Bactericidal flame retardant, preparation method thereof and bactericidal flame-retardant BOPET film

Abstract

The invention relates to the technical field of high polymer materials, particularly provides a bactericidal flame retardant, and also provides a preparation method thereof and a bactericidal flame-retardant BOPET (Biaxially Oriented Polyethylene Terephthalate) film based on the bactericidal flame retardant. The bactericidal flame retardant provided by the invention is a polyguanidine organic acid salt, and is prepared from a water-soluble polyguanidine salt and an organic acid through a salt forming reaction. The water-insoluble polyguanidine organic acid salt with antibacterial and flame-retardant functions is prepared by combining a guanidine compound with halogen / phosphorus-containing flame-retardant organic acid through a salt forming reaction, has excellent chemical stability, can stably exist in a polymer matrix for a long time and is not easy to migrate or separate out, so that the durability of sterilization and flame-retardant properties is ensured.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a bactericidal flame retardant, as well as its preparation method and a bactericidal and flame retardant BOPET film based on the bactericidal flame retardant. Background Technology

[0002] Solar cells, as green, environmentally friendly, and sustainable clean energy conversion devices, are mainly composed of tempered glass, ethylene-vinyl acetate copolymer (EVA), solar cells, a backsheet, and a junction box. Among these, the solar cell backsheet is a key protective component ensuring the long-term stable operation of photovoltaic modules. It plays a crucial role in supporting the solar cells, isolating them from external moisture and impurities, and providing electrical insulation. Polyethylene terephthalate (PET, or polyester) film, due to its high mechanical strength, good insulation, and resistance to chemical corrosion, has become the mainstream substrate for current solar cell backsheets.

[0003] However, traditional PET films have significant shortcomings in functionality. On the one hand, they lack antibacterial properties and are prone to bacterial and mold growth in humid and polluted environments, affecting not only the film's appearance but also potentially accelerating material aging and shortening the lifespan of photovoltaic modules. On the other hand, PET is a flammable material with a low limiting oxygen index (LOI), posing a fire hazard under extreme conditions such as lightning strikes and short circuits, failing to meet the high safety requirements of photovoltaic backsheets. Currently, to improve the functionality of PET films, antibacterial agents or flame retardants are typically introduced through physical blending or surface coating. However, most modification methods only optimize a single property, resulting in limited functionality; moreover, conventional additives have poor compatibility with the PET matrix, easily migrating and precipitating, leading to functional degradation over time; some additives lack thermal stability and are prone to decomposition under the high-temperature conditions of PET processing, affecting the film's molding quality and final performance. Therefore, developing a biaxially oriented polyester (BOPET) film that combines highly efficient antibacterial and flame-retardant properties with high weather resistance and is suitable for industrial production has significant technological value and market potential. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a bactericidal and flame-retardant agent with excellent chemical stability, capable of long-term stable existence within a polymer matrix without easy migration or precipitation, thereby ensuring the durability of its bactericidal and flame-retardant properties. Furthermore, this invention also provides its preparation method and a bactericidal and flame-retardant BOPET film based on this bactericidal and flame-retardant agent.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: In a first aspect, the present invention provides a bactericidal flame retardant, wherein the bactericidal flame retardant is a polyguanidine organic acid salt, which is prepared by a salt-forming reaction between a water-soluble polyguanidine salt and an organic acid; The water-soluble polyguanidine salt includes one or more of the following: water-soluble salts of polyhexamethylene guanidine, water-soluble salts of polyhexamethylene biguanide, and water-soluble salts of polyaminopropyl biguanide. The organic acid includes one or more of 1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic acid, diphenylphosphine, and 2-carboxyethylphenylphosphine.

