阅读说明：本技术 一种食品包装用铝塑复合袋及其加工方法 (Aluminum-plastic composite bag for food packaging and processing method thereof ) 是由 索利元 窦永伟 焦守清 王军 于 2021-10-13 设计创作，主要内容包括：本发明公开了一种食品包装用铝塑复合袋及其加工方法,属于食品包装技术领域。铝塑复合袋最内层为铝箔层,向外依次为双向拉伸聚丙烯层和热封膜层,层与层之间通过胶黏剂粘结；铝箔层为厚度0.008～0.009mm的1235双零箔,由以下重量份的原料组成：Si：0.086％-0.10％、Fe：0.37％-0.43％、Cu：0.005％-0.01％、Mn：0.005％-0.01％、Mg：0.005％-0.01％、Cr：0.005％-0.01％、Zn：0.005％-0.01％、V：0.02％～0.03％、Ti：0.013％-0.030％,其他单个杂质≤0.01％、总杂质合计≤0.05％,余量为Al,经熔铸、锯铣、均热、热轧、一次冷轧、一次退火、二次冷轧、箔轧、成品退火加工而成。利用本发明方法加工的铝箔抗拉强度和延伸率有了不同程度的提升,耐腐蚀性能提高,应用于食品包装用时铝塑复合袋金属元素迁移速度慢,延长食品的保藏时间。(The invention discloses an aluminum-plastic composite bag for food packaging and a processing method thereof, belonging to the technical field of food packaging. The innermost layer of the aluminum-plastic composite bag is an aluminum foil layer, a biaxially oriented polypropylene layer and a heat-sealing film layer are arranged outwards in sequence, and the layers are bonded through an adhesive; the aluminum foil layer is a 1235 double-zero foil with the thickness of 0.008-0.009 mm and is composed of the following raw materials in parts by weight: si: 0.086% -0.10%, Fe: 0.37% -0.43%, Cu: 0.005% -0.01%, Mn: 0.005% -0.01%, Mg: 0.005% -0.01%, Cr: 0.005% -0.01%, Zn: 0.005% -0.01%, V: 0.02% -0.03%, Ti: 0.013-0.030 percent of the total impurity, less than or equal to 0.01 percent of other single impurities, less than or equal to 0.05 percent of the total impurity and the balance of Al, and the aluminum alloy is prepared by casting, sawing and milling, soaking, hot rolling, primary cold rolling, primary annealing, secondary cold rolling, foil rolling and finished product annealing. The tensile strength and the elongation percentage of the aluminum foil processed by the method are improved to different degrees, the corrosion resistance is improved, the metal element migration speed of the aluminum-plastic composite bag is low when the aluminum foil is applied to food packaging, and the preservation time of food is prolonged.)

1. An aluminum-plastic composite bag for food packaging is characterized in that the innermost layer is an aluminum foil layer, a biaxially oriented polypropylene layer and a heat-sealing film layer are sequentially arranged outwards, and the layers are bonded through an adhesive layer;

the aluminum foil layer is 1235 double-zero foil with the thickness of 0.008-0.009 mm and is composed of the following raw materials in parts by weight: si: 0.086% -0.10%, Fe: 0.37% -0.43%, Cu: 0.005% -0.01%, Mn: 0.005% -0.01%, Mg: 0.005% -0.01%, Cr: 0.005% -0.01%, Zn: 0.005% -0.01%, V: 0.02% -0.03%, Ti: 0.013-0.030 percent, less than or equal to 0.01 percent of other single impurities, less than or equal to 0.05 percent of total impurities and the balance of Al.

2. The aluminum-plastic composite bag for food packaging as recited in claim 1, wherein said aluminum-plastic composite bag is sealed by heat sealing.

