BOPET (Biaxially Oriented Polyethylene Terephthalate) film for cooking-resistant aluminized packaging bag, preparation method and application

Abstract

The invention relates to the technical field of films, particularly discloses a BOPET (Biaxially Oriented Polyethylene Terephthalate) film for a cooking-resistant aluminized packaging bag, and also discloses a preparation method and application of the BOPET film. The BOPET film for the cooking-resistant aluminized packaging bag comprises a BOPET base film and a coating layer arranged on the surface of one side of the BOPET base film, the coating layer is prepared by coating of water-based coating liquid, and the water-based coating liquid comprises water-based polyester, water-based acrylic resin, a water-based isocyanate cross-linking agent and an alkynol wetting agent. The prepared BOPET film for the cooking-resistant aluminized packaging bag can be applied to packaging of food, medicines, medical instruments and the like needing to be cooked and sterilized at the high temperature of 120 DEG C or above after aluminizing processing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin films, in particular to a BOPET film for a cooking-resistant aluminized packaging bag, and to a preparation method and application thereof. BACKGROUND

[0002] Biaxially oriented polyester film (BOPET) is one of the most widely used plastic films due to its excellent physical and chemical properties. BOPET film is most commonly used in the packaging field, and when used for packaging, it often involves printing, lamination, and aluminizing. The main role of aluminizing on the surface of BOPET film is to block light, prevent ultraviolet radiation, and improve barrier properties, which not only prolongs the shelf life of the contents but also improves the brightness of the film, to some extent, replacing aluminum foil. The most basic requirement for aluminized packaging film in use is that the aluminum layer cannot fall off, and the adhesion strength of the aluminum layer is different for different packaging applications. When used for food packaging that needs to be sterilized by high-temperature boiling or even high-temperature cooking at 120℃ or above, the adhesion strength of the aluminum layer is more demanding. The aluminized cooking-resistant packaging film currently used on the market is mainly composed of a plastic film and an aluminum foil, and the complex lamination process has a high production cost. By vacuum aluminizing on the surface of the film, the thickness of the aluminum layer can be reduced to a few hundred or even a few tens of nanometers, which not only simplifies the process but also greatly reduces the cost.

[0003] In order to improve the bonding force between the aluminized layer and the surface of the BOPET film and increase the adhesion strength of the aluminum layer, the surface of the BOPET film often needs to be treated. The main methods of surface treatment are corona treatment and coating. Corona treatment is more common, and its advantages are simple operation and low cost. However, the surface energy of the film treated by corona treatment decreases rapidly, and the adhesion strength of the aluminum layer is still low, especially after water immersion, the aluminum layer is more likely to fall off. Compared with corona treatment, the coating method has more obvious effect. The coating method is to coat a layer of resin solution on the surface of the film, and after curing, a very thin film is formed on the surface of the base film. Commonly used resins include polyester, polyurethane, acrylic resin, and silicone resin. The adhesion strength of the aluminum layer of the aluminized film on the market after coating has been improved, but the water resistance is poor, especially when subjected to high-temperature boiling or high-temperature cooking, the aluminum layer will fall off, which cannot be applied to food packaging that needs to be sterilized by high-temperature boiling or even high-temperature cooking at 120℃ or above.

[0004] Therefore, it is of great significance to provide a BOPET film for an aluminized packaging bag with simple production process, low cost, and resistance to high-temperature and high-pressure cooking at 120℃ or above. SUMMARY

[0005] The technical problem solved by the present application is to provide a BOPET film for a cooking-resistant aluminized packaging bag, and a preparation method and application thereof.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a BOPET film for retort-resistant aluminized packaging bags, the film comprising a BOPET base film and a coating layer arranged on a single side surface of the BOPET base film, the coating layer being made by coating an aqueous coating liquid, the mass percentage of the aqueous coating liquid being: 15%-20% aqueous polyester, 25%-30% aqueous acrylic resin, 5%-6% aqueous isocyanate crosslinking agent, 0.1%-0.2% acetylene alcohol wetting agent, and the balance being water.

[0007] As an embodiment of the present invention, the thickness of the coating layer is 40-80 nm.

