An acid and alkali resistant protective film and its preparation method

Abstract

This invention relates to the field of protective film materials technology, and discloses an acid and alkali resistant protective film and its preparation method. The protective film prepared by this invention comprises the following raw materials in parts by weight: 100 parts PET resin, 25-35 parts modified PET resin, 3-6 parts ethylene-methyl acrylate, 10-15 parts modified boron nitride nanosheets, 7-10 parts nano-silica, 0.5-1.5 parts coupling agent, 1.5-2.5 parts antioxidant, and 1-3 parts lubricant; wherein, the modified PET resin and modified boron nitride nanosheets work synergistically to improve the mechanical properties and acid and alkali resistance of the protective film.

Description

Technical Field

[0001] This invention relates to the field of protective film materials technology, specifically to an acid and alkali resistant protective film and its preparation method. Background Technology

[0002] With the rapid development of the electronic device, semiconductor manufacturing, and chemical processing industries, more stringent requirements have been placed on the protective materials used in the processing. Especially in processes such as LCD panel thinning, etching, electroless plating, and circuit board fabrication, protective films need to be in contact with strong acids, strong alkalis, or various organic solvents for extended periods. Traditional polyester protective films, such as ordinary polyethylene terephthalate (PET) films, while possessing good transparency and mechanical strength, contain a large number of ester bonds in their molecular chains. These bonds are highly susceptible to hydrolytic degradation in acidic or alkaline environments, leading to problems such as fogging, a sharp decline in mechanical properties, and even cracking and failure. This makes them unable to meet the durability and reliability requirements of high-end manufacturing processes.

[0003] To improve the chemical corrosion resistance of PET protective films, existing technologies typically employ methods such as coating the PET substrate with functional coatings or introducing comonomers for modification during PET synthesis. However, surface coating technologies are susceptible to peeling and detachment under prolonged immersion or harsh conditions, making it difficult to provide lasting protection. While conventional copolymer modification can alter the aggregated structure of molecular chains to some extent, it often fails to simultaneously improve acid and alkali resistance and mechanical properties. For example, introducing too many rigid segments can lead to brittle films and reduced processability. Therefore, developing a PET protective film that possesses both excellent resistance to strong acids and alkalis and good mechanical strength, based on the material's bulk structure and through a combination of molecular design and nanocomposite technology, has become a pressing technical challenge in this field. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an acid and alkali resistant protective film and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] An acid and alkali resistant protective film comprises the following raw materials in parts by weight: 100 parts PET resin, 25-35 parts modified PET resin, 3-6 parts ethylene-methyl acrylate, 10-15 parts modified boron nitride nanosheets, 7-10 parts nano silica, 0.5-1.5 parts coupling agent, 1.5-2.5 parts antioxidant, and 1-3 parts lubricant;

[0007] Furthermore, the modified boron nitride nanosheets are obtained by modifying alkali-treated boron nitride nanosheets with KH560 silane coupling agent;

[0008] Furthermore, the coupling agent is one of a silane coupling agent or a titanate coupling agent;

[0009] Furthermore, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168, with a mass ratio of 1:1.

[0010] Furthermore, the lubricant is one of polyethylene wax, calcium stearate, or zinc stearate;

[0011] The modified PET resin is prepared by the following steps:

[0012] Step A1: Thoroughly mix β-(acryloyloxy)propionic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide and deionized water, sonicate at room temperature for 15 min, add 2(1H-imidazol-1-yl)ethylamine and stir at room temperature for 10-12 h. After the reaction is complete, rotary evaporate to 10 mL, add dichloromethane and mix well, let stand to separate the layers, collect the organic layer, add anhydrous sodium sulfate to dry, filter, and rotary evaporate a second time to obtain acrylate imidazolium;

[0013] Further, in step A1, the molar ratio of β-(acryloyloxy)propionic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide and 2-(1H-imidazol-1-yl)ethylamine is 1:1.15-1.2:0.9-0.95:1-1.03;

[0014] Step A2: Add diethylenetriamine to N,N-dimethylacetamide and stir until homogeneous. Place the mixture in an ice-water bath, add triethylamine and mix well. Then add 2-hydroxy-6-naphthoyl chloride and stir until homogeneous. Heat the mixture to 65°C and stir for 5.5-6.5 hours. After the reaction is complete, transfer the mixture to distilled water at 10°C, filter, wash, and dry to obtain the terminal hydroxynaphthalene derivative.