3. The processing method of the aluminum-plastic composite bag for food packaging as claimed in claim 1 or 2, characterized in that the aluminum foil layer of the innermost layer is 1235 double-zero foil, and the two-way stretching polypropylene layer and the heat-sealing film layer are arranged outwards in sequence, and the layers are bonded through the adhesive layer;

the processing method of the 1235 double-zero foil comprises the following steps:

(1) casting: smelting and refining the 1235 double-zero foil according to the mass percentage of the chemical components, and casting the alloy into an ingot;

(2) Sawing and milling;

(3) soaking the raw materials: the ingot after sawing and milling is heated in two stages, the first stage is subjected to heat preservation for 6-9 hours at the temperature of 560-580 ℃, and the second stage is subjected to heat preservation for 1.5-2.5 hours at the temperature of 480-500 ℃;

(4) hot rolling: carrying out rough rolling on the ingot after soaking for 16 times, processing the ingot to the thickness of 50-60 mm, then carrying out finish rolling, and finishing rolling to obtain a strip with the thickness of 6.7-7.0, wherein the finish rolling temperature of hot rolling is 290 +/-5 ℃, and the hot rolling speed is 320-350 m/min;

(5) primary cold rolling: carrying out one-time cold rolling on the hot-rolled strip, wherein the thickness of the cold-rolled strip is 3.6-4.0 mm;

(6) primary annealing: keeping the temperature of the strip subjected to primary cold rolling at 560-570 ℃ for 20-25 h;

(7) secondary cold rolling: the strip after the primary annealing is subjected to four or five cold rolling passes to form a strip with the thickness of 0.23-0.28 mm;

(8) foil rolling: the strip after the secondary cold rolling is subjected to foil rolling into an aluminum foil coil with the thickness of 0.02-0.025 mm according to the processing rate of 55-60% of each pass, and then the aluminum foil coil is subjected to double-overlapping rolling to the thickness of 0.008-0.009 mm, so that a finished double-zero foil is obtained;

(9) and (5) annealing the finished product.

4. A process according to claim 3, characterized in that the strip after the cold rolling in steps (5) and (7) is subjected to a trimming treatment.

5. The processing method according to claim 3, wherein the melting temperature in the step (1) is 750-760 ℃, the refining temperature is 690-700 ℃, the casting speed is 60mm/min, and the water temperature is 20-30 ℃.

6. The process according to claim 3, wherein the cold rolling speed in the step (5) and the step (7) is 450 to 500mm/min, and the cold rolling exit temperature is 130 to 150 ℃.

7. The processing method according to claim 3, wherein the thickness of the ingot after the sawing and milling in the step (2) is 560-580 mm.

8. The process of claim 3, wherein the final annealing conditions in step (9) are: the temperature is 220-240 ℃, and the heat preservation time is 20-30 h.

Technical Field

The invention belongs to the technical field of food packaging, and particularly relates to an aluminum-plastic composite bag for food packaging and a processing method thereof.

Background

With the increase of living standard, food packaging has become an important component of food industry, and has irreplaceable effects in protecting food, preventing food from being polluted by external microorganisms or other substances, and preventing or reducing food oxidation and other reactions. Aluminum foil is the only metal material used for composite packaging materials at present, and the aluminum foil is light-tight, oxygen-tight and moisture-tight without pinhole defects and has ideal theoretical barrier property. The aluminum-plastic composite bag (vacuum bag or aluminum foil bag) is a packaging product integrating various packaging advantages, has low cost, is applied to food packaging, can be used for packaging aquatic product products, cured meat, quick-frozen food, salted meat product, pickles, seasonings and other foods, and has the functions of keeping fragrance, quality and color. With the increase of the consumption level of people and the abundance of food types, people pay attention to the food quality and also pay more attention to the safety of food packaging materials.

The aluminum foil layer in the aluminum-plastic composite bag is mainly positioned on the middle layer or the inner layer, and when the aluminum foil is used as the innermost layer and is directly contacted with food, the food safety problem is particularly important. For example, corrosion of aluminum foil results in migration of aluminum or other metal elements into food products (particularly some seafood or marinated products), which, when accumulated to some extent, can pose a serious food safety concern. In order to improve the corrosion resistance of the aluminum foil, the most direct method is to carry out pretreatment on the aluminum foil, such as chromizing treatment, and form a layer of passive film on the surface of a product through chemical reaction to enhance the corrosion resistance of the aluminum foil.

