CalenderedAluminum Foil

It is a kind of hot stamping material which is directly calendered into thin sheet with aluminum. Its hot stamping effect is similar to that of pure silver foil, so it is also called false silver foil. Because of its soft texture, good ductility and silvery white luster, aluminum foil can also be printed if the calendered sheet is mounted on offset paper with sodium silicate and other substances. However, aluminum foil itself is easy to oxidize and darken, and will fade when rubbing and touching, so it is not suitable for long-term preservation of books and periodicals cover.

铝箔胶带

Overview of aluminum foil

Because of its excellent characteristics, aluminum foil is widely used in food, beverage, cigarette, medicine, photographic plate, household goods, etc., and is usually used as its packaging material; Electrolytic capacitor materials; Thermal insulation materials for buildings, vehicles, ships, houses, etc; It can also be used as decorative gold and silver thread, wallpaper and decoration trademark of all kinds of stationery, printed goods and light industrial products. Among all the above applications, the most effective one is as packaging material. Aluminum foil is a soft metal film, which not only has the advantages of moisture-proof, air tightness, shading, abrasion resistance, fragrance preservation, non-toxic and tasteless, but also has elegant silver white luster, and is easy to process beautiful patterns and patterns of various colors, so it is more easily favored by people. In particular, after aluminum foil is compounded with plastic and paper, the shielding property of aluminum foil is integrated with the strength of paper and the thermal sealing property of plastic, which further improves the shielding property of water vapor, air, ultraviolet and bacteria, which is necessary for packaging materials, and greatly expands the application market of aluminum foil. Because the packaged goods are completely isolated from the outside light, humidity and gas, the packaged goods are well protected. Especially for the packaging of cooked food, the use of this composite aluminum foil material can ensure that the food will not deteriorate for at least one year. Moreover, heating and unpacking are very convenient, which is very popular with consumers.

With the improvement of people's living standards and the development of tourism, the demand for beer, soda and other drinks and canned food is increasing day by day. All of these need modern packaging and decoration to facilitate the competition in the international market. In order to meet the requirements of the market, packaging materials such as plastic film and spray foil with good shielding property have been developed. However, their comprehensive properties are not as good as those of over coating and laminating. Therefore, it can be said that aluminum foil is a perfect packaging material with a variety of excellent properties, which fully shows its broad application prospects in many fields.

In order to improve the rolling efficiency and the quality of aluminum foil products, the modern aluminum foil rolling mill develops in four directions: large coil, wide width, high speed and automation. The roll width of modern aluminum foil rolling mill has reached more than 2200mm, the rolling speed has reached more than 2000m / min, and the coil weight has reached more than 20t. The automation level of rolling mill has been greatly improved. AGC and AFC are widely installed. Aluminum foil industry is facing a period of rapid development.

Shape

According to the shape, aluminum foil can be divided into rolled aluminum foil and sheet aluminum foil. Most of the aluminum foil deep processing raw materials are supplied in coils, and only a few handicraft packaging occasions use sheet aluminum foil.

According to the state, aluminum foil can be divided into hard foil, semi hard foil and soft foil.

① Hard foil: rolled aluminum foil without softening treatment (annealing), without degreasing treatment, the surface is covered with residue. Therefore, the hard foil must be degreased before printing, laminating and coating. If it is used for forming, it can be used directly.

② Semi hard foil: aluminum foil with hardness (or strength) between hard foil and soft foil, usually used for forming.

③ Soft foil: aluminum foil softened after full annealing after rolling, with soft material and no residual oil on the surface. Most applications, such as packaging, composite, electrical materials, use soft foil.

characteristic

Aluminum foil has a clean, sanitary and shiny appearance. It can be made into integrated packaging materials with many other packaging materials, and the printing effect of aluminum foil surface is better than other materials. In addition, aluminum foil has the following characteristics:

(1) The surface of aluminum foil is extremely clean and sanitary, and no bacteria or microorganism can grow on it.

(2) Aluminum foil is a non-toxic packaging material, it can be in direct contact with food without any danger to human health.

(3) Aluminum foil is a kind of tasteless and odorless packaging material, which will not make the packaged food have any peculiar smell.

(4) If the foil itself is not volatile, it and the packaged food will never dry or shrink.

(5) No matter at high temperature or low temperature, there will be no oil penetration in aluminum foil.

