High-temperature-resistant and high-weather-resistant eva encapsulating adhesive film for photovoltaic modules and preparation method thereof

Abstract

This invention belongs to the field of photovoltaic encapsulation film technology, specifically relating to a high-temperature resistant and high-weather resistant EVA encapsulation film for photovoltaic modules and its preparation method, including: alumina masterbatch granulation; and / or silica masterbatch granulation; and hydrotalcite masterbatch granulation. The hydrotalcite nanoparticles are modified with a silane coupling agent or stearic acid, then dried, premixed with EVA particles at a mass ratio of 10-30:70-90, then blended with EVA particles, extruded at 120-150°C, air-dried, granulated, and sheared to obtain hydrotalcite masterbatch; EVA particles are mixed uniformly with high-temperature resistant masterbatch and additives, extruded and kneaded at 110-120°C, and then cast, embossed, and cooled to obtain the EVA encapsulation film; wherein the high-temperature resistant masterbatch includes hydrotalcite masterbatch, alumina masterbatch, and / or silica masterbatch.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic encapsulation film technology, specifically relating to a high-temperature resistant and high-weather resistant EVA encapsulation film for photovoltaic modules and its preparation method. Background Technology

[0002] Photovoltaic module encapsulation films are one of the key materials for photovoltaic modules, primarily used to protect solar cells from environmental impacts while ensuring efficient light transmission and long-term stability. Among these, ethylene-vinyl acetate copolymer (EVA) films have become a mainstream encapsulation material due to their excellent light transmittance, adhesion, and cost advantages. However, with the rapid development of photovoltaic technology, especially the widespread adoption of high-efficiency cells such as N-type TOPCon and HJT, higher requirements have been placed on the high-temperature resistance and weather resistance of encapsulation films.

[0003] The main component of EVA film is ethylene-vinyl acetate copolymer, and it typically contains crosslinking agents, antioxidants, and light stabilizers to improve its performance. However, traditional EVA films have a high crosslinking and curing temperature (140-145℃) and a long curing time (20-30 minutes), affecting production efficiency. Furthermore, traditional EVA films are prone to yellowing, delamination, and decreased light transmittance at high temperatures (>85℃). The decomposition of crosslinking agents leads to reduced bonding strength, and insufficient resistance to ultraviolet radiation and damp heat aging significantly impacts module lifespan. Photovoltaic modules operate outdoors for extended periods, enduring harsh environments such as high temperatures, ultraviolet radiation, and humidity variations; therefore, high temperature resistance, high weather resistance, and anti-aging properties are crucial.

[0004] Although novel inorganic nano-high temperature resistant fillers have been introduced into existing EVA films, these fillers and EVA resin still exhibit severe yellowing and power reduction problems after aging.

[0005] Therefore, overcoming the defect of high-temperature resistant EVA encapsulation films being not resistant to aging is a technical problem that urgently needs to be solved in this field.

[0006] It should be noted that the information disclosed in this background section is only for understanding the background technology of the present application concept, and therefore, the above description is not considered to constitute prior art information. Summary of the Invention

[0007] This disclosure provides at least one high-temperature resistant and weather-resistant EVA encapsulating film for photovoltaic modules and its preparation method.

[0008] In a first aspect, embodiments of this disclosure provide a method for preparing an EVA encapsulating film, comprising: granulation of alumina masterbatch, modifying nano-alumina with a titanate coupling agent or polyethylene glycol, premixing it with liquid paraffin at a mass ratio of 20-40:60-80, blending it with EVA particles, extruding it at 130-160°C, air-drying and granulating it, and shearing it to obtain alumina masterbatch; and / or granulation of silica masterbatch, subjecting nano-silica to hydrophobic treatment, premixing it with EVA particles at a mass ratio of 10-20:80-90, blending it with EVA particles, and low-temperature extrusion at 100-130°C. The process involves: 1) preparing silica masterbatch by air-drying, granulating, and shearing; 2) preparing hydrotalcite masterbatch by granulating nano-hydrotalcite using a silane coupling agent or stearic acid, followed by drying, premixing with EVA particles at a mass ratio of 10–30:70–90, then blending with EVA particles, extruding at 120–150°C, air-drying, granulating, and shearing to obtain hydrotalcite masterbatch; 3) mixing EVA particles with high-temperature resistant masterbatch and additives uniformly, extruding and kneading at 110–120°C, and obtaining EVA encapsulation film through casting, embossing, and cooling; wherein the high-temperature resistant masterbatch includes hydrotalcite masterbatch, alumina masterbatch, and / or silica masterbatch.