[0015] Further, in step A2, the molar ratio of diethylenetriamine, 2-hydroxy-6-naphthoyl chloride, and triethylamine is 1:2-2.02:2.1-2.2;

[0016] Further, the 2-hydroxy-6-naphthoyl chloride described in step A2 is prepared by the following steps: 0.4 mol of 2-hydroxy-6-naphthoic acid is added to 40 mL of toluene, followed by 10 mL of thionyl chloride. The mixture is then placed in an oil bath and refluxed at 116 °C for 1.5-2.5 h. The solvent and excess thionyl chloride are removed by rotary evaporation, and then 10 mL of toluene is added and stirred until homogeneous. The mixture is then rotary evaporated a second time to obtain 2-hydroxy-6-naphthoyl chloride.

[0017] Step A3: Mix the terminal hydroxyl naphthalene derivative with anhydrous methanol and stir evenly under room temperature and nitrogen conditions. Then, while stirring, add acrylate imidazole. After the addition is complete, raise the system temperature to 35°C and react for 4-6 hours. Then, rotary evaporate to obtain the terminal hydroxyl modifier.

[0018] Furthermore, in step A3, the molar ratio of the terminal hydroxynaphthalene derivative and the acrylate imidazole is 1:1.5-2.2;

[0019] Step A4: Mix the hydroxyl-terminated modifier and ethylene glycol evenly to obtain a mixed diol; mix 2,2-bis(4-carboxyphenyl)hexafluoropropane and terephthalic acid evenly to obtain a mixed dicarboxylic acid; esterify the mixed diol and mixed dicarboxylic acid under 0.1-0.15 MPa and 240-260℃ for 2-3 hours. After the reaction is complete, perform a polycondensation reaction under 15-25 kPa and 280-290℃ for 4-6 hours. After the acid value of the reaction solution reaches 35-50 mg KOH / g, remove the excess diol by rotary evaporation to obtain the modified PET resin.

[0020] Further, in step A4, the molar ratio of the mixed diol and the mixed diacid is 1.2-1.3:1, and the molar ratio of the terminal hydroxyl modifier and ethylene glycol in the mixed diol is 1:0.2-0.3, and the molar ratio of 2,2-bis(4-carboxyphenyl)hexafluoropropane and terephthalic acid in the mixed diacid is 0.05-0.15:0.85-0.95.

[0021] A method for preparing an acid and alkali resistant protective film includes the following steps:

[0022] Weigh the raw materials according to the weight proportions, add each component raw material to the mixer and mix evenly, then transfer to a twin-screw extruder for melt extrusion, stretch into a film, heat set, cool, and roll up to obtain an acid and alkali resistant protective film.

[0023] The beneficial effects of this invention are:

[0024] The protective film prepared by this invention is made of PET resin as the main base resin, with the addition of modified PET resin, modified boron nitride nanosheets, ethylene-methyl acrylate, nano-silica, and coupling agents and other functional additives; wherein, the modified PET resin and modified boron nitride nanosheets work synergistically to improve the mechanical properties and acid and alkali resistance of the protective film.

[0025] The modified boron nitride nanosheets introduced in this invention are uniformly dispersed in the matrix, acting like countless tiny "baffles" within the film. When corrosive media attempt to penetrate the film, they must bypass these baffles, significantly extending the diffusion path and greatly enhancing the barrier properties of the protective film. Because the boron nitride nanosheets form a good interfacial bond with the PET matrix through KH560, they preferentially contact invading acidic or alkaline media, thereby protecting the more easily hydrolyzed PET ester bonds, acting as a sacrificial protection. Furthermore, when the film is stretched, stress can be effectively transferred from the soft PET matrix to the rigid boron nitride nanosheets, allowing them to bear the main load and thus improving the mechanical properties of the matrix.