(6) Aluminum foil is a kind of opaque packaging material, so it is a good packaging material for products exposed to sunlight, such as margarine.

(7) Aluminum foil has good plasticity, so it can be used to package products of various shapes. It can also be used to make containers of various shapes.

(8) Aluminum foil has high hardness and tensile strength, but its tear strength is small, so it is easy to tear.

(9) Aluminum foil itself can not be sealed by heating, so it must be coated with thermal materials, such as PE.

(10) When aluminum foil is in contact with other heavy metals or heavy metals, there may be adverse reactions.

rolling

Particularity of aluminum foil rolling

In the production of double sheet foil, the rolling of aluminum foil can be divided into three processes: rough rolling, medium rolling and finishing rolling. From the point of view of technology, it can be roughly divided from the thickness of rolling exit. The general method is rough rolling when the thickness of exit is greater than or equal to 0.05mm, medium rolling when the thickness of exit is between 0.013 and 0.05, and finishing rolling when the thickness of exit is less than 0.013mm. Rough rolling is similar to the rolling characteristics of aluminum plate and strip. The thickness control mainly depends on rolling force and back tension. The thickness of rough rolling processing rate is very small. Its rolling characteristics are completely different from the rolling of aluminum plate and strip. It has the particularity of aluminum foil rolling. Its main characteristics are as follows:

(1) Aluminum strip rolling. In order to make the aluminum strip thin, the rolling force is the main factor. Therefore, the automatic control mode of plate thickness is the control mode with constant roll gap as the main body of AGC. Even if the rolling force changes, the roll gap can be adjusted at any time to keep a certain value, and the strip with the same thickness can be obtained. When aluminum foil is rolled to medium finish rolling, because the thickness of aluminum foil is extremely thin, it is easier for the roll to produce elastic deformation than the material to be rolled to produce plastic deformation when the rolling force is increased. The elastic flattening of the roll can not be ignored. The elastic flattening of the roll determines that the rolling force can not play the same role as rolling plate in aluminum foil rolling, Aluminum foil rolling is generally non roll gap rolling under constant pressure, and the adjustment of aluminum foil thickness mainly depends on the adjusted tension and rolling speed.

(2) Stacking rolling. For the very thin aluminum foil whose thickness is less than 0.012mm (the thickness is related to the diameter of the work roll), it is very difficult to roll by single sheet because of the elastic flattening of the roll. Therefore, the double rolling method is adopted, that is, adding lubricating oil between the two pieces of aluminum foil, and then rolling together (also known as overlapping rolling). Stacking rolling can not only produce very thin aluminum foil which can not be produced by single sheet rolling, but also reduce the times of strip breaking and improve labor productivity. By using this process, single-sided smooth aluminum foil of 0.006 mm ~ 0.03 mm can be produced in batch.

(3) Speed effect. In the process of aluminum foil rolling, the phenomenon of foil thickness thinning with the increase of rolling schedule is called speed effect. The explanation of the mechanism of velocity effect needs to be further studied

1) With the increase of rolling speed, the amount of lubricating oil is increased, which makes the lubrication state between roll and rolling material change. As the friction coefficient decreases, the oil film becomes thicker and the thickness of aluminum foil becomes thinner.

2) Change of rolling mill itself. In the rolling mill with cylindrical bearing, the roll neck will float in the bearing with the increase of rolling speed, so that the two interactive loaded rolls will move in the direction of mutual contact.

3) The material is softened during rolling deformation. The rolling speed of high-speed aluminum foil rolling mill is very high. With the increase of rolling speed, the temperature of rolling deformation zone increases. According to the calculation, the metal temperature of deformation zone can rise to 200 ℃, which is equivalent to an intermediate recovery annealing, thus causing the processing softening phenomenon of rolled materials.

The principle of making aluminum foil rolling process

① The determination of the total processing rate the total processing rate refers to the total deformation degree of the foil after recrystallization annealing to rolling out the finished product. Generally speaking, the total processing rate of series 1 can reach more than 99%, and some series 8 products can also reach this value, but the total processing rate of aluminum alloy foil is generally below 90%.

② The determination of pass processing rate is the core of rolling process. For pure aluminum series products, the pass processing rate can reach 65%. For the first pass after annealing, it is not suitable to use excessive processing rate, generally about 50%.

