Multi-layer packaging adhesive film and preparation method and application thereof

Abstract

The invention relates to a multi-layer packaging adhesive film and a preparation method and application thereof. The multi-layer packaging adhesive film comprises a first transparent layer, a flame-retardant layer and a second transparent layer which are sequentially stacked, the flame-retardant layer is prepared from the following raw materials in parts by weight: 70-120 parts of a resin matrix A, 0.5-10 parts of a coupling agent A, 0.5-10 parts of a cross-linking agent A and 5-20 parts of a halogen-free flame retardant. According to the invention, the structure of the packaging adhesive film and the formula of each layer are designed, so that the high optical transmittance is ensured, and meanwhile, the excellent flame retardant property is realized.

Description

Technical Field

[0001] This invention relates to the field of adhesive film technology, and in particular to a multilayer encapsulation film, its preparation method, and its application. Background Technology

[0002] As the global energy system transitions towards low-carbon and sustainable development, photovoltaic (PV) power generation, as a clean energy source with zero carbon emissions and low operating and maintenance costs, is rapidly gaining popularity in both distributed and centralized power generation. The long-term reliability and operational safety of PV modules directly depend on the comprehensive performance of the encapsulation materials. Currently, commercially available crystalline silicon PV modules generally employ a sandwich-type encapsulation structure (e.g., glass / encapsulation film / cell / encapsulation film / backsheet). The encapsulation film not only provides adhesion, buffering, and electrical insulation, but also must ensure excellent optical transmittance, weather resistance, and long-term physicochemical stability.

[0003] Commonly used encapsulation substrates such as EVA (ethylene-vinyl acetate copolymer) and POE (ethylene-octene copolymer) are widely used due to their cost, process compatibility, and electrical / adhesive properties. However, their inherent oxygen index is low (typically <20), making them flammable polymers. When modules encounter high temperatures, partial discharge, mechanical damage, or other abnormal operating conditions, the encapsulation film is prone to combustion and accelerates the spread of fire, as confirmed by numerous rooftop and ground-mounted photovoltaic power station fires. Therefore, improving the flame-retardant properties of encapsulation systems while maintaining transparency and long-term stability has become an urgent need in photovoltaic material research and development.

[0004] Traditional high-efficiency flame retardant strategies often rely on halogen-based halogen-free flame retardants. While these significantly improve the flame retardant efficiency of materials, they release large amounts of halogen-containing toxic gases and corrosive fumes during combustion, threatening personnel safety and damaging equipment. On the other hand, while some existing halogen-free flame retardant solutions can effectively improve combustion safety, they often require the addition of large amounts of inorganic filler-type halogen-free flame retardants or high-refractive-index organophosphorus halogen-free flame retardants. This can lead to a significant decrease in material transparency, failing to meet the requirements of photovoltaic modules for high-transmittance encapsulation materials, thus reducing photoelectric conversion efficiency.

[0005] Therefore, developing an encapsulating film that combines high transparency, low smoke and halogen-free properties (mainly based on nitrogen and phosphorus flame retardant systems), excellent mechanical and interfacial properties, and compatibility with existing encapsulation processes for practical applications of photovoltaic modules has become an urgent problem to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a multilayer encapsulating film, its preparation method, and its application. By designing the structure of the encapsulating film and the formulation of each layer, excellent flame-retardant properties are achieved while ensuring high optical transmittance.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a multilayer encapsulating film, the multilayer encapsulating film comprising a first transparent layer, a flame-retardant layer and a second transparent layer stacked sequentially;

[0009] The raw materials for preparing the flame retardant layer include, by weight, 70-120 parts of resin matrix A, 0.5-10 parts of coupling agent A, 0.5-10 parts of crosslinking agent A, and 5-20 parts of halogen-free flame retardant.

[0010] Among them, 70-120 portions can be, for example, 70 portions, 80 portions, 90 portions, 100 portions, 110 portions, or 120 portions; 0.5-10 portions can be, for example, 0.5 portions, 1 portion, 2 portions, 4 portions, 5 portions, 6 portions, 8 portions, or 10 portions; 5-20 portions can be, for example, 5 portions, 6 portions, 8 portions, 10 portions, 12 portions, 14 portions, 15 portions, 16 portions, 18 portions, or 20 portions.

