Flame-retardant master batch as well as preparation method and application thereof

Abstract

The invention provides a flame-retardant master batch and a preparation method and application thereof.According to the flame-retardant master batch and the preparation method and application thereof, Si3N4 is coated with ammonium polyacrylate through emulsion polymerization, DOPO is grafted to the surface of the ammonium polyacrylate, a flame retardant of a core-shell structure is prepared, the functional aging of the flame retardant is enhanced, migration is prevented, the flame retardant master batch is prepared by blending the flame retardant and PET, and the expected effect is achieved. The PET flame-retardant master batch provided by the invention is unique, ingenious and reasonable in formula design. The flame-retardant property of the composite material can be effectively improved through the synergistic effect of various flame retardants, the flame-retardant master batch does not contain halogen, and the polyester film does not generate a large amount of gas harmful to a human body during combustion.

Description

Technical Field

[0001] The present invention belongs to the technical field of films, and relates to flame-retardant films, and in particular to a flame-retardant masterbatch which does not contain halogen and does not generate a large amount of gas harmful to the human body when the polyester film is burned, as well as a preparation method and application thereof. Background Art

[0002] PET flame-retardant film presents a new technology and presents technical challenges. Internationally, only Mitsubishi of Japan boasts a truly V0 flame retardant grade and excellent mechanical properties. Its technology remains a secret, monopolistic technology, and its products are expensive. Domestic research is also underway to introduce phosphate esters into the PET molecular backbone through transesterification, but this approach is inconvenient, costly, and difficult to achieve a true V0 rating, making it difficult to expand at this stage.

[0003] As a new environmentally friendly material, polyester film is widely used in our daily lives. With the continuous advancement of biaxial stretching technology, the application of polyester film has continued to expand. More and more electronic appliances are using polyester film. Concerned about user safety, flame-retardant polyester film has become a new focus. However, common flame retardants significantly affect the performance of polyester film, so achieving a balance between the film's inherent properties and flame retardancy has become a key research topic.

[0004] Chinese patent application number 200480000122.5 (publication number CN1329471C; publication date August 1, 2007) discloses flame-retardant heat-expandable microspheres. The flame-retardant mechanism involves adding a fluorine-containing compound as a foaming agent to the microspheres, which expands and releases fluorine upon ignition, achieving the flame-retardant effect. However, the release of fluorine-containing compounds can have adverse environmental impacts, making this a suboptimal flame-retardant approach from an environmental perspective.

[0005] Chinese invention patent application number 200910034637.1 (publication number CN101643574; publication date February 10, 2010) discloses a method for preparing a flame-retardant polyester film. The method mainly involves adding a flame retardant to a polyester material through copolymerization and blending to achieve the purpose of flame retardancy. The resulting product has a wide thickness range and good flame retardant effect, but the production investment is relatively large, the process is complicated, and the production cost is high.

[0006] The Chinese invention patent with application number 202410296402.4 (announcement number CN117887225A; announcement date April 16, 2024) discloses an environmentally friendly flame retardant masterbatch, its preparation method and polyester film. It mainly uses polyaniline, ZIF-67 and dimethyl methylphosphonate as flame retardant raw materials to prepare a flame retardant with a core-shell structure. However, a variety of organic solvents are used in its preparation process. The subsequent treatment of a large amount of solvent residues is likely to cause an environmental burden, and the high cost of raw materials hinders large-scale industrial production.

[0007] However, traditional halogen-containing flame retardants have problems such as compatibility, dispersibility, inherent toxicity, and the easy release of irritating and corrosive gases and large amounts of toxic smoke.

[0008] It is difficult to meet high flame retardancy requirements by using phosphorus or nitrogen flame retardants alone, and ordinary halogen-free flame retardants are easily decomposed during high-temperature processing (such as biaxial stretching process), resulting in a decrease in flame retardancy efficiency. Summary of the Invention

[0009] In order to solve the above problems, the present invention first provides a flame retardant masterbatch and a preparation method. The present invention abandons the use of conventional halogenated flame retardants and adopts halogen-free flame retardants. Ammonium polyacrylate is coated on Si3N4 through emulsion polymerization, and DOPO is grafted on the surface of the ammonium polyacrylate to obtain a core-shell structure flame retardant, which enhances its functional aging and prevents migration. The flame retardant is blended with PET to obtain a flame retardant masterbatch, which solves the above problems and achieves the expected effect.

