A short-process casting and rolling billet to produce semi-rigid antibacterial aluminum foil and its preparation method

Abstract

The present invention belongs to the field of aluminum foil production and processing, and discloses a preparation method for producing semi-rigid antibacterial aluminum foil from a short-process cast-rolled billet, which sequentially undergoes the processes of smelting, casting and rolling, cold rolling, homogenization annealing, intermediate rolling, longitudinal shearing, finishing rolling, foil rolling, coiling, rolling products, slitting, and furnace annealing. Compared with existing aluminum alloy materials, it has excellent deep drawing performance, good deformation ability, high bursting strength, excellent antibacterial effect, high cleanliness, and short process. After forming, it has certain structural rigidity and is not easy to deform. At the same time, through innovative heat treatment control technology, it effectively reduces the thickness of the oxide film on the surface of the cast-rolled billet aluminum and the surface residues, and can better disperse and precipitate the antibacterial second phase in the aluminum alloy matrix. It has the advantages of good antibacterial, clean surface, and controllable wetting angle. It meets the technical requirements of semi-rigid, high cleanliness, and antibacterial aluminum foil. It has important practical value in the production of food packaging industry.

Description

Technical Field

[0001] The invention belongs to the field of aluminum foil production and processing, and specifically relates to a short-process casting and rolling billet to produce semi-rigid antibacterial aluminum foil and a preparation method thereof. Background Art

[0002] In recent years, as people's quality requirements for daily necessities have become higher and higher, more and more antibacterial materials have entered scientific research and people's daily lives. In terms of food and hygiene, people hope that the hygiene status is very high. Not only in food and hygiene, but also in medical and research institutions, the demand for antibacterial properties is also very high.

[0003] The existing antibacterial aluminum foil used in air conditioner radiators and pharmaceutical packaging all uses antibacterial coatings on the surface of the aluminum foil to achieve the antibacterial effect, while there are few products in the field of semi-rigid food aluminum foil that have antibacterial properties. The antibacterial coating in the aluminum foil is inevitably contaminated by microorganisms during the production and packaging process, and the production cost of the antibacterial coating is relatively high; in order to reduce the degree of contamination, the cleanliness of the production workshop is required to be higher. Therefore, if a short-process semi-rigid deep-drawing antibacterial aluminum foil with its own antibacterial properties can be developed, the production process can be simplified, production efficiency can be improved, and costs can be reduced.

[0004] Chinese patent CN 108118195 A discloses a novel antibacterial edible aluminum foil, which comprises the following components: Si, Fe, Cu, Mn, Mg, Zn, Ti, Y, and the rest is Al and inevitable impurities, wherein the mass percentage of each component is: Si: ≤0.16%, Fe: 0.80-1.70%, Cu: 0.08-0.17%, Mn: ≤0.4%, Mg: ≤0.04%, Zn: ≤0.06%, Ti: ≤0.06%, Y: 0.05-0.10%, each of other impurity elements is <0.05%, the total of impurity elements is <0.15%, and the balance is Al. The composition of alloy elements has been adjusted. Compared with the 1 series alloy, Fe (from 0.4% to 0.8-1.7%) and Y (from 0 to 0.1%) are increased. The addition of alloy elements will increase the material cost on the one hand, and increase the difficulty of alloy casting and rolling on the other hand, and easily form intermetallic compounds in the ingot. In addition, the product obtained by four annealing processes according to the method of patent document 1 has the problems of greatly increased cost, extended production cycle, reduced strength, poor antibacterial stability, etc., and the structural rigidity of the material is greatly reduced after molding. There is a problem of insufficient improvement in processability leading to increased production cost and cycle, which makes it difficult to use in semi-rigid food containers and packaging materials.

[0005] The existing antibacterial aluminum alloy foil and its manufacturing method have the following problems: currently, antibacterial coating is generally used to achieve the antibacterial effect; and due to the poor cold formability, high cost, poor cleanliness, low bursting strength and poor antibacterial effect of aluminum alloy foil, the aluminum alloy foil cracks during deformation, breaks easily and has poor antibacterial effect during use; at the same time, the production cost is high, the process is long, the yield is low, and the surface odor is heavy, which cannot meet the technical requirements of semi-rigid antibacterial aluminum foil for food. Therefore, it is urgent to provide a good antibacterial aluminum alloy foil with a short process, good deformation ability, high bursting strength, excellent antibacterial effect, cleanliness, certain structural bearing capacity after forming, and not easy to deform. At the same time, through innovative heat treatment control technology, the thickness of the aluminum surface oxide film and surface residues are effectively reduced, which can better disperse and precipitate the antibacterial second phase evenly in the aluminum alloy matrix; it has the advantages of good antibacterial properties, clean surface, and controllable wetting angle; it meets the technical requirements of aluminum alloy foil for cold deformation, low odor, and excellent antibacterial properties; it has important practical value in the production of the food packaging industry; it solves the problems of poor antibacterial effect of aluminum alloy foil, cracking during deformation, insufficient load-bearing rigidity, and poor cleanliness. Summary of the invention