Rolling thickness

The thickness measurement methods of aluminum foil rolling mainly include eddy current measurement, isotope ray measurement and X-ray measurement. X-ray thickness measurement is the most common method in aluminum foil production, especially in high-speed aluminum foil rolling mill. Thickness control methods of aluminum foil rolling: rolling force control, tension control, rolling speed control, tension / speed, speed / tension control.

Product defects

The main defects of aluminum foil are as follows:

(1) Pinhole. Pinhole is the main defect of aluminum foil. The size of dust in raw material, roll, rolling oil and even air reaches 6 μ The needle hole will be caused when the roller gap is about 6 m μ It is impossible for M aluminum foil to have no pinholes. It can only be evaluated by the number and size of pinholes. Due to the improvement of aluminum foil rolling conditions, especially the dust-proof and rolling oil effective filtration and convenient roll changing system, the number of aluminum foil pinholes increasingly depends on the metallurgical quality and processing defects of raw materials. Because pinholes are often the shedding of raw material defects, it is difficult to find the corresponding relationship with the original defects. It is generally believed that the pinhole is mainly related to gas content, inclusion, compound and component segregation. Effective purification, filtration and grain refinement are helpful to reduce pinholes. Of course, improving the hardening properties of materials by means of alloying also helps to reduce pinholes. 6 times of high quality hot rolled products μ M aluminum foil pinholes can be less than 100 / m2. When the purification of cast rolled products is good, 6 μ M aluminum foil pinholes less than 200 / m2. In the process of aluminum foil rolling, there are many other factors causing pinholes, even catastrophic. Thousands of pinholes per square meter are not uncommon. Effective filtration of rolling oil, short-term roll replacement and dust-proof measures are all necessary conditions to reduce the pinhole of aluminum foil. Large rolling force and small tension rolling can also help to reduce the pinhole.

(2) Uneven roll print, roll hole and gloss. It is mainly caused by the roll of aluminum foil defects, divided into point, line, surface three kinds. The most significant feature is the emergence of three cycles. The main reasons for this defect are: incorrect grinding of roller; Foreign material damage roll: incoming material defect damage roll; Roll fatigue; Collision and slipping between rolls. All the factors that can cause the surface damage of the roll are harmful to the aluminum foil rolling. Because the aluminum foil rolling roll surface finish is very high, slight uneven gloss will also affect its surface state. Regular cleaning of the rolling mill, keeping the rolling mill clean, ensuring the normal operation of the roller cleaner, regular roll change and reasonable grinding are the basic conditions to ensure the uniform surface of aluminum foil after rolling.

(3) Wrinkles. Due to the serious bad shape of the sheet, the aluminum foil will be wrinkled when it is rolled or unfolded. The essence is that the tension is not enough to make the foil flat. For the device with a tension dimension of 20MPa, the shape of the foil surface should not be greater than 30i. When it is greater than 30i, it is bound to wrinkle. Because the tension of aluminum foil during rolling is often greater than that of subsequent processing, some of them only show bad shape during rolling, including incorrect grinding of roll, incorrect roll shape, bad incoming shape and incorrect adjustment of shape.

(4) Bright spot, bright mark, bright spot. The bright spots, bright marks and bright spots on the double joint surface caused by improper use of the double joint oil are mainly due to insufficient strength of the double joint oil film, or uneven rolling deformation caused by uneven roll surface, with the appearance of hemp skin or foreign matter pressed in. It is an effective measure to select reasonable double compound oil, keep incoming material clean and roll surface uniform. Of course, it is also necessary to change the reduction and select excellent aluminum plate.

(5) Thickness difference. It is a characteristic of aluminum foil rolling that the thickness difference is difficult to control. 3% thickness difference may not be difficult in plate production, but it is very difficult in aluminum foil production. The reason is that the thickness is thin, and other trace conditions can affect it, such as temperature, oil film, oil gas concentration, etc. One roll of aluminum foil can reach several hundred thousand meters, and the rolling time is about 10 hours. With the extension of time, the thickness difference is easy to form, and the only way to adjust the thickness is tension speed. All these factors make it difficult to control the thickness of aluminum foil rolling. Therefore, it is very difficult to control the thickness difference within 3%

(6) Oil pollution. Oil pollution refers to the excess oil on the surface of aluminum foil after rolling, that is, oil other than rolling oil film. These oils are often thrown, splashed and dripped on the foil surface from the roll neck or above or below the exit of the rolling mill, and they are dirty and have complex components. The oil pollution on the surface of aluminum foil is more harmful than that on other rolled strips. Firstly, as most aluminum foil products are used as decoration or packaging materials, they must have a clean surface; The second is that it is thin and easy to form bubbles during post annealing, and because of the large amount of oil, too much residue is formed at this place, which affects the use. The number of oil defects is a very important index to evaluate the quality of aluminum foil.

