Pressure-sensitive adhesive film and preparation method thereof

Abstract

The invention relates to a pressure-sensitive adhesive film and a preparation method thereof, and belongs to the technical field of high polymer materials. The pressure-sensitive adhesive film is prepared from the following components in parts by weight: 70 to 95 parts of 2-ethylhexyl acrylate, 5 to 20 parts of methyl methacrylate, 2 to 15 parts of acrylic acid, 0.1 to 2.0 parts of an emulsifier, 30 to 140 parts of deionized water, 0.02 to 1.2 parts of a buffering agent, 0.1 to 10 parts of a high-temperature-resistant modifier, 0.1 to 5 parts of a flame retardant and 0.2 to 1.5 parts of an initiator, the maleimide enhances the intermolecular force and improves the glass transition temperature, the melting point and the heat resistance of the material, the phosphite decomposes hydroperoxide and prevents yellowing, and the carbazole monomer improves the high temperature resistance; phenyl dichlorophosphate and ammonium polyphosphate in the flame retardant form phosphate, air and heat are effectively isolated, phosphorus-oxygen and silicon-oxygen bonds are cooperated, and the flame retardant efficiency is improved. The pressure-sensitive adhesive film prepared by the preparation method disclosed by the invention not only has an excellent permanent adhesion effect, but also has good flame retardance and high-temperature resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a pressure-sensitive adhesive film and a preparation method thereof. Background Art

[0002] Pressure-sensitive adhesive is an adhesive that is sensitive to pressure. It is mainly used to prepare pressure-sensitive tapes or pressure-sensitive adhesive sheets. It is widely used in packaging, labeling, electrical insulation, medical and health care and other fields. Pressure-sensitive adhesive can be divided into two types: rubber type and resin type according to the main resin component. Among them, acrylic pressure-sensitive adhesive has attracted much attention and favor due to its simple process, low manufacturing cost, little or even no environmental pollution.

[0003] With the rapid development of global industrialization, the market has an urgent need for pressure-sensitive adhesive films with high bonding strength and excellent high-temperature resistance. However, traditional acrylic pressure-sensitive adhesive films have problems such as debonding and low adhesion during use in high-temperature environments, which affects their use. In order to meet people's increasing product needs, the high-temperature resistance of acrylic pressure-sensitive adhesive films also needs to be continuously improved and perfected; in addition, although acrylic pressure-sensitive adhesive films have certain flame retardancy, with the increase in actual application needs, their own flame retardancy no longer meets the needs. Therefore, the research and development of a pressure-sensitive adhesive film with excellent performance has important practical significance and application value. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a pressure-sensitive adhesive film and a preparation method thereof.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A pressure-sensitive adhesive film comprises the following raw materials in parts by weight: 70-95 parts of isooctyl acrylate, 5-20 parts of methyl methacrylate, 2-15 parts of acrylic acid, 0.1-2.0 parts of emulsifier, 30-140 parts of deionized water, 0.02-1.2 parts of buffer, 0.1-10 parts of high temperature resistant modifier, 0.1-5 parts of flame retardant, and 0.2-1.5 parts of initiator; The emulsifier is sodium lauryl sulfate; The buffer is sodium bicarbonate; The initiator is potassium persulfate.