[0009] In one optional embodiment, the alumina masterbatch contains 5-10% nano-alumina with a particle size of 3-5 mm; the silica masterbatch contains 5-10% nano-silica with a particle size of 3-5 mm; and the hydrotalcite masterbatch contains 5-10% nano-hydrotalcite with a particle size of 3-5 mm.

[0010] In one optional embodiment, the mass parts of each component in which the EVA particles, high-temperature resistant masterbatch, and additives are uniformly mixed are: 100 parts of EVA particles; 1 to 10 parts of high-temperature resistant masterbatch; and the additives include the following mass parts: 0.4 to 0.8 parts of crosslinking agent, 0.4 to 0.8 parts of co-crosslinking agent, 0.7 to 1 part of UV curing agent, 0.4 to 1 part of antioxidant, 0.1 to 1 part of light stabilizer, and 0.2 to 0.8 parts of silane coupling agent.

[0011] In one optional embodiment, the EVA particles contain 5% to 40% VA, have a melt index of 0.1 to 40 g / 10 min at 120°C, a melting point of 50 to 90°C, and a light transmittance of not less than 90%.

[0012] In one optional embodiment, the crosslinking agent includes at least one of tert-butyl peroxide-2-ethylhexyl carbonate, tert-amyl peroxide-2-ethylhexyl carbonate, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl peroxide-2-ethylhexanoate, tert-butyl peroxide, benzoyl peroxide, and dicumyl peroxide.

[0013] In one optional embodiment, the co-crosslinking agent includes at least one of triallyl isocyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, 1,6-hexanediol diacrylate, γ-(methacryloyloxy)propyltrimethoxysilane, and N,N′-m-phenylbismaleimide.

[0014] In one optional embodiment, the UV curing agent includes at least one of ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, propoxylated glycerol triacrylate, and neopentyl glycol polymethyl ethylene oxide diacrylate.

[0015] In one alternative embodiment, the antioxidant comprises at least one of bis(4-octylphenol) diphosphate, butylated hydroxytoluene, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and tris[2,4-di-tert-butylphenyl] phosphite.

[0016] In one alternative embodiment, the light stabilizer comprises at least one of hindered amine light stabilizers, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, mono(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and a polymer of succinic acid and (2,2,6,6-tetramethyl-4-piperidinyl) alcohol.

[0017] In one alternative embodiment, the silane coupling agent comprises at least one of γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriperoxytert-butylsilane, vinyltriacetoxysilane, or vinyltri(β-methoxyethoxy)silane.

[0018] Secondly, embodiments of this disclosure also provide an EVA encapsulation film, comprising, by weight parts: 100 parts of EVA particles; 1-10 parts of high-temperature resistant masterbatch; and the additives comprising, by weight parts: 0.4-0.8 parts of crosslinking agent, 0.4-0.8 parts of co-crosslinking agent, 0.7-1 parts of UV curing agent, 0.4-1 parts of antioxidant, 0.1-1 parts of light stabilizer, and 0.2-0.8 parts of silane coupling agent; and the yellowing index ΔYI of the EVA encapsulation film at 85°C / 85%RH for 1000h is <2; the yellowing index ΔYI of the EVA encapsulation film at 150°C for 1000h is <2.

[0019] Thirdly, embodiments of this disclosure also provide a photovoltaic module, including the EVA encapsulation film as described above.