[0006] In order to solve the deficiencies in the prior art, the present invention provides a method for producing semi-rigid antibacterial aluminum foil by short-process casting and rolling billets, which solves the technical problems of aluminum foil cold forming cracking, strong odor, poor antibacterial effect and the like in the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A short-process casting and rolling billet is used to produce a semi-rigid antibacterial aluminum foil. The aluminum foil is prepared from the following raw materials in percentage by mass: Si = 0.005-0.3%, Fe = 0.1-0.75%, Cu: 0.05-0.25%, Mn < 0.15%, Mg < 0.1%, Cr < 0.05%, Zn: 0.05-0.5%, Ti = 0.01-0.10%, and the rest is Al; Fe: Si > 3.0; Fe: Zn > 4.0; Fe: Cu > 2.5.

[0009] The present invention also provides a method for producing a semi-rigid antibacterial aluminum foil by using the short-process cast-rolled billet, comprising the following steps:

[0010] The raw materials are sequentially smelted and cast-rolled, wherein the smelting temperature is not higher than 760°C, and the temperature range of the furnace conduction is 730-760°C; after cold rolling, a billet 1 with a thickness of 1.0-5.5 mm is obtained, and after homogenization heat treatment, intermediate rolling and longitudinal shearing are performed to roll the billet 2 with a thickness of 0.35-0.8 mm; the billet 2 is finely rolled to roll the billet 3 with a thickness of 0.2-0.45 mm; the foil rolling process is transferred to the foil rolling rough rolling to a single-layer double-sided smooth aluminum alloy foil product with a thickness of 0.010 mm-0.12 mm; the foil is rolled into a single-sided smooth aluminum alloy foil product with a thickness of 0.005 mm-0.06 mm, and the finished product is stabilization annealed after slitting.

[0011] Further, the homogenization heat treatment comprises the following steps:

[0012] Heat up to 150-300℃ at 3.0℃ / min-5.0℃ / min, keep warm for 100-360min; purge air volume is controlled at 100%;

[0013] Heat up to 400-560℃ at 1.5℃ / min-3.5℃ / min, keep warm for 600-1500min; control the purge air volume at 0-50%;

[0014] Cool down to 350-530℃ at 0.8℃ / min-1.5℃ / min, keep warm for 180-600min; control the purge air volume at 10-50%;

[0015] Cool quickly to below 200℃ and take out of the furnace to cool.

[0016] Furthermore, the specific steps of the stabilization annealing are as follows:

[0017] Adopt positive or negative pressure annealing control, keep the temperature at 80℃~200℃ for 5~25 hours; control the speed of circulating fan at 300~800rpm / min; keep the temperature at 50℃~100℃ for 3~20 hours and then take out of the furnace to cool; control the speed of circulating fan at 300~600rpm / min; finally take out of the furnace to cool.

[0018] Furthermore, after smelting for 4-6 hours, the aluminum liquid is sent to a static furnace for refining, and 99.99% high-purity argon inert gas and refining agent are used for refining for 20-30 minutes, and the inert gas and refining agent are used for refining at 750°C for 15 to 30 minutes. After the refining is completed, the slag is removed, and the refining is repeated again after an interval of 1 hour. The smelting in the static furnace is completed by standing for 20-40 minutes.

[0019] Furthermore, a modifier with a mass ratio of 0.007-0.010% is added during the refining process, wherein the modifier is an Al-Ti alloy; and the refining agent is a salt synthesized from anhydrous magnesium chloride and potassium chloride.

[0020] Furthermore, the metal temperature of the billet after homogenization heat treatment and cooling out of the furnace is less than 45°C.

[0021] Furthermore, the melt is fully stirred during the smelting process to ensure uniform composition; high-intensity electromagnetic stirring of 5 to 99% is used for electromagnetic stirring intensity: stirring frequency: 0.5 to 5 Hz, stirring time: 0.5-12 hours of continuous operation; after a cycle of 10 to 30 minutes, the temperature difference between the upper and lower parts of the melt does not exceed 5°C, and the uniformity deviation value of the melt alloy composition is ≤5%.