The 1235 aluminum foil has a series of advantages of low temperature resistance, light weight, good sealing and coating properties, and the like, and is widely used as a packaging material for food, beverage, cigarettes, medicines, household daily necessities, and the like. At present, the aluminum foil has high technical content and is widely applied to double-zero aluminum foils, and except for the double-zero aluminum foils with high quality used in electrolytic capacitors, the aluminum foils for most food packaging are also double-zero aluminum foils. The existing 1235 double-zero foil has the defects of low tensile strength and poor ductility, a high-quality 1235 aluminum foil blank needs to be produced, an ingot is usually processed into a strip with the thickness of 6.5-7.0 mm before foil rolling, the ductility and the corrosion resistance of the strip can influence the performance of the final double-zero foil, meanwhile, in the rolling process, due to the solubility difference of alloy elements in aluminum solid solution and melt, the alloy elements are usually gathered on crystal faces in the form of intermetallic compounds, and compound particles are precipitated to cause intergranular corrosion, so that the corrosion resistance and the service life of the alloy are seriously influenced. In addition, the aluminum foil needs to be annealed for multiple times in the rolling process, but the process is long in time consumption, is not favorable for quick turnover of materials, is high in cost, and is not favorable for carbon neutralization environment due to emission of fossil fuels and greenhouse gases.

Disclosure of Invention

The invention provides an aluminum-plastic composite bag for food packaging and a processing method thereof, aiming at the problems of low elongation and tensile strength and poor corrosion resistance of an aluminum foil in the aluminum-plastic composite bag for food packaging in the prior art.

The invention is realized by the following technical scheme:

an aluminum-plastic composite bag for food packaging, the innermost layer is an aluminum foil layer, and the innermost layer is a biaxially oriented polypropylene layer and a heat-sealing film layer which are sequentially arranged outwards, and the layers are bonded through an adhesive layer; the aluminum foil layer is 1235 double-zero foil with the thickness of 0.008-0.009 mm and is composed of the following raw materials in parts by weight: si: 0.086% -0.10%, Fe: 0.37% -0.43%, Cu: 0.005% -0.01%, Mn: 0.005% -0.01%, Mg: 0.005% -0.01%, Cr: 0.005% -0.01%, Zn: 0.005% -0.01%, V: 0.02% -0.03%, Ti: 0.013-0.030 percent, less than or equal to 0.01 percent of other single impurities, less than or equal to 0.05 percent of total impurities and the balance of Al.

Further, the aluminum-plastic composite bag is sealed by adopting a heat sealing process.

According to the processing method of the aluminum-plastic composite bag for food packaging, the aluminum foil layer of the innermost layer is 1235 double-zero foil, the two-way stretching polypropylene layer and the heat-sealing film layer are arranged outwards in sequence, and the layers are bonded through the adhesive layer;

the processing method of the 1235 double-zero foil comprises the following steps:

(1) casting: smelting and refining the 1235 double-zero foil according to the mass percentage of the chemical components, and casting the alloy into an ingot;

(2) sawing and milling;

(3) soaking the raw materials: the ingot after sawing and milling is heated in two stages, the first stage is subjected to heat preservation for 6-9 hours at the temperature of 560-580 ℃, and the second stage is subjected to heat preservation for 1.5-2.5 hours at the temperature of 480-500 ℃;

(4) hot rolling: carrying out rough rolling on the ingot after soaking for 16 times, processing the ingot to the thickness of 50-60 mm, then carrying out finish rolling, and finishing rolling to obtain a strip with the thickness of 6.7-7.0, wherein the finish rolling temperature of hot rolling is 290 +/-5 ℃, and the hot rolling speed is 320-350 m/min;

(5) primary cold rolling: carrying out one-time cold rolling on the hot-rolled strip, wherein the thickness of the cold-rolled strip is 3.6-4.0 mm;

(6) primary annealing: keeping the temperature of the strip subjected to primary cold rolling at 560-570 ℃ for 20-25 h;

(7) secondary cold rolling: the strip after the primary annealing is subjected to four or five cold rolling passes to form a strip with the thickness of 0.23-0.28 mm;

(8) Foil rolling: the strip after the secondary cold rolling is subjected to foil rolling into an aluminum foil coil with the thickness of 0.02-0.025 mm according to the processing rate of 55-60% of each pass, and then the aluminum foil coil is subjected to double-overlapping rolling to the thickness of 0.008-0.009 mm, so that a finished double-zero foil is obtained;

(9) and (5) annealing the finished product.