[0026] The naphthyl and amide structures introduced into the main chain of the modified PET resin of this invention, as well as the -CF3 and imidazole structures branched onto the side chains, are all large-volume groups. These groups can utilize steric hindrance to physically hinder the contact between water molecules, H⁺, or OH⁻ and the ester bonds, thereby significantly delaying the hydrolysis reaction. The -CF3 side chain has extremely low surface energy, endowing the modified resin with excellent hydrophobicity and oleophobicity. This property makes the protective film surface less susceptible to wetting and penetration by acid and alkali solutions, further preventing the intrusion of corrosive media. The introduced naphthyl... The amide structure and imidazole heterocycles have high chemical bond energies, making them far more resistant to acids and alkalis than aliphatic segments, thus enhancing the chemical stability of the entire molecular chain. In addition, imidazole can form hydrogen bonds with carbonyl groups (C=O) on the PET main chain, as well as with other imidazole rings or amide groups to form a strong hydrogen bond network. These strong physical cross-linking points make the molecular chain more compact, and the dense structure itself means a smaller free volume, making it more difficult for corrosive media (water, acids, alkalis) to penetrate, thereby improving the resistance to permeation corrosion. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The modified boron nitride nanosheets in the following examples were prepared by the following steps: 1 g of boron nitride nanosheets were ultrasonically dispersed in 20 mL of 5 mol / L sodium hydroxide solution and stirred at 100 °C for 24 h. After filtration and washing, the nanosheets were redispersed in 50 mL of ethanol aqueous solution (ethanol to water volume ratio of 9:1). 0.2 mL of KH560 was added and stirred evenly. The mixture was then reacted at 55 °C for 6 h. After filtration, washing, and drying, the modified boron nitride nanosheets were obtained.

[0029] Example 1: 2-Hydroxy-6-naphthoyl chloride was prepared by the following steps: 0.4 mol of 2-hydroxy-6-naphthoic acid was added to 40 mL of toluene, followed by 10 mL of thionyl chloride. The mixture was then placed in an oil bath and refluxed at 116 °C for 1.5 h. The solvent and excess thionyl chloride were removed by rotary evaporation. Then, 10 mL of toluene was added and stirred until homogeneous. The mixture was then rotary evaporated a second time to obtain 2-hydroxy-6-naphthoyl chloride.

[0030] The modified PET resin is prepared by the following steps:

[0031] Step A1: Thoroughly mix β-(acryloyloxy)propionic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide, and deionized water, sonicate at room temperature for 15 min, add 2(1H-imidazol-1-yl)ethylamine, stir at room temperature for 10 h, after the reaction is complete, rotary evaporate to 10 mL, add dichloromethane, mix well, allow to stand for separation, collect the organic layer, add anhydrous sodium sulfate to dry, filter, and rotary evaporate a second time to obtain acrylate imidazolium, β-(acryloyloxy)propionic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide, and 2(1H-imidazol-1-yl)ethylamine in a molar ratio of 1:1.15:0.9:1;

[0032] Step A2: Add diethylenetriamine to N,N-dimethylacetamide and stir until homogeneous. Place the mixture in an ice-water bath, add triethylamine and mix well. Then add 2-hydroxy-6-naphthoyl chloride and stir until homogeneous. Heat the mixture to 65°C and stir for 5.5 hours. After the reaction is complete, transfer the mixture to distilled water at 10°C, filter, wash, and dry to obtain the terminal hydroxynaphthalene derivative. The molar ratio of diethylenetriamine, 2-hydroxy-6-naphthoyl chloride, and triethylamine is 1:2:2.1.

[0033] Step A3: Mix the terminal hydroxy naphthalene derivative with anhydrous methanol and stir evenly under room temperature and nitrogen conditions. Then, add acrylate imidazole while stirring. After the addition is complete, raise the system temperature to 35°C and react for 4 hours. Then, rotary evaporate to obtain the terminal hydroxyl modifier. The molar ratio of terminal hydroxy naphthalene derivative to acrylate imidazole is 1:1.5.