[0011] This invention provides a multilayer encapsulating film using a halogen-free flame-retardant system. While maintaining excellent optical transmittance, the film exhibits good flame-retardant properties, meeting the environmental and safety requirements for long-term use of photovoltaic modules. The encapsulating film has a three-layer composite structure: a flame-retardant layer in the middle and transparent layers on both sides. This structural difference achieves synergistic optimization of flame retardancy and light transmittance. Because the middle flame-retardant layer contains a halogen-free flame retardant, its combustion rate is lower than that of the outer transparent film. During combustion, molten droplets from the outer film accumulate on the surface of the middle flame-retardant layer, forming a localized heat barrier, thereby inhibiting the spread of combustion and promoting self-extinguishing of the flame, significantly improving the flame-retardant stability of the film. Since the halogen-free flame retardant is only added to the middle layer, the overall amount of halogen-free flame retardant is effectively controlled. While ensuring flame-retardant performance, this improves the visible light transmittance of the film, reduces optical loss, and helps improve the photoelectric conversion efficiency of photovoltaic modules. Furthermore, this encapsulating film structure design reduces the cost of flame-retardant materials, offering good economic efficiency and process compatibility. The multilayer encapsulating film provided by this invention achieves a comprehensive balance between flame retardant properties, optical properties, and environmental protection characteristics, which can effectively improve the fire resistance of photovoltaic modules and related building materials and broaden their application scope in high-safety application fields.

[0012] Preferably, the thickness of the first transparent layer and the second transparent layer is independently 100-150 μm, for example, it can be 100 μm, 110 μm, 120 μm, 130 μm, 140 μm or 150 μm, etc.

[0013] Preferably, the thickness of the flame-retardant layer is 200-300 μm, for example, it can be 200 μm, 220 μm, 240 μm, 250 μm, 260 μm, 280 μm or 300 μm.

[0014] Preferably, the raw materials for preparing the first transparent layer and the second transparent layer each independently include 70-120 parts of resin matrix B, 0.5-10 parts of coupling agent B and 0.5-10 parts of crosslinking agent B by weight.

[0015] Among them, 70-120 portions can be, for example, 70 portions, 80 portions, 90 portions, 100 portions, 110 portions, or 120 portions; 0.5-10 portions can be, for example, 0.5 portions, 1 portion, 2 portions, 4 portions, 5 portions, 6 portions, 8 portions, or 10 portions; 5-20 portions can be, for example, 5 portions, 6 portions, 8 portions, 10 portions, 12 portions, 14 portions, 15 portions, 16 portions, 18 portions, or 20 portions.

[0016] Preferably, the resin matrix A and the resin matrix B each independently comprise EVA resin.

[0017] Preferably, the VA content of the EVA resin is 20-35% by mass, for example, it can be 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34% or 35%, etc.

[0018] Preferably, the melting temperature of the EVA resin is 50-100℃, for example, it can be 50℃, 60℃, 70℃, 80℃, 90℃ or 100℃.

[0019] Preferably, coupling agent A and coupling agent B each independently comprise any one or a combination of at least two of vinyltrimethoxysilane, dimethylethoxyvinylsilane, vinyltritert-butoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, or vinyltriisopropoxysilane.

[0020] Preferably, crosslinking agent A and crosslinking agent B each independently comprise any one or a combination of at least two of 2,4,6-tris(allyloxy)triazine, tripropylene isocyanurate, propoxylated glycerol triacrylate, ethoxylated pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, divinylbenzene, or tripropyleneoxyphosphazene.

[0021] Preferably, the halogen-free flame retardant comprises dimelamine pyrophosphate.

[0022] This invention preferably uses di- and tricyanamide pyrophosphate as a halogen-free flame retardant. It utilizes a phosphorus source to promote a high-quality condensed phase carbonization layer and releases inert nitrogen gas during the pyrolysis of the melamine component, thereby realizing a phosphorus-nitrogen synergistic flame retardant mechanism. This inhibits combustion at two levels: preventing heat-oxygen transfer and diluting combustible decomposition products. This ensures high light transmittance and long-term reliability in EVA films used for photovoltaic encapsulation.