[0022] Furthermore, the finishing rolling adopts a finishing mill, and the oil quality control of the finishing mill is: viscosity 40℃: 1.7-2.1mm 2 / s; saponification value 4.0-6.0mgKOH / g; hydroxyl value ≤1.0mgKOH / g; ester: 1.7-2.8%; alcohol: ≤0.5%; colloid ≤12g / L; moisture ≤150ppm; flash point ≥82℃.

[0023] Furthermore, during the rough rolling process of the foil, the roughness of the working roll surface is 0.25-0.4 μm, the double convexity is 0.03-0.06 mm, and the rough rolling speed is 600-1200 m / min; the cooling pressure of the rolling oil used in the foil rolling process is 0.4-0.6 MPa, the temperature is 35-50°C, the mass concentration of the rolling oil additive is 5.0-9%, and the gum content is ≤15 g / L.

[0024] Beneficial Effects

[0025] The present invention adopts aluminum alloy material to produce short-process cast and rolled billets to produce semi-rigid antibacterial aluminum foil. Compared with the existing aluminum alloy materials, the present invention has the advantages of short process, excellent antibacterial effect, good deformation ability, high bursting strength and low odor. After forming, it has certain load-bearing rigidity and is not easy to deform. At the same time, through innovative heat treatment control technology, the thickness of the aluminum surface oxide film and surface residues are effectively reduced, and the antibacterial second phase can be better dispersed and precipitated uniformly in the aluminum alloy matrix. It has the advantages of good antibacterial effect, clean surface, controllable wetting angle, etc. It meets the technical requirements of aluminum alloy foil with cold deformation, low odor and excellent antibacterial effect. It has important practical value in the production of food packaging industry. It solves the problems of poor antibacterial effect of aluminum alloy foil, cracking during deformation process, insufficient load-bearing rigidity, poor cleanliness, etc. The invention has the advantages of low odor, good antibacterial properties, clean surface, and controllable wetting angle. It meets the technical requirements of aluminum alloy foil with excellent deformation ability, low odor, and excellent antibacterial properties. Through the combination of special alloying component design and heat treatment process, on the basis of 1 series aluminum alloy, the invention adds a certain amount of Cu and Zn multi-elements to the aluminum liquid during the preparation of aluminum foil, and combines high and low temperature heat treatment to make the aluminum foil surface and the inside uniformly disperse and precipitate fine copper-rich and zinc-rich second phases, so that it has certain antibacterial properties, thereby obtaining a new type of antibacterial edible aluminum foil. At the same time, the uniformity of the grain structure is ensured, and the deformation ability of the material is improved. The finished product adopts a low-temperature treatment combined step to ensure that the aluminum alloy surface uniformly disperses and precipitates the second phase of antibacterial ions; and the surface wetting angle of the treated aluminum foil is controllable, which meets the surface wettability and low odor product requirements of aluminum foil for food, and the quality and rolling performance of the finished product can be completely comparable to those of hot-rolled aluminum foil blanks. At the same time, the production cost is low and it has important practical value in the production of food packaging industry.

[0026] After testing, the aluminum foil obtained by the process of the present invention has a longitudinal / transverse mechanical property control δb of 140-230MPa, an elongation of ≥1.0-6%, a yield strength ratio of greater than 75%, a burst strength of greater than 100KPa, a wetting angle of 20-75°, an antibacterial activity value R of Staphylococcus aureus and Escherichia coli of greater than 2.0, and an antibacterial rate of more than 99.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Surface electron microscope images of the products in Comparative Example 2 and Example 2. DETAILED DESCRIPTION

[0028] The present invention is further described below. The following examples are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0029] The invention discloses a method for preparing a semi-rigid antibacterial aluminum foil by using a short-process casting and rolling billet, comprising the following steps:

[0030] (1) Melting and casting process: The aluminum alloy is melted and cast in sequence, where the melting temperature is not higher than 760°C and the temperature range of the furnace is 730-760°C. The smelting and casting process must be cleanly deslagging and degassing to ensure uniform composition;

[0031] (2) Cold rolling and homogenization heat treatment: The billet of step (1) is subjected to billet rolling, and the billet is rolled into a billet 1 with a thickness of 1.0 to 5.5 mm through 1 to 3 passes, and the outer ring of the billet 1 is welded, tightened with a strapping tape, and transferred to an annealing furnace for production; the metal temperature of the billet after homogenization annealing and cooling is less than 45° C., and rolling oil is used for lubrication and cooling to obtain an aluminum alloy coil;

[0032] (3) Intermediate rolling and longitudinal shearing: the semi-finished product of step (2) is intermediate rolled and then rolled through 3 to 5 passes into a second billet with a thickness of 0.35 to 0.8 mm, and longitudinally sheared;

