Epe three-layer co-extruded adhesive film, preparation method and application thereof

Abstract

The present application relates to the technical field of photovoltaic packaging materials, and particularly relates to an EPE three-layer co-extrusion adhesive film and a preparation method and application thereof.The EPE three-layer co-extrusion adhesive film comprises a first EVA layer, a POE layer and a second EVA layer arranged in sequence;the first EVA layer and the second EVA layer each independently comprise EVA resin, modified EVA resin, a compatilizer, a crosslinking agent, a crosslinking aid, a silane coupling agent and an antioxidant;the POE layer comprises modified POE resin, a compatilizer, a crosslinking agent, a crosslinking aid, a silane coupling agent and an antioxidant;the modified EVA resin comprises at least two EVA resins grafted and modified by polybutadiene with different molecular weights; and the modified POE resin comprises at least two POE resins grafted and modified by polybutadiene with different vinyl contents.The EPE three-layer co-extrusion adhesive film has high adhesion, high crosslinking degree, high water resistance and aging resistance, and the like, and the additives are not prone to migration.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic encapsulation materials technology, and in particular to an EPE three-layer co-extruded film, its preparation method, and its application. Background Technology

[0002] In recent years, the rapid development of the photovoltaic industry has driven the continuous upgrading and optimization of photovoltaic encapsulant films. The main types of photovoltaic encapsulant films include EVA, POE, and EPE. POE films not only possess excellent electrical insulation and water vapor barrier properties, but also effectively resist PID effects. Furthermore, POE films exhibit high elasticity, high strength, and low-temperature resistance, and do not produce corrosive acidic substances. However, compared to EVA films, POE films have a more complex manufacturing process and higher costs. EPE three-layer co-extruded films combine the advantages and disadvantages of both EVA and POE films, offering more combination options. Compared to EVA films, EPE films excel in PID resistance, possessing comprehensive characteristics such as high water resistance, UV resistance, and resistance to damp heat aging. Compared to POE films, EPE films retain the convenience of EVA material lamination processes and high adhesion, with a more adaptable process window, improving production efficiency. Moreover, using EPE encapsulation films can reduce the amount of POE material used, thus lowering production costs and alleviating raw material supply constraints.

[0003] While EPE co-extruded films offer numerous advantages, they also present certain challenges in practical applications. First, EPE co-extruded films are essentially produced by casting and extruding EVA and POE materials in a molten state at high temperatures. However, EVA and POE are completely different polymers with different glass transition temperatures. At ambient temperatures below -20°C, EVA hardens while POE retains its elasticity. Second, the difference in molecular polarity results in significantly different absorption rates and degrees of additives by EVA and POE, leading to inherent differences in their crosslinking rates. This necessitates the introduction of different proportions of functional additives into the two materials during formulation design. After EPE film production, due to the polar characteristics of EVA and its greater compatibility with most additives, the EVA layer continuously absorbs effective additives from the POE layer, causing changes in the internal structural properties of the film. Third, after the additives migrate, the crosslinking speed of POE slows down, resulting in a decrease in the degree of crosslinking of the POE layer. This makes it easy for delamination to occur between the film layers and between the film and the glass or battery cells. In addition, during long-term aging, the difference in water vapor permeability between the POE layer and the EVA layer, as well as the fact that EVA is more prone to aging and releasing acidic substances, can cause externally intruded water vapor and internally acidic substances to accumulate at the interface between the two materials, making the interfacial bonding strength weaker and weaker, thus triggering the risk of delamination.

[0004] Therefore, it is of great significance to prepare an EPE three-layer co-extruded film with a stable EVA / POE / EVA three-layer structure, where the additives are not prone to migration, it is easy to produce and process, and it also has high adhesion, high crosslinking degree, high water resistance and excellent aging resistance.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] One objective of this invention is to provide a three-layer co-extruded EPE film with stable EVA and POE structures, minimal migration of additives, and high adhesion, high crosslinking degree, high water resistance, and aging resistance.

[0007] Another object of the present invention is to provide a method for preparing EPE three-layer co-extruded film.

[0008] Another object of the present invention is to provide the application of EPE three-layer co-extruded film in the preparation of photovoltaic modules.

[0009] To achieve the above-mentioned objectives of the present invention, the present invention provides an EPE three-layer co-extruded film, comprising a first EVA layer, a POE layer and a second EVA layer arranged sequentially;

[0010] The first EVA layer and the second EVA layer each independently comprise the following components by weight: 50-85 parts of EVA resin, 15-45 parts of modified EVA resin, 1-5 parts of compatibilizer, 0.1-2 parts of crosslinking agent, 0.1-2 parts of co-crosslinking agent, 0.1-2 parts of silane coupling agent, and 0.01-1 parts of antioxidant;

[0011] The POE layer comprises the following components by weight: 100 parts modified POE resin, 1-5 parts compatibilizer, 0.1-2 parts crosslinking agent, 0.1-2 parts co-crosslinking agent, 0.1-2 parts silane coupling agent, and 0.01-1 parts antioxidant;

[0012] The modified EVA resin includes at least two EVA resins grafted with polybutadiene of different molecular weights; the modified POE resin includes at least two POE resins grafted with polybutadiene of different vinyl contents.

[0013] In a specific embodiment of the present invention, the molecular weight of the polybutadiene of different molecular weights is 1400 to 8000 g / mol.

[0014] In a specific embodiment of the present invention, the vinyl content of polybutadiene in the polybutadiene with different vinyl contents is 18% to 70%.

[0015] In a specific embodiment of the present invention, the modified EVA resin includes a first modified EVA resin, a second modified EVA resin, and a third modified EVA resin; the first modified EVA resin, the second modified EVA resin, and the third modified EVA resin are EVA resins grafted with first polybutadiene, second polybutadiene, and third polybutadiene, respectively, wherein the molecular weight of the first polybutadiene is 3800-4100 g / mol, the molecular weight of the second polybutadiene is 1800-2000 g / mol, and the molecular weight of the third polybutadiene is 1400-1600 g / mol.