[0008] As an embodiment of the present invention, the thickness of the BOPET base film is 8-30 μm.

[0009] As an embodiment of the present invention, the haze of the BOPET film for aluminized packaging bags provided by the present invention is ≤5%.

[0010] As an embodiment of the present invention, the mass percentage composition of the water-based polyester is: 25% polyester resin, 5% ethylene glycol tert-butyl ether, and 70% water.

[0011] As a specific embodiment of the present invention, the water-based polyester is produced by Japan Huying Chemical Co., Ltd. and the model is BR-303.

[0012] As an embodiment of the present invention, the water-based acrylic resin comprises the following components in percentage by weight: 23%-27% polyurethane-modified acrylic resin, 5% ethylene glycol monobutyl ether, and 68%-72% water.

[0013] As a specific embodiment of the present invention, the water-based acrylic resin is produced by Takamatsu Oil & Fats Co., Ltd. of Japan, and its model is PESRESIN A-124GP.

[0014] As an embodiment of the present invention, the mass percentage composition of the water-based isocyanate cross-linking agent is: 36%-40% of hydrophilic modified blocked polyisocyanate based on hexamethyl diisocyanate, and 60%-64% of water.

[0015] As a specific embodiment of the present invention, the water-based isocyanate cross-linking agent is produced by Kawaguchi Chemical Co., Ltd. of Japan, and the model number is YPN-07.

[0016] As an embodiment of the present invention, the acetylene alcohol wetting agent is an acetylene glycol wetting agent, which is selected from at least one of acetylene glycol ethylene oxide and ethoxyacetylene glycol.

[0017] As a specific embodiment of the present invention, the acetylene alcohol wetting agent is produced by Evonik Tego of Germany, and the model is WET510.

[0018] In one embodiment of the present invention, the BOPET base film comprises a three-layer structure, namely, a surface layer, an intermediate layer, and a surface layer stacked in sequence (i.e., an A / B / A three-layer structure, with A being the surface layer and B being the intermediate layer). The intermediate layer is made from film-grade glossy PET chips; the surface layer is made from film-grade glossy PET chips and PET masterbatch containing an anti-blocking agent, wherein the PET masterbatch containing the anti-blocking agent comprises 10%-15% by weight, and the film-grade glossy PET chips comprise 85%-90% by weight. Furthermore, the ratio of the mass of the intermediate layer's raw materials to the total mass of the surface layer's raw materials is (4-5):1.

[0019] The present invention provides a method for preparing the BOPET film for the retort-resistant aluminized packaging bag of the present invention, comprising the steps of: (1) Prepare water-based coating liquid Mixing water-based polyester, water-based acrylic resin, water-based isocyanate crosslinking agent, acetylene alcohol wetting agent and water according to the mass percentage composition of the water-based coating liquid to prepare a water-based coating liquid; The mass percentage composition of the aqueous coating liquid is: 15%-20% aqueous polyester, 25%-30% aqueous acrylic resin, 5%-6% aqueous isocyanate crosslinking agent, 0.1%-0.2% acetylene alcohol wetting agent, and the balance is water; (2) Using melt co-extrusion technology, the raw materials for preparing the middle layer are melted and extruded through a twin-screw main extruder, and the raw materials for preparing the surface layer are melted and extruded through a twin-screw auxiliary extruder to obtain a melt; the melt is compounded and flowed out from a die distributor, and then attached to a chilled roller to form a BOPET cast sheet; The raw material for preparing the intermediate layer is film-grade glossy PET chips; the raw material for preparing the surface layer is film-grade glossy PET chips and PET masterbatch containing an anti-blocking agent, wherein the mass percentage content of the PET masterbatch containing the anti-blocking agent is 10%-15%, and the mass percentage content of the film-grade glossy PET chips is 85%-90%; the mass ratio of the raw material for preparing the intermediate layer to the total mass of the raw material for preparing the surface layer is (4-5):1; The BOPET cast sheet is longitudinally stretched and then cooled on a cooling roller to form a uniaxially stretched sheet; The uniaxially stretched sheet is subjected to a corona treatment on one side of the surface layer, and then the aqueous coating liquid is coated on the corona-treated surface layer by a coating machine, and after the coating is completed, the sheet is transversely stretched to obtain a BOPET film with a single-side coating; (3) The BOPET film containing the single-side coating is subjected to high-temperature shaping, air-cooling and winding to obtain a BOPET film for a retort-resistant aluminum-coated packaging bag; The temperature of the twin-screw main extruder and the twin-screw auxiliary extruder is 260-280°C; the temperature of the chilled roller is 22-25°C; the temperature of the longitudinal stretching is 80-100°C, and the stretching ratio of the longitudinal stretching is 3.2-4.0; the voltage of the corona treatment is 14-15 kV; the speed ratio of the coating roller of the coating machine to the production line is 0.2-2.0, the temperature of the coating machine is 15-20°C, and the amount of liquid on the coating roller is 3-5 g / m 2 The temperature of the transverse stretching is 100-130°C, and the stretching ratio of the transverse stretching is 3.5-4.0; the temperature of the high-temperature setting is 220-240°C, and the temperature of the air-cooling is 180-60°C.