[0033] (4) Finish rolling: The semi-finished product of step (3) is subjected to finish rolling, and after the intermediate rolling, the finish rolling is continued for 1 to 2 passes, and the finished product of the rough material is rolled to a billet of 0.2 to 0.45 mm in thickness, and the finish rolling is completed;

[0034] (5) Foil rolling: The aluminum foil blank obtained in step (4) is rolled into an aluminum foil raw material with a thickness of 0.2 mm to 0.45 mm by a cold rolling mill, and then transferred to a foil rough rolling process, and then the foil is rolled for 1 to 4 passes to a single-layer double-sided smooth aluminum alloy foil finished product with a thickness of 0.010 mm to 0.12 mm;

[0035] (6) Coiling and rolling finished products: The single double-glazed foil obtained in step (5) is then sent to a four-roll irreversible foil rolling mill for double-glazed foil rolling, and the foil is rolled into a single-sided glazed aluminum alloy foil with a thickness of 0.005 mm to 0.06 mm. An adjustable high-speed air knife-type blowing device is installed in the middle of the outlet side of the rolling mill, and the surface oil content of the finished product is less than 10 mg / m 2 Finished aluminum foil products;

[0036] (7) Cutting and annealing in a furnace: The finished aluminum foil in step (6) is cut into finished aluminum foil products, and then sent to an annealing furnace for stabilization annealing of the finished products. After the annealing is completed, the finished aluminum foil is allowed to cool naturally.

[0037] (8) Inspection and finished product packaging: After stabilization annealing and cooling, the final product is inspected for size, surface, and end face, mainly including thickness tolerance and width tolerance; the surface quality is inspected. There should be no bright lines, stripes, scratches, black threads or black stripes on the surface that affect the surface appearance quality; the end face quality is inspected. The end face should be flat and clean. There should be no staggered layers, wrinkles, tower shapes, stains, etc. There should be no ruffles, broken waves, etc. There should be no joints. After the inspection is completed, the film is wrapped and packaged. After packaging, the sleeve is sealed with black plugs at both ends.

[0038] In the above process, during the smelting and casting process of step (1), the melt is stirred by electromagnetic stirring. During the smelting process of step (1), the mass percentage of each element in the aluminum foil is as follows:

[0039] a. Adding the aluminum alloy including aluminum ingots and AL-Fe, AL-Cu, and AL-Zn master alloys in the smelting furnace according to the above ratio, the AL-Fe master alloy is an alloy containing 20±2% Fe by mass, or an additive containing 75±2% Fe by mass; the AL-Cu master alloy is an alloy containing 50±2% Cu by mass, or an additive containing 75±3% Cu by mass; the AL-Zn master alloy is an alloy containing 80-85% Zn by mass; the mass ratio of each element in the aluminum alloy during the smelting process is Si = 0.005-0.3%, Fe = 0.1-0.75%, Cu: 0.05-0.25%, Mn < 0.15%, Mg < 0.1%, Cr < 0.05%, Zn: 0.05-0.5%, Ti = 0.01-0.10%, and the rest is Al; Fe: Si> 3.0; Fe: Zn> 4.0; Fe: Cu> 2.5;

[0040] Preferably, the proportions of the elements in the aluminum alloy are: Si=0.08%, Fe=0.45%, Cu: 0.135%, Mn<0.05%, Mg<0.05%, Cr<0.05%, Zn: 0.09%, Ti=0.035%, and the rest is Al;

[0041] Preferably, the proportions of the elements in the aluminum alloy are: Si=0.08%, Fe=0.48%, Cu: 0.16%, Mn<0.05%, Mg<0.05%, Cr<0.05%, Zn: 0.08%, Ti=0.027%, and the rest is Al;

[0042] Preferably, the proportions of the elements in the aluminum alloy are: Si = 0.19%, Fe = 0.52%, Cu: 0.18%, Mn < 0.05%, Mg < 0.05%, Cr < 0.05%, Zn: 0.05%, Ti = 0.03%, and the rest is Al

[0043] b. After smelting for 4-6 hours, the aluminum liquid after smelting in step a is sent to a static furnace for refining, and 99.99% high-purity argon inert gas and refining agent are used for refining for 20-30 minutes, and the inert gas and refining agent are used for refining at 750°C for 15-30 minutes. The inert gas can be argon inert gas. After the refining is completed, the scum is removed, and the refining is repeated again at an interval of 1 hour. The smelting in the static furnace is completed by standing for 20-40 minutes, preferably standing for 40 minutes; in the above smelting process, the melt needs to be fully stirred to ensure uniform composition; 5-99% high-intensity electromagnetic stirring can be used for electromagnetic stirring intensity: stirring frequency: 0.5-5HZ, stirring time: 0.5-12 hours continuous operation, preferably 3.5HZ stirring frequency The melt is continuously stirred for 6 hours; after implementing a cycle of 10-30 minutes, the temperature difference between the upper and lower parts of the melt does not exceed the temperature of 5°C, and the uniformity deviation value of the melt alloy composition is ≤5%. During the refining process, a modifier with a mass ratio of 0.007-0.010% is added, wherein the modifier is an Al-Ti alloy; and the refining agent is a salt synthesized from anhydrous magnesium chloride and potassium chloride.