[0034] Step A4: Mix the hydroxyl-terminated modifier and ethylene glycol evenly to obtain a mixed diol; mix 2,2-bis(4-carboxyphenyl)hexafluoropropane and terephthalic acid evenly to obtain a mixed diacid; esterify the mixed diol and mixed diacid at 0.1 MPa and 240℃ for 2 hours. After the reaction is complete, perform a polycondensation reaction at 15 kPa and 280℃ for 4 hours. When the acid value of the reaction solution reaches 35-50 mg KOH / g, remove excess diol by rotary evaporation to obtain modified PET resin. The molar ratio of the mixed diol to the mixed diacid is 1.2:1, and the molar ratio of the hydroxyl-terminated modifier to ethylene glycol in the mixed diol is 1:0.2. The molar ratio of 2,2-bis(4-carboxyphenyl)hexafluoropropane to terephthalic acid in the mixed diacid is 0.05:0.95.

[0035] Example 2: 2-Hydroxy-6-naphthoyl chloride was prepared by the following steps: 0.4 mol of 2-hydroxy-6-naphthoic acid was added to 40 mL of toluene, followed by 10 mL of thionyl chloride. The mixture was then placed in an oil bath and refluxed at 116 °C for 2 h. The solvent and excess thionyl chloride were removed by rotary evaporation. Then, 10 mL of toluene was added and stirred until homogeneous. The mixture was then rotary evaporated a second time to obtain 2-hydroxy-6-naphthoyl chloride.

[0036] The modified PET resin is prepared by the following steps:

[0037] Step A1: Thoroughly mix β-(acryloyloxy)propionic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide, and deionized water, sonicate at room temperature for 15 min, add 2(1H-imidazol-1-yl)ethylamine, stir at room temperature for 11 h, after the reaction is complete, rotary evaporate to 10 mL, add dichloromethane, mix well, allow to stand for separation, collect the organic layer, add anhydrous sodium sulfate to dry, filter, and rotary evaporate a second time to obtain acrylate imidazolium, β-(acryloyloxy)propionic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide, and 2(1H-imidazol-1-yl)ethylamine in a molar ratio of 1:1.18:0.92:1.02;

[0038] Step A2: Add diethylenetriamine to N,N-dimethylacetamide and stir until homogeneous. Place the mixture in an ice-water bath, add triethylamine and mix well. Then add 2-hydroxy-6-naphthoyl chloride and stir until homogeneous. Heat the mixture to 65°C and stir for 6 hours. After the reaction is complete, transfer the mixture to distilled water at 10°C, filter, wash, and dry to obtain the terminal hydroxynaphthalene derivative. The molar ratio of diethylenetriamine, 2-hydroxy-6-naphthoyl chloride, and triethylamine is 1:2.01:2.15.

[0039] Step A3: Mix the terminal hydroxy naphthalene derivative with anhydrous methanol and stir evenly under room temperature and nitrogen conditions. Then, add acrylate imidazole while stirring. After the addition is complete, raise the system temperature to 35°C and react for 5 hours. Then, rotary evaporate to obtain the terminal hydroxyl modifier. The molar ratio of terminal hydroxy naphthalene derivative to acrylate imidazole is 1:1.8.

[0040] Step A4: Mix the hydroxyl-terminated modifier and ethylene glycol evenly to obtain a mixed diol; mix 2,2-bis(4-carboxyphenyl)hexafluoropropane and terephthalic acid evenly to obtain a mixed diacid; esterify the mixed diol and mixed diacid at 0.15 MPa and 250 °C for 2.5 h. After the reaction is complete, perform a polycondensation reaction at 20 kPa and 285 °C for 5 h. After the acid value of the reaction solution reaches 35-50 mg KOH / g, remove excess diol by rotary evaporation to obtain modified PET resin. The molar ratio of the mixed diol to the mixed diacid is 1.25:1, and the molar ratio of the hydroxyl-terminated modifier to ethylene glycol in the mixed diol is 1:0.25. The molar ratio of 2,2-bis(4-carboxyphenyl)hexafluoropropane to terephthalic acid in the mixed diacid is 0.1:0.9.

[0041] Example 3: 2-Hydroxy-6-naphthoyl chloride was prepared by the following steps: 0.4 mol of 2-hydroxy-6-naphthoic acid was added to 40 mL of toluene, followed by 10 mL of thionyl chloride. The mixture was then placed in an oil bath and refluxed at 116 °C for 2.5 h. The solvent and excess thionyl chloride were removed by rotary evaporation. 10 mL of toluene was then added and stirred until homogeneous. The mixture was then rotary evaporated a second time to obtain 2-hydroxy-6-naphthoyl chloride.