[0020] The present invention also provides a use of the BOPET film for retort-resistant aluminized packaging bags in the preparation of retort-resistant aluminized packaging bags.

[0021] The present invention provides a BOPET film for retort-resistant aluminum-plated packaging bags, comprising a BOPET base film and a coating layer disposed on one side of the BOPET base film. The coating layer is formed by coating with an aqueous coating liquid comprising a water-based polyester, a water-based acrylic resin, a water-based isocyanate crosslinking agent, and an acetylene alcohol wetting agent. The water-based polyester and water-based acrylic resin are compounded for use. The polyester resin in the water-based polyester has a similar chemical structure to the BOPET base film, resulting in a coating film having greater adhesion to the BOPET base film than other types of resins. The carboxylic acid groups of the polyurethane-modified acrylic resin in the water-based acrylic resin can chelate with aluminum particles deposited during the aluminum plating process, resulting in a coating film having greater adhesion to the aluminum layer than other types of resins. The water-based isocyanate crosslinking agent is selected, and a hydrophilically modified blocked polyisocyanate crosslinking agent is selected, which can cause the polyester resin and the polyurethane-modified acrylic resin in the system to undergo a crosslinking and curing reaction, thereby increasing the hardness and density of the coating. The coating film formed by the compound use of three different types of components, namely water-based polyester, water-based acrylic resin, and water-based isocyanate crosslinking agent, not only greatly improves the adhesion between the aluminum layer and the BOPET base film layer, but also makes the water vapor and oxygen barrier properties of the aluminized film better than those of ordinary aluminized films.

[0022] The retort-resistant aluminized BOPET film provided by the present invention is coated on one side of a BOPET base film with a film layer formed by cross-linking polyester resin and acrylic resin to form a dense network structure. This film layer not only firmly adheres to the BOPET base film but also firmly locks aluminum particles deposited on its surface. After vacuum aluminization, the adhesion between the aluminum layer and the BOPET film is greatly improved. Even under conditions of 121°C and 100% humidity, the aluminum layer maintains strong adhesion to the film, making it particularly suitable for packaging foods, pharmaceuticals, medical devices, and the like that require high-temperature treatment above 120°C. Furthermore, the present invention utilizes an in-line coating process to prepare the aluminized BOPET film for packaging bags, resulting in a simple preparation method and low manufacturing cost. The aluminized BOPET film can be used to package foods, pharmaceuticals, medical devices, and the like that require retort sterilization at temperatures above 120°C. DETAILED DESCRIPTION

[0023] The following examples are intended to further illustrate the present invention, but are not intended to limit the scope of protection of the present invention.

[0024] The raw materials used in the embodiments and comparative examples provided by the present invention are specifically described as follows.

[0025] The water-based polyester is produced by Japan Huying Chemical Co., Ltd., model BR-303. The mass percentage composition of the water-based polyester is: polyester resin 25%, ethylene glycol tert-butyl ether 5%, and water 70%.

[0026] The water-based acrylic resin, model PESRESIN A-124GP, is produced by Takamatsu Oil & Fats Co., Ltd. of Japan. The weight percentage composition of the water-based acrylic resin is: 23%-27% polyurethane-modified acrylic resin, 5% ethylene glycol monobutyl ether, and 68%-72% water.