[0006] The high temperature resistant modifier is prepared by the following method: Step A1: p-Aminophenol, maleic anhydride and tetrahydrofuran were mixed, stirred in an ice-water bath for 5 min, filtered, washed, placed in a 20°C water bath, and triethylamine, toluene and phenylphosphonium dichloride were added dropwise. After the addition, the temperature was slowly raised to 110°C, kept warm for reaction for 3 h, cooled to room temperature, filtered, and dried to obtain compound 1; Further, the dosage ratio of p-aminophenol, maleic anhydride, tetrahydrofuran, triethylamine, toluene, and phenylphosphonium dichloride is 10.75-11.04 g: 9.2-9.8 g: 15-30 mL: 10-15 g: 65-90 g: 16-18 g; First, the amino group of p-aminophenol reacts with maleic anhydride, and then the hydroxyl group of p-aminophenol reacts with the chlorine atom of phenylphosphonium dichloride to generate compound 1; Step A2: Carbazole, methylbutynol, potassium hydroxide and dimethyl sulfoxide were added into a four-necked flask, mixed, introduced with nitrogen, stirred at 140° C. for 12 h, filtered, distilled under reduced pressure, cooled, filtered, and dried under vacuum to obtain compound 2; Further, the mass ratio of carbazole, methylbutynol, potassium hydroxide, and dimethyl sulfoxide is 4.96-5.57 g: 2.0-2.3 g: 0.4-1 g: 20 g; Secondly, carbazole was used to react with the hydroxyl group of methylbutynol to generate compound 2 containing a carbon-carbon double bond; Step A3: Compound 1 and Compound 2 are mixed, stirred for 10 minutes, and then azobisisobutyronitrile and ethanol are added and mixed evenly, the mixture is heated to 70-80° C., reacted for 3 hours, and cooled to room temperature to obtain a high temperature resistant modifier; Further, the usage ratio of compound 1, compound 2, azobisisobutyronitrile, and ethanol is 5-7 g: 2-4 g: 0.35-0.55 g: 20 mL; Finally, the high temperature resistant modifier was synthesized by copolymerizing the carbon-carbon double bonds of compound 1 and compound 2.

[0007] The flame retardant is prepared by the following method: Step B1: 3-chloropropyltriethoxysilane and ethanol-water mixed solution were mixed at 35° C. for 10 min, and then dichlorophenyl phosphate and triethylamine were added, and the temperature was raised to 60° C. for reaction for 5 h. After the temperature was lowered to room temperature, the mixture was washed, rotary evaporated, and dried at 60° C. to obtain an intermediate; Furthermore, the usage ratio of 3-chloropropyltriethoxysilane, ethanol-water mixed solution, phenyl dichlorophosphate, and triethylamine is 0.04-0.06 mol: 150 mL: 0.06-0.09 mol: 8-10 g; the volume ratio of ethanol to water in the ethanol-water mixed solution is 4:1.

[0008] First, the chlorine atom of phenyl dichlorophosphate reacts with the silanol group of 3-chloropropyltriethoxysilane hydrolyzed to generate an intermediate; Step B2: Mix the pre-product, N,N-dimethylbenzylamine and methanol, stir at 80° C., react for 12 h, cool to room temperature, and dry under nitrogen protection to obtain a pre-product; Further, the ratio of the pre-product, N,N-dimethylbenzylamine, and methanol is 1-2 mol: 1-2 mol: 10-30 mL; Secondly, the chlorine atom of the pre-product reacts with the amino group of N, N-dimethylbenzylamine to generate the pre-product; Step B3: evenly dispersing ammonium polyphosphate in deionized water, adding the pre-product and mixing, stirring at 40° C. for 1-2 hours, centrifuging, washing, and drying in a vacuum oven at 80° C. for 12 hours to obtain a flame retardant; Further, the usage ratio of ammonium polyphosphate, deionized water, and pre-product is 18-22 g: 180-210 mL: 10.3-12.4 g; Finally, the flame retardant is synthesized by utilizing the electrostatic interaction between the positive charge of the pre-product and the negative charge of ammonium polyphosphate.

[0009] A method for preparing a pressure-sensitive adhesive film comprises the following steps: S1, emulsifying the emulsifier, isooctyl acrylate, methyl methacrylate and acrylic acid for 20-40 minutes at an emulsification speed of 600-900 r / min to obtain a pre-emulsion; S2, adding deionized water, buffer, high temperature modifier and flame retardant to the pre-emulsion, mixing, heating to 70-80°C while stirring at a speed of 50-200r / min, adding initiator, adjusting the pH to 7-8, filtering, discharging, and obtaining a pressure-sensitive adhesive latex; S3. Evenly apply the pressure-sensitive adhesive latex on the corona-treated PE film, then put the film into an oven and dry it at 90-100° C. to obtain a pressure-sensitive adhesive film.