[0006] This invention utilizes a water-soluble polyguanidine salt to undergo a salt-forming reaction with halogenated and phosphorus-containing organic acids, forming a structurally stable insoluble polyguanidine organic acid salt. In this polyguanidine organic acid salt structure, the polyguanidine component achieves long-lasting antibacterial properties by disrupting microbial cell membranes, while the flame-retardant elements in the organic acids exert highly efficient flame-retardant functions at high temperatures through synergistic effects between the gas and condensed phases, effectively solving the problems of easy migration and performance degradation associated with traditional blending additives. Furthermore, it exhibits good compatibility with the polymer matrix, enabling products to simultaneously achieve both long-lasting antibacterial properties and significantly improved flame-retardant properties with only small amounts added, without affecting the mechanical and processing characteristics of the material. This makes it particularly suitable for high-end thin film applications requiring high weather resistance.

[0007] Preferably, in the salt-forming reaction, the molar ratio of the NH2 group of the water-soluble polyguanidine salt to the anion group of the organic acid is (0.8-1.1):1.

[0008] The preferred molar ratio of this invention ensures sufficient reaction between the amino groups in the water-soluble polyguanidine salt and the anions in the organic acid, promoting complete ionic bond formation and yielding structurally regular polyguanidine organic acid salts. If the ratio is below 0.8, excess organic acid may lead to unreacted acidic residues, affecting product purity and stability; if the ratio is above 1.1, excess water-soluble polyguanidine salt may be lost during subsequent processing, reducing the final yield.

[0009] Preferably, the water-soluble polyguanidine salt is selected from one or more of the following: hydrochloride, phosphate, gluconate, sulfate, nitrate, carbonate, sulfite, formate, and acetate of polyguanidine.

[0010] Secondly, the present invention provides a method for preparing the above-mentioned bactericidal flame retardant, comprising the following steps: The organic acid is dissolved in a solvent to form an organic acid mixture; the water-soluble polyguanidine salt is prepared into an aqueous solution of polyguanidine salt. The polyguanidine salt aqueous solution is added dropwise to the organic acid mixture to carry out a salt formation reaction, thereby obtaining the bactericidal flame retardant. Preferably, the solvent is selected from one or more of water, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0011] Thirdly, the present invention provides the application of the above-mentioned bactericide and flame retardant as a bactericide and flame retardant additive in the preparation of polymer products.

[0012] Preferably, the polymer articles include, but are not limited to, one or more of the following: polysulfone, polyethersulfone, polyvinylidene fluoride, polyvinylidene chloride, polytetrafluoroethylene, polyacrylonitrile, polyetheretherketone, polyvinyl chloride, polyethylene, polyethylene acetate, polyethylene vinyl alcohol, polypropylene, polystyrene, polyethylene terephthalate, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polystyrene-butadiene-acrylonitrile, polymethyl methacrylate, polyamide-6, polyamide-8, polyamide-66, polyamide-10, polyamide-610, polyamide-1010, polyamide-1212, polyamide-6T, epoxy resin, and polyurethane.

[0013] The bactericidal and flame-retardant agent provided by this invention can be used as a functional additive and compounded with a polymer matrix through processing methods such as solution blending or melt blending. During solution blending, solvents that can be used include, but are not limited to, one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, acetone, ethyl acetate, tetrahydrofuran, toluene, xylene, dichloromethane, chloroform, or carbon tetrachloride. After the above processing and molding, a polymer product with both excellent bactericidal and flame-retardant properties can be obtained.

[0014] Fourthly, the present invention provides a bactericidal and flame-retardant BOPET film, the bactericidal and flame-retardant BOPET film comprising a core layer and surface layers located on both sides of the core layer, forming a stacked structure of surface layer-core layer-surface layer, wherein the raw materials for preparing the surface layer include the bactericidal and flame-retardant agent provided by the present invention.

[0015] Preferably, the surface layer comprises the following raw materials by weight: 100 parts PET masterbatch, 1-10 parts bactericide and flame retardant, and 1-3 parts opening agent; the core layer is prepared from PET masterbatch.

[0016] Preferably, the opening agent includes one or more of talc, silica, diatomaceous earth, and calcium carbonate.

[0017] Preferably, the thickness ratio of the core layer to the surface layer on either side is (9-11):1; the thickness ratio of the surface layers on both sides of the core layer is 1:(1-1.1).