[0010] The present invention also provides the use of the flame retardant masterbatch in preparing a flame retardant film.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] The present invention first provides a flame retardant masterbatch. The raw materials of the flame retardant masterbatch include 40-45 parts of DOPO grafted core-shell flame retardant, 2-4 parts of dispersant and 51-68 parts of PET polyester in parts by weight.

[0013] As a preferred embodiment of the present invention, the dispersant is a compound combination of one or more of calcium stearate and zinc stearate.

[0014] As a preferred embodiment of the present invention, the raw materials of the DOPO-grafted core-shell flame retardant include silicon nitride, ammonium polyacrylate and DOPO.

[0015] The present invention also provides a method for preparing the flame retardant masterbatch, which comprises the following steps:

[0016] 1) immersing silicon nitride in a sodium hydroxide solution, ultrasonically treating the silicon nitride, filtering and drying the solution to obtain hydroxylated silicon nitride with surface impurities removed and active hydroxyl groups generated;

[0017] 2) dispersing the hydroxylated silicon nitride obtained in step 1) in alcohol, adding a coupling agent, and stirring uniformly to obtain modified silicon nitride;

[0018] 3) dispersing the modified silicon nitride obtained in step 2) in deionized water, adding sodium lauryl sulfate, and ultrasonically treating to obtain a suspension, adding ammonium acrylate monomer and N,N-methylenebisacrylamide, stirring and reacting to obtain a pre-emulsion;

[0019] 4) adding the pre-emulsion obtained in step 3) to a reaction vessel, venting oxygen, heating, adding ammonium persulfate for reaction, cooling to room temperature, adjusting the pH value, centrifuging, washing, and vacuum drying to obtain polyacrylate-coated silicon nitride;

[0020] 5) dissolving DOPO in anhydrous tetrahydrofuran, adding epichlorohydrin, adding sodium hydroxide in an ice-water bath, stirring to react, filtering, distilling under reduced pressure, and purifying by column chromatography to obtain epoxy-modified DOPO;

[0021] 6) dispersing the ammonium polyacrylate-coated silicon nitride obtained in step 4) in an ethanol solution, adding EDC and NHS, stirring thoroughly at room temperature, adding a coupling agent, ultrasonically dispersing, heating, refluxing, centrifuging, washing, and vacuum drying to obtain amino-modified ammonium polyacrylate / silicon nitride microspheres;

[0022] 7) adding the amino-modified ammonium polyacrylate / silicon nitride microspheres obtained in step 6) to the epoxy-modified DOPO obtained in step 5), heating, and stirring to react; after the reaction is completed, centrifuging and washing, and vacuum drying to obtain a DOPO-grafted core-shell flame retardant;

[0023] 8) The DOPO-grafted core-shell flame retardant obtained in step 7) and the dispersant are uniformly mixed with PET polyester, and then extruded to obtain a flame retardant masterbatch.

[0024] As a preferred embodiment of the present invention, in step 1), the mass fraction of the sodium hydroxide solution is 1-5%, and the ultrasonic treatment time is 1-2 hours.

[0025] As a preferred embodiment of the present invention, in step 2), the stirring reaction speed is 500-600 r / s, and the reaction time is 4-6 h.

[0026] As a preferred embodiment of the present invention, in step 4), the mass ratio of ammonium acrylate monomer to silicon nitride is (1-3):1, the amount of N,N-methylenebisacrylamide added is 0.8-1.5% of the ammonium acrylate monomer; and the pH value is adjusted to 7-8.

[0027] As a preferred embodiment of the present invention, in step 5), the molar ratio of DOPO to epichlorohydrin is 1:(1-1.3), and the molar ratio of sodium hydroxide to epichlorohydrin is 1:0.8-1.2.

[0028] As a preferred embodiment of the present invention, in step 5), the mass ratio of silicon nitride coated with ammonium polyacrylate to DOPO is 5:(2-4).

