. Block gas and light; The inner or outer layer of aluminum foil is usually nylon film, with a thickness of about 20 μ m. In order to provide toughness, mechanical impact resistance, etc., the outermost layer is usually polyester, with a thickness of about 12 μ m. It has the function of preventing aluminum foil from cracking, and has gloss, waterproof and other properties. This soft can aluminum foil bag has good mechanical performance and sealing processing performance, good moisture resistance, gas resistance, fragrance retention, oil resistance, corrosion resistance, non-toxic, odorless, tasteless, hygienic, safe and reliable, and convenient for printing. It is suitable for automatic and mechanized operations, which is lighter, more economical and more energy-saving than metal cans

aluminum foil composite cooking bag is also a widely used aluminum plastic composite flexible packaging material. It is made of aluminum foil and plastic film. It is a packaging material with air tightness, high barrier, high flexibility and certain heat resistance. After the bag is made, it is put into the food, which is sealed by hot pressing and sterilized by heating, which can greatly improve the storage time of food at room temperature. The typical three-layer structure of aluminum foil composite cooking bag includes bopet/al/cpp, bopp/al/hdpe, ny/al/ldpe, etc. The aluminum foil composite cooking bag has the following advantages: it can significantly extend the shelf life of food, can withstand the high-temperature sterilization treatment of 120 ~ 150 ℃, and the shelf life can reach 1.5 ~ 2 years; Effectively maintain the nutritional level of food, and the color and taste are not damaged; Saving resources, 1t cooking bag can replace the packaging capacity of 40t glass, 6T tinplate and 5T aluminum foil respectively. At present, aluminum plastic composite cooking bags have been widely used in cooking food packaging of sauce, paste and solid and space food packaging

4. Aluminum plastic composite hose

aluminum plastic composite material has good isolation performance, is not easy to crack, has beautiful appearance, bright colors, is clean and sanitary, is convenient to use, feels soft, and has good wrinkle resistance. The hose made of this material is superior to the all aluminum hose, and can be used as the packaging material for toothpaste, ointment, cosmetics, washing supplies, chemical supplies, pigments, etc. among them, the consumption of toothpaste packaging is the largest. With the rapid popularization of domestic aluminum-plastic composite hose production line, the cost of aluminum foil hose toothpaste is reduced, and the utilization rate of aluminum-plastic composite materials used for toothpaste packaging will increase rapidly

aluminum foil composite hose is made of aluminum foil composite tape with aluminum foil, plastic or resin as the base material, and then processed into tubular semi-rigid packaging products by a special pipe making machine. It is an updated product of all aluminum hose. It is mainly used for small capacity sealed packaging of semi-solid (paste, dew, colloid), such as jelly, jam, toothpaste, cosmetics, ointment, shoe polish, pigments, lubricants, adhesives, etc

compared with the all aluminum hose, the aluminum foil composite hose has many advantages: ① it is 20% - 30% lighter than the all aluminum hose of the same specification, and the aluminum consumption per unit product is reduced by 80%, which greatly lightens the packaging. ② The pipe making process is simple, suitable for high-speed and continuous production, with less energy consumption, low cost and high production efficiency. All aluminum hoses need to go through the processes of punching discs, deburring, intermediate annealing, surface oiling agent, punching round tubes by reverse extrusion with 4 ~ 5mm aluminum plates, which has low efficiency, high cost, and large environmental load caused by the production process. The composite hose only uses one pipe making equipment to complete the pipe making operation at one time. Aluminum plastic composite hose material is compounded by coextrusion process without adhesive, which is a clean production process. ③ The wall thickness of the composite hose is 2 ~ 3 times thicker than that of the full aluminum tube, and the rupture strength is also significantly higher than that of the full aluminum tube, which enhances the safety of transportation and storage. ④ With plastic as the inner wall material, the corrosion resistance and health safety are enhanced. For corrosive contents (such as fluorinated paste), under the action of some chemicals, it will lead to the corrosion of all aluminum tubes, causing penetrating holes and leaks, and aluminum ions will also enter the contents. When extruding paste with high measurement accuracy, the mouth of all aluminum tubes will also cause pollution. The aluminum plastic composite hose can avoid these phenomena

5. Aluminum plastic composite blister

the aluminum plastic blister packaging of medical and health products is also called blister packaging, which is made of barrier plastic blister hard pieces and aluminum foil. The blister packaging of drugs has good protective performance, fast production speed, low cost, small storage space, light weight and low transportation energy consumption; It provides patients with a single dose of drug packaging, which is convenient and economical; Since the instructions are printed on the aluminum foil of the blister package, the drug dispenser can avoid the wrong drugs and mixing drugs in the distribution of a variety of tablets. At present, China's pharmaceutical industry has greatly increased the production of high-quality blister drugs. It is expected that the materials used for blister packaging of drugs will account for about 60% - 70% of the packaging materials of tablets and capsules of drugs in the future

the aluminum foil used in the blister packaging of drugs is the sealing material (also known as the capping material) sealed on the hard plastic sheet, which is usually called 'PTP' medicinal aluminum foil. It has the advantages of non-toxic, non corrosive, impermeable, hygienic, heat resistant, moisture-proof and so on. It is easy to carry out high-temperature disinfection and sterilization, and can block light, which can protect the drug tablet from light deterioration. Before sealing the aluminum foil cover with the plastic hard sheet, the text pattern should be printed on the special printing coater and coated with protective agent, and the other side of the aluminum foil should be coated with adhesive to bond with the plastic hard sheet. The protective agent can prevent the abrasion of the ink and text, and also prevent the pollution caused by the contact between the outer ink and the inner adhesive during the mechanical winding of aluminum foil

in addition to the packaging of tablets and capsules, aluminum plastic blister packaging materials will also be used for the external packaging of drugs such as injections. It is a new packaging material with great development potential

(Zhao Qingxue)

source: China packaging 2005/2

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