[0018] Preferably, the thickness of the bactericidal and flame-retardant BOPET film is 10-50 μm.

[0019] Fifthly, the present invention provides a method for preparing the above-mentioned bactericidal and flame-retardant BOPET film, comprising the following steps: The PET masterbatch, bactericide, flame retardant, and opening agent are added to the first extruder for melt extrusion to obtain a surface melt; the PET masterbatch is added to the second extruder for melt extrusion to obtain a core melt. The surface melt and the core melt are co-extruded in three layers to obtain a cast sheet. The cast sheet is then stretched longitudinally, stretched laterally, shaped, and wound up to obtain the bactericidal and flame-retardant BOPET film.

[0020] Preferably, the production speed of the entire preparation process is controlled at 150-400 m / min; during the longitudinal stretching process, the longitudinal stretching ratio is 2.0-3.5 times; during the transverse stretching process, the transverse stretching ratio is 2.5-3.7 times; during the setting process, the preheating temperature is 75-100℃, the heat setting temperature is 225-250℃, the heating air volume is 4000-6000 kg / h, and the cooling air volume is 12000-35000 kg / h.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention combines bactericidal guanidine compounds with halogenated / phosphorus-containing flame-retardant organic acids via a salt-forming reaction to obtain water-insoluble polyguanidine organic acid salts with both antibacterial and flame-retardant functions. These salts exhibit excellent chemical stability, remaining stable in the polymer matrix for extended periods without migration or precipitation, thus ensuring the durability of both bactericidal and flame-retardant properties. This solves the problems of uneven component dispersion and functional conflicts commonly found in traditional physical blending. Furthermore, this additive is resistant to high processing temperatures and exhibits stability during extrusion melt processing, without affecting the film forming process or mechanical properties.

[0022] (2) The bactericide and flame retardant provided by the present invention can be used as a multifunctional additive in polymer products such as BOPET film. Only one component needs to be added to simultaneously improve multiple properties of the film. The resulting BOPET film has excellent hydrophobic self-cleaning function and high weather resistance. The limiting oxygen index is increased by 9.5%, the disinfect rate of Escherichia coli reaches 100%, and the water contact angle of the film surface is increased by 25°. It is especially suitable for outdoor application scenarios such as photovoltaic backsheets. It can effectively reduce the adhesion of surface pollutants, reduce the frequency of manual cleaning, and extend the service life in extreme environments. Detailed Implementation

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the specific embodiments will be briefly introduced below. Obviously, the embodiments described below are some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these embodiments without creative effort.

[0024] Where specific experimental steps or conditions are not specified in the embodiments, they can be performed according to the conventional experimental steps or conditions described in the literature in this field. All raw materials or instruments used are commercially available conventional products, including but not limited to those used in the embodiments of this application.

[0025] Example 1 This embodiment provides a bactericidal flame retardant, which is a polyguanidine organic acid salt, prepared by a salt-forming reaction between a water-soluble polyguanidine salt and an organic acid; The water-soluble polyguanidine salt is polyhexamethylene biguanide nitrate, and the organic acid is 2-carboxyethylphenyl hypophosphite; The molar ratio of the NH2 group of the water-soluble polyguanidine salt to the anion group of the organic acid is 1:1.

[0026] The method for preparing the bactericidal flame retardant provided in this embodiment includes the following steps: 2-Carboxyethylphenyl hypophosphoric acid was dissolved in 35 mL of N,N-dimethylformamide to form a mixture; polyhexamethylene biguanide nitrate was prepared into a 25 wt% aqueous solution. 66g of polyhexamethylene biguanide nitrate aqueous solution was added dropwise to the mixture, and the mixture was stirred for 4 hours to carry out the salt formation reaction. The white solid was collected by filtration, and the filter cake was washed three times with pure water. The filter cake was dried under vacuum at 50℃ to obtain 12.3g of white solid bactericide and flame retardant, with a yield of 55.2%.