[0027] The water-based isocyanate crosslinker, model YPN-07, is manufactured by Kawaguchi Chemical Co., Ltd. in Japan. Its mass percentage composition is: 36%-40% hydrophilically modified blocked polyisocyanate based on hexamethyl diisocyanate and 60%-64% water.

[0028] The acetylene alcohol wetting agent is produced by Evonik Dico of Germany, and its model is WET510.

[0029] The film-grade glossy PET chips are produced by Kanghui New Material Technology Co., Ltd., model KH2650A.

[0030] The PET masterbatch containing the anti-blocking agent is produced by Kanghui New Material Technology Co., Ltd., model KH201.

[0031] In the following examples and comparative examples, unless otherwise specified, all reagents used are commercially available products.

[0032] In the following examples and comparative examples, unless otherwise specified, the experimental methods used are conventional experimental methods.

[0033] In the following examples and comparative examples, the water used in the preparation of the aqueous coating liquid is treated pure water at a temperature of 15°C-20°C.

[0034] Example 1 This embodiment provides a BOPET film for retort-resistant aluminized packaging bags. The film comprises a BOPET base film and a coating layer disposed on one side of the BOPET base film. The coating layer is formed by applying an aqueous coating liquid. The aqueous coating liquid comprises, by weight, 15% aqueous polyester, 30% aqueous acrylic resin, 5% aqueous isocyanate crosslinking agent, 0.2% acetylene alcohol wetting agent, and the balance water.

[0035] The thickness of the BOPET base film is 12 μm.

[0036] The thickness of the coating layer was 65 nm.

[0037] The haze of the BOPET film for the retort-resistant aluminized packaging bag provided in this embodiment is 3.0%.

[0038] The method for preparing the BOPET film for the retort-resistant aluminized packaging bag provided in this embodiment comprises the following steps: (1) Prepare water-based coating liquid According to the mass percentage composition of the above aqueous coating liquid, aqueous polyester, aqueous acrylic resin, aqueous isocyanate crosslinking agent, acetylene alcohol wetting agent and water are mixed to prepare an aqueous coating liquid; the specific steps are as follows: First, add a certain amount of water into a stainless steel barrel, then add water-based polyester and water-based acrylic resin in sequence, start stirring at 300 rpm / min, then add water-based isocyanate crosslinker and acetylene alcohol wetting agent in sequence, and finally add the remaining water into the stainless steel barrel, continue stirring for 10 minutes, and let it stand for 10 minutes to obtain the water-based coating liquid; (2) The BOPET base film has a structure of three layers of a surface layer, an intermediate layer and a surface layer stacked in sequence, and the intermediate layer is prepared from a raw material (400 parts by weight) by a melt extrusion through a double-screw main extruder and the surface layer is prepared from a raw material (100 parts by weight) by a melt extrusion through a double-screw auxiliary extruder, to obtain a melt, which is then compounded and discharged from an ABA type three-layer die distributor, and then attached to a chill roll to form a BOPET cast sheet; wherein the raw material for the intermediate layer is a film-grade bright PET chip; the raw material for the surface layer is a film-grade bright PET chip and a PET master batch containing an opening agent, wherein the mass percentage of the PET master batch containing the opening agent is 10%, and the mass percentage of the film-grade bright PET chip is 90%. The prepared BOPET cast sheet is longitudinally stretched, and then cooled on a cooling roll to form a unidirectionally stretched sheet. The unidirectionally stretched sheet is subjected to single-side surface layer corona treatment, and then a water-based coating liquid is coated on the surface layer after the corona treatment by a coating machine, and after the coating is completed, transverse stretching is performed to obtain a BOPET film containing a single-side coating layer. (3) The BOPET film containing a single-side coating layer is subjected to high-temperature setting, air cooling and winding to obtain a BOPET film for a cooking-resistant aluminum-coated packaging bag.