(7) Water spots. Water spot refers to the white spot formed by water drops on the foil surface before rolling and after rolling, which will affect the surface condition of the foil surface if it is slight and cause strip breakage if it is serious. Water spots are caused by water drops in the oil or in the rolling mill. The only way to avoid water spots is to control the water in the oil and the water source.

(8) Vibration marks. Vibration marks are periodic transverse waves on the surface of aluminum foil. There are two reasons for vibration marks: one is caused by grinding of roller, and the period is about 10 ~ 20 mm; The other is vibration due to discontinuous oil film during rolling, which often occurs in a speed range with a period of 5 ~ 10 mm. The root cause of vibration mark is insufficient oil film strength, which can be eliminated by improving lubrication state.

(9) Tension line. When the thickness is less than 0.015mm, parallel stripes are formed in the longitudinal direction of aluminum foil, commonly known as tension line. The tension line spacing is about 5 ~ 20 mm. The smaller the tension, the wider the tension line and the more obvious the stripe. When the tension reaches a certain value, the tension line is very slight or even disappears. The smaller the thickness is, the greater the possibility of producing tension line. The possibility of producing tension line in double rolling is greater than that in single rolling. Increasing tension and roll roughness is an effective measure to reduce and eliminate tension line, and large tension must be based on good shape.

(10) Slit. Slitting is a special defect in foil rolling. It splits straightly along the longitudinal direction and is often accompanied by wire. The root cause of slotting is the entrance side discount, which often occurs in the middle, mainly due to the middle loose of incoming material or poor roll. Serious slits can't be rolled, while slight slits crack in the later slitting, which often causes a lot of waste products.

(11) Airway. In the rolling time, strip crushing appears, the edge is droplet like curve, with a certain width, mild airway is not crushed, white strip and dense pinholes. The existence of dense pinholes at the front and rear ends of the crushed aluminum foil is the main sign to judge the airway and other defects. The gas path comes from the raw material, so it is very important to choose the material with low air content as the aluminum blank.

(12) Coiling defects. Coiling defect mainly refers to loose coil or loose inside and tight outside. Due to the limited tension of aluminum foil, it is difficult to take up the hard coil. It is the most ideal to get a tight inside and loose outside coil, and enough tension is the condition to form a certain tension gradient. Therefore, the coiling quality ultimately depends on the shape of the plate, loose inside and tight outside the coil will form a transverse edge, and loose coil will form an ellipse, which will affect the future processing.

Although there are many kinds of defects in aluminum foil rolling, the main defects are pinholes, roll holes, slits and air passages characterized by holes; Oil stain, uneven luster, vibration mark, tension line, water spot and bright spot characterized by surface condition; In order to affect the shape, wrinkling, discount and coiling of the later process; Thickness difference characterized by size, etc. In fact, the only defect unique to aluminum foil is pinhole, which is also found in other kinds of defect plates, but the severity or requirements are different.

Editing voice

The main reason for corrosion is that the product is affected with damp or water in the process of production and circulation. Therefore, the main way to control the generation of corrosion waste is to prevent the aluminum foil from contacting with water. Anti corrosion measures: ① strengthen the management of the air dryer to ensure that there is no moisture in the compressed air. ② Strengthen the management of rolling oil, and control its water content within 400 × Below 0.00000 1. ③ The package of aluminum foil roll should be sealed, and appropriate amount of desiccant should be put into each roll. ④ The humidity of the wooden shaft and board of the packing box is not more than 18%, and the temperature of the aluminum coil is not more than 45 ℃. ⑤ When transporting from low temperature area to high temperature and humidity area, do not open the sealed package immediately. ⑥ Aluminum foil roll should not be placed on the roof of workshop and warehouse where there is rain and snow leakage. ⑦ When transporting aluminum foil from low-temperature area to high-temperature area, it is necessary to strengthen the sealing of packaging and add desiccant if necessary. ⑧ When packaging aluminum foil products in rainy season, it is necessary to strengthen the sealing packaging and add desiccant.