[0027] This embodiment also provides a bactericidal and flame-retardant BOPET film, including a core layer and surface layers located on both sides of the core layer, forming a stacked structure of surface layer-core layer-surface layer, with a thickness ratio of surface layer-core layer-surface layer of 1:10:1 (surface layer:core layer:surface layer). The surface layer comprises the following raw materials by weight: 100 parts PET masterbatch, 3 parts bactericide and flame retardant prepared in this embodiment, and 1.2 parts opening agent; the opening agent is silica; the core layer raw material is PET masterbatch. The thickness ratio of the core layer to the surface layer on either side is 10:1; the thickness ratio of the surface layers on both sides of the core layer is 1:1; the thickness of the bactericidal and flame-retardant BOPET film is 12μm.

[0028] The method for preparing the bactericidal and flame-retardant BOPET film provided in this embodiment includes the following steps: PET masterbatch, bactericide, flame retardant, and opening agent are added to the first extruder for melt extrusion to obtain the surface melt; PET masterbatch is added to the second extruder for melt extrusion to obtain the core melt. The surface melt and core melt are simultaneously fed into a three-layer co-extrusion die. The surface melt is evenly distributed to both sides of the core melt. Following a three-layer structure (surface-core-surface), the two sets of melts are stacked and merged, and a cast sheet is obtained through a cooling drum. The cast sheet is then longitudinally stretched at 85°C with a stretch ratio of 3.5 times; subsequently, it is transversely stretched at a speed of 300 m / min with a stretch ratio of 3.6 times, and preheated at 90°C. After stretching, it undergoes heat setting at 243°C with a heating air volume of 5000 kg / h; after gradual cooling, it is traction and winding with a cooling air volume of 30000 kg / h to produce a bactericidal and flame-retardant BOPET film.

[0029] The antibacterial and flame-retardant BOPET film has a thickness of 12μm, with the surface layer having a thickness of 1μm and the core layer having a thickness of 10μm.

[0030] Example 2 This embodiment provides a bactericidal flame retardant, which is a polyguanidine organic acid salt, prepared by a salt-forming reaction between a water-soluble polyguanidine salt and an organic acid; The water-soluble polyguanidine salt is polyhexamethylene guanidine hydrochloride, and the organic acid is diphenylphosphine. The molar ratio of the NH2 group of the water-soluble polyguanidine salt to the anion group of the organic acid is 0.8:1.

[0031] The method for preparing the bactericidal flame retardant provided in this embodiment includes the following steps: 12g of diphenylphosphine was dissolved in 60mL of N,N-dimethylformamide to form a mixture; polyhexamethylene guanidine hydrochloride was prepared into an aqueous solution with a mass concentration of 15wt%; Add 65g of polyhexamethylene guanidine hydrochloride aqueous solution dropwise to the mixture, stir for 5h to carry out the salt formation reaction, filter and collect the white solid, wash the filter cake three times with pure water, and vacuum dry the filter cake at 40℃ to obtain 9.4g of white solid bactericide and flame retardant, with a yield of 43.4%.

[0032] This embodiment also provides a bactericidal and flame-retardant BOPET film, including a core layer and surface layers located on both sides of the core layer, forming a stacked structure of surface layer-core layer-surface layer, with a thickness ratio of surface layer-core layer-surface layer of 1:10:1 (surface layer:core layer:surface layer). The surface layer comprises the following raw materials by weight: 100 parts PET masterbatch, 3 parts bactericide and flame retardant prepared in this embodiment, and 1.2 parts opening agent; the opening agent is silica; the core layer raw material is PET masterbatch. The thickness ratio of the core layer to the surface layer on either side is 10:1; the thickness ratio of the surface layers on both sides of the core layer is 1:1; the thickness of the bactericidal and flame-retardant BOPET film is 12μm.