[0039] In the above steps, the temperature of the double-screw main extruder and the double-screw auxiliary extruder is 260-280℃; the temperature of the chill roll is 22-25℃; the temperature of the longitudinal stretching is 90-100℃, and the stretching ratio of the longitudinal stretching is 3.6; the voltage of the corona treatment is 14-15kV; the speed ratio of the coating roll to the production line of the coating machine is 1.0, the temperature of the coating machine is 15-20℃, and the liquid amount on the coating roll is 4.5g / m 2 ; the temperature of the transverse stretching is 100-110℃, and the stretching ratio of the transverse stretching is 4.0; the temperature of the high-temperature setting is 220-240℃, and the temperature of the air cooling is 180-60℃.

[0040] Example 2 The present embodiment provides a BOPET film for a cooking-resistant aluminum-coated packaging bag, which comprises a BOPET base film and a coating layer arranged on one side surface of the BOPET base film, and the coating layer is made of a water-based coating liquid. The mass percentage composition of the water-based coating liquid is: 20% of a water-based polyester, 25% of a water-based acrylic resin, 6% of a water-based isocyanate crosslinking agent, 0.1% of an alkyne alcohol wetting agent, and the balance is water.

[0041] The thickness of the BOPET base film is 12μm.

[0042] The thickness of the coating layer is 60nm.

[0043] The haze of the BOPET film for the retort-resistant aluminized packaging bag provided in this embodiment is 3.3%.

[0044] The method for preparing the BOPET film for the retort-resistant aluminized packaging bag provided in this embodiment comprises the following steps: (1) Prepare water-based coating liquid According to the mass percentage composition of the above aqueous coating liquid, aqueous polyester, aqueous acrylic resin, aqueous isocyanate crosslinking agent, acetylene alcohol wetting agent and water are mixed to prepare an aqueous coating liquid; the specific steps are as follows: First, add a certain amount of water into a stainless steel barrel, then add water-based polyester and water-based acrylic resin in sequence, start stirring at 300 rpm / min, then add water-based isocyanate crosslinker and acetylene alcohol wetting agent in sequence, and finally add the remaining water into the stainless steel barrel, continue stirring for 10 minutes, and let it stand for 10 minutes to obtain the water-based coating liquid; (2) The BOPET base film is a structure in which three layers are stacked in sequence, namely, a surface layer, an intermediate layer, and a surface layer. The melt co-extrusion technology is adopted to melt and extrude the raw materials for the intermediate layer (500 parts by weight) through a twin-screw main extruder and the raw materials for the surface layer (100 parts by weight) through a twin-screw auxiliary extruder to obtain a melt; the melt is compounded and flowed out from an ABA-type three-layer die distributor, and then attached to a chilled roller to form a BOPET cast sheet; wherein, the raw materials for the intermediate layer are film-grade glossy PET chips; the raw materials for the surface layer are film-grade glossy PET chips and PET masterbatch containing an opening agent, wherein the mass percentage content of the PET masterbatch containing an opening agent is 15%, and the mass percentage content of the film-grade glossy PET chips is 85%; The obtained BOPET cast sheet is longitudinally stretched and then cooled on a cooling roller to form a uniaxially stretched sheet; The uniaxially stretched sheet is subjected to a single-side surface corona treatment, and then an aqueous coating liquid is coated on the corona-treated surface by a coating machine. After the coating is completed, the sheet is stretched transversely to obtain a BOPET film with a single-side coating. (3) The BOPET film with a single-side coating is subjected to high-temperature shaping, air-cooling and winding to obtain a BOPET film for retort-resistant aluminized packaging bags.

[0045] In the above steps, the temperature of the twin-screw main extruder and the twin-screw auxiliary extruder is 260-280°C; the temperature of the chilled roller is 22-25°C; the temperature of the longitudinal stretching is 80-90°C, and the stretching ratio of the longitudinal stretching is 4.0; the voltage of the corona treatment is 14-15kV; the speed ratio of the coating roller of the coating machine to the production line is 1.5, the temperature of the coating machine is 15-20°C, and the amount of liquid on the coating roller is 4g / m 2The temperature of transverse stretching is 100-110°C, and the stretching ratio of transverse stretching is 3.5; the temperature of high-temperature setting is 220-240°C, and the temperature of air cooling is 180-60°C.