Further, the strips after the cold rolling in the step (5) and the step (7) are subjected to edge cutting treatment.

Further, the smelting temperature in the step (1) is 750-760 ℃, the refining temperature is 690-700 ℃, the casting speed is 60mm/min, and the water temperature is 20-30 ℃.

Further, the cold rolling speed in the step (5) and the step (7) is 450-500 mm/min, and the cold rolling outlet temperature is 130-150 ℃.

Further, the thickness of the cast ingot after the sawing and milling in the step (2) is 560-580 mm.

Further, the annealing conditions of the finished product in the step (9) are as follows: the temperature is 220-240 ℃, and the heat preservation time is 20-30 h.

In the invention, the mechanical property and the elongation of the prepared 1235 double-zero foil are obviously improved. Firstly, the ingot after sawing and milling is heated in two stages, so that the growth of the second crystal phase and the dissolution of other impurities can be hindered, the growth tendency of crystal grains is weakened, the crystal grains are refined by soaking at high temperature for a short time, the intragranular segregation is eliminated and reduced, the ingot has better chemical homogeneity and tissue homogeneity, the tensile strength and the elongation performance are improved, and the machinability of the material is improved. On the other hand, only one-time annealing treatment is adopted in the cold rolling process, but the annealing treatment temperature is increased, the one-time annealing time is prolonged, and the mechanical property and the elongation of the prepared double-zero foil are improved in a small range. The 1235 double-zero foil prepared by the method is applied to processing of the aluminum-plastic composite bag, and the aluminum foil is not easy to crack and break.

The 1235 double-zero foil prepared by the invention adopts a two-stage heating and gradient cooling process, alloy elements in the aluminum alloy are dissolved in a matrix in a solid manner, the alloy precipitation is inhibited, the tendency of intergranular corrosion is reduced, the salt and alkali corrosion resistance of the prepared 1235 double-zero foil is finally improved, the 1235 double-zero foil is applied to the processing of aluminum-plastic composite bags, the migration tendency of the metal elements to food is reduced, the application range of the aluminum-plastic composite bags is expanded, the safety of the food is improved, and the storage time of the food is prolonged.

The 1235 double-zero foil for the aluminum-plastic composite bag shortens soaking time, directly saves secondary annealing time, shortens production time, is favorable for accelerating material turnover, simultaneously reduces energy consumption, saves cost and is favorable for environmental protection.

Advantageous effects

According to the invention, a two-stage heating process is adopted for ingot casting and uniform heating, and two annealing processes are improved into one annealing process, so that the production time is shortened, the prepared 1235 double-zero aluminum foil has higher strength and elongation and improved corrosion resistance, and when the aluminum foil is applied to food packaging aluminum-plastic materials, the aluminum foil is not easy to crack and fracture, the migration speed of metal elements to food is reduced, and the aluminum foil is safer and more environment-friendly.

Drawings

Fig. 1 is a sectional structure view of the aluminum-plastic composite bag for food packaging of the present invention, wherein 1 is an aluminum foil layer, 2 is a biaxially oriented polypropylene layer, 3 is a heat-seal film layer, and 4 is an adhesive layer.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The aluminum-plastic composite bag for food packaging has a three-layer structure, the cross-sectional view of the aluminum-plastic composite bag is shown in figure 1, the aluminum foil layer 1, the biaxially oriented polypropylene layer 2 and the heat-sealing film layer 3 are sequentially arranged from inside to outside, the layers are bonded through the adhesive layer, and the heat-sealing process is adopted for sealing; the aluminum foil layer is a 1235 double-zero foil with the thickness of 0.008-0.009 mm and is composed of the following raw materials in parts by weight: si: 0.86% -0.10%, Fe: 0.37% -0.43%, Cu: 0.005% -0.01%, Mn: 0.005% -0.01%, Mg: 0.005% -0.01%, Cr: 0.005% -0.01%, Zn: 0.0018% -0.0020%, V: 0.005% -0.1%, Ti: 0.013-0.030 percent, less than or equal to 0.01 percent of other single impurities, less than or equal to 0.05 percent of total impurities and the balance of Al.

The processing method of the 1235 double-zero foil is an important factor for determining the quality (tensile strength, elongation percentage and corrosion resistance) of the aluminum foil and influencing the practicability of the final aluminum-plastic composite bag, and the processing method of the 1235 double-zero foil is specifically described by combining with specific examples.