[0044] Preferably, the mass percentage of the modifier Sr is: 0.015%; after the modifier Sr is added, the smelting is carried out at 760°C for 6 hours and then refined for 30 minutes. After the slag on the surface of the melt is removed, and the refining is repeated again after an interval of 1 hour to complete the smelting in the smelting furnace.

[0045] Preferably, the mass percentage of the modifier Sr is: 0.02%; after the modifier Sr is added, the melt is smelted at 770°C for 4.5 hours and then refined for 20 minutes. After completion, the scum on the surface of the melt is removed, and the refining is repeated again after an interval of 1 hour to complete the smelting in the smelting furnace.

[0046] The finishing rolling adopts a finishing mill, and the oil quality control of the finishing mill is: viscosity 40℃: 1.7-2.1mm 2 / s; saponification value 4.0-6.0mgKOH / g; hydroxyl value ≤1.0mgKOH / g; ester: 1.7-2.8%; alcohol: ≤0.5%; colloid ≤12g / L; moisture ≤150ppm; flash point ≥82℃.

[0047] c. Casting and rolling the aluminum liquid after smelting in a static furnace in step b into a billet with a thickness of 6.0 to 10 mm. During the casting and rolling process, a 99.99% high-purity nitrogen inert gas high-speed rotary blowing method is used for online degassing. The speed of the graphite rotor during online degassing is 400 to 600 r / min. After online degassing, the hydrogen content in the aluminum liquid is ≤0.13 ml / 100 g (Al); after the online degassing is completed, the aluminum liquid is introduced into a three-stage filtration, wherein the filter plate accuracy of the second-stage filtration is 50+70 PPi, and the filtering device used in the third-stage filtration is an RB-level 7-tube filter device. The diameter of the aluminum slag removed by filtration is ≤0.005 mm. After the filtration is completed, continuous casting and rolling is continued to obtain the billet;

[0048] d. The aluminum liquid after degassing and filtration in step c is continuously cast and rolled, and a small casting and rolling area of ​​40 to 70 mm and a low rolling speed of 0.65 to 1.2 m / min are used during the vertical plate and production, and the casting and rolling cooling strength capacity is 700 to 3000 L / min, so as to reduce the precipitation of supersaturated solid solution during the solidification of the melt and obtain a metallurgical structure with uniform and fine grains.

[0049] Preferably, the homogenization heat treatment in step (2) comprises the following steps:

[0050] Heat up to 150-300℃ at 3.0℃ / min-5.0℃ / min, keep warm for 100-360min; purge air volume is controlled at 100%;

[0051] Heat up to 400-560℃ at 1.5℃ / min-3.5℃ / min, keep warm for 600-1500min; control the purge air volume at 0-50%;

[0052] Cool down to 350-530℃ at 0.8℃ / min-1.5℃ / min, keep warm for 180-600min; control the purge air volume at 10-50%;

[0053] Cool quickly to below 200℃ and take out of the furnace to cool.

[0054] After high-temperature homogenization annealing, the segregation of the structure is eliminated, and the compounds in the aluminum alloy matrix are spheroidized, dissolved and reprecipitated, and the uniformity of the structure is further improved; at the same time, the aluminum matrix is ​​evenly dispersed with fine precipitates of multi-element antibacterial second phases, with a size of less than 10μm. After homogenization and high-temperature annealing, the performance of the first semi-finished product is controlled at 70-100MPa, the elongation is greater than 40%, the yield strength ratio is greater than 45%, and the average grain size after annealing is less than 120μm; by effectively controlling the precipitation, growth and distribution of the second phase, a larger number of second phases and a finer grain structure are obtained, so that it can be broken into fine dispersed particles in the subsequent cold rolling process.