[0029] As a preferred embodiment of the present invention, the coupling agent is a compound combination of one or more of KH-550, KH-560, A-151, OFS-6020 and KH-792.

[0030] Finally, the present invention provides the use of the flame retardant masterbatch in preparing a flame retardant film. The raw materials of the flame retardant film include 30-40 parts of the flame retardant masterbatch and 60-70 parts of PET chips in parts by weight.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1) The formula design of the PET flame retardant masterbatch provided by the present invention is unique, ingenious and reasonable, and the flame retardant properties of the composite material can be effectively improved through the synergistic effect of multiple flame retardants.

[0033] 2) The flame retardant masterbatch of the present invention does not contain halogen, and the combustion of the polyester film will not produce a large amount of gas harmful to the human body.

[0034] 3) The twin-screw extrusion used in the present invention is stable and can accurately control the desired effect; the preparation method provided by the present invention has strong process feasibility, low cost, high preparation efficiency, and the obtained PET flame retardant film product has excellent mechanical properties, which is conducive to large-scale promotion. DETAILED DESCRIPTION

[0035] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] The present invention first provides a flame retardant masterbatch. The flame retardant masterbatch is firstly prepared by coating ammonium polyacrylate on Si3N4 through emulsion polymerization, and then grafting DOPO on the surface of the ammonium polyacrylate to obtain a DOPO-grafted core-shell flame retardant, so as to enhance the functional aging and prevent migration; finally, the DOPO-grafted core-shell flame retardant is blended and extruded with PET polyester to obtain the flame retardant masterbatch.

[0037] This ternary synergistic system achieves highly effective flame retardancy through multiple mechanisms, including condensed-phase char formation and gas-phase free radical inhibition. Ammonium polyacrylate provides acid catalysis and nitrogen dilution, DOPO enhances both gas- and condensed-phase flame retardancy, and Si3N4 optimizes the carbon layer through physical reinforcement. The three complement each other to form a multi-layered protective network.

[0038] The present invention also provides a method for preparing the flame retardant masterbatch, comprising the following steps:

[0039] 1) Silicon nitride (particle size 200±50 nm) is immersed in a sodium hydroxide solution with a concentration of 1-5%, ultrasonically treated for 2 hours, filtered and dried to obtain hydroxylated silicon nitride with surface impurities removed and active hydroxyl groups generated.

[0040] 2) Dispersing the hydroxylated silicon nitride in ethanol, adding KH-550 at a concentration of 1-3%, stirring at a speed of 500-600 r / s at 60° C. for 4-6 hours to allow the silane coupling agent to bond with the surface hydroxyl groups.

[0041] 3) Dispersing the modified silicon nitride in deionized water, adding 1-2% sodium lauryl sulfate, and ultrasonically treating for 30 minutes to form a suspension, then adding ammonium acrylate monomer and N,N'-methylenebisacrylamide, and stirring at 1000-1500 rpm for 1 hour to form a pre-emulsion. The mass ratio of ammonium acrylate monomer to silicon nitride is (1-3):1, and the amount of N,N'-methylenebisacrylamide added is 0.8-1.5% of the mass of the ammonium acrylate monomer.

[0042] 4) Transfer the pre-emulsion to a three-necked flask and introduce nitrogen to remove oxygen. Raise the temperature to 70-80°C and slowly add 0.5-1% ammonium persulfate dropwise. Allow to react for 3-5 hours to allow the monomer to polymerize in situ on the silicon nitride surface to form a poly(ammonium acrylate) shell. Then, cool to room temperature and adjust the pH to 7-8 with aqueous ammonia to terminate the reaction. Finally, centrifuge, wash, and vacuum dry to obtain poly(ammonium acrylate)-coated silicon nitride. The mass ratio of silicon nitride to poly(ammonium acrylate) is 3:(2-6).

[0043] 5) DOPO was dissolved in anhydrous tetrahydrofuran, epichlorohydrin was added, and 1-2 mol / L sodium hydroxide was slowly added dropwise in an ice-water bath. The mixture was then warmed to room temperature and stirred for 8-12 hours. The mixture was filtered and the solvent was removed by distillation under reduced pressure to obtain a crude product. The crude product was purified by column chromatography to obtain epoxy-modified DOPO. The molar ratio of DOPO to epichlorohydrin was 1:1-1.3, and the molar ratio of sodium hydroxide to epichlorohydrin was 1:0.8-1.2.