[0020] The beneficial effects of this invention are that the high-temperature resistant and high-weather resistant EVA encapsulation film for photovoltaic modules and its preparation method improve the compatibility with EVA particles and avoid agglomeration by pre-dispersing the nano high-temperature resistant filler after surface modification. Subsequently, different types of high-temperature resistant fillers are subjected to differentiated extrusion granulation, which avoids both resin degradation and filler structural decomposition. The cross-linking degree of the encapsulation film is improved during the extrusion of high-temperature resistant masterbatch and EVA resin. In conjunction with the synergistic effect of hydrotalcite and SiO2 / Al2O3 to form physical cross-linking points, the long-term weather resistance and high-temperature resistance of the EVA encapsulation film are achieved.

[0021] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. 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.

[0024] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0025] In this document, as used herein, expressions such as “at least one of…” modify the entire list of elements when following a list of elements, rather than individual elements in the list. For example, the expression “at least one of a, b, and c” should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0026] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise clearly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.

[0027] This disclosure provides a method for preparing an EVA encapsulating film, comprising: granulation of alumina masterbatch, modifying nano-alumina with a titanate coupling agent or polyethylene glycol, premixing it with liquid paraffin at a mass ratio of 20-40:60-80, blending it with EVA particles, extruding it at 130-160°C, air-drying, granulating, and shearing to obtain alumina masterbatch; and / or granulation of silica masterbatch, hydrophobizing the surface of nano-silica, premixing it with EVA particles at a mass ratio of 10-20:80-90, blending it with EVA particles, low-temperature extrusion at 100-130°C, and air-drying. A silica masterbatch is prepared by dry granulation and shearing; and a hydrotalcite masterbatch is prepared by granulation of nano-hydrotalcite, which is modified with a silane coupling agent or stearic acid, then dried, premixed with EVA particles at a mass ratio of 10-30:70-90, then blended with EVA particles, extruded at 120-150°C, air-dried, granulated and sheared to obtain a hydrotalcite masterbatch; EVA particles are mixed evenly with high-temperature resistant masterbatch and additives, extruded and kneaded at 110-120°C, and then cast, embossed and cooled to obtain an EVA encapsulation film; wherein, the high-temperature resistant masterbatch includes hydrotalcite masterbatch, alumina masterbatch and / or silica masterbatch.

[0028] Specifically, hydrotalcite (LDH) is a layered bimetallic hydroxide with UV shielding and absorption properties. Its layered structure reflects and scatters ultraviolet (UV) radiation, reducing the degradation effect of UV on EVA. Simultaneously, interlayer anions (such as CO32-) 2-Hydrotalcite can absorb UV energy and convert it into harmless heat. Its thermal stability allows it to decompose and absorb heat at high temperatures (releasing interlayer water molecules and CO2), thus slowing down the thermal aging of EVA. Its decomposition products (such as MgO and Al2O3) can further block heat transfer. The layered structure hinders the penetration of oxygen and water molecules, slowing down the oxidation and hydrolysis reactions of EVA. SiO2 nanoparticles form a three-dimensional network structure in EVA, restricting molecular chain movement and increasing the heat distortion temperature. Its high melting point (approximately 1700℃) can delay the softening of EVA at high temperatures. Simultaneously, SiO2 has high reflectivity to UV light (especially short-wavelength UV), reducing photo-oxidation reactions. The hydrophobic surface of SiO2 reduces the water absorption of EVA and inhibits the release of acetic acid caused by hydrolysis (acetic acid accelerates the yellowing of EVA). The high melting point (2050℃) and low thermal conductivity of Al2O3 can block heat radiation and reduce the thermal degradation of EVA. Al2O3 can also absorb high-energy UV photons, dissipate energy through electronic transitions, reduce free radical generation, and exhibit excellent UV resistance and anti-aging capabilities. Simultaneously, Al2O3 has surface passivation properties; nano-Al2O3 can fill micro-defects in EVA, reducing oxygen and water penetration pathways and inhibiting oxidation reactions.