[0055] During the intermediate rolling process of step (3), the roughness of the working roll surface is 0.35-0.6 μm, the convexity is 0.01-0.04 mm on the upper side and flat on the lower side, and the finishing rolling speed is 400-800 m / min; the rolling oil cooling pressure used in the cold rolling process is 0.4-0.6 MPa, the temperature is 30-45° C., the mass concentration of the rolling oil additive is 6.5-11%, and the colloid content is ≤20 g / L;

[0056] During the rough rolling process of the foil in step (4), the roughness of the working roll surface is 0.25-0.4 μm, the double convexity is 0.03-0.06 mm, and the rough rolling speed is 600-1200 m / min; the cooling pressure of the rolling oil used in the foil rolling process is 0.4-0.6 MPa, the temperature is 35-50°C, the mass concentration of the rolling oil additive is 5.0-9%, and the colloid content is ≤15 g / L.

[0057] During the process of coiling and rolling the finished product in step (5), the single-layer coil obtained in step (5) is evenly divided into coils (i.e., a large coil is divided into two small coils with the same coil diameter), and after the coiling, the coiling operation is performed (the two small coils are double-rolled), and the coiling machine performs online oil spraying and coiling; the double-rolling oil is a low-viscosity, low-aromatic content double-rolling oil with a viscosity of ≤1.25mm2 / s;

[0058] The single-layer coil obtained in step (5) is divided into coils, and then the coils are closed (two small coils are double-rolled), and the rolling mill is double-unrolled to close the coils online by dripping oil, and the online oil is evenly and continuously dripped every 5-10 cm;

[0059] The surface roughness of the finished product working roll is 0.10-0.19 μm, the double convexity is 0.04-0.08 mm, and the rough rolling speed is 500-1100 m / min; the cooling pressure of the rolling oil used in the foil rolling process is 0.4-0.6 MPa, the temperature is 40-60°C, the mass concentration of the rolling oil additive is 5.0-8.5%, and the colloid content is ≤10 g / L.

[0060] During the slitting and furnace annealing process of step (7), the above-mentioned method for preparing a semi-rigid antibacterial aluminum foil by a short-process cast-rolled billet, wherein the specific steps of the stabilization annealing in step (7) are as follows:

[0061] Adopt positive or negative pressure annealing control, keep the temperature at 80℃~200℃ for 5~25 hours; control the speed of circulating fan at 300~800rpm / min; keep the temperature at 50℃~100℃ for 3~20 hours and then take out of the furnace to cool; control the speed of circulating fan at 300~600rpm / min; finally take out of the furnace to cool. After stabilization annealing, the surface layer of the aluminum alloy matrix is ​​evenly dispersed with fine precipitated antibacterial second phase, with a size of less than 5μm.

[0062] After low-temperature stabilization annealing, the surface of the aluminum alloy matrix is ​​evenly dispersed with fine precipitated ionic antibacterial second phase, with a size less than 5 μm; the wetting angle of the aluminum foil surface is controlled at 20-75°.

[0063] During the inspection and finished product packaging process of step (7), the longitudinal / transverse mechanical properties are controlled to have δb of 140-230 MPa, elongation ≥1.0-6%; yield strength ratio greater than 75%; burst strength greater than 100 KPa; wetting angle of 20-75°; antibacterial activity value R against Staphylococcus aureus and Escherichia coli greater than 2.0, and the antibacterial rate is above 99.5%.

[0064] The invention adopts aluminum alloy material to produce short-process cast-rolled billets to produce semi-rigid antibacterial aluminum foil. Compared with the existing aluminum alloy material, the invention has the advantages of short process, excellent antibacterial effect, good deformation ability, high bursting strength and low odor. After forming, the invention has certain load-bearing rigidity and is not easy to deform. At the same time, through innovative heat treatment control technology, the thickness of the aluminum surface oxide film and surface residues are effectively reduced, and the antibacterial second phase can be better dispersed and precipitated in the aluminum alloy matrix. The invention has the advantages of low odor, good antibacterial effect, clean surface, controllable wetting angle and the like. The invention meets the technical requirements of aluminum alloy foil with excellent deformation ability, low odor and antibacterial effect. At the same time, through the combination of special alloying component design and heat treatment process, on the basis of 1 series aluminum alloy, in the preparation process of aluminum foil, a certain amount of Cu and Zn multi-elements are added to the aluminum liquid to act together, and combined with high and low temperature heat treatment, the fine copper-rich and zinc-rich second phases are uniformly dispersed and precipitated from the surface to the inside of the aluminum foil, so that the aluminum foil has certain antibacterial ability, thereby obtaining a novel antibacterial edible aluminum foil. At the same time, the uniformity of the grain structure is guaranteed, and the deformation ability of the material is improved. The finished product adopts a combination of low-temperature treatment steps to ensure that the antibacterial ion second phase is evenly dispersed on the surface of the aluminum alloy; and the wetting angle of the treated aluminum foil surface is controllable, which meets the surface wettability and low-odor product requirements of aluminum foil for food use, and the quality and rolling performance of the finished product are completely comparable to those of hot-rolled aluminum foil blanks. At the same time, the low production cost has important practical value in the food packaging industry.