[0044] 6) Disperse the silicon nitride-coated ammonium polyacrylate in a 90% or greater ethanol solution, add EDC and NHS, and stir at room temperature for 30 minutes. Add 2-5% KH550, ultrasonically disperse for 30 minutes, heat to 70°C, reflux for 6 hours, wash by centrifugation, and vacuum dry to obtain amino-modified ammonium polyacrylate / silicon nitride microspheres.

[0045] 7) Disperse the amino-modified ammonium polyacrylate / silicon nitride microspheres in an ethanol solution, add the epoxy-modified DOPO, heat to 60°C, and stir at 600-800 rpm for 18-24 hours. Finally, centrifuge, wash, and vacuum dry to obtain a DOPO-grafted core-shell flame retardant. The mass ratio of ammonium polyacrylate-coated silicon nitride to DOPO is 5:(2-4).

[0046] 8) The DOPO-grafted core-shell flame retardant obtained in step 7) is uniformly mixed with PET polyester, and then extruded to obtain a flame retardant masterbatch.

[0047] The method of blending and extruding the DOPO-grafted core-shell flame retardant, dispersant and PET polyester is a commonly used method for preparing masterbatch in this field, which will not be described in detail below.

[0048] Finally, the present invention provides an application of the flame retardant masterbatch to produce a PET flame retardant film, comprising 30-40 parts of the flame retardant masterbatch and 60-70 parts of high-gloss PET chips. This preparation method is a commonly used method for preparing films in the art and will not be described in detail below.

[0049] Example 1

[0050] This embodiment provides a method for preparing a flame retardant masterbatch, comprising the following steps:

[0051] 1) Silicon nitride (particle size 200 nm) was immersed in a 3% sodium hydroxide solution, ultrasonically treated for 2 hours, filtered and dried to obtain hydroxylated silicon nitride with surface impurities removed and active hydroxyl groups generated.

[0052] 2) The hydroxylated silicon nitride was dispersed in ethanol, and KH-550 with a concentration of 2% was added. The mixture was stirred at 60° C. and a rotation speed of 500 r / s for 5 h to allow the silane coupling agent to bond with the surface hydroxyl groups.

[0053] 3) Dispersing the modified silicon nitride in deionized water, adding 1.5% sodium lauryl sulfate, and ultrasonically treating for 30 minutes to form a suspension, then adding ammonium acrylate monomer and N,N'-methylenebisacrylamide, and stirring at 1000 rpm for 1 hour to form a pre-emulsion. The amount of N,N'-methylenebisacrylamide added is 1.2% by weight of the ammonium acrylate monomer.

[0054] 4) Transfer the pre-emulsion to a three-necked flask and introduce nitrogen to remove oxygen. Raise the temperature to 70-80°C and slowly add 0.8% ammonium persulfate dropwise. Allow to react for 5 hours to allow the monomer to in situ polymerize on the silicon nitride surface to form a poly(ammonium acrylate) shell. Then cool to room temperature and adjust the pH to 7-8 with aqueous ammonia to terminate the reaction. Finally, centrifuge, wash, and vacuum dry to obtain poly(ammonium acrylate)-coated silicon nitride. The mass ratio of silicon nitride to poly(ammonium acrylate) is 4:3.

[0055] 5) DOPO was dissolved in anhydrous tetrahydrofuran, epichlorohydrin was added, and 1 mol / L sodium hydroxide was slowly added dropwise in an ice-water bath. The mixture was then warmed to room temperature and stirred for 12 hours. The mixture was filtered and the solvent was removed by vacuum distillation to obtain a crude product. The crude product was purified by column chromatography to obtain epoxy-modified DOPO. The molar ratio of DOPO to epichlorohydrin was 1:1.2, and the molar ratio of sodium hydroxide to epichlorohydrin was 1:1.