2008-2012年我国铝箔行业出口额分析

Export data

Aluminum foil is a high value-added product in the aluminum processing material industry. The industry is developing rapidly, and the market scale and production and sales volume maintain a high growth year after year. Due to its excellent application performance in the field of heat conduction and recycling, the application of aluminum foil in household appliances, packaging and other aspects has been greatly expanded.

The development of China's packaging industry has greatly driven the consumption of aluminum foil industry. During the "12th Five Year Plan" period, there will be a strong demand for high-performance aluminum foil for the construction of livelihood projects and the development of low-carbon economy. China's annual demand for aluminum foil has reached more than 300000 tons, and China has developed into the third largest packaging country after the United States and Japan. In the next few years, the growth rate of aluminum foil for packaging will greatly exceed that of China's air conditioning and cable applications.

Development prospects

Introduction of several key aluminum foil products

（1） Air conditioner foil

Air conditioning foil is a special material for manufacturing fins of heat exchanger used in air conditioner. In order to improve the surface properties of the plain foil, the anti-corrosion inorganic coating and hydrophilic organic coating were applied before forming to form hydrophilic foil. Hydrophilic foil accounts for 50% of the total amount of air conditioning foil, and its use proportion will be further improved. In addition, there is a kind of hydrophobic foil, which makes the fin surface hydrophobic and prevents condensation from adhering. Because the technology of hydrophobic foil to improve the surface defrosting needs further study, the actual production is very few.

The thickness of the foil is 0.1 mm ~ 0.15 mm. With the development of technology, air conditioning foil has a trend of further thinning. The thickness of Japan's leading product is 0.09mm. In the very thin state, aluminum foil must have good formability, its structure and properties must be uniform, less metallurgical defects, small anisotropy, and high strength, good ductility, uniform thickness, good flatness. The specification and alloy of air-conditioning foil is relatively single, which is suitable for large-scale production. However, its market is highly seasonal. It is difficult for professional manufacturers of air-conditioning foil to solve the contradiction between short supply in peak season and almost no demand in off-season.

Driven by the strong market demand, the production capacity and technical level of China's air-conditioning foil have been continuously improved in recent years. Now a large, medium, small, medium and low-grade enterprise group has formed. The product quality of some large enterprises, such as Huabei aluminum and Bohai aluminum, has basically reached the international advanced level. Due to the excess domestic production capacity, the market competition is extremely fierce.

（2） Cigarette packaging foil

China is the largest cigarette producer and consumer in the world. There are 146 large cigarette factories in China, with an annual output of 34 million large cases of cigarettes. Most of them are packed with cigarette foil, 30% of which are spray coated and 70% are rolled aluminum foil. The consumption of rolled aluminum foil is 35000 tons. With the enhancement of people's health awareness and the impact of imported cigarettes, the growth of demand for cigarette foil has slowed down significantly, It is expected to increase slightly in recent years. Cigarette packaging foil accounts for 70% of the total double zero foil in China. At present, there are two or three domestic enterprises that can produce high-quality cigarette foil, and the technical level is equivalent to the international level, but there is a certain gap between the overall quality of domestic cigarette foil and the international level.

（3） Decorative foil

Decorative foil is a kind of decorative material which is applied in the form of aluminum plastic composite. It makes use of the characteristics of aluminum foil, such as good coloring and high light and heat reflectivity. It is mainly used for decoration of architecture and furniture and part of gift box packaging. The application of decorative foil in China's construction industry began in the 1990s. It has spread rapidly from Shanghai, Beijing, Guangzhou and other central cities to all parts of the country. In recent years, the demand for decorative foil has increased sharply. Generally, as the decorative material for the interior wall of buildings and interior furniture, it is also widely used in the door and interior decoration of commercial institutions.

Decorative foil has the advantages of heat insulation, moisture-proof, sound insulation, fire prevention and easy cleaning, and has luxurious appearance, convenient processing and fast construction and installation speed. China's construction, home decoration industry has formed a decorative foil application boom. With the rapid development of China's construction industry and the popularization of decorative foil application, the demand for decorative foil will increase significantly. In addition, the use of decorative foil packaging gifts is very popular in foreign countries, in recent years in China's rapid development, is expected to have a good prospect.