Example 1

The processing method of the 1235 double-zero foil comprises the following steps:

(1) casting: according to the mass percentage of the chemical components of the aluminum alloy strip: si: 0.086%, Fe: 0.4%, Cu: 0.005%, Mn: 0.005%, Mg: 0.005%, Cr: 0.01%, Zn: 0.0051%, V: 0.02%, Ti: 0.030 percent of other single impurities, less than or equal to 0.01 percent of other single impurities, less than or equal to 0.05 percent of total impurities, the balance of Al and the balance of Al are smelted, refined and cast into ingots, wherein the smelting temperature is 755 +/-5 ℃, the refining temperature is 695 +/-5 ℃, the casting speed is 60mm/min, and the water temperature is 25 +/-5 ℃;

(2) sawing and milling: sawing and milling the cast ingot obtained in the step (1), wherein the thickness of the cast ingot after sawing and milling is 580 mm;

(3) soaking the raw materials: the ingot after sawing and milling is heated by two stages, the first stage is kept at the temperature of 570 ℃ for 8 hours, and the second stage is kept at the temperature of 490 ℃ for 2 hours;

(4) hot rolling: carrying out rough rolling on the ingot after soaking for 16 times, processing the ingot to the thickness of 50mm, then carrying out finish rolling, and finishing to obtain a strip with the thickness of 6.7mm, wherein the hot rolling finishing temperature is 290 +/-5 ℃, and the hot rolling speed is 320 m/min;

(5) Primary cold rolling: carrying out one-time cold rolling on the hot-rolled strip, wherein the thickness of the cold-rolled strip is 3.7mm, the cold rolling speed is 500mm/min, the cold rolling outlet temperature is 150 ℃, and trimming;

(6) primary annealing: keeping the temperature of the strip subjected to primary cold rolling at 565 ℃ for 22 h;

(7) secondary cold rolling: and (3) carrying out five-pass cold rolling on the strip subjected to the primary annealing, and distributing cold rolling passes (from 3.7mm to 0.24mm after five-pass processing, wherein the pass processing rate is shown in parentheses): 3.7 → 1.9 (48.6%) → 1.1 (42.1%) → 0.68 (38.2%) → 0.4 (41.2%) → 0.24 (40%), forming a strip having a thickness of 0.24mm, a cold rolling speed of 500mm/min, a cold rolling outlet temperature of 150 ℃, and a trimming process;

(8) foil rolling: foil rolling is carried out on the strip subjected to secondary cold rolling according to the processing rate of 55-60% of each pass, and the foil rolling pass is distributed (the strip is processed from 0.24mm to 0.020mm through three passes, and the pass processing rate is shown in parentheses): 0.24 → 0.1 (58.3%) → 0.045 (55%) → 0.020 (55.6%), and then double-laminating to a thickness of 0.009mm, so as to obtain a finished double-zero foil;

(9) annealing of a finished product: the temperature is 230 ℃, and the holding time is 28 h.

Example 2

The processing method of the 1235 double-zero foil comprises the following steps:

(1) casting: according to the mass percentage of the chemical components of the aluminum alloy strip: si: 0.09%, Fe: 0.43%, Cu: 0.01%, Mn: 0.005%, Mg: 0.01%, Cr: 0.005%, Zn: 0.005%, V: 0.03%, Ti: 0.013 percent, less than or equal to 0.01 percent of other single impurities, less than or equal to 0.05 percent of total impurities and the balance of Al, smelting, refining and casting into ingots, wherein the smelting temperature is 755 +/-5 ℃, the refining temperature is 695 +/-5 ℃, the casting speed is 60mm/min and the water temperature is 25 +/-5 ℃;

(2) Sawing and milling: sawing and milling the cast ingot obtained in the step (1), wherein the thickness of the cast ingot after sawing and milling is 560 mm;

(3) soaking the raw materials: the ingot after sawing and milling is heated by two stages, the first stage is kept at the temperature of 580 ℃ for 6 hours, and the second stage is kept at the temperature of 500 ℃ for 1.5 hours;