[0046] Comparative Example 1 This comparative example provides a BOPET film comprising a BOPET base film and a coating layer disposed on one side of the BOPET base film. The coating layer is formed by applying an aqueous coating liquid. The aqueous coating liquid comprises, by weight, 45% aqueous polyester, 5% aqueous isocyanate crosslinking agent, 0.2% acetylene alcohol wetting agent, and the balance water.

[0047] The BOPET film provided in this comparative example is prepared in the same manner as in Example 1, except that the composition of the aqueous coating liquid used is different from that in Example 1.

[0048] In the BOPET film provided in this comparative example, the thickness of the BOPET base film is 12 μm and the thickness of the coating layer is 65 nm.

[0049] The haze of the BOPET film provided in this comparative example is 3.1%.

[0050] Comparative Example 2 This comparative example provides a BOPET film comprising a BOPET base film and a coating layer disposed on one side of the BOPET base film. The coating layer is formed by applying an aqueous coating liquid. The aqueous coating liquid comprises, by weight, 45% aqueous acrylic resin, 5% aqueous isocyanate crosslinking agent, 0.2% acetylene alcohol wetting agent, and the balance water.

[0051] The BOPET film provided in this comparative example is prepared in the same manner as in Example 1, except that the composition of the aqueous coating liquid used is different from that in Example 1.

[0052] In the BOPET film provided in this comparative example, the thickness of the BOPET base film is 12 μm and the thickness of the coating layer is 65 nm.

[0053] The haze of the BOPET film provided in this comparative example is 3.5%.

[0054] The BOPET film for aluminized packaging bags prepared in Example 1, the BOPET film prepared in Comparative Example 1, and the BOPET film prepared in Comparative Example 2 were respectively taken and vacuum-plated with aluminum on the side having the coating layer.

[0055] Vacuum aluminum plating is carried out in a vacuum aluminum plating machine. When the vacuum degree reaches below 0.1 Pa, the evaporation boat is opened to heat, the heating temperature is about 1800℃, then the aluminum wire transmission is opened, the equipment is started to wind to a speed of 3.0 m / s, the evaporation is started, the thickness of the aluminum plating layer is controlled to be about 20 nm, and the cooling, vacuum exhaust and evaporation are ended.

[0056] The BOPET films after vacuum aluminum plating are subjected to the following performance tests, and the test results are shown in Table 1.

[0057] Oxygen transmission amount: GB-T 19789-2005 standard, coulomb meter detection method is adopted; Water vapor transmission amount: GBT 21529-2008 standard, electrolytic sensor method is adopted.

[0058] Cooking resistance test: The aluminum-plated BOPET film is cut into a 25mmx200mm sample, which is put into an aging oven for cooking, the conditions are 121℃, humidity 100%, and the treatment time is 30min. The peeling strength and residual aluminum layer area of the aluminum-plated film after cooking treatment are tested; the peeling strength is determined according to GB8808-1988 standard.

[0059] Table 1 From the above Table 1 data, it can be seen that the aluminum-plated film further obtained from the aluminum-plated packaging bag BOPET film prepared by Example 1 has a peeling strength of the aluminum layer significantly higher than that of the aluminum-plated film further obtained from Comparative Example 1 and Comparative Example 2 after cooking treatment at a temperature of 120℃ or above, and the aluminum layer peeling is very little.

[0060] In addition, the oxygen and water vapor transmission amounts of the aluminum-plated film further obtained from the aluminum-plated packaging bag BOPET film prepared by Example 1 are significantly reduced, so the barrier property to water vapor and oxygen is better than that of the aluminum-plated film further obtained from Comparative Example 1 and Comparative Example 2.

[0061] The above is only an embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent transformation or direct or indirect application in other related technical fields based on the content of the present application is included in the patent protection scope of the present application.

Claims

1. A BOPET film for retort-resistant aluminized packaging bags, characterized in that: The film includes a BOPET base film and a coating layer arranged on one side of the BOPET base film. The coating layer is made by coating an aqueous coating liquid. The mass percentage of the aqueous coating liquid is: 15%-20% aqueous polyester, 25%-30% aqueous acrylic resin, 5%-6% aqueous isocyanate crosslinking agent, 0.1%-0.2% acetylene alcohol wetting agent, and the balance is water.