[0065] After testing, the aluminum foil obtained by the process of the present invention has a longitudinal / transverse mechanical property control δb of 140-230MPa, an elongation of ≥1.0-6%, a yield strength ratio of greater than 75%, a burst strength of greater than 100KPa, a wetting angle of 20-75°, an antibacterial activity value R of Staphylococcus aureus and Escherichia coli of greater than 2.0, and an antibacterial rate of more than 99.5%.

[0066] Hereinafter, the present invention will be described in detail with reference to Examples 1 to 4.

[0067] Table 1

[0068]

[0069]

[0070] Note: The temperature and time of the homogenization heat treatment in Examples 1 to 3 are compared according to the temperature range of 350 to 530°C in the third stage of the homogenization annealing process. The temperature and time in the stabilization annealing are compared according to the temperature range of 80°C to 200°C and time in the first stage of the stabilization annealing process.

[0071] The aluminum alloy melt metal of the composition shown in Table 1 was made into a cast slab with a thickness of 7 mm by a twin-roll continuous casting method, and the cast slab after continuous casting was cold rolled to an intermediate thickness and heat treated as shown in Table 2. After the heat treatment, cold rolling and foil rolling were continuously performed to obtain an aluminum alloy foil with a foil thickness of 16 / 10 μm, and a product stabilization annealing was performed.

[0072] Comparative Examples 1 to 3 were carried out in the same manner as in Example 1, and aluminum alloy foils with a thickness of 16 / 10 μm were obtained by a twin-roll continuous casting method under the conditions shown in Table 1.

[0073] In Examples 1-4, good evaluation results were obtained for the mechanical properties, yield strength ratio, antibacterial effect and wetting angle, and second phase particle distribution density of the finished product.

[0074] In Comparative Example 1, the homogenization heat treatment thickness of 0.5mm is too small, resulting in insufficient total processing rate and deformation of the rolled product thickness, reduced grain breakage, reduced dislocation density, and corresponding reduction in storage energy inside the grains, which will affect the precipitation and size of the second phase particles after stabilization annealing; at the same time, the Cu content is low, so the number of antibacterial particles of fine intermetallic compounds is small, and the intermediate thickness is set small, so the cold rolling reduction after the intermediate homogenization heat treatment until the final foil rolled product thickness is reduced; therefore, the antibacterial activity value and antibacterial rate are insufficient after the stabilization annealing of the finished product.

[0075] In Comparative Example 2, compared with Example 2, the homogenization annealing temperature adopts a high-temperature heat treatment of 580°C. Too high annealing temperature will lead to coarse grains; the elongation is reduced; too high temperature will cause overburning of the structure, which will seriously affect the structure and performance; at the same time, the stabilization annealing time of the finished product is short, and the Fe:Si and Fe:Zn ratios are both low, and the distribution of the second phase compounds is less; therefore, the wettability angle of the finished product after stabilization annealing is large, and the antibacterial effect and antibacterial rate are reduced.

[0076] In Comparative Example 3, the homogenization heat treatment temperature is too low, and the homogenization heat treatment effect is not achieved, which affects the morphology, size and uniformity of the second phase compound; at the same time, the homogenization annealing thickness of 0.8mm is too thin, resulting in insufficient total processing rate and deformation of the rolled product thickness, reduced grain breakage, reduced dislocation density, and corresponding reduction in storage energy inside the grains, as well as a high stabilization annealing temperature for the finished product, which will affect the precipitation and size of the second phase particles after stabilization annealing, and the low performance affects the reduced bearing capacity after stamping; the Zn content is low, and the Fe:Si and Fe:Cu ratios are both low, resulting in fewer second phase compounds after heat treatment; therefore, the number of antibacterial particles of the fine intermetallic compounds is reduced, and the antibacterial effect and antibacterial rate become worse.