[0023] Preferably, the raw materials for preparing the first transparent layer, the flame-retardant layer, and the second transparent layer each independently include 0.1-5 parts by weight of antioxidant and / or 0.1-5 parts by weight of light stabilizer.

[0024] The quantities range from 0.1 to 5, for example, 0.1, 1, 2, 3, 4, or 5 portions.

[0025] Preferably, the antioxidant comprises any one or a combination of at least two of the following: octyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, decyl β-(4-hydroxy-3,5-di-tert-butylphenyl)propionate, tris(2,4-di-tert-butylphenyl) phosphite, distearate pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(3,5-di-tert-butyl-4-hydroxybenzoic acid) hexanediol ester, or tris(nonylphenyl) phosphite.

[0026] Preferably, the light stabilizer comprises any one or a combination of at least two of the following: bis(2,2,6,6-tetramethylpiperidinyl) sebacate, tris(2,2,6,6-tetramethylpiperidinyl) phosphate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, N-ethoxy-2,2,6,6-tetramethylpiperidine, dihydroxy-tetra-n-octylhydroxybenzophenone, or 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole.

[0027] In a second aspect, the present invention provides a method for preparing a multilayer encapsulating film as described in the first aspect, the method comprising the following steps:

[0028] The raw materials for preparing the first transparent layer, the flame-retardant layer, and the second transparent layer are mixed and then extruded to obtain the multilayer encapsulation film.

[0029] Preferably, the mixing is carried out under stirring.

[0030] Preferably, the stirring speed is 50-100 r / min, for example, it can be 50 r / min, 60 r / min, 70 r / min, 80 r / min, 90 r / min or 100 r / min, etc.

[0031] Preferably, the stirring time is 3-8 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours.

[0032] Preferably, the multi-layer extrusion molding is performed in a three-screw extruder.

[0033] Preferably, in the three-screw extruder, the inner screw feeds the mixture of the flame-retardant layer, and the inner and outer screws respectively feed the mixture of the first transparent layer and the second transparent layer.

[0034] Preferably, the temperature of the multilayer extrusion molding is 80-110℃, for example, it can be 80℃, 90℃, 100℃ or 110℃.

[0035] Thirdly, the present invention provides an application of the multilayer encapsulating film as described in the first aspect in photovoltaic modules.

[0036] Compared with the prior art, the present invention has at least the following beneficial effects:

[0037] (1) The present invention provides a multilayer encapsulating film. The film adopts a halogen-free flame retardant system. While maintaining excellent optical transmittance (transmittance of 80.3-91.5%), it has good flame retardant effect (reaching UL94 standard V2-V0 level), meeting the environmental protection and safety requirements for long-term use of photovoltaic modules.

[0038] (2) The multilayer encapsulation film provided by the present invention has a structural design that reduces the cost of flame retardant materials and has good economic efficiency and process compatibility.

[0039] (3) The multilayer encapsulating film provided by the present invention achieves a comprehensive balance between flame retardant performance, optical performance and environmental protection characteristics, which can effectively improve the fire resistance of photovoltaic modules and related building materials and broaden their application scope in high safety application fields. Attached Figure Description

[0040] Figure 1 This is a cross-sectional view of the multilayer encapsulation film provided by the present invention;

[0041] Among them, 1-first transparent layer, 2-flame retardant layer, 3-second transparent layer. Detailed Implementation

[0042] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0043] The specific information of the materials used in the following specific embodiments of the present invention is as follows:

[0044] EVA, 2825, purchased from Sirbon;

[0045] Di- and tri-melamine pyrophosphate, purchased from Hunan Yongshuo New Materials.

[0046] Example 1

[0047] This embodiment provides a multilayer encapsulating film, its preparation method and application. The multilayer encapsulating film includes a first transparent layer (120 μm), a flame-retardant layer (250 μm) and a second transparent layer (120 μm) stacked sequentially.