[0016] In a specific embodiment of the present invention, the modified EVA resin comprises 5-15 parts by weight of a first modified EVA resin, 5-15 parts by weight of a second modified EVA resin, and 5-15 parts by weight of a third modified EVA resin. Further, the amounts of the first modified EVA resin, the second modified EVA resin, and the third modified EVA resin increase sequentially.

[0017] In a specific embodiment of the present invention, the modified POE resin includes a first modified POE resin, a second modified POE resin, and a third modified POE resin; the first modified POE resin, the second modified POE resin, and the third modified POE resin are respectively POE resins grafted with fourth polybutadiene, fifth polybutadiene, and sixth polybutadiene, wherein the vinyl content of the fourth polybutadiene is 65% to 70%, the vinyl content of the fifth polybutadiene is 50% to 60%, and the vinyl content of the sixth polybutadiene is 18% to 25%.

[0018] In a specific embodiment of the present invention, the modified POE resin comprises 10-40 parts by weight of a first modified POE resin, 20-40 parts by weight of a second modified POE resin, and 30-60 parts by weight of a third modified POE resin. Further, the amounts of the first modified POE resin, the second modified POE resin, and the third modified POE resin increase sequentially.

[0019] In a specific embodiment of the present invention, the modified EVA resin is mainly prepared by extrusion granulation of EVA resin, peroxide initiator and polybutadiene in a mass ratio of 100:(0.01~0.5):(1~10).

[0020] In a specific embodiment of the present invention, the modified POE resin is mainly prepared by extrusion granulation of POE resin, peroxide initiator and polybutadiene in a mass ratio of 100:(0.01~0.5):(1~10).

[0021] In a specific embodiment of the present invention, the thickness of the first EVA layer and the second EVA layer are each independently 100-200 μm; the thickness of the POE layer is 100-300 μm.

[0022] In a specific embodiment of the present invention, the compatibilizer includes at least one selected from ethylene propylene diene monomer (EPDM), ethylene propylene diene monomer (EPDM), and butadiene-styrene copolymer. Further, the butadiene-styrene copolymer has a vinyl content of 20% to 70% and a molecular weight of 3000 to 9000 g / mol.

[0023] Another aspect of the present invention provides a method for preparing any one of the above-described EPE three-layer co-extruded films, comprising the following steps:

[0024] The EPE three-layer co-extruded film is obtained by melt co-extrusion according to the composition of the first EVA layer, POE layer and second EVA layer.

[0025] In another aspect, the present invention provides the application of any of the above-described EPE three-layer co-extruded films in the preparation of photovoltaic modules.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) In the EPE three-layer co-extruded film of the present invention, EVA resin with different molecular weights grafted with polybutadiene is introduced into the EVA layer, which can make the microstructure of the EVA layer more compact under physical action; on the other hand, some vinyl groups that did not participate in the grafting reaction participate in the crosslinking of the EVA layer during the later high-temperature lamination and vulcanization process, further increasing the degree of crosslinking of the EVA layer, forming a more compact three-dimensional network structure, and improving the water vapor barrier ability of the EVA layer.

[0028] (2) In the EPE three-layer co-extruded film of the present invention, POE resin with different vinyl content grafted with polybutadiene is introduced into the POE layer, which can reduce the migration rate of POE layer additives to EVA layer; and the polybutadiene long chain used in the modified POE resin can interpenetrate into each other's layers with the polybutadiene long chain of the modified EVA resin, which improves the compatibility of POE layer and EVA layer. During high temperature lamination, the vinyl groups at the interface of the two layers react and crosslink with each other, which improves the adhesion of the two layers and avoids delamination during aging, which can greatly improve the comprehensive performance of EPE film.

[0029] (3) The EVA layer of the present invention uses a certain amount of compatibilizer, which can further improve the barrier performance of the EVA layer, reduce the water vapor permeability of the EPE three-layer co-extruded film, and increase the cross-linking degree of the EVA layer, thereby improving the chemical resistance, damp heat aging resistance and electrical insulation performance of the EPE film; the POE layer of the present invention uses a certain amount of compatibilizer to increase the rigidity and hydrophobicity of the POE layer, avoid the situation where the POE layer is squeezed thin by the EVA layer during the lamination process, and improve the barrier performance of EPE. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0031] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the shown orientation or positional relationship, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] The present invention provides an EPE three-layer co-extruded film, comprising a first EVA layer, a POE layer and a second EVA layer arranged in sequence;

[0033] The first EVA layer and the second EVA layer each independently comprise the following components by weight: 50-85 parts of EVA resin, 15-45 parts of modified EVA resin, 1-5 parts of compatibilizer, 0.1-2 parts of crosslinking agent, 0.1-2 parts of co-crosslinking agent, 0.1-2 parts of silane coupling agent, and 0.01-1 parts of antioxidant.

[0034] The POE layer comprises the following components by weight: 100 parts modified POE resin, 1-5 parts compatibilizer, 0.1-2 parts crosslinking agent, 0.1-2 parts co-crosslinking agent, 0.1-2 parts silane coupling agent, and 0.01-1 parts antioxidant;

[0035] The modified EVA resin includes at least two EVA resins grafted with polybutadiene of different molecular weights; the modified POE resin includes at least two POE resins grafted with polybutadiene of different vinyl contents.

[0036] The EPE three-layer co-extruded film of the present invention has stable EVA and POE structures, and the additives are not prone to migration. It also has high adhesion, high crosslinking degree, high water resistance and aging resistance.