[0010] Beneficial effects of the present invention: The pressure-sensitive adhesive film of the present invention uses acrylate as a matrix and has a good adhesive holding effect. Flame retardants and macromolecular polymer high-temperature resistant modifiers are added to give the pressure-sensitive adhesive film excellent flame retardant and high-temperature resistant properties, effectively extending the service life of the material.

[0011] In the high temperature resistant modifier prepared by the present invention, the maleimide group has a dipole moment perpendicular to the main axis of the molecular chain, which enhances the intermolecular force, thereby improving the glass transition temperature and melting point of the material, and increasing the rigidity and heat resistance of the molecular chain; at the same time, the phosphite compound can not only effectively decompose the hydroperoxide in the acrylic pressure-sensitive adhesive, prevent free radical oxidation reaction, thereby improving the stability of the pressure-sensitive adhesive, but also inhibit yellowing at high temperature by virtue of a strong redox effect, and maintain a good appearance of the pressure-sensitive adhesive; the phosphite compound and the maleimide group work synergistically, and significantly enhance the anti-yellowing performance of the acrylic pressure-sensitive adhesive; in addition, by introducing a carbazole monomer for chemical modification, the molecular chain of the acrylic pressure-sensitive adhesive is more stable, and the high temperature resistance is further improved; in addition, the high temperature resistant modifier has good compatibility with acrylic acid, and effectively prevents migration.

[0012] The phenyl dichloride phosphate in the flame retardant prepared by the present invention contains phosphorus element, which can form phosphate compounds in the combustion process to synthesize a protective layer to inhibit the spread of flames, thereby achieving a flame retardant effect. At the same time, the phenyl dichloride phosphate has good compatibility with acrylic pressure-sensitive adhesive, ensuring the uniform distribution and long-term stability of the flame retardant in the material; in addition, ammonium polyphosphate is dehydrated into polyphosphoric acid when heated, which promotes carbonization of the surface of organic matter to form a heat-insulating foam layer, effectively isolates air and heat, further enhances the flame retardant effect, and synergizes with phosphorus-oxygen double bonds and silicon-oxygen bonds to improve the flame retardant efficiency; in addition, the flame retardant prepared by the present invention is halogen-free, helps to reduce pollution to the environment and damage to the ecosystem, is harmless to human health, and achieves sustainable development. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] Embodiment 1: A method for preparing a pressure-sensitive adhesive film, comprising the following steps: S1. Weigh the raw materials by weight: 70 parts of isooctyl acrylate, 5 parts of methyl methacrylate, 2 parts of acrylic acid, 0.1 parts of emulsifier, 30 parts of deionized water, 0.02 parts of buffer, 0.1 parts of high temperature resistant modifier (prepared in this embodiment), 0.1 parts of flame retardant (prepared in this embodiment), and 0.2 parts of initiator; mix and emulsify sodium lauryl sulfate, isooctyl acrylate, methyl methacrylate and acrylic acid for 20 minutes at an emulsification speed of 600 r / min to obtain a pre-emulsion; S2, adding deionized water, sodium bicarbonate, high temperature resistant modifier and flame retardant to the pre-emulsion, mixing, heating to 70°C while stirring at a speed of 50r / min, adding potassium persulfate, adjusting the pH to 7, filtering, discharging, and obtaining a pressure-sensitive adhesive latex; S3, evenly apply the pressure-sensitive adhesive latex on the corona-treated PE film, then put the film into an oven and dry it at 90° C. to obtain a pressure-sensitive adhesive film; The high temperature resistant modifier is prepared by the following method: Step A1: 10.75 g of p-aminophenol, 9.2 g of maleic anhydride and 15 mL of tetrahydrofuran were mixed, stirred in an ice-water bath for 5 min, filtered, washed, placed in a 20°C water bath, and then 10 g of triethylamine, 65 g of toluene and 16 g of phenylphosphonium dichloride were added dropwise. After the addition was complete, the temperature was slowly raised to 110°C, the reaction was kept at this temperature for 3 h, cooled to room temperature, filtered, and dried to obtain compound 1; Step A2: 4.96 g of carbazole, 2.0 g of methylbutynol, 0.4 g of potassium hydroxide and 20 g of dimethyl sulfoxide were added to a four-necked flask, mixed, introduced with nitrogen, stirred at 140° C. for 12 h, filtered, distilled under reduced pressure, cooled, filtered, and dried under vacuum to obtain compound 2; Step A3: 5 g of compound 1 and 2 g of compound 2 were mixed, stirred for 10 min, and then 0.35 g of azobisisobutyronitrile and 20 mL of ethanol were added and mixed evenly, the mixture was heated to 70° C., reacted for 3 h, and cooled to room temperature to obtain a high temperature resistant modifier; The flame retardant is prepared by the following method: Step B1: Mix 0.04 mol 3-chloropropyltriethoxysilane and 150 mL ethanol-water mixed solution at 35°C for 10 min, then add 0.06 mol phenyl dichlorophosphate and 8 g triethylamine, heat to 60°C for reaction for 5 h, wait until the temperature drops to room temperature, wash, rotary evaporate, and dry at 60°C to obtain an intermediate. The volume ratio of ethanol to water in the ethanol-water mixed solution is 4:1.