(4) hot rolling: roughly rolling the ingot after soaking for 16 times, processing the ingot to the thickness of 56mm, then performing finish rolling, and finishing rolling to form a strip with the thickness of 6.8mm, wherein the hot rolling finishing temperature is 290 +/-5 ℃, and the hot rolling speed is 340 m/min;

(5) primary cold rolling: carrying out one-time cold rolling on the hot-rolled strip, wherein the thickness of the cold-rolled strip is 3.8mm, the cold rolling speed is 450mm/min, the cold rolling outlet temperature is 130 ℃, and trimming;

(6) primary annealing: keeping the temperature of the strip subjected to the primary cold rolling at 570 ℃ for 20 hours;

(7) secondary cold rolling: and (3) carrying out four-pass cold rolling on the strip subjected to the primary annealing, and distributing cold rolling passes (from 3.8mm to 0.28mm after four-pass processing, wherein the pass processing rate is shown in parentheses): 3.8 → 1.9 (50%) → 1.0 (47.4%) → 0.54 (46%) → 0.28 (48.1%), forming a strip having a thickness of 0.28mm, a cold rolling speed of 450mm/min, a cold rolling outlet temperature of 130 ℃, and a trimming process;

(8) foil rolling: foil rolling is carried out on the strip subjected to secondary cold rolling according to the processing rate of 55-60% of each pass, and the foil rolling pass is distributed (from 0.28mm to 0.025mm after three passes, and the pass processing rate is shown in parentheses): 0.28 → 0.126 (55%) → 0.056 (55.6%) → 0.025 (55.4%), and then double-laminating to a thickness of 0.009mm, thereby obtaining a finished double zero foil;

(9) Annealing of a finished product: the temperature is 240 ℃, and the holding time is 22 h.

Example 3

The processing method of the 1235 double-zero foil comprises the following steps:

(1) casting: according to the mass percentage of the chemical components of the aluminum alloy strip: si: 0.10%, Fe: 0.37%, Cu: 0.005%, Mn: 0.01%, Mg: 0.005%, Cr: 0.005%, Zn: 0.01%, V: 0.025%, Ti: 0.02 percent, less than or equal to 0.01 percent of other single impurities, less than or equal to 0.05 percent of total impurities and the balance of Al, smelting, refining and casting into ingots, wherein the smelting temperature is 755 +/-5 ℃, the refining temperature is 695 +/-5 ℃, the casting speed is 60mm/min and the water temperature is 25 +/-5 ℃;

(2) sawing and milling: sawing and milling the cast ingot obtained in the step (1), wherein the thickness of the cast ingot after sawing and milling is 560 mm;

(3) soaking the raw materials: the ingot after sawing and milling is heated by two stages, wherein the first stage is kept at 560 ℃ for 9 hours, and the second stage is kept at 480 ℃ for 2.5 hours;

(4) hot rolling: roughly rolling the ingot after soaking for 16 times, processing the ingot to the thickness of 60mm, then performing finish rolling, and finishing rolling to form a strip with the thickness of 7.0, wherein the hot rolling finishing temperature is 290 +/-5 ℃, and the hot rolling speed is 350 m/min;

(5) primary cold rolling: carrying out one-time cold rolling on the hot-rolled strip, wherein the thickness of the cold-rolled strip is 4.0mm, the cold rolling speed is 450mm/min, the cold rolling outlet temperature is 130 ℃, and trimming;

(6) Primary annealing: keeping the temperature of the strip subjected to primary cold rolling at 560 ℃ for 25 h;

(7) secondary cold rolling: and (3) carrying out five-pass cold rolling on the strip subjected to the primary annealing, and distributing cold rolling passes (from 4.0mm to 0.26mm after five-pass processing, wherein the pass processing rate is shown in parentheses): 4.0 → 2.4 (40%) → 1.4 (41.7%) → 0.79 (43.6%) → 0.44 (44.3%) → 0.26 (40.9%), forming a strip having a thickness of 0.26mm, a cold rolling speed of 450mm/min, a cold rolling outlet temperature of 130 ℃, and a trimming process;

(8) foil rolling: foil rolling is carried out on the strip subjected to secondary cold rolling according to the processing rate of 55-60% per pass, and the foil rolling pass is distributed (from 0.26mm to 0.022mm after three passes, and the pass processing rate is shown in parentheses): 0.26 → 0.116 (55.4%) → 0.052 (55.2%) → 0.022 (57.7%), and then double-lap-rolling to a thickness of 0.008mm, so as to obtain a finished double zero foil;

(9) annealing of a finished product: the temperature is 220 ℃, and the holding time is 30 h.