[0037] In this process, polybutadiene-grafted modified EVA resins with different molecular weights are introduced into the EVA layer. The relatively high molecular weight polybutadiene-grafted modified EVA resin has longer molecular chains that can form a large number of entangled segments with the EVA resin matrix and the modified EVA resin. The relatively low molecular weight polybutadiene-grafted modified EVA resin has shorter molecular chains that can penetrate into the gaps between the EVA resin matrix and the modified EVA resin for further filling. These entangled segments and gap-filling segments make the microstructure of the EVA layer more compact under physical action. On the other hand, some vinyl groups that did not participate in the grafting reaction participate in the crosslinking of the EVA layer during the later high-temperature lamination and vulcanization process, further increasing the degree of crosslinking of the EVA layer and forming a denser three-dimensional network structure, thereby improving the water vapor barrier capacity of the EVA layer. The EVA layer of this invention uses a certain amount of compatibilizer, which can further improve the barrier properties of the EVA layer, reduce the water vapor permeability of the EPE three-layer co-extruded film, and increase the crosslinking degree of the EVA layer, thereby improving the chemical resistance, damp heat aging resistance and electrical insulation properties of the EPE film.

[0038] In different embodiments, the amounts of each component in the first EVA layer and the second EVA layer, by weight, can be as follows:

[0039] The amount of EVA resin can be 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, or any combination thereof.

[0040] The amount of modified EVA resin can be 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, or any combination thereof.

[0041] The amount of compatibilizer can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, or any combination thereof;

[0042] The amount of crosslinking agent can be 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 part, 1.5 parts, 2 parts, or any combination thereof;

[0043] The amount of the crosslinking agent can be 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 part, 1.5 parts, 2 parts, or any combination thereof;

[0044] The amount of silane coupling agent can be 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 part, 1.5 parts, 2 parts, or any combination thereof;

[0045] The amount of antioxidant can be 0.01 parts, 0.05 parts, 0.1 parts, 0.5 parts, 0.8 parts, 1 part, or any combination thereof.

[0046] It is understood that the composition of the first EVA layer and the second EVA layer may be the same or different, as long as their respective compositions remain within the scope of this invention.

[0047] In the EPE three-layer co-extruded film of the present invention, the POE layer incorporates POE resin grafted with polybutadiene and modified with different vinyl contents. This further increases the polarity of the POE layer, adsorbs the additives in the POE layer, and locks the additives within the POE layer, reducing the migration rate of the POE layer additives to the EVA layer. Furthermore, the long polybutadiene chains used in the modified POE resin can interpenetrate with the long polybutadiene chains of the modified EVA resin within each other's layers, interlocking and adsorbing under the polarity of free vinyl groups. This improves the compatibility between the POE and EVA layers. During high-temperature lamination, the vinyl groups at the interface of the two layers react and crosslink, improving the adhesion between the two layers and preventing delamination during aging. This significantly enhances the overall performance of the EPE film. The POE layer of the present invention uses a certain amount of compatibilizer to increase the rigidity and hydrophobicity of the POE layer, preventing the POE layer from being squeezed thinner by the EVA layer during lamination, thus improving the barrier properties of the EPE.

[0048] Furthermore, the POE layer of this invention is entirely made of modified POE resin, which can improve the problem of slow absorption of additives by POE resin, greatly reduce mixing time, and improve production efficiency.

[0049] In different embodiments, the amounts of the remaining components in the POE layer, relative to 100 parts by weight of modified POE resin, can be as follows:

[0050] The amount of compatibilizer can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, or any combination thereof;

[0051] The amount of crosslinking agent can be 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 part, 1.5 parts, 2 parts, or any combination thereof;

[0052] The amount of the crosslinking agent can be 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 part, 1.5 parts, 2 parts, or any combination thereof;

[0053] The amount of silane coupling agent can be 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 part, 1.5 parts, 2 parts, or any combination thereof;

[0054] The amount of antioxidant can be 0.01 parts, 0.05 parts, 0.1 parts, 0.5 parts, 0.8 parts, 1 part, or any combination thereof.

[0055] In a specific embodiment of the present invention, the molecular weight of polybutadiene varies from 1400 to 8000 g / mol.

[0056] In different embodiments, the molecular weight of polybutadiene can be 1400 g / mol, 1600 g / mol, 1800 g / mol, 2000 g / mol, 2500 g / mol, 3000 g / mol, 3500 g / mol, 4000 g / mol, 4500 g / mol, 5000 g / mol, 5500 g / mol, 6000 g / mol, 6500 g / mol, 7000 g / mol, 7500 g / mol, 8000 g / mol, or any combination thereof.

[0057] In a specific embodiment of the present invention, the molecular weight difference of polybutadiene with different molecular weights is 300 to 3000 g / mol.

[0058] In a specific embodiment of the present invention, the difference in vinyl content of polybutadiene with different molecular weights is ≤5%. Polybutadiene used for EVA resin modification has different molecular weights, and its vinyl content can be close or the same.

[0059] In a specific embodiment of the present invention, the vinyl content of polybutadiene in polybutadiene with different vinyl contents is 18% to 70%.

[0060] In different embodiments, the vinyl content of polybutadiene can be 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or any combination thereof.

[0061] In a specific embodiment of the present invention, the difference in vinyl content of polybutadiene among polybutadienes with different vinyl contents is 30% to 60%.

[0062] In polybutadiene with different vinyl contents, the molecular weight of polybutadiene is not limited and can be the same or different.

[0063] In a specific embodiment of the present invention, the modified EVA resin includes a first modified EVA resin, a second modified EVA resin, and a third modified EVA resin; the first modified EVA resin, the second modified EVA resin, and the third modified EVA resin are EVA resins grafted with first polybutadiene, second polybutadiene, and third polybutadiene, respectively, wherein the molecular weight of the first polybutadiene is 3800-4100 g / mol, the molecular weight of the second polybutadiene is 1800-2000 g / mol, and the molecular weight of the third polybutadiene is 1400-1600 g / mol.

[0064] In a specific embodiment of the present invention, the modified EVA resin includes 5 to 15 parts by weight of a first modified EVA resin, 5 to 15 parts by weight of a second modified EVA resin, and 5 to 15 parts by weight of a third modified EVA resin.

[0065] In different embodiments, the amounts of each component in the modified EVA resin, by weight, can be as follows:

[0066] The amount of the first modified EVA resin can be 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, or any combination thereof.

[0067] The amount of the second modified EVA resin can be 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, or any combination thereof.