[0015] Step B2: 1 mol of the pre-product, 1 mol of N,N-dimethylbenzylamine and 10 mL of methanol were mixed, stirred at 80° C., reacted for 12 h, cooled to room temperature, and dried under nitrogen protection to obtain a pre-product; Step B3: 18 g of ammonium polyphosphate was evenly dispersed in 180 mL of deionized water, and 10.3 g of the pre-product was added and mixed, stirred at 40° C. for 1 h, centrifuged, washed, and dried in a vacuum oven at 80° C. for 12 h to obtain a flame retardant.

[0016] Embodiment 2: A method for preparing a pressure-sensitive adhesive film, comprising the following steps: S1. Weigh the raw materials by weight: 82 parts of isooctyl acrylate, 12 parts of methyl methacrylate, 8 parts of acrylic acid, 1 part of emulsifier, 85 parts of deionized water, 0.6 parts of buffer, 5 parts of high temperature resistant modifier (prepared in this embodiment), 2.5 parts of flame retardant (prepared in this embodiment), and 0.8 parts of initiator; mix and emulsify sodium lauryl sulfate, isooctyl acrylate, methyl methacrylate and acrylic acid for 30 minutes at an emulsification speed of 750 r / min to obtain a pre-emulsion; S2, adding deionized water, sodium bicarbonate, high temperature resistant modifier and flame retardant to the pre-emulsion, mixing, heating to 75°C while stirring at a speed of 125r / min, adding potassium persulfate, adjusting the pH to 7.5, filtering, discharging, and obtaining a pressure-sensitive adhesive latex; S3, evenly apply the pressure-sensitive adhesive latex on the corona-treated PE film, then put the film into an oven and dry it at 95° C. to obtain a pressure-sensitive adhesive film; The high temperature resistant modifier is prepared by the following method: Step A1: 10.9 g of p-aminophenol, 9.5 g of maleic anhydride and 22.5 mL of tetrahydrofuran were mixed, stirred in an ice-water bath for 5 min, filtered, washed, placed in a 20°C water bath, and then 12 g of triethylamine, 77.5 g of toluene and 17 g of phenylphosphonium dichloride were added dropwise. After the addition was complete, the temperature was slowly raised to 110°C, the reaction was kept at this temperature for 3 h, cooled to room temperature, filtered, and dried to obtain compound 1; Step A2: 5.265 g of carbazole, 2.15 g of methylbutynol, 0.7 g of potassium hydroxide and 20 g of dimethyl sulfoxide were added to a four-necked flask, mixed, introduced with nitrogen, stirred at 140° C. for 12 h, filtered, distilled under reduced pressure, cooled, filtered, and dried in vacuo to obtain compound 2; Step A3: 6 g of compound 1 and 3 g of compound 2 were mixed, stirred for 10 min, and then 0.45 g of azobisisobutyronitrile and 20 mL of ethanol were added and mixed evenly, the mixture was heated to 75 ° C, reacted for 3 h, and cooled to room temperature to obtain a high temperature resistant modifier; The flame retardant is prepared by the following method: Step B1: Mix 0.05 mol 3-chloropropyltriethoxysilane and 150 mL ethanol-water mixed solution at 35°C for 10 min, then add 0.075 mol phenyl dichlorophosphate and 9 g triethylamine, heat to 60°C for reaction for 5 h, wait until the temperature drops to room temperature, wash, rotary evaporate, and dry at 60°C to obtain an intermediate. The volume ratio of ethanol to water in the ethanol-water mixed solution is 4:1.