[0048] The raw materials for preparing the flame retardant layer include, by weight, 100 parts of EVA, 5 parts of vinyltrimethoxysilane, 4 parts of 2,4,6-tris(allyloxy)triazine, 10 parts of melamine pyrophosphate, 2 parts of octyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 1 part of bis(2,2,6,6-tetramethylpiperidinyl)sebacate.

[0049] The raw materials for preparing the first and second transparent layers include, by weight, 100 parts of EVA, 5 parts of vinyltrimethoxysilane, 4 parts of 2,4,6-tris(allyloxy)triazine, 2 parts of octyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 1 part of bis(2,2,6,6-tetramethylpiperidinyl)sebacate.

[0050] The preparation method includes:

[0051] The raw materials for preparing the first transparent layer, the flame-retardant layer, and the second transparent layer were mixed at 60 r / min for 4 h, and then extruded at 80°C using a three-screw extruder to obtain the multilayer encapsulation film.

[0052] Example 2

[0053] This embodiment provides a multilayer encapsulating film, its preparation method and application. The multilayer encapsulating film includes a first transparent layer (100 μm), a flame-retardant layer (300 μm) and a second transparent layer (100 μm) stacked sequentially.

[0054] The raw materials for preparing the flame retardant layer include, by weight, 70 parts EVA, 1 part dimethylethoxyvinylsilane, 1 part propoxyglycerol triacrylate, 5 parts di- and tricyanamide pyrophosphate, 1 part distearate pentaerythritol diphosphite, and 2 parts N-ethoxy-2,2,6,6-tetramethylpiperidine.

[0055] The raw materials for preparing the first and second transparent layers include, by weight, 70 parts EVA, 1 part dimethylethoxyvinylsilane, 1 part propoxyglycerol triacrylate, 1 part distearate pentaerythritol diphosphite, and 2 parts N-ethoxy-2,2,6,6-tetramethylpiperidine.

[0056] The preparation method includes:

[0057] The raw materials for preparing the first transparent layer, the flame-retardant layer, and the second transparent layer were mixed at 60 r / min for 4 h, and then extruded at 80°C using a three-screw extruder to obtain the multilayer encapsulation film.

[0058] Example 3

[0059] This embodiment provides a multilayer encapsulating film, its preparation method and application. The multilayer encapsulating film includes a first transparent layer (150 μm), a flame-retardant layer (300 μm) and a second transparent layer (150 μm) stacked sequentially.

[0060] The raw materials for preparing the flame retardant layer include, by weight, 120 parts of EVA, 10 parts of vinyltriacetoxysilane, 10 parts of tripropyleneoxyphosphazene, 20 parts of melamine pyrophosphate, 5 parts of bis(3,5-di-tert-butyl-4-hydroxybenzoic acid)hexanediol ester, and 5 parts of 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole.

[0061] The raw materials for preparing the first and second transparent layers include, by weight, 120 parts of EVA, 10 parts of vinyltriacetoxysilane, 10 parts of tripropyleneoxyphosphazene, 5 parts of bis(3,5-di-tert-butyl-4-hydroxybenzoic acid)hexanediol ester, and 5 parts of 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole.

[0062] The preparation method includes:

[0063] The raw materials for preparing the first transparent layer, the flame-retardant layer, and the second transparent layer were mixed at 60 r / min for 4 h, and then extruded at 80°C using a three-screw extruder to obtain the multilayer encapsulation film.

[0064] Example 4

[0065] This embodiment provides a multilayer encapsulating film, its preparation method, and its application. The difference from Embodiment 1 is that the amount of di- and tri-melamine pyrophosphate is adjusted to 5 parts by weight.

[0066] Example 5

[0067] This embodiment provides a multilayer encapsulating film, its preparation method, and its application. The difference from Embodiment 1 is that the amount of di- and tri-melamine pyrophosphate is adjusted to 15 parts by weight.

[0068] Example 6

[0069] This embodiment provides a multilayer encapsulating film, its preparation method, and its application. The difference from Embodiment 1 is that the amount of di- and tri-melamine pyrophosphate is adjusted to 20 parts by weight.

[0070] Example 7

[0071] This embodiment provides a multilayer encapsulating film, its preparation method and application. The difference from Embodiment 1 is that melamine pyrophosphate is replaced with tri(chloroisopropyl) phosphate (DTZR-TCPP, Suzhou Dongtuo Chemical).