[0068] The amount of the third modified EVA resin can be 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, or any combination thereof.

[0069] In a specific embodiment of the present invention, the amounts of the first modified EVA resin, the second modified EVA resin, and the third modified EVA resin increase sequentially. The amounts that meet the above conditions are more conducive to improving the overall performance of the EPE three-layer co-extruded film.

[0070] In a specific embodiment of the present invention, the modified POE resin includes a first modified POE resin, a second modified POE resin, and a third modified POE resin; the first modified POE resin, the second modified POE resin, and the third modified POE resin are respectively POE resins grafted with fourth polybutadiene, fifth polybutadiene, and sixth polybutadiene, respectively, wherein the vinyl content of the fourth polybutadiene is 65% to 70%, the vinyl content of the fifth polybutadiene is 50% to 60%, and the vinyl content of the sixth polybutadiene is 18% to 25%.

[0071] In a specific embodiment of the present invention, the modified POE resin includes 10-40 parts by weight of a first modified POE resin, 20-40 parts by weight of a second modified POE resin, and 30-60 parts by weight of a third modified POE resin.

[0072] In different embodiments, the amounts of each component in the modified POE resin, by weight, can be as follows:

[0073] The amount of the first modified POE resin can be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, or any combination thereof.

[0074] The amount of the second modified POE resin can be 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, or any combination thereof.

[0075] The amount of the third modified POE resin can be 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, or any combination thereof.

[0076] In a specific embodiment of the present invention, the amounts of the first modified POE resin, the second modified POE resin, and the third modified POE resin increase sequentially. The amounts that meet the above conditions are more conducive to improving the overall performance of the EPE three-layer co-extruded film, avoiding excessive use of polybutadiene-grafted modified POE resin with high vinyl content, which could lead to excessive cross-linking of the film, increased hardness, and deterioration of adhesion and aging performance.

[0077] In a specific embodiment of the present invention, the modified EVA resin is mainly prepared by extrusion granulation of EVA resin, peroxide initiator and polybutadiene in a mass ratio of 100:(0.01~0.5):(1~10).

[0078] In a specific embodiment of the present invention, the modified POE resin is mainly prepared by extrusion granulation of POE resin, peroxide initiator and polybutadiene in a mass ratio of 100:(0.01~0.5):(1~10).

[0079] In practice, during the preparation of modified EVA and modified POE resins, the peroxide initiator can be at least one of benzoyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, dicumyl peroxide, and tert-butylperoxycarbonate-2-ethylhexyl ester. The amount of peroxide initiator can be 0.01%, 0.1%, 0.3%, 0.4%, 0.5%, or any combination thereof, based on the mass of the EVA or POE resin; the amount of polybutadiene can be 1%, 3%, 5%, 8%, 10%, or any combination thereof, based on the mass of the EVA or POE resin.

[0080] In the preparation of modified EVA resin and modified POE resin, the specific type of polybutadiene is selected according to the aforementioned modification requirements. For example, the first type of polybutadiene is used to prepare the first modified EVA resin, the second type of polybutadiene is used to prepare the second modified EVA resin, and the third type of polybutadiene is used to prepare the third modified EVA resin; the fourth type of polybutadiene is used to prepare the first modified POE resin, the fifth type of polybutadiene is used to prepare the second modified POE resin, and the sixth type of polybutadiene is used to prepare the third modified POE resin.

[0081] In a specific embodiment of the present invention, the preparation of modified EVA resin or modified POE resin may include the following steps: (1) mixing peroxide initiator with the corresponding polybutadiene and heating to 60-80°C and stirring at a constant speed for 0.1-2 hours, and then cooling to room temperature; (2) setting eleven temperature zones of a twin-screw extruder, with the temperature of the first four temperature zones being 70-140°C, the temperature of the middle two temperature zones being 160-180°C, and the temperature of the last two temperature zones being 140-100°C; (3) controlling the temperature according to the set temperature for 1-2 hours, then adding EVA resin or POE resin to wash the machine for 1-2 hours, and then adding the material obtained in step (1) to the feed port between the fourth and fifth temperature zones, and extruding and granulating to obtain the corresponding modified EVA resin or modified POE resin.

[0082] In a specific embodiment of the present invention, the thickness of the first EVA layer and the second EVA layer are each independently 100-200 μm; the thickness of the POE layer is 100-300 μm.

[0083] In different embodiments, the thickness of the first EVA layer and the second EVA layer can each be independently selected from a range of 100μm, 120μm, 150μm, 180μm, 200μm or any combination thereof; the thickness of the POE layer can be a range of 100μm, 150μm, 200μm, 250μm, 300μm or any combination thereof.

[0084] In a specific embodiment of the present invention, the compatibilizer includes at least one of ethylene propylene diene monomer (EPDM), ethylene propylene diene monomer (EPDM), and butadiene-styrene copolymer.

[0085] In a specific embodiment of the present invention, the compatibilizer of the EVA layer includes at least one of ethylene propylene diene monomer (EPDM) rubber and / or ethylene propylene diene monomer (EPDM) rubber. Introducing a certain amount of EPDM rubber into the EVA layer can further improve the barrier properties of the EVA layer, reducing the water vapor permeability of the EPE three-layer co-extruded film to 9.04 g / (m²). 2 • 24h), while improving the crosslinking degree of the EVA layer, thereby enhancing the chemical resistance, damp heat aging resistance and electrical insulation properties of the EPE three-layer co-extruded film.

[0086] In a specific embodiment of the present invention, the compatibilizer of the POE layer includes butadiene-styrene copolymer. Further, the butadiene-styrene copolymer has a vinyl content of 20% to 70% and a molecular weight of 3000 to 9000 g / mol.

[0087] In different embodiments, the vinyl content of the butadiene-styrene copolymer can be in the range of 20%, 30%, 40%, 50%, 60%, 70%, or any combination thereof, and the molecular weight can be in the range of 3000 g / mol, 4000 g / mol, 5000 g / mol, 6000 g / mol, 8000 g / mol, 9000 g / mol, or any combination thereof.