[0033] The method for preparing the bactericidal and flame-retardant BOPET film provided in this embodiment includes the following steps: PET masterbatch, bactericide, flame retardant, and opening agent are added to the first extruder for melt extrusion to obtain the surface melt; PET masterbatch is added to the second extruder for melt extrusion to obtain the core melt. The surface melt and core melt are simultaneously fed into a three-layer co-extrusion die. The surface melt is evenly distributed to both sides of the core melt. Following a three-layer structure of surface-core-surface, the two sets of melts are stacked and merged, and a cast sheet is obtained through a cooling drum. The cast sheet is then longitudinally stretched at 85°C with a stretch ratio of 3.5. It is then transversely stretched at a speed of 300 m / min with a stretch ratio of 2.7, and preheated at 90°C. After stretching, it undergoes heat setting at 243°C with a heating air volume of 5000 kg / h. After gradual cooling, it is traction and winding with a cooling air volume of 30000 kg / h to obtain a bactericidal and flame-retardant BOPET film.

[0034] The antibacterial and flame-retardant BOPET film has a thickness of 12μm, with the surface layer having a thickness of 1μm and the core layer having a thickness of 10μm.

[0035] Example 3 This embodiment provides a bactericidal flame retardant, which is a polyguanidine organic acid salt, prepared by a salt-forming reaction between a water-soluble polyguanidine salt and an organic acid; The water-soluble polyguanidine salt is polyaminopropyl biguanide sulfate, and the organic acid is diphenylphosphine and 2-carboxyethylphenylphosphine. The molar ratio of the NH2 group of the water-soluble polyguanidine salt to the anion group of the organic acid is 1.1:1.

[0036] The method for preparing the bactericidal flame retardant provided in this embodiment includes the following steps: Dissolve 50g of diphenylphosphine and 45g of 2-carboxyethylphenylphosphine in 500g of dimethyl sulfoxide to form a mixture; prepare a 10wt% polyurethane biguanide sulfate aqueous solution. 1000g of polyurethane biguanide sulfate aqueous solution was added dropwise to the mixture, and the mixture was stirred for 6 hours to carry out the salt formation reaction. The white solid was collected by filtration, and the filter cake was washed three times with pure water. The filter cake was then dried under vacuum at 40℃ to obtain 96g of white solid bactericide and flame retardant, with a yield of 50.5%.

[0037] This embodiment also provides a bactericidal and flame-retardant BOPET film, including a core layer and surface layers located on both sides of the core layer, forming a stacked structure of surface layer-core layer-surface layer, with a thickness ratio of surface layer-core layer-surface layer of 1:10:1 (surface layer:core layer:surface layer). The surface layer comprises the following raw materials by weight: 100 parts PET masterbatch, 3 parts bactericide and flame retardant prepared in this embodiment, and 1.2 parts opening agent; the opening agent is silica; the core layer raw material is PET masterbatch. The thickness ratio of the core layer to the surface layer on either side is 10:1; the thickness ratio of the surface layers on both sides of the core layer is 1:1; the thickness of the bactericidal and flame-retardant BOPET film is 12μm.

[0038] The method for preparing the bactericidal and flame-retardant BOPET film provided in this embodiment includes the following steps: PET masterbatch, bactericide, flame retardant, and opening agent are added to the first extruder for melt extrusion to obtain the surface melt; PET masterbatch is added to the second extruder for melt extrusion to obtain the core melt. The surface melt and core melt are simultaneously fed into a three-layer co-extrusion die. The surface melt is evenly distributed to both sides of the core melt. Following a three-layer structure (surface-core-surface), the two sets of melts are stacked and merged, and a cast sheet is obtained through a cooling drum. The cast sheet is then longitudinally stretched at 85°C with a stretch ratio of 3.5 times; subsequently, it is transversely stretched at a speed of 300 m / min with a stretch ratio of 3.6 times, and preheated at 90°C. After stretching, it undergoes heat setting at 243°C with a heating air volume of 5000 kg / h; after gradual cooling, it is traction and winding with a cooling air volume of 30000 kg / h to produce a bactericidal and flame-retardant BOPET film.

[0039] The antibacterial and flame-retardant BOPET film has a thickness of 12μm, with the surface layer having a thickness of 1μm and the core layer having a thickness of 10μm.