[0029] The synergistic effect of LDH and SiO2 / Al2O3 is manifested in the following ways: the layered structure of LDH forms "physical cross-linking points" with the nanoparticles of SiO2 / Al2O3, jointly enhancing mechanical strength and barrier properties. The alkaline surfaces of Al2O3 and LDH can neutralize acidic substances (such as acetic acid) produced by EVA degradation, while the surface hydroxyl groups of SiO2 can capture free radicals and delay the chain reaction. In practical applications, the composite filler increases the initial decomposition temperature of EVA by 20-30°C, reduces bubbles and delamination at high temperatures, and exhibits high-temperature resistance. Simultaneously, under damp heat (85°C / 85%RH) and UV aging (e.g., 2000 hours) testing conditions, the yellowing index (ΔYI) of the composite-modified EVA is reduced by more than 50%, and the light transmittance retention exceeds 90%, demonstrating excellent weather resistance.

[0030] In summary, hydrotalcite, SiO2, and Al2O3 synergistically enhance the high-temperature resistance and weather resistance of EVA films through multiple mechanisms, including UV shielding, thermal stabilization, barrier effect, and free radical capture.

[0031] In some embodiments, specifically, the alumina masterbatch contains 5-10% nano-alumina with a particle size of 3-5 mm; the silica masterbatch contains 5-10% nano-silica with a particle size of 3-5 mm; and the hydrotalcite masterbatch contains 5-10% nano-hydrotalcite with a particle size of 3-5 mm.

[0032] In some embodiments, specifically, the mass parts of each component in which the EVA particles, high-temperature resistant masterbatch, and additives are uniformly mixed are: 100 parts of EVA particles; 1 to 10 parts of high-temperature resistant masterbatch; and the additives include the following mass parts: 0.4 to 0.8 parts of crosslinking agent, 0.4 to 0.8 parts of co-crosslinking agent, 0.7 to 1 part of UV curing agent, 0.4 to 1 part of antioxidant, 0.1 to 1 part of light stabilizer, and 0.2 to 0.8 parts of silane coupling agent.

[0033] In some embodiments, specifically, the EVA particles contain 5% to 40% VA, and have a melt index of 0.1 to 40 g / 10 min at 120°C, a melting point of 50 to 90°C, and a light transmittance of not less than 90%.

[0034] In some embodiments, the crosslinking agent specifically includes at least one of tert-butyl peroxide-2-ethylhexyl carbonate, tert-amyl peroxide-2-ethylhexyl carbonate, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl peroxide-2-ethylhexanoate, tert-butyl peroxide, benzoyl peroxide, and dicumyl peroxide.

[0035] In some embodiments, the co-crosslinking agent specifically includes at least one of triallyl isocyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, 1,6-hexanediol diacrylate, γ-(methacryloyloxy)propyltrimethoxysilane, and N,N′-m-phenylbismaleimide.

[0036] In some embodiments, the UV curing agent specifically includes at least one of ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, propoxylated glycerol triacrylate, and neopentyl glycol polymethyl ethylene oxide diacrylate.

[0037] In some embodiments, the antioxidant specifically includes at least one of bis(4-octylphenol) diphosphate, butylated hydroxytoluene, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and tris[2,4-di-tert-butylphenyl] phosphite.

[0038] In some embodiments, the light stabilizer specifically includes at least one of hindered amine light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, mono(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and a polymer of succinic acid and (2,2,6,6-tetramethyl-4-piperidinyl) alcohol.

[0039] In some embodiments, specifically, the silane coupling agent includes at least one of γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriperoxytert-butylsilane, vinyltriacetoxysilane, or vinyltri(β-methoxyethoxy)silane.