[0088] Butadiene-styrene copolymer is introduced into the POE layer as a compatibilizer. The styrene groups in butadiene-styrene are used to increase the rigidity and hydrophobicity of the POE layer, prevent the POE layer from being squeezed thin by the EVA layer during the lamination process, and improve the barrier properties of EPE.

[0089] In different embodiments, the types of other additives in the first EVA layer, the second EVA layer, and the POE layer can be referred to as follows:

[0090] The crosslinking agent includes at least one of (2-ethylhexyl)peroxycarbonate tert-amyl, tert-butylperoxycarbonate-2-ethylhexyl, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane;

[0091] The crosslinking agent includes at least one of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, triallyl isocyanurate, and diallyl phthalate;

[0092] Silane coupling agents include at least one of vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, triacetoxyvinylsilane, vinyltris(2-methoxyethoxy)silane, γ-glycidoxypropyltrimethoxysilane, and γ-(methacryloyloxy)propyltrimethoxysilane;

[0093] Antioxidants include at least one of antioxidant 1035, antioxidant 168, antioxidant 1010, and antioxidant 1098.

[0094] Another aspect of the present invention provides a method for preparing any of the above-mentioned EPE three-layer co-extruded films, comprising the following steps:

[0095] According to the composition of the first EVA layer, POE layer and the second EVA layer, melt co-extrusion is carried out to obtain EPE three-layer co-extruded film.

[0096] In another aspect, the present invention provides the application of any of the above-mentioned EPE three-layer co-extruded films in the preparation of photovoltaic modules.

[0097] The material information used in the following specific embodiments of the present invention may be as follows, but is not limited thereto:

[0098] EVA resin: Sirbon Corporation, UE2825;

[0099] POE resin: SK Corporation, 8813V;

[0100] Butadiene-styrene copolymer Ricon 181: Shanghai Wandao Chemical Co., Ltd., Ricon 181, ethylene content 20%~40%, styrene content 20%~30%, molecular weight 3200g / mol;

[0101] Butadiene-styrene copolymer Ricon 184: Shanghai Wandao Chemical Co., Ltd., Ricon 184, ethylene content 20%~40%, styrene content 17%~27%, molecular weight 8600g / mol;

[0102] Information on polybutadiene is shown in Table 1.

[0103] Table 1 Information on different polybutadienes

[0104] serial number model Manufacturers ethylene content molecular weight 1 Ricon 131 Shanghai Wandao Chemical Co., Ltd. 18％ 4500g / mol 2 Ricon 130 Shanghai Wandao Chemical Co., Ltd. 20％ 2500g / mol 3 Ricon 134 Shanghai Wandao Chemical Co., Ltd. 35％ 8000g / mol 4 Ricon 142 Shanghai Wandao Chemical Co., Ltd. 55％ 4100g / mol 5 Ricon 150 Shanghai Wandao Chemical Co., Ltd. 70％ 3900g / mol 6 Ricon 156 Shanghai Wandao Chemical Co., Ltd. 70％ 1400g / mol 7 Ricon 157 Shanghai Wandao Chemical Co., Ltd. 70％ 1800g / mol

[0105] Depending on the type of polybutadiene used in the modification, different modified EVA resins are named EVA-131 resin, EVA-130 resin, EVA-134 resin, EVA-142 resin, EVA-150 resin, EVA-156 resin, and EVA-157 resin, respectively. Similarly, different modified POE resins are named POE-131 resin, POE-130 resin, POE-134 resin, POE-142 resin, POE-150 resin, POE-156 resin, and POE-157 resin, respectively.

[0106] Taking EVA-131 resin as an example, its preparation method is described below. The preparation method of EVA-131 resin includes the following steps:

[0107] (1) Mix the peroxide initiator 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane with polybutadiene Ricon131 and heat to 70°C while stirring at a constant speed for 1 hour, then cool to room temperature.

[0108] (2) The twin-screw extruder is set with eleven temperature zones, namely Zone I 80-85℃, Zone II 85-95℃, Zone III 100-120℃, Zone IV 120-140℃, Zone V 160-180℃, Zone VI 160-180℃, Zone VII 160-180℃, Zone VIII 160-180℃, Zone IX 160-180℃, Zone X and Zone IV 120-140℃, and the die head 110℃; among them, the first four low-temperature feeding sections allow the EVA resin to become molten in the screw as quickly as possible, the middle five high-temperature sections are the EVA grafting chemical reaction sections, and the last two are cooling sections.

[0109] (3) First, control the temperature according to the set temperature for 1.5 hours, then add EVA resin to wash the machine for 1.5 hours, then add the material obtained in step (1) to the feeding port between the fourth and fifth temperature zones, and perform extrusion granulation and cooling.

[0110] (4) The modified EVA resin obtained in step (3) is placed in a constant temperature reactor at 40-55℃ for stirring and drying to remove moisture and then cooled to obtain EVA-131 resin.

[0111] For EVA-130, EVA-134, EVA-142, EVA-150, EVA-156, and EVA-157 resins, simply replace Ricon 131 with an equal weight of Ricon 130, Ricon 134, Ricon 142, Ricon 150, Ricon 156, and Ricon 157, respectively, following the method described above. For POE-131 resin, simply replace the EVA resin with an equal weight of POE resin, and for POE-130, POE-134, POE-142, POE-150, POE-156, and POE-157 resins, replace the EVA resin with an equal weight of POE resin, and replace Ricon 131 with an equal weight of Ricon 130, Ricon 134, Ricon 142, Ricon 150, Ricon 156, and Ricon 157, respectively, following the method described above. 157 is sufficient.

[0112] The specific embodiments and comparative examples described below use, but are not limited to, EVA-150 resin, EVA-156 resin, EVA-157 resin, POE-130 resin, POE-142 resin, and POE-156 resin.

[0113] Example 1

[0114] This embodiment provides a three-layer co-extruded EPE film, comprising a first EVA layer, a POE layer, and a second EVA layer arranged sequentially. The thickness of both the first and second EVA layers is 150 μm, and the thickness of the POE layer is 250 μm.