[0042] The modified PET resin is prepared by the following steps:

[0043] Step A1: Thoroughly mix β-(acryloyloxy)propionic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide, and deionized water, sonicate at room temperature for 15 min, add 2(1H-imidazol-1-yl)ethylamine, stir at room temperature for 12 h, after the reaction is complete, rotary evaporate to 10 mL, add dichloromethane, mix well, allow to stand for separation, collect the organic layer, add anhydrous sodium sulfate to dry, filter, and rotary evaporate a second time to obtain acrylate imidazolium, β-(acryloyloxy)propionic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide, and 2(1H-imidazol-1-yl)ethylamine in a molar ratio of 1:1.2:0.95:1.03;

[0044] Step A2: Add diethylenetriamine to N,N-dimethylacetamide and stir until homogeneous. Place the mixture in an ice-water bath, add triethylamine and mix well. Then add 2-hydroxy-6-naphthoyl chloride and stir until homogeneous. Heat the mixture to 65°C and stir for 6.5 hours. After the reaction is complete, transfer the mixture to distilled water at 10°C, filter, wash, and dry to obtain the terminal hydroxynaphthalene derivative. The molar ratio of diethylenetriamine, 2-hydroxy-6-naphthoyl chloride, and triethylamine is 1:2.02:2.2.

[0045] Step A3: Mix the terminal hydroxy naphthalene derivative with anhydrous methanol and stir evenly under room temperature and nitrogen conditions. Then, add acrylate imidazole while stirring. After the addition is complete, raise the system temperature to 35°C and react for 6 hours. Then, rotary evaporate to obtain the terminal hydroxyl modifier. The molar ratio of terminal hydroxy naphthalene derivative to acrylate imidazole is 1:2.2.

[0046] Step A4: Mix the hydroxyl-terminated modifier and ethylene glycol evenly to obtain a mixed diol; mix 2,2-bis(4-carboxyphenyl)hexafluoropropane and terephthalic acid evenly to obtain a mixed diacid; esterify the mixed diol and mixed diacid at 0.15 MPa and 260 °C for 3 hours. After the reaction is complete, perform a polycondensation reaction at 25 kPa and 290 °C for 6 hours. When the acid value of the reaction solution reaches 35-50 mg KOH / g, remove excess diol by rotary evaporation to obtain modified PET resin. The molar ratio of the mixed diol to the mixed diacid is 1.3:1, and the molar ratio of the hydroxyl-terminated modifier to ethylene glycol in the mixed diol is 1:0.3. The molar ratio of 2,2-bis(4-carboxyphenyl)hexafluoropropane to terephthalic acid in the mixed diacid is 0.15:0.85.

[0047] Example 4: A method for preparing an acid and alkali resistant protective film includes the following steps:

[0048] 100 parts of PET resin, 25 parts of modified PET resin prepared in Example 1, 3 parts of ethylene-methyl acrylate, 10 parts of modified boron nitride nanosheets, 7 parts of nano-silica, 0.5 parts of coupling agent, 1.5 parts of antioxidant, and 1 part of lubricant; wherein, the coupling agent is silane coupling agent KH550; the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1; and the lubricant is polyethylene wax;

[0049] Weigh the raw materials according to the weight proportions, add each component raw material to the mixer and mix evenly, then transfer to a twin-screw extruder for melt extrusion, stretch into a film, heat set, cool, and roll up to obtain an acid and alkali resistant protective film.

[0050] Example 5: A method for preparing an acid and alkali resistant protective film includes the following steps:

[0051] 100 parts of PET resin, 30 parts of modified PET resin prepared in Example 2, 4.5 parts of ethylene-methyl acrylate, 12 parts of modified boron nitride nanosheets, 8 parts of nano-silica, 1 part of coupling agent, 2 parts of antioxidant, and 2 parts of lubricant; wherein, the coupling agent is a silane coupling agent titanate coupling agent NDZ-401; the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1; and the lubricant is calcium stearate;

[0052] Weigh the raw materials according to the weight proportions, add each component raw material to the mixer and mix evenly, then transfer to a twin-screw extruder for melt extrusion, stretch into a film, heat set, cool, and roll up to obtain an acid and alkali resistant protective film.