[0072] Comparative Example 1

[0073] This comparative example provides a multilayer encapsulating film, its preparation method, and its application. The multilayer encapsulating film includes three flame-retardant layers (each single layer is 250 μm).

[0074] The raw materials for preparing the flame retardant layer include, by weight, 100 parts of EVA, 5 parts of vinyltrimethoxysilane, 4 parts of 2,4,6-tris(allyloxy)triazine, 10 parts of melamine pyrophosphate, 2 parts of octyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 1 part of bis(2,2,6,6-tetramethylpiperidinyl)sebacate.

[0075] The preparation method includes:

[0076] The raw materials for preparing the three flame-retardant layers were mixed at 60 r / min for 4 h, and then extruded at 80°C using a three-screw extruder to obtain the multi-layer encapsulating film.

[0077] Comparative Example 2

[0078] This comparative example provides a multilayer encapsulating film, its preparation method, and its application. The difference from Comparative Example 1 is that the amount of di- and tri-melamine pyrophosphate is adjusted to 15 parts by weight.

[0079] Comparative Example 3

[0080] This comparative example provides a multilayer encapsulating film, its preparation method, and its application. The difference from Comparative Example 1 is that the amount of di- and tri-melamine pyrophosphate is adjusted to 20 parts by weight.

[0081] Comparative Example 4

[0082] This comparative example provides a multilayer encapsulating film, its preparation method, and its application. The difference from Example 1 is that the amount of di- and tri-melamine pyrophosphate is adjusted to 2 parts by weight.

[0083] Comparative Example 5

[0084] This comparative example provides a multilayer encapsulating film, its preparation method, and its application. The difference from Example 1 is that the amount of di- and tri-melamine pyrophosphate is adjusted to 25 parts by weight.

[0085] Test methods

[0086] The following performance tests were performed on the multilayer encapsulating films provided in Examples 1-7 and Comparative Examples 1-5:

[0087] (1) Transmittance (%): Tested in accordance with GB / T 2410-2008 standard, test range 380-1100 nm;

[0088] (2) Flame retardancy rating: Tested in accordance with UL94 standard.

[0089] The test results are shown in Table 1 below:

[0090] Table 1

[0091]

[0092] The test results show that:

[0093] (1) As can be seen from Examples 1 to 7, the multilayer encapsulation film provided by the present invention, by designing the structure of the encapsulation film and the formulation of each layer, achieves excellent flame retardant performance (up to UL94 standard V2-V0 level) while ensuring high optical transmittance (transmittance of 80.3-91.5%).

[0094] (2) As can be seen from Examples 1, 4-6 and Comparative Examples 4-5, the present invention further limits the amount of halogen-free flame retardant. If the amount of halogen-free flame retardant is too large, the flame retardant rating will reach V0, but the light transmittance will be greatly affected. Conversely, if the amount of halogen-free flame retardant is too small, the flame retardant performance will deteriorate.

[0095] (3) As can be seen from Examples 1 and 7, the present invention preferably uses melamine pyrophosphate as a halogen-free flame retardant. It utilizes phosphorus source to promote high-quality condensed phase carbonization layer and releases inert nitrogen gas during pyrolysis of melamine component to realize phosphorus-nitrogen synergistic flame retardant mechanism. This inhibits combustion on two levels: preventing heat-oxygen transfer and diluting combustible decomposition products. This ensures high light transmittance and long-term reliability in EVA film for photovoltaic encapsulation.

[0096] (4) As can be seen from Examples 1 and 7, the present invention preferably uses di- and tri-melamine pyrophosphate as a halogen-free flame retardant. The phosphorus source promotes a high-quality condensed phase carbonization layer and the melamine component releases inert nitrogen gas during pyrolysis, thereby realizing the phosphorus-nitrogen synergistic flame retardant mechanism. This inhibits combustion on two levels: preventing heat-oxygen transfer and diluting combustible decomposition products, thus maintaining high light transmittance and long-term reliability in EVA films used for photovoltaic encapsulation.