[0115] Both the first and second EVA layers comprise the following components by weight: 55 parts EVA resin, 15 parts EVA-156 resin, 15 parts EVA-157 resin, 15 parts EVA-150 resin, 3 parts 4045 EPDM rubber, 0.5 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.5 parts trimethylolpropane triacrylate, 0.4 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0116] The POE layer comprises the following components by weight: 50 parts POE-130 resin, 30 parts POE-142 resin, 20 parts POE-156 resin, 3 parts Ricon 181 resin, 0.9 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.7 parts trimethylolpropane triacrylate, 0.2 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0117] The preparation method of the EPE three-layer co-extruded film in this embodiment includes the following steps: according to the composition of the first EVA layer, the POE layer and the second EVA layer, the film is melt co-extruded to obtain the EPE three-layer co-extruded film; wherein, the melt co-extrusion includes: zone I 50-100℃, zone II 50-100℃, zone III 50-100℃, zone IV 50-100℃, zone V 50-100℃, zone VI 50-100℃, and die head 115℃.

[0118] Example 2

[0119] This embodiment provides a three-layer co-extruded EPE film, comprising a first EVA layer, a POE layer, and a second EVA layer arranged sequentially. The thickness of both the first and second EVA layers is 150 μm, and the thickness of the POE layer is 250 μm.

[0120] Both the first and second EVA layers comprise the following components by weight: 79 parts EVA resin, 7 parts EVA-156 resin, 7 parts EVA-157 resin, 7 parts EVA-150 resin, 3 parts 4045 EPDM rubber, 0.5 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.5 parts trimethylolpropane triacrylate, 0.4 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0121] The POE layer comprises the following components by weight: 50 parts POE-130 resin, 30 parts POE-142 resin, 20 parts POE-156 resin, 3 parts Ricon 181 resin, 0.9 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.7 parts trimethylolpropane triacrylate, 0.2 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0122] The preparation method of the EPE three-layer co-extruded film in this embodiment is the same as that in Embodiment 1.

[0123] Example 3

[0124] This embodiment provides a three-layer co-extruded EPE film, comprising a first EVA layer, a POE layer, and a second EVA layer arranged sequentially. The thickness of both the first and second EVA layers is 150 μm, and the thickness of the POE layer is 250 μm.

[0125] Both the first and second EVA layers comprise the following components by weight: 70 parts EVA resin, 5 parts EVA-156 resin, 10 parts EVA-157 resin, 15 parts EVA-150 resin, 3 parts 4045 EPDM rubber, 0.5 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.5 parts trimethylolpropane triacrylate, 0.4 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0126] The POE layer comprises the following components by weight: 50 parts POE-130 resin, 30 parts POE-142 resin, 20 parts POE-156 resin, 3 parts Ricon 181 resin, 0.9 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.7 parts trimethylolpropane triacrylate, 0.2 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0127] The preparation method of the EPE three-layer co-extruded film in this embodiment is the same as that in Embodiment 1.

[0128] Example 4

[0129] This embodiment provides a three-layer co-extruded EPE film, comprising a first EVA layer, a POE layer, and a second EVA layer arranged sequentially. The thickness of both the first and second EVA layers is 150 μm, and the thickness of the POE layer is 250 μm.

[0130] Both the first and second EVA layers comprise the following components by weight: 70 parts EVA resin, 15 parts EVA-156 resin, 10 parts EVA-157 resin, 5 parts EVA-150 resin, 3 parts 4045 EPDM rubber, 0.5 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.5 parts trimethylolpropane triacrylate, 0.4 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0131] The POE layer comprises the following components by weight: 50 parts POE-130 resin, 30 parts POE-142 resin, 20 parts POE-156 resin, 3 parts Ricon 181 resin, 0.9 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.7 parts trimethylolpropane triacrylate, 0.2 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0132] The preparation method of the EPE three-layer co-extruded film in this embodiment is the same as that in Embodiment 1.

[0133] Example 5

[0134] This embodiment provides a three-layer co-extruded EPE film, comprising a first EVA layer, a POE layer, and a second EVA layer arranged sequentially. The thickness of both the first and second EVA layers is 150 μm, and the thickness of the POE layer is 250 μm.

[0135] Both the first and second EVA layers comprise the following components by weight: 70 parts EVA resin, 15 parts EVA-156 resin, 10 parts EVA-157 resin, 5 parts EVA-150 resin, 3 parts 4045 EPDM rubber, 0.5 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.5 parts trimethylolpropane triacrylate, 0.4 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0136] The POE layer comprises the following components by weight: 60 parts POE-130 resin, 30 parts POE-142 resin, 10 parts POE-156 resin, 3 parts Ricon 181 resin, 0.9 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.7 parts trimethylolpropane triacrylate, 0.2 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0137] The preparation method of the EPE three-layer co-extruded film in this embodiment is the same as that in Embodiment 1.

[0138] Example 6

[0139] This embodiment provides a three-layer co-extruded EPE film, comprising a first EVA layer, a POE layer, and a second EVA layer arranged sequentially. The thickness of both the first and second EVA layers is 150 μm, and the thickness of the POE layer is 250 μm.

[0140] Both the first and second EVA layers comprise the following components by weight: 70 parts EVA resin, 15 parts EVA-156 resin, 10 parts EVA-157 resin, 5 parts EVA-150 resin, 3 parts 4045 EPDM rubber, 0.5 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.5 parts trimethylolpropane triacrylate, 0.4 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0141] The POE layer comprises the following components by weight: 40 parts POE-130 resin, 40 parts POE-142 resin, 20 parts POE-156 resin, 3 parts Ricon 181 resin, 0.9 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.7 parts trimethylolpropane triacrylate, 0.2 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0142] The preparation method of the EPE three-layer co-extruded film in this embodiment is the same as that in Embodiment 1.

[0143] Example 7

[0144] This embodiment provides a three-layer co-extruded EPE film, comprising a first EVA layer, a POE layer, and a second EVA layer arranged sequentially. The thickness of both the first and second EVA layers is 150 μm, and the thickness of the POE layer is 250 μm.