[0017] Step B2: 1.5 mol of the pre-product, 1.5 mol of N,N-dimethylbenzylamine and 20 mL of methanol were mixed, stirred at 80° C., reacted for 12 h, cooled to room temperature, and dried under nitrogen protection to obtain a pre-product; Step B3: 20 g of ammonium polyphosphate was evenly dispersed in 195 mL of deionized water, and 11 g of the pre-product was added and mixed, stirred at 40° C. for 1.5 h, centrifuged, washed, and dried in a vacuum oven at 80° C. for 12 h to obtain a flame retardant.

[0018] Embodiment 3: A method for preparing a pressure-sensitive adhesive film, comprising the following steps: S1. Weigh the raw materials by weight: 95 parts of isooctyl acrylate, 20 parts of methyl methacrylate, 15 parts of acrylic acid, 2.0 parts of emulsifier, 140 parts of deionized water, 1.2 parts of buffer, 10 parts of high temperature resistant modifier (prepared in this embodiment), 5 parts of flame retardant (prepared in this embodiment), and 1.5 parts of initiator; mix and emulsify sodium lauryl sulfate, isooctyl acrylate, methyl methacrylate and acrylic acid for 40 minutes at an emulsification speed of 900 r / min to obtain a pre-emulsion; S2, adding deionized water, sodium bicarbonate, high temperature resistant modifier and flame retardant to the pre-emulsion and mixing, heating to 80°C while stirring at a speed of 200 r / min, adding potassium persulfate, adjusting the pH to 8, filtering, discharging, and obtaining a pressure-sensitive adhesive latex; S3, evenly apply the pressure-sensitive adhesive latex on the corona-treated PE film, then put the film into an oven and dry it at 100° C. to obtain a pressure-sensitive adhesive film; The high temperature resistant modifier is prepared by the following method: Step A1: 11.04 g of p-aminophenol, 9.8 g of maleic anhydride and 30 mL of tetrahydrofuran were mixed, stirred in an ice-water bath for 5 min, filtered, washed, placed in a 20° C. water bath, and then 15 g of triethylamine, 90 g of toluene and 18 g of phenylphosphonium dichloride were added dropwise. After the addition was complete, the temperature was slowly raised to 110° C., the reaction was kept at this temperature for 3 h, cooled to room temperature, filtered, and dried to obtain compound 1; Step A2: 5.57 g of carbazole, 2.3 g of methylbutynol, 1 g of potassium hydroxide and 20 g of dimethyl sulfoxide were added to a four-necked flask, mixed, introduced with nitrogen, stirred at 140° C. for 12 h, filtered, distilled under reduced pressure, cooled, filtered, and dried under vacuum to obtain compound 2; Step A3: 7 g of compound 1 and 4 g of compound 2 were mixed, stirred for 10 min, and then 0.55 g of azobisisobutyronitrile and 20 mL of ethanol were added and mixed evenly, the mixture was heated to 80° C., reacted for 3 h, and cooled to room temperature to obtain a high temperature resistant modifier; The flame retardant is prepared by the following method: Step B1: Mix 0.06 mol 3-chloropropyltriethoxysilane and 150 mL ethanol-water mixed solution at 35°C for 10 min, then add 0.09 mol phenyl dichlorophosphate and 10 g triethylamine, heat to 60°C for reaction for 5 h, wait until the temperature drops to room temperature, wash, rotary evaporate, and dry at 60°C to obtain an intermediate. The volume ratio of ethanol to water in the ethanol-water mixed solution is 4:1.