[0040] Comparative Example 1 The polyester film provided in this comparative example is made from pure PET masterbatch, which does not contain flame retardant components and has a thickness of 12μm.

[0041] Performance testing The limiting oxygen index (LOI) refers to the volume fraction of oxygen at which a polymer can just sustain combustion in a mixture of oxygen and nitrogen. Test method: 30g of the bactericidal flame retardant prepared in Examples 1-3 was mixed uniformly with 1000g of PET masterbatch, and then melt-plasticized and extruded using a twin-screw extruder to obtain modified masterbatch. The modified masterbatch was then injection molded into test strips. The test strips prepared in Examples 1-3 and those made from pure PET were vertically fixed inside a combustion chamber, ensuring that the top of the test strip was at least 100mm below the top of the combustion chamber. The test strips were ignited from the top using an igniter, and the combustion was observed. The oxygen concentration was adjusted according to the combustion time or length of the test strips, and the test was repeated until the minimum oxygen concentration required to sustain combustion was found.

[0042] Flame retardancy rating test method: The VTM flame retardancy standard belongs to the vertical burning test system for thin film materials in the US UL94 standard, which includes three levels: VTM-0, VTM-1, and VTM-2. Test method: The sample is made into a 200mm × 50mm rectangle and rolled into a cylinder. After being vertically fixed on the UL-94 burning test machine, a specified ignition source is applied twice (10 seconds each time) to ignite the lower end of the sample. The burning time, whether the dripping material ignites the absorbent cotton, and other parameters are recorded.

[0043] Grading and Judgment Criteria: VTM-0: Burning time ≤ 10 seconds, no dripping or residue, fastest self-extinguishing, and highest flame retardant performance.

[0044] VTM-1: Burning time ≤30 seconds, no dripping or residue, flame retardancy is slightly lower.

[0045] VTM-2: Burning time ≤ 60 seconds, allows brief dripping but cannot ignite absorbent cotton, lowest flame retardancy.

[0046] Antibacterial activity test method: 10g of the bactericidal and flame-retardant film prepared in Examples 1-3 and the polyester film prepared in Comparative Example 1 were placed on the surface of agar medium inoculated with Escherichia coli (volume ratio of bacterial solution to nutrient solution was 9:1). After activating the bacterial strain by culturing at 25°C for 24h, the culture was continued at a constant temperature for another 24h. The antibacterial rate was calculated by comparing the number of colonies before and after culture.

[0047] Water contact angle test method: The wettability of the film surface was determined using an OCA 25 contact angle meter based on the static droplet method. A droplet of ultrapure water (2 μL) was steadily dropped onto the surface of the bactericidal and flame-retardant films prepared in Examples 1-3 and the polyester film prepared in Comparative Example 1, and the contact angle between the droplet and the film surface was measured. A larger contact angle indicates stronger hydrophobicity of the material surface.

[0048] The results are shown in Table 1 below.

[0049] Table 1 As can be seen from the above data, the bactericidal and flame-retardant BOPET film prepared by this invention exhibits significant improvements in flame retardancy, antibacterial properties, and hydrophobicity compared to pure PET film. Specifically, the excellent hydrophobic properties effectively inhibit the accumulation of rainwater and other contaminants on the surface of components, reducing direct contact between contaminants and materials. Simultaneously, the film's long-lasting antibacterial function effectively kills microorganisms attached to the surface, preventing material degradation caused by biological contamination and thus extending its effective protection period. These characteristics collectively endow the film with excellent self-cleaning capabilities. Furthermore, the enhanced flame-retardant properties enable the film to effectively suppress flame spread under extreme conditions such as fires, providing reliable protection for internal components and reducing the risk of spontaneous combustion caused by long-term material aging. The synergistic effect of bactericidal, flame-retardant, and hydrophobic functions significantly improves the film's weather resistance and long-term reliability, making it an ideal protective material for outdoor devices such as photovoltaic backsheets.