[0097] (5) As can be seen from Example 1 and Comparative Example 1, by designing the middle layer as a flame-retardant layer and the two sides as transparent layers, the synergistic optimization of flame retardancy and light transmittance is achieved through structural differences. The halogen-free flame retardant is only added to the middle layer, and the overall amount of halogen-free flame retardant is effectively controlled. While ensuring flame retardant performance, the visible light transmittance of the film is improved, optical loss is reduced, and the photoelectric conversion efficiency of the photovoltaic module is improved.

[0098] (6) Comparative Examples 1-3 show that although excessive use of halogen-free flame retardant can make the flame retardant level reach V0, it has a greater impact on light transmittance. Conversely, if the amount of halogen-free flame retardant is too small, the flame retardant performance will deteriorate.

[0099] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A multilayer encapsulating film, characterized in that, The multilayer encapsulating film includes a first transparent layer, a flame-retardant layer, and a second transparent layer stacked sequentially. The raw materials for preparing the flame retardant layer include, by weight, 70-120 parts of resin matrix A, 0.5-10 parts of coupling agent A, 0.5-10 parts of crosslinking agent A, and 5-20 parts of halogen-free flame retardant.

2. The multilayer encapsulating film according to claim 1, characterized in that, The thickness of the first transparent layer and the second transparent layer are each independently 100-150 μm; Preferably, the thickness of the flame-retardant layer is 200-300 μm.

3. The multilayer encapsulating film according to claim 1 or 2, characterized in that, The raw materials for preparing the first transparent layer and the second transparent layer each independently include, by weight, 70-120 parts of resin matrix B, 0.5-10 parts of coupling agent B, and 0.5-10 parts of crosslinking agent B.

4. The multilayer encapsulating film according to claim 3, characterized in that, The resin matrix A and resin matrix B each independently comprise EVA resin; Preferably, the VA content of the EVA resin is 20-35% by mass; Preferably, the melting temperature of the EVA resin is 50-100℃; Preferably, coupling agent A and coupling agent B each independently comprise any one or a combination of at least two of vinyltrimethoxysilane, dimethylethoxyvinylsilane, vinyltritert-butoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, or vinyltriisopropoxysilane; Preferably, crosslinking agent A and crosslinking agent B each independently comprise any one or a combination of at least two of 2,4,6-tris(allyloxy)triazine, tripropylene isocyanurate, propoxylated glycerol triacrylate, ethoxylated pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, divinylbenzene, or tripropyleneoxyphosphazene.

5. The multilayer encapsulating film according to any one of claims 1-4, characterized in that, The halogen-free flame retardant includes dimelamine pyrophosphate.

6. The multilayer encapsulating film according to any one of claims 1-5, characterized in that, The raw materials for preparing the first transparent layer, the flame-retardant layer, and the second transparent layer each independently include 0.1-5 parts by weight of antioxidant and / or 0.1-5 parts by weight of light stabilizer.

7. The multilayer encapsulating film according to claim 6, characterized in that, The antioxidants include any one or a combination of at least two of the following: octyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, decyl β-(4-hydroxy-3,5-di-tert-butylphenyl)propionate, tris(2,4-di-tert-butylphenyl)phosphite, distearate pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(3,5-di-tert-butyl-4-hydroxybenzoic acid) hexanediol ester, or tris(nonylphenyl)phosphite. Preferably, the light stabilizer comprises any one or a combination of at least two of the following: bis(2,2,6,6-tetramethylpiperidinyl) sebacate, tris(2,2,6,6-tetramethylpiperidinyl) phosphate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, N-ethoxy-2,2,6,6-tetramethylpiperidine, dihydroxy-tetra-n-octylhydroxybenzophenone, or 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole.

8. A method for preparing a multilayer encapsulating film as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: The raw materials for preparing the first transparent layer, the flame-retardant layer, and the second transparent layer are mixed and then extruded to obtain the multilayer encapsulation film.

9. The method for preparing the multilayer encapsulating film according to claim 8, characterized in that, The multi-layer extrusion molding is carried out in a three-screw extruder; Preferably, the temperature of the multilayer extrusion molding is 80-110℃.

10. The application of a multilayer encapsulating film as described in any one of claims 1-7 in a photovoltaic module.

Images