[0019] Step B2: 2 mol of the pre-product, 2 mol of N, N-dimethylbenzylamine and 30 mL of methanol were mixed, stirred at 80° C., reacted for 12 h, cooled to room temperature, and dried under nitrogen protection to obtain a pre-product; Step B3: 22 g of ammonium polyphosphate was evenly dispersed in 210 mL of deionized water, and 12.4 g of the pre-product was added and mixed, stirred at 40° C. for 2 h, centrifuged, washed, and dried in a vacuum oven at 80° C. for 12 h to obtain a flame retardant.

[0020] Comparative Example 1: This comparative example is a pressure-sensitive adhesive film, which differs from Example 3 in that an equal amount of N-phenylmaleimide is used to replace the high temperature resistant modifier prepared in Example 3, and the rest are the same.

[0021] Comparative Example 2: This comparative example is a pressure-sensitive adhesive film, which differs from Example 3 in that an equal amount of magnesium hydroxide is used to replace the flame retardant prepared in Example 3, and the rest are the same.

[0022] Performance test: The pressure-sensitive adhesive films prepared in Examples 1-3 and Comparative Examples 1-2 were cut into standard test sizes, and the holding force was tested according to standard GB4851-2014; the flame retardant grade was tested according to GB 10707-2008 "Determination of Combustion Performance of Rubber"; the 180° peel strength at 25°C and 150°C was measured according to GB / T2792-2014; the test results are shown in Table 1 below: ; It can be seen from the test data in Table 1 that the pressure-sensitive adhesive film prepared in the present invention has excellent adhesion and flame retardant effects. It can also be seen from the above table that the pressure-sensitive adhesive film prepared in the present invention has good high temperature resistance.

[0023] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a pressure-sensitive adhesive film, characterized in that: The specific steps include: S1. Weigh the raw materials by weight: 70-95 parts of isooctyl acrylate, 5-20 parts of methyl methacrylate, 2-15 parts of acrylic acid, 0.1-2.0 parts of emulsifier, 30-140 parts of deionized water, 0.02-1.2 parts of buffer, 0.1-10 parts of high temperature resistant modifier, 0.1-5 parts of flame retardant, and 0.2-1.5 parts of initiator; mix and emulsify the emulsifier, isooctyl acrylate, methyl methacrylate and acrylic acid for 20-40 minutes at an emulsification speed of 600-900 r / min to obtain a pre-emulsion; S2, adding deionized water, buffer, high temperature modifier and flame retardant to the pre-emulsion, mixing, heating to 70-80°C while stirring at a speed of 50-200r / min, adding initiator, adjusting the pH to 7-8, filtering, discharging, and obtaining a pressure-sensitive adhesive latex; S3, evenly apply the pressure-sensitive adhesive latex on the corona-treated PE film, then put the film into an oven and dry it at 90-100° C. to obtain a pressure-sensitive adhesive film; The high temperature resistant modifier is prepared by the following method: Step A1: p-Aminophenol, maleic anhydride and tetrahydrofuran were mixed, stirred in an ice-water bath for 5 min, filtered, washed, placed in a 20°C water bath, and triethylamine, toluene and phenylphosphonium dichloride were added dropwise. After the addition, the temperature was slowly raised to 110°C, kept warm for reaction for 3 h, cooled to room temperature, filtered, and dried to obtain compound 1; Step A2: Carbazole, methylbutynol, potassium hydroxide and dimethyl sulfoxide were added into a four-necked flask, mixed, introduced with nitrogen, stirred at 140° C. for 12 h, filtered, distilled under reduced pressure, cooled, filtered, and dried under vacuum to obtain compound 2; Step A3: Compound 1 and Compound 2 are mixed, stirred for 10 minutes, and then azobisisobutyronitrile and ethanol are added and mixed evenly, the mixture is heated to 70-80° C., reacted for 3 hours, and cooled to room temperature to obtain a high temperature resistant modifier.