[0050] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A bactericidal flame retardant, characterized in that, The bactericidal flame retardant is a polyguanidine organic acid salt, which is prepared by a salt-forming reaction between water-soluble polyguanidine salt and organic acid; The water-soluble polyguanidine salt includes one or more of the following: water-soluble salts of polyhexamethylene guanidine, water-soluble salts of polyhexamethylene biguanide, and water-soluble salts of polyaminopropyl biguanide. The organic acid includes one or more of 1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic acid, diphenylphosphine, and 2-carboxyethylphenylphosphine.

2. The bactericidal flame retardant as described in claim 1, characterized in that, In the salt-forming reaction, the molar ratio of the NH2 group of the water-soluble polyguanidine salt to the anion group of the organic acid is (0.8-1.1):1; and / or The water-soluble polyguanidine salt is selected from one or more of the following: hydrochloride, phosphate, gluconate, sulfate, nitrate, carbonate, sulfite, formate, and acetate of polyguanidine.

3. A method for preparing the bactericidal flame retardant according to any one of claims 1 or 2, characterized in that, Includes the following steps: The organic acid is dissolved in a solvent to form an organic acid mixture; the water-soluble polyguanidine salt is prepared into an aqueous solution of polyguanidine salt. The polyguanidine salt aqueous solution is added dropwise to the organic acid mixture to carry out a salt formation reaction, thereby obtaining the bactericidal flame retardant.

4. The method for preparing the bactericidal flame retardant as described in claim 3, characterized in that, The solvent is selected from one or more of water, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone.

5. The application of the bactericidal and flame-retardant agent as described in any one of claims 1 or 2 as a bactericidal and flame-retardant additive in the preparation of polymer products, characterized in that, The polymer products include one or more of the following: polysulfone, polyethersulfone, polyvinylidene fluoride, polyvinylidene chloride, polytetrafluoroethylene, polyacrylonitrile, polyetheretherketone, polyvinyl chloride, polyethylene, polyethylene acetate, polyethylene vinyl alcohol, polypropylene, polystyrene, polyethylene terephthalate, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polystyrene-butadiene-acrylonitrile, polymethyl methacrylate, polyamide-6, polyamide-8, polyamide-66, polyamide-10, polyamide-610, polyamide-1010, polyamide-1212, polyamide-6T, epoxy resin, and polyurethane.

6. A bactericidal and flame-retardant BOPET film, characterized in that, The bactericidal and flame-retardant BOPET film includes a core layer and surface layers located on both sides of the core layer, forming a stacked structure of surface layer-core layer-surface layer, wherein the raw materials for preparing the surface layer include the bactericidal and flame-retardant agent as described in any one of claims 1 or 2.

7. The bactericidal and flame-retardant BOPET film as described in claim 6, characterized in that, The surface layer comprises, by weight, the following raw materials: 100 parts PET masterbatch, 1-10 parts bactericide and flame retardant, 1-3 parts opening agent; and / or The core layer is prepared from PET masterbatch.

8. The bactericidal and flame-retardant BOPET film as described in claim 7, characterized in that, The opening agent includes one or more of talc, silica, diatomaceous earth, and calcium carbonate.

9. The bactericidal and flame-retardant BOPET film as described in claim 6, characterized in that, The thickness ratio of the core layer to the surface layer on either side is (9-11):1; the thickness ratio of the surface layers on both sides of the core layer is 1:(1-1.1); and / or The thickness of the bactericidal and flame-retardant BOPET film is 10-50 μm.

10. A method for preparing a bactericidal and flame-retardant BOPET film according to any one of claims 6-9, characterized in that, Includes the following steps: The PET masterbatch, bactericide, flame retardant, and opening agent are added to the first extruder for melt extrusion to obtain a surface melt; the PET masterbatch is added to the second extruder for melt extrusion to obtain a core melt. The surface melt and the core melt are co-extruded in three layers to obtain a cast sheet. The cast sheet is then stretched longitudinally, stretched laterally, shaped, and wound up to obtain the bactericidal and flame-retardant BOPET film.

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