[0053] Example 6: A method for preparing an acid and alkali resistant protective film includes the following steps:

[0054] 100 parts of PET resin, 35 parts of modified PET resin prepared in Example 3, 6 parts of ethylene-methyl acrylate, 15 parts of modified boron nitride nanosheets, 10 parts of nano-silica, 1.5 parts of coupling agent, 2.5 parts of antioxidant, and 3 parts of lubricant; wherein, the coupling agent is silane coupling agent KH570; the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1; and the lubricant is zinc stearate.

[0055] Weigh the raw materials according to the weight proportions, add each component raw material to the mixer and mix evenly, then transfer to a twin-screw extruder for melt extrusion, stretch into a film, heat set, cool, and roll up to obtain an acid and alkali resistant protective film.

[0056] Comparative Example 1: This comparative example is a protective film. The difference between this example and Example 6 is that ethylene glycol is used instead of the terminal hydroxyl modifier in the modified PET resin prepared in Example 3. All other aspects are the same.

[0057] Comparative Example 2: This comparative example is a protective film. The difference between this example and Example 6 is that terephthalic acid is used instead of 2,2-bis(4-carboxyphenyl)hexafluoropropane in the modified PET resin prepared in Example 3. All other aspects are the same.

[0058] Comparative Example 3: This comparative example is a protective film, which differs from Example 6 in that boron nitride nanosheets are used instead of modified boron nitride nanosheets.

[0059] Comparative Example 4: This comparative example is a protective film, which differs from Example 6 in that no modified boron nitride nanosheets were added.

[0060] Comparative Example 5: This comparative example is a protective film, which differs from Example 6 in that no coupling agent was added.

[0061] The protective films prepared in Examples 4-6 and Comparative Examples 1-5 were subjected to performance tests:

[0062] Mechanical property testing: Tensile strength and elongation at break were tested according to the national standard GB / T 13022-1991 "Test Method for Tensile Properties of Plastic Films";

[0063] Acid and alkali resistance test: (1) After soaking in 5wt% HCl solution at 25℃ for 1 day, 10 days and 30 days, the change in tensile strength was tested and expressed as tensile strength retention rate; (2) After soaking in 5wt% NaOH solution at 25℃ for 1 day, 10 days and 30 days respectively, the tensile strength was tested and expressed as tensile strength retention rate; where, tensile strength retention rate (%) = (tensile strength after soaking / tensile strength before soaking) × 100%;

[0064] The test results are shown in Table 1:

[0065] Table 1: Performance Test Results

[0066]

[0067] As can be seen from Table 1, the protective film prepared by the present invention using PET resin as the matrix not only has excellent tensile strength and elongation at break, but also excellent acid and alkali resistance.

[0068] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the scope defined by the inventive concept, they should all fall within the protection scope of the present invention.

Claims

1. An acid and alkali resistant protective film, characterized in that, The raw materials include the following parts by weight: 100 parts PET resin, 25-35 parts modified PET resin, 3-6 parts ethylene-methyl acrylate, 10-15 parts modified boron nitride nanosheets, 7-10 parts nano silica, 0.5-1.5 parts coupling agent, 1.5-2.5 parts antioxidant, and 1-3 parts lubricant. The modified boron nitride nanosheets are obtained by modifying alkali-treated boron nitride nanosheets with KH560 silane coupling agent. The modified PET resin is prepared by esterification and polycondensation reactions using a hydroxyl-terminated modifier and ethylene glycol as alcohols, and 2,2-bis(4-carboxyphenyl)hexafluoropropane and terephthalic acid as acids. The hydroxyl-terminated modifier is prepared by Michael addition reaction of a hydroxyl-terminated naphthalene derivative and an acrylate-based imidazole. The acrylate-based imidazole is prepared by activating β-(acryloyloxy)propionic acid and then reacting it with 2(1H-imidazol-1-yl)ethylamine. The hydroxyl-terminated naphthalene derivative is prepared by reacting 2-hydroxy-6-naphthoyl chloride with diethylenetriamine.