2. The method for preparing a pressure-sensitive adhesive film according to claim 1, characterized in that: In step A1, the usage ratio of p-aminophenol, maleic anhydride, tetrahydrofuran, triethylamine, toluene and phenylphosphonium dichloride is 10.75-11.04 g: 9.2-9.8 g: 15-30 mL: 10-15 g: 65-90 g: 16-18 g.

3. The method for preparing a pressure-sensitive adhesive film according to claim 1, characterized in that: In step A2, the mass ratio of carbazole, methylbutynol, potassium hydroxide and dimethyl sulfoxide is 4.96-5.57 g: 2.0-2.3 g: 0.4-1 g: 20 g.

4. The method for preparing a pressure-sensitive adhesive film according to claim 1, characterized in that: In step A3, the usage ratio of compound 1, compound 2, azobisisobutyronitrile and ethanol is 5-7 g: 2-4 g: 0.35-0.55 g: 20 mL.

5. The method for preparing a pressure-sensitive adhesive film according to claim 1, characterized in that: The flame retardant is prepared by the following method: Step B1: 3-chloropropyltriethoxysilane and ethanol-water mixed solution were mixed at 35° C. for 10 min, and then dichlorophenyl phosphate and triethylamine were added, and the temperature was raised to 60° C. for reaction for 5 h. After the temperature was lowered to room temperature, the mixture was washed, rotary evaporated, and dried at 60° C. to obtain an intermediate; Step B2: Mix the pre-product, N,N-dimethylbenzylamine and methanol, stir at 80° C., react for 12 h, cool to room temperature, and dry under nitrogen protection to obtain a pre-product; Step B3: Disperse ammonium polyphosphate evenly in deionized water, add the pre-product and mix, stir at 40° C. for 1-2 hours, centrifuge, wash, and dry in a vacuum oven at 80° C. for 12 hours to obtain a flame retardant.

6. The method for preparing a pressure-sensitive adhesive film according to claim 5, characterized in that: In step B1, the usage ratio of 3-chloropropyltriethoxysilane, ethanol-water mixed solution, phenyl dichlorophosphate, and triethylamine is 0.04-0.06 mol: 150 mL: 0.06-0.09 mol: 8-10 g; the volume ratio of ethanol to water in the ethanol-water mixed solution is 4:

1.

7. The method for preparing a pressure-sensitive adhesive film according to claim 5, characterized in that: The usage ratio of the product, N,N-dimethylbenzylamine and methanol in step B2 is 1-2 mol: 1-2 mol: 10-30 mL.

8. The method for preparing a pressure-sensitive adhesive film according to claim 5, characterized in that: In step B3, the dosage ratio of ammonium polyphosphate, deionized water and pre-product is 18-22 g: 180-210 mL: 10.3-12.4 g.

9. The method for preparing a pressure-sensitive adhesive film according to claim 1, characterized in that: The emulsifier is sodium dodecyl sulfate, the buffer is sodium bicarbonate, and the initiator is potassium persulfate.

10. A pressure-sensitive adhesive film, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 9.