[0145] Both the first and second EVA layers comprise the following components by weight: 70 parts EVA resin, 15 parts EVA-156 resin, 10 parts EVA-157 resin, 5 parts EVA-150 resin, 3 parts 4045 EPDM rubber, 0.5 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.5 parts trimethylolpropane triacrylate, 0.4 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0146] The POE layer comprises the following components by weight: 40 parts POE-130 resin, 20 parts POE-142 resin, 40 parts POE-156 resin, 3 parts Ricon 181 resin, 0.9 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.7 parts trimethylolpropane triacrylate, 0.2 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0147] The preparation method of the EPE three-layer co-extruded film in this embodiment is the same as that in Embodiment 1.

[0148] Example 8

[0149] This embodiment refers to the EPE three-layer co-extruded film and its preparation method in Example 4, the only difference being that the composition of the first EVA layer and the second EVA layer are different.

[0150] In this embodiment, both the first and second EVA layers comprise the following components by weight: 70 parts EVA resin, 22.5 parts EVA-156 resin, 7.5 parts EVA-150 resin, 3 parts 4045 EPDM rubber, 0.5 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.5 parts trimethylolpropane triacrylate, 0.4 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0151] Example 9

[0152] This embodiment refers to the EPE three-layer co-extruded film and its preparation method in Example 4, the only difference being that the composition of the POE layer is different.

[0153] The POE layer in this embodiment comprises the following components by weight: 71 parts POE-130 resin, 29 parts POE-156 resin, 3 parts Ricon 181 resin, 0.9 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.7 parts trimethylolpropane triacrylate, 0.2 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0154] Example 10

[0155] This embodiment refers to the EPE three-layer co-extruded film and its preparation method in Example 4, with the only difference being that the thickness of the first EVA layer and the second EVA layer is 200 μm, and the thickness of the POE layer is 150 μm.

[0156] Comparative Example 1

[0157] Comparative Example 1 refers to the EPE three-layer co-extruded film and its preparation method in Example 4, the difference being that the compositions of the first EVA layer, the second EVA layer and the POE layer are different.

[0158] The first and second EVA layers of Comparative Example 1 both comprise the following components by weight: 100 parts of EVA resin, 0.5 parts of tert-amyl peroxide-2-ethylhexyl carbonate, 0.5 parts of trimethylolpropane triacrylate, 0.4 parts of 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts of antioxidant 1010.

[0159] The POE layer of Comparative Example 1 comprises the following components by weight: 100 parts POE resin, 0.9 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.7 parts trimethylolpropane triacrylate, 0.2 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0160] Comparative Example 2

[0161] Comparative Example 2 refers to the EPE three-layer co-extruded film and its preparation method in Example 4, the difference being that the composition of the first EVA layer and the second EVA layer are different.

[0162] The first and second EVA layers of Comparative Example 2 both comprise the following components by weight: 100 parts of EVA resin, 0.5 parts of tert-amyl peroxide-2-ethylhexyl carbonate, 0.5 parts of trimethylolpropane triacrylate, 0.4 parts of 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts of antioxidant 1010.

[0163] Comparative Example 3

[0164] Comparative Example 3 refers to the EPE three-layer co-extruded film and its preparation method in Example 4, the difference being that the composition of the POE layer is different.

[0165] The POE layer of Comparative Example 3 comprises the following components by weight: 100 parts POE resin, 0.9 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.7 parts trimethylolpropane triacrylate, 0.2 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0166] Comparative Example 4

[0167] Comparative Example 4 refers to the EPE three-layer co-extruded film and its preparation method in Example 4, the difference being that the compositions of the first EVA layer, the second EVA layer and the POE layer are different.

[0168] The first and second EVA layers of Comparative Example 4 both comprise the following components by weight: 70 parts EVA resin, 15 parts EVA-156 resin, 10 parts EVA-157 resin, 5 parts EVA-150 resin, 0.5 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.5 parts trimethylolpropane triacrylate, 0.4 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0169] The POE layer of Comparative Example 4 comprises the following components by weight: 50 parts of POE-130 resin, 30 parts of POE-142 resin, 20 parts of POE-156 resin, 0.9 parts of tert-amyl peroxide-2-ethylhexyl carbonate, 0.7 parts of trimethylolpropane triacrylate, 0.2 parts of 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts of antioxidant 1010.

[0170] Comparative Example 5

[0171] Comparative Example 5 refers to the EPE three-layer co-extruded film and its preparation method in Example 4, the difference being that the compositions of the first EVA layer and the second EVA layer are different.

[0172] The first and second EVA layers of Comparative Example 5 both comprise the following components by weight: 50 parts EVA resin, 50 parts EVA-150 resin, 3 parts 4045 EPDM rubber, 0.5 parts tert-amyl peroxide-2-ethylhexyl carbonate, 0.5 parts trimethylolpropane triacrylate, 0.4 parts 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts antioxidant 1010.

[0173] Comparative Example 6

[0174] Comparative Example 6 refers to the EPE three-layer co-extruded film and its preparation method in Example 4, the difference being that the composition of the POE layer is different.

[0175] The POE layer of Comparative Example 6 comprises the following components by weight: 100 parts of POE-156 resin, 3 parts of Ricon 181 resin, 0.9 parts of tert-amyl peroxide-2-ethylhexyl carbonate, 0.7 parts of trimethylolpropane triacrylate, 0.2 parts of 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts of antioxidant 1010.

[0176] Experimental Example

[0177] To compare and illustrate the performance differences of different EPE three-layer co-extruded films, the following tests were conducted on the EPE three-layer co-extruded films prepared in different examples and comparative examples. The test results are shown in Table 2.

[0178] Preparation of film samples: Take the EPE three-layer co-extruded film prepared in the examples and comparative examples, and place the film in a vacuum laminator according to the test method of GB / T 29848-2018. Laminate at 145℃ for 15 min to prepare the sample; and perform the following tests (1) and (2) on the prepared film sample.