Application

Preparation of polyaluminum chloride from waste aluminum foil

Polyaluminum chloride is a kind of inorganic polymer flocculant. The wide sources of raw materials for the production of polyaluminum chloride lay the foundation for its development. In particular, the variety of production process provides convenience for the development of polyaluminum chloride.

聚合氯化铝

At home and abroad, the production and application of inorganic polymer flocculants have been on a large scale, and the theoretical research has also made in-depth development. The main raw materials are bauxite, aluminum hydroxide, waste molecular sieve catalyst, etc. the main preparation methods are wet method, electrolysis method, etc. Some scholars think that waste aluminum foil has high economic value of recycling. Through experiments, he studied the best conditions for the preparation of polyaluminum chloride from waste aluminum foil and the scope of application for water purification.

With the development of industry and the rapid growth of urban population, the pollution of water resources is becoming more and more serious. Because polyaluminum chloride molecules contain different amounts of hydroxyl groups, when polyaluminum chloride is added to turbid source water, it will continue to hydrolyze under the pH condition of source water, accompanied by a series of physical and chemical processes such as coagulation, adsorption and precipitation, so as to achieve the purpose of purifying water. Waste aluminum foil comes from a wide range of sources, mainly from cigarettes, food and drug packaging. Its main component is metal aluminum, which has high economic and social value of recycling. Through the experimental study, the best conditions and application scope of polyaluminum chloride made from waste aluminum foil have certain practical significance in improving the utilization rate of resources and protecting the environment.

development

China's aluminum foil consumption is increasing year by year, from 300000 tons in 2001 to about 1.3 million tons in 2010, with a compound annual growth rate of 18%; Although China is the second largest aluminum foil consumer in the world after the United States, China's aluminum foil market still has a large room for growth.

In the production and operation of specialized aluminum foil enterprises, we need to be meticulous, to meet the needs of specific aluminum foil market users with professional skills, and to develop more suitable new aluminum foil materials combined with the continuous innovation of users' products. By providing special high-quality, high-performance and high value-added products and services to specific users, specialized aluminum foil enterprises can obtain stable business income.

Aluminum foil enterprises can cooperate with aluminum processing market research institutions to fully study and demonstrate their market, and adopt the mode of professional development to make brands in the subdivided aluminum foil market. Although the horizontal scale of the new aluminum foil market is small, it can vertically extend the industrial chain, and process the aluminum foil materials into terminal products. Relying on the high added value of products, it can offset the lack of professional market capacity and scale, and relying on the competitive advantage of professional brands, it can still obtain better business benefits.

铝箔

Industry advantages

Advantages of carbon coated aluminum foil in lithium battery application

1. Restrain the cell polarization, reduce the thermal effect and improve the rate performance;

2. The internal resistance of the battery is reduced, and the dynamic increase of the internal resistance during the cycle is obviously reduced;

3. Improve the consistency and increase the cycle life of the battery;

4. Improve the adhesion between the active substance and the collector, and reduce the manufacturing cost of the electrode;

5. Protect the collector from electrolyte corrosion;

6. Improve the processability of lithium iron phosphate and lithium titanate.

Coating thickness on both sides: type a 4-6 μ m. B 2-3 μ m。

Conductive coating

It is a breakthrough technology innovation to use functional coating to treat the surface of battery conductive substrate. Carbon coated aluminum foil / copper foil is to evenly and finely coat the dispersed nano conductive graphite and carbon coated particles on the aluminum foil / copper foil. It can provide excellent static conductivity and collect the micro current of active materials, which can greatly reduce the contact resistance between positive / negative materials and current collector, improve the adhesion between them, reduce the amount of binder used, and thus significantly improve the integrity of the battery. The coating can be divided into two types: water (water agent system) and oil (organic solvent system).

Performance advantages

Performance advantages of carbon coated aluminum foil / copper foil

1. Significantly improve the consistency of the battery pack, greatly reduce the cost of the battery pack. For example:

·The increase of dynamic internal resistance of the cell is obviously reduced;

·Improve the consistency of pressure difference of battery pack;

·Extend the battery life;

·Greatly reduce the cost of battery pack.

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