[0056] 6) The silicon nitride-coated ammonium polyacrylate was dispersed in a 90% ethanol solution, EDC and NHS were added, and the mixture was stirred at room temperature for 30 minutes. Then, 5% by mass of KH550 was added, and the mixture was ultrasonically dispersed for 30 minutes. The mixture was heated to 70°C and refluxed for 6 hours. The mixture was washed by centrifugation and dried in vacuo to obtain amino-modified ammonium polyacrylate / silicon nitride microspheres.

[0057] 7) Disperse the amino-modified ammonium polyacrylate / silicon nitride microspheres in an ethanol solution, add epoxy-modified DOPO, heat to 60°C, and stir at 800 rpm for 24 hours. Finally, centrifuge, wash, and vacuum dry to obtain a DOPO-grafted core-shell flame retardant. The mass ratio of ammonium polyacrylate-coated silicon nitride to DOPO is 7:3.

[0058] 8) After fully mixing 40% of the flame retardant, 57% of the PET and 3% of the dispersant by mass, the mixture was added to an extruder for extrusion and granulation to obtain a flame retardant masterbatch.

[0059] Finally, PET flame retardant film was made by combining 35% by weight of flame retardant masterbatch and 65% by weight of high-gloss PET chips.

[0060] Example 2

[0061] The difference between this embodiment and embodiment 1 is that the proportions of raw materials for preparing the flame retardant masterbatch are different, and the specific ratios are: 45 parts of flame retardant, 52 parts of PET, and 3 parts of dispersant.

[0062] Example 3

[0063] The difference between this embodiment and embodiment 1 is that the distribution ratio of each component in the flame retardant is different. In terms of mass percentage, the weight ratio of Si3N4, ammonium polyacrylate and DOPO is 3:5:5.

[0064] Comparative Example 1

[0065] The difference between this embodiment and embodiment 1 is that the proportions of raw materials for preparing the polyester film are different, specifically, the ratio is: 25 parts of flame retardant masterbatch to 75 parts of PET.

[0066] Comparative Example 2

[0067] The difference between this comparative example and Example 1 is that the proportions of raw materials for preparing the flame retardant masterbatch are different, and the specific ratios are: 20 parts of flame retardant, 77 parts of PET, and 3 parts of dispersant.

[0068] Comparative Example 3

[0069] This comparative example is different from Example 1 in that DOPO is not used as the flame retardant.

[0070] Table 1. Dosage table of Examples 1-3 and Comparative Examples 1-3

[0071]

[0072] The flame retardant films prepared in Examples 1-3 and the films prepared in Comparative Examples 1-3 were tested. The testing method was as follows: the flame height was adjusted to 20 mm, the flame was applied for the first time for 3 seconds, annealing was performed and the flaming burning time t1 was recorded, the flame was applied for the second time for 3 seconds, annealing was performed and the flaming burning time t2 and the flameless burning time t3 were recorded, and it was recorded whether the burning exceeded the 125 mm mark and whether there were any drips that ignited the absorbent cotton below. The results are shown in Table 2.

[0073] Table 2. Test results

[0074] T1 / S T2 / S T1+2 / S Is there any molten dripping? Whether the dripping material ignites the cotton wool assessment Example 1 7.9 9.5 17.4 no no VTM-0 Example 2 6.5 7.6 14.1 no no VTM-0 Example 3 8.2 10.1 18.3 no no VTM-0 Comparative Example 1 10.3 13.2 23.5 yes no VTM-1 Comparative Example 2 13.5 15.9 29.4 yes no VTM-1 Comparative Example 3 —— —— —— yes yes No level

[0075] It can be seen that the formula design of the PET flame retardant masterbatch provided by the present invention is unique, ingenious and reasonable, and the flame retardant properties of the composite material can be effectively improved through the synergistic effect of multiple flame retardants; the flame retardant masterbatch of the present invention does not contain halogen, and the combustion of the polyester film does not produce a large amount of gas harmful to the human body; the twin-screw extrusion used in the present invention is stable and can accurately control the desired effect; the preparation method provided by the present invention has strong process feasibility, low cost, high preparation efficiency, and the obtained PET film products have excellent mechanical properties, which is conducive to large-scale promotion.