[0179] (1) Crosslinking degree test: The test was conducted according to the method in GB / T 29848-2018 "Ethylene-vinyl acetate copolymer (EVA) film for photovoltaic module encapsulation";

[0180] (2) Water vapor transmission rate test: The test shall be conducted in accordance with the method in GB / T 30412-2013 "Determination of water vapor transmission rate of plastic film and sheet by humidity sensor".

[0181] Sample preparation: Take the EPE three-layer co-extruded film prepared in the examples and comparative examples, and place it in a vacuum laminator in the order of "tempered glass / film / backsheet" according to the test method of GB / T29848-2018. Laminate at 145℃ for 15 minutes to prepare a single-glass sample. Perform the following tests (3), (4), and (5) on the prepared sample, record the adhesive strength test data, and observe whether the sample delaminates from the glass and / or backsheet, and whether the film itself delaminates.

[0182] (3) High temperature and high humidity aging test: The test shall be conducted in accordance with the test method provided in GB / T 29848-2018;

[0183] (4) UV aging resistance test: The test shall be conducted in accordance with the test method provided in GB / T 29848-2018;

[0184] (5) PCT aging test: The test shall be conducted in accordance with the test method provided in GB / T 29848-2018.

[0185] Table 2 Performance test results of different EPE three-layer co-extruded films

[0186]

[0187] The test results above show that the EPE three-layer co-extruded film of the present invention exhibits high adhesion, water resistance, and excellent resistance to high temperature and humidity aging, UV radiation, and long-term damp heat aging. The EPE film of Comparative Example 1, without modified EVA and modified POE resin, showed poor performance. Comparative Examples 2 and 3 only improved the POE layer or EVA layer, offering limited improvement to the compatibility of the EVA and POE layers in the EPE film, leading to delamination during aging. Comparative Example 4, without compatibilizer, showed limited improvement to the aging resistance and other properties of the EPE film. In Comparative Example 5, an excessive amount of modified EVA resin was added, and only a single modified EVA resin was used. In Comparative Example 6, the POE layer was made of POE resin with high vinyl content grafted with polybutadiene. The cross-linking network formed during the cross-linking process of the adhesive films in Comparative Examples 5 and 6 was too dense, which led to poor wettability between the adhesive film and the glass or battery cell, and consequently, poor adhesion and aging performance of the adhesive film.

[0188] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An EPE three-layer co-extruded film, characterized in that, This includes the first EVA layer, the POE layer, and the second EVA layer, which are set in sequence. The first EVA layer and the second EVA layer each independently comprise the following components by weight: 50-85 parts of EVA resin, 15-45 parts of modified EVA resin, 1-5 parts of compatibilizer, 0.1-2 parts of crosslinking agent, 0.1-2 parts of co-crosslinking agent, 0.1-2 parts of silane coupling agent, and 0.01-1 parts of antioxidant; The POE layer comprises the following components by weight: 100 parts modified POE resin, 1-5 parts compatibilizer, 0.1-2 parts crosslinking agent, 0.1-2 parts co-crosslinking agent, 0.1-2 parts silane coupling agent, and 0.01-1 parts antioxidant; The modified EVA resin comprises 5-15 parts by weight of a first modified EVA resin, 5-15 parts by weight of a second modified EVA resin, and 5-15 parts by weight of a third modified EVA resin; the first modified EVA resin, the second modified EVA resin, and the third modified EVA resin are EVA resins grafted with first polybutadiene, second polybutadiene, and third polybutadiene, respectively, wherein the molecular weight of the first polybutadiene is 3800-4100 g / mol, the molecular weight of the second polybutadiene is 1800-2000 g / mol, and the molecular weight of the third polybutadiene is 1400-1600 g / mol; in the modified EVA resin, the mass ratio of EVA resin to polybutadiene is 100:(1-10). The modified POE resin comprises, by weight, 10-40 parts of a first modified POE resin, 20-40 parts of a second modified POE resin, and 30-60 parts of a third modified POE resin; the first, second, and third modified POE resins are POE resins grafted with fourth, fifth, and sixth polybutadiene, respectively, wherein the vinyl content of the fourth polybutadiene is 65%-70%, the vinyl content of the fifth polybutadiene is 50%-60%, and the vinyl content of the sixth polybutadiene is 18%-25%; in the modified POE resin, the mass ratio of POE resin to polybutadiene is 100:(1-10).

2. The EPE three-layer co-extruded film according to claim 1, characterized in that, The amounts of the first modified EVA resin, the second modified EVA resin, and the third modified EVA resin increase sequentially.

3. The EPE three-layer co-extruded film according to claim 1, characterized in that, The amounts of the first modified POE resin, the second modified POE resin, and the third modified POE resin increase sequentially.

4. The EPE three-layer co-extruded film according to claim 1, characterized in that, The modified EVA resin is mainly prepared by extrusion granulation of EVA resin, peroxide initiator and polybutadiene in a mass ratio of 100:(0.01~0.5):(1~10); The modified POE resin is mainly prepared by extrusion granulation of POE resin, peroxide initiator and polybutadiene in a mass ratio of 100:(0.01~0.5):(1~10).

5. The EPE three-layer co-extruded film according to claim 1, characterized in that, The compatibilizer includes at least one of ethylene propylene diene monomer (EPDM), ethylene propylene diene monomer (EPDM), and butadiene-styrene copolymer.

6. The EPE three-layer co-extruded film according to claim 5, characterized in that, The butadiene-styrene copolymer has a vinyl content of 20% to 70% and a molecular weight of 3000 to 9000 g / mol.

7. A method for preparing an EPE three-layer co-extruded film, characterized in that, The EPE three-layer co-extruded film is obtained by melt co-extrusion according to the composition of the first EVA layer, POE layer and second EVA layer of the EPE three-layer co-extruded film according to any one of claims 1 to 6.

8. The application of the EPE three-layer co-extruded film according to any one of claims 1 to 6 in the preparation of photovoltaic modules.

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