Comparative example 1

Comparative example 1 the soaking conditions in step (3) were changed, the ingot after sawing and milling was subjected to primary heating and kept at 570 ℃ for 10 hours, and the remaining steps were the same as in example 1.

Comparative example 2

The steps (1) to (4) are the same as in example 1;

(5) primary cold rolling: carrying out one-time cold rolling on the hot-rolled strip, wherein the thickness of the cold-rolled strip is 3.7mm, and carrying out edge cutting treatment;

(6) Primary annealing: keeping the temperature of the strip subjected to the primary cold rolling at 550 ℃ for 18 h;

(7) secondary cold rolling: and (3) carrying out five-pass cold rolling on the strip subjected to the primary annealing, and distributing cold rolling passes (from 3.7mm to 0.24mm after five-pass processing, wherein the pass processing rate is shown in parentheses): 3.7 → 1.9 (48.6%) → 1.1 (42.1%) → 0.68 (38.2%) → 0.4 (41.2%) → 0.24 (40%), forming a tape having a thickness of 0.24mm, and trimming;

(8) secondary annealing: keeping the temperature of the strip subjected to secondary cold rolling at 550 ℃ for 12 h;

(9) foil rolling is carried out on the strip subjected to secondary annealing according to the processing rate of 55-60% of each pass, and the foil rolling pass is distributed (the strip is processed from 0.24mm to 0.020mm through three passes, and the pass processing rate is shown in parentheses): 0.24 → 0.1 (58.3%) → 0.045 (55%) → 0.020 (55.6%), and then double-laminating to a thickness of 0.009mm, so as to obtain a finished double-zero foil;

(10) annealing of a finished product: the temperature is 230 ℃, and the holding time is 28 h.

Dual zero foil performance testing and analysis

(1) The tensile strength and the elongation of the 1235 aluminum foil prepared in the examples 1 to 3 and the comparative examples 1 and 2 are tested, and the test results are shown in the following table 1, as can be seen from the table 1, the soaking process in the invention has a large influence on the mechanical properties of the prepared aluminum alloy strip, the two-stage heating process is adopted to hinder the growth of the second phase and the dissolution of other impurities, so that the growth tendency of crystal grains is weakened, the intragranular segregation is favorably eliminated and reduced, the aluminum foil has good chemical uniformity and tissue uniformity, and the genetic property of the metal material determines that the rolled aluminum foil has good tensile strength and elongation and the machinability is enhanced. In addition, only one-time annealing is adopted during cold rolling, so that the annealing temperature and the annealing time are increased, the tensile strength and the elongation of the prepared double-zero foil are improved to a small extent, and the prepared double-zero foil is not easy to crack and break.

TABLE 11235 analysis of mechanical properties of aluminum foil

(2) And (3) corrosion resistance analysis: the corrosion resistance of the 1235 aluminum alloy strips after the secondary cold rolling in examples 1 to 3 and comparative examples 1 to 2 was tested, the size of the aluminum alloy strip used in the test was 60mm × 30mm, the temperature in the salt spray corrosion chamber was set to 50 ℃ ± 2 ℃, the salt spray test was performed by means of coupon continuous spraying, the concentration of sodium chloride was 5%, the pH was 3.2, and after the salt spray corrosion was 8, 24, 48, and 72 hours, the corrosion weight loss was analyzed, and the results are shown in table 2 below: as can be seen from table 2, by adopting the two-stage heating and gradient cooling process, the alloy elements in the aluminum alloy are dissolved in the matrix in a solid manner, so that the alloy precipitation is inhibited, and the tendency of intergranular corrosion is reduced, thereby improving the salt and alkali corrosion resistance of the cold-rolled 1235 aluminum alloy strip, and the hereditary property of the metal material also determines that the formed 1235 double-zero foil liquid also has relatively good corrosion resistance.

Salt spray corrosion weight loss ratio (%) analysis of aluminum alloy strip of Table 21235