[0077] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for producing semi-rigid antibacterial aluminum foil by short-process casting and rolling, characterized in that: The aluminum foil is prepared from the following raw materials in mass percentage: Si = 0.005-0.3%, Fe = 0.1-0.75%, Cu: 0.05-0.25%, Mn < 0.15%, Mg < 0.1%, Cr < 0.05%, Zn: 0.05-0.5%, Ti = 0.01-0.10%, and the rest is Al; Fe: Si> 3.0; Fe:Zn>4.0; Fe:Cu>2.5; The preparation method comprises the following steps: The raw materials are sequentially smelted and cast-rolled, wherein the smelting temperature is not higher than 760°C, and the temperature range of the furnace conduction is 730-760°C; after cold rolling, a billet 1 with a thickness of 1.0-5.5 mm is obtained, and after homogenization heat treatment, intermediate rolling and longitudinal shearing are performed to roll the billet 2 with a thickness of 0.35-0.8 mm; the billet 2 is finely rolled to roll the billet 3 with a thickness of 0.2-0.45 mm; the foil rolling process is transferred to the foil rolling rough rolling to a single-layer double-sided smooth aluminum alloy foil product with a thickness of 0.010 mm-0.12 mm; the foil is rolled into a single-sided smooth aluminum alloy foil product with a thickness of 0.005 mm-0.06 mm, and the finished product is stabilization annealed after slitting; Homogenization heat treatment includes the following steps: Heat up to 150~300℃ at 3.0℃ / min~5.0℃ / min, keep warm for 100~360min; purge air volume control 100%; Heat up to 400~560℃ at 1.5℃ / min~3.5℃ / min, keep warm for 600~1500min; control the purge air volume at 0-50%; Cool down to 350~530℃ at 0.8℃ / min~1.5℃ / min, keep warm for 180~600min; control the purge air volume at 10-50%; Quickly cool to below 200℃ and then take out of the furnace for cooling; The specific steps of the stabilization annealing are as follows: Adopt positive or negative pressure annealing control, keep the temperature at 80℃~200℃ for 5~25 hours; control the speed of circulating fan at 300~800rpm / min; keep the temperature at 50℃~100℃ for 3~20 hours and then take out of the furnace to cool; control the speed of circulating fan at 300~600rpm / min; finally take out of the furnace to cool.

2. The method for producing semi-rigid antibacterial aluminum foil by short-process casting and rolling according to claim 1, characterized in that: After smelting for 4-6 hours, the molten aluminum is sent to a static furnace for refining. It is refined for 20-30 minutes using 99.99% high-purity argon inert gas and refining agent. It is refined for 15-30 minutes at 750°C using inert gas and refining agent. After the refining is completed, the slag is removed and the refining is repeated after an interval of 1 hour. The smelting in the static furnace is completed by standing for 20-40 minutes.

3. The method for producing semi-rigid antibacterial aluminum foil by short-process casting and rolling according to claim 2, characterized in that: During the refining process, a modifier with a mass ratio of 0.007-0.010% is added, wherein the modifier is an Al-Ti alloy; and the refining agent is a salt synthesized from anhydrous magnesium chloride and potassium chloride.

4. The method for producing semi-rigid antibacterial aluminum foil by short-process casting and rolling according to claim 1, characterized in that: The metal temperature of the billet after homogenization heat treatment is less than 45°C after cooling out of the furnace.

5. The method for producing semi-rigid antibacterial aluminum foil by short-process casting and rolling according to claim 1, characterized in that: During the smelting process, the melt is fully stirred to ensure uniform composition; 5~99% high-intensity electromagnetic stirring is used for electromagnetic stirring intensity: stirring frequency: 0.5~5HZ, stirring time: 0.5-12 hours of continuous operation; after implementing a cycle of 10-30min, the temperature difference between the upper and lower parts of the melt does not exceed 5°C, and the uniformity deviation value of the melt alloy composition is ≤5%.

6. The method for producing semi-rigid antibacterial aluminum foil by short-process casting and rolling according to claim 1, characterized in that: The finishing rolling adopts a finishing mill, and the oil quality control of the finishing mill is: viscosity 40℃: 1.7-2.1mm 2 / s; saponification value 4.0-6.0mgKOH / g; hydroxyl value ≤1.0mgKOH / g; ester: 1.7-2.8%; Alcohol: ≤0.5%; colloid ≤12 g / L; moisture ≤150ppm; flash point ≥82℃.

7. The method for producing semi-rigid antibacterial aluminum foil by short-process casting and rolling according to claim 1, characterized in that: During the rough rolling process of the foil, the roughness of the working roll surface is 0.25~0.4μm, the double convexity is 0.03~0.06mm, and the rough rolling speed is 600~1200m / min; the cooling pressure of the rolling oil used in the foil rolling process is 0.4~0.6MPa, the temperature is 35~50℃, the mass concentration of the rolling oil additive is 5.0~9%, and the gum content is ≤15 g / L.

8. A short process for producing semi-rigid antibacterial aluminum foil by casting and rolling billets, characterized in that: The method is prepared by any one of claims 1 to 7.

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