2. The acid and alkali resistant protective film according to claim 1, characterized in that, The modified PET resin is prepared by the following steps: Step A1: Thoroughly mix β-(acryloyloxy)propionic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide and deionized water, sonicate at room temperature for 15 min, add 2(1H-imidazol-1-yl)ethylamine and stir at room temperature for 10-12 h. After the reaction is complete, rotary evaporate to 10 mL, add dichloromethane and mix well, let stand to separate the layers, collect the organic layer, add anhydrous sodium sulfate to dry, filter, and rotary evaporate a second time to obtain acrylate imidazolium; Step A2: Add diethylenetriamine to N,N-dimethylacetamide and stir until homogeneous. Place the mixture in an ice-water bath, add triethylamine and mix well. Then add 2-hydroxy-6-naphthoyl chloride and stir until homogeneous. Heat the mixture to 65°C and stir for 5.5-6.5 hours. After the reaction is complete, transfer the mixture to distilled water at 10°C, filter, wash, and dry to obtain the terminal hydroxynaphthalene derivative. Step A3: Mix the terminal hydroxyl naphthalene derivative with anhydrous methanol and stir evenly under room temperature and nitrogen conditions. Then, while stirring, add acrylate imidazole. After the addition is complete, raise the system temperature to 35°C and react for 4-6 hours. Then, rotary evaporate to obtain the terminal hydroxyl modifier. Step A4: Mix the hydroxyl-terminated modifier and ethylene glycol evenly to obtain a mixed diol; mix 2,2-bis(4-carboxyphenyl)hexafluoropropane and terephthalic acid evenly to obtain a mixed dicarboxylic acid; esterify the mixed diol and mixed dicarboxylic acid at 0.1-0.15 MPa and 240-260℃ for 2-3 hours. After the reaction is complete, perform a polycondensation reaction at 15-25 kPa and 280-290℃ for 4-6 hours. After the acid value of the reaction solution reaches 35-50 mg KOH / g, remove the excess diol by rotary evaporation to obtain the modified PET resin.

3. The acid and alkali resistant protective film according to claim 2, characterized in that, In step A1, the molar ratio of β-(acryloyloxy)propionic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide and 2(1H-imidazol-1-yl)ethylamine is 1:1.15-1.2:0.9-0.95:1-1.

03.

4. The acid and alkali resistant protective film according to claim 2, characterized in that, In step A2, the molar ratio of diethylenetriamine, 2-hydroxy-6-naphthoyl chloride and triethylamine is 1:2-2.02:2.1-2.

2.

5. The acid and alkali resistant protective film according to claim 2, characterized in that, The 2-hydroxy-6-naphthoyl chloride described in step A2 is prepared by the following steps: 0.4 mol of 2-hydroxy-6-naphthoic acid is added to 40 mL of toluene, followed by 10 mL of thionyl chloride. The mixture is then placed in an oil bath and refluxed at 116 °C for 1.5-2.5 h. The solvent and excess thionyl chloride are removed by rotary evaporation, and then 10 mL of toluene is added and stirred until homogeneous. The mixture is then subjected to a second rotary evaporation to obtain 2-hydroxy-6-naphthoyl chloride.

6. The acid and alkali resistant protective film according to claim 2, characterized in that, In step A3, the molar ratio of the terminal hydroxynaphthalene derivative and acrylate imidazole is 1:1.5-2.

2.

7. The acid and alkali resistant protective film according to claim 2, characterized in that, In step A4, the molar ratio of the mixed diol and the mixed diacid is 1.2-1.3:1, and the molar ratio of the terminal hydroxyl modifier to ethylene glycol in the mixed diol is 1:0.2-0.

3. The molar ratio of 2,2-bis(4-carboxyphenyl)hexafluoropropane to terephthalic acid in the mixed diacid is 0.05-0.15:0.85-0.

95.

8. The acid and alkali resistant protective film according to claim 1, characterized in that, The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:

1.

9. The acid and alkali resistant protective film according to claim 1, characterized in that, The lubricant is one of polyethylene wax, calcium stearate, or zinc stearate.

10. A method for preparing the acid and alkali resistant protective film according to any one of claims 1-9, characterized in that, Includes the following steps: Weigh the raw materials according to the weight proportions, add each component raw material to the mixer and mix evenly, then transfer to a twin-screw extruder for melt extrusion, stretch into a film, heat set, cool, and roll up to obtain an acid and alkali resistant protective film.

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