[0076] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form or substance. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention. Any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the spirit and scope of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A flame retardant masterbatch, characterized in that: The raw materials of the flame retardant masterbatch are calculated by weight, including 40-45 parts of DOPO grafted core-shell flame retardant, 2-4 parts of dispersant, and 51-68 parts of PET polyester.

2. The flame retardant masterbatch according to claim 1, characterized in that: The dispersant is any one of calcium stearate and zinc stearate or a combination thereof.

3. The flame retardant masterbatch according to claim 1, characterized in that: The raw materials of the DOPO-grafted core-shell flame retardant include silicon nitride, ammonium polyacrylate and DOPO.

4. A method for preparing a flame retardant masterbatch according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: 1) immersing silicon nitride in a sodium hydroxide solution, ultrasonically treating the silicon nitride, filtering and drying the solution to obtain hydroxylated silicon nitride with surface impurities removed and active hydroxyl groups generated; 2) dispersing the hydroxylated silicon nitride obtained in step 1) in alcohol, adding a coupling agent, and stirring uniformly to obtain modified silicon nitride; 3) dispersing the modified silicon nitride obtained in step 2) in deionized water, adding sodium lauryl sulfate, and ultrasonically treating to obtain a suspension, adding ammonium acrylate monomer and N,N-methylenebisacrylamide, stirring and reacting to obtain a pre-emulsion; 4) adding the pre-emulsion obtained in step 3) to a reaction vessel, heating under nitrogen protection, adding ammonium persulfate for reaction, cooling to room temperature, adjusting the pH value, centrifuging, washing, and vacuum drying to obtain polyacrylate ammonium coated silicon nitride; 5) dissolving DOPO in anhydrous tetrahydrofuran, adding epichlorohydrin, adding sodium hydroxide in an ice-water bath, stirring to react, filtering, distilling under reduced pressure, and purifying by column chromatography to obtain epoxy-modified DOPO; 6) dispersing the ammonium polyacrylate-coated silicon nitride obtained in step 4) in an ethanol solution, adding EDC and NHS, stirring thoroughly at room temperature, adding a coupling agent, ultrasonically dispersing, heating, refluxing, washing by centrifugation, and vacuum drying to obtain amino-modified ammonium polyacrylate / silicon nitride microspheres; 7) adding the amino-modified ammonium polyacrylate / silicon nitride microspheres obtained in step 6) to the epoxy-modified DOPO obtained in step 5), heating, and stirring to react; after the reaction is completed, centrifuging and washing, and vacuum drying to obtain a DOPO-grafted core-shell flame retardant; 8) The DOPO-grafted core-shell flame retardant obtained in step 7) and the dispersant are uniformly mixed with PET polyester, and then extruded to obtain a flame retardant masterbatch.

5. The method for preparing the flame retardant masterbatch according to claim 4, characterized in that: In step 1), the mass fraction of the sodium hydroxide solution is 1-5%, and the ultrasonic treatment time is 1-2 hours.

6. The method for preparing the flame retardant masterbatch according to claim 4, characterized in that: In step 2), the stirring reaction speed is 500-600 r / s, and the reaction time is 4-6 h.

7. The method for preparing the flame retardant masterbatch according to claim 4, characterized in that: In step 4), the mass ratio of ammonium acrylate monomer to silicon nitride is 1-3:1, and the amount of N,N-methylenebisacrylamide added is 0.8-1.5% of the ammonium acrylate monomer; and the pH value is adjusted to 7-8.

8. The method for preparing a flame retardant masterbatch according to claim 4, characterized in that: In step 5), the molar ratio of DOPO to epichlorohydrin is 1:1-1.3, and the molar ratio of sodium hydroxide to epichlorohydrin is 1:0.8-1.

2.

9. The method for preparing a flame retardant masterbatch according to claim 4, characterized in that: In step 5), the mass ratio of silicon nitride coated with ammonium polyacrylate to DOPO is 5:2-4.

10. The method for preparing the flame retardant masterbatch according to claim 4, characterized in that: The coupling agent is a compound combination of one or more of KH-550, KH-560, A-151, OFS-6020 and KH-792.

11. Use of the flame retardant masterbatch according to any one of claims 1 to 3 or the flame retardant masterbatch prepared by the preparation method according to any one of claims 5 to 10 in preparing a flame retardant film.

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