2. The BOPET film for retort-resistant aluminized packaging bags according to claim 1, characterized in that: The thickness of the coating layer is 40-80 nm.

3. The BOPET film for retort-resistant aluminized packaging bags according to claim 1 or 2, characterized in that: The thickness of the BOPET base film is 8-30 μm.

4. The BOPET film for retort-resistant aluminized packaging bags according to claim 1, characterized in that: The mass percentage composition of the water-based polyester is: 25% polyester resin, 5% ethylene glycol tert-butyl ether, and 70% water.

5. The BOPET film for retort-resistant aluminized packaging bags according to claim 1, characterized in that: The mass percentage composition of the water-based acrylic resin is: 23%-27% of polyurethane-modified acrylic resin, 5% of ethylene glycol monobutyl ether, and 68%-72% of water.

6. The BOPET film for retort-resistant aluminized packaging bags according to claim 1, characterized in that: The mass percentage composition of the water-based isocyanate cross-linking agent is: 36%-40% of hydrophilic modified blocked polyisocyanate based on hexamethyl diisocyanate and 60%-64% of water.

7. The BOPET film for retort-resistant aluminized packaging bags according to claim 1, characterized in that: The acetylene alcohol wetting agent is an acetylene glycol wetting agent, which is selected from at least one of acetylene glycol ethylene oxide and ethoxyacetylene glycol.

8. The BOPET film for retort-resistant aluminized packaging bags according to claim 3, characterized in that: The BOPET base film is a structure in which a surface layer, an intermediate layer and a surface layer are stacked in sequence; The raw material for preparing the middle layer is film-grade glossy PET chips; the raw material for preparing the surface layer is film-grade glossy PET chips and PET masterbatch containing an opening agent, wherein the mass percentage content of the PET masterbatch containing the opening agent is 10%-15%, and the mass percentage content of the film-grade glossy PET chips is 85%-90%.

9. A method for preparing the BOPET film for retort-resistant aluminized packaging bags according to any one of claims 1 to 8, characterized in that: Including steps: (1) Prepare water-based coating liquid Mixing water-based polyester, water-based acrylic resin, water-based isocyanate crosslinking agent, acetylene alcohol wetting agent and water according to the mass percentage composition of the water-based coating liquid to prepare a water-based coating liquid; (2) Using melt co-extrusion technology, the raw materials for preparing the middle layer are melted and extruded through a twin-screw main extruder, and the raw materials for preparing the surface layer are melted and extruded through a twin-screw auxiliary extruder to obtain a melt; the melt is compounded and flowed out from a die distributor, and then attached to a chilled roller to form a BOPET cast sheet; The BOPET cast sheet is longitudinally stretched and then cooled on a cooling roller to form a uniaxially stretched sheet; The uniaxially stretched sheet is subjected to a corona treatment on one side of the surface layer, and then the aqueous coating liquid is coated on the corona-treated surface layer by a coating machine, and after the coating is completed, the sheet is transversely stretched to obtain a BOPET film with a single-side coating; (3) The BOPET film containing the single-side coating is subjected to high-temperature shaping, air-cooling and winding to obtain a BOPET film for a retort-resistant aluminum-coated packaging bag; The temperature of the twin-screw main extruder and the twin-screw auxiliary extruder is 260-280°C; the temperature of the chilled roller is 22-25°C; the temperature of the longitudinal stretching is 80-100°C, and the stretching ratio of the longitudinal stretching is 3.2-4.0; the voltage of the corona treatment is 14-15 kV; the speed ratio of the coating roller of the coating machine to the production line is 0.2-2.0, the temperature of the coating machine is 15-20°C, and the amount of liquid on the coating roller is 3-5 g / m 2 The temperature of the transverse stretching is 100-130°C, and the stretching ratio of the transverse stretching is 3.5-4.0; the temperature of the high-temperature setting is 220-240°C, and the temperature of the air-cooling is 180-60°C.

10. Use of the BOPET film for retort-resistant aluminized packaging bags according to any one of claims 1 to 8 in the preparation of retort-resistant aluminized packaging bags.

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