[0040] This disclosure also provides an EVA encapsulation film, comprising, by weight parts: 100 parts EVA particles; 1-10 parts high-temperature resistant masterbatch; and the additives comprising, by weight parts: 0.4-0.8 parts crosslinking agent, 0.4-0.8 parts co-crosslinking agent, 0.7-1 part UV curing agent, 0.4-1 part antioxidant, 0.1-1 part light stabilizer, and 0.2-0.8 parts silane coupling agent; and the yellowing index ΔYI of the EVA encapsulation film at 85°C / 85%RH for 1000h is <2; the yellowing index ΔYI of the EVA encapsulation film at 150°C for 1000h is <2.

[0041] This disclosure also provides a photovoltaic module, including the EVA encapsulation film as described above.

[0042] The following describes some embodiments of the present invention in detail. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0043] Example 1:

[0044] Granulation of alumina (Al2O3) masterbatch: a. Pretreatment: Nano-Al2O3 is modified with a titanate coupling agent to improve dispersibility. It is then premixed with liquid paraffin at a mass ratio of 20:80, and then blended with EVA particles. b. Blending and extrusion: Nano-alumina powder with a surface-treated coupling agent and EVA particles are sequentially added to a high-speed mixer, with an Al2O3 addition of 5%. After uniform mixing in the high-speed mixer, the extrusion temperature is controlled at 130–160℃ to avoid resin degradation. Extrusion is carried out in a twin-screw extruder at 100 rpm, followed by air drying, granulation, and shearing to prepare high-temperature resistant masterbatch (content 5%) with a particle size of 3 mm.

[0045] Example 2:

[0046] Granulation of alumina (Al2O3) masterbatch: a. Pretreatment: Nano-Al2O3 is modified with polyethylene glycol (PEG) to improve dispersibility. It is then premixed with liquid paraffin at a mass ratio of 30:70, and then blended with EVA particles. b. Blending and extrusion: PEG-treated nano-alumina powder and EVA particles are sequentially added to a high-speed mixer. The Al2O3 addition is 10% (too high a content will reduce the flexibility of the film). After uniform mixing in the high-speed mixer, the extrusion temperature is controlled at 130–160℃ to avoid resin degradation. Extrusion is carried out in a twin-screw extruder at 100 rpm. The mixture is then air-dried, granulated, and sheared to prepare a high-temperature resistant masterbatch (10% content) with a particle size of 3 mm.

[0047] Example 3:

[0048] Silica (SiO2) Masterbatch Granulation: a. Pretreatment: Nano-SiO2 is treated with hexamethyldisilazane to achieve surface hydrophobicity and prevent agglomeration. It can be pre-dispersed with EVA resin at a mass ratio of 10:90 in a high-speed mixer, and then blended with EVA particles. b. Blending and Extrusion: The surface-treated nano-silica powder and EVA particles are added sequentially to a high-speed mixer. The SiO2 addition is 5% (too high a content will affect light transmittance). Low-temperature extrusion (100-130℃) is used to avoid SiO2 aggregation. Extrusion is carried out in a twin-screw extruder at a speed of 100 rpm to improve dispersibility. Then, it is air-dried, granulated, and sheared to prepare high-temperature resistant masterbatch (content 5%) with a particle size of 3 mm.

[0049] Example 4:

[0050] Silica (SiO2) Masterbatch Granulation: a. Pretreatment: Nano-SiO2 is treated with hexamethyldisilazane to achieve surface hydrophobicity and prevent agglomeration. It can be pre-dispersed with EVA resin at a mass ratio of 20:80 in a high-speed mixer, and then blended with EVA particles. b. Blending and Extrusion: The surface-treated nano-silica powder and EVA particles are added sequentially to a high-speed mixer, with a SiO2 addition of 10% (too high a content will affect light transmittance). Low-temperature extrusion (100-130℃) is used to avoid SiO2 aggregation. Extrusion is carried out in a twin-screw extruder at a speed of 100 rpm to improve dispersibility, followed by air drying and granulation, and shearing to prepare high-temperature resistant masterbatch (content 10%) with a particle size of 3 mm.

[0051] Example 5:

[0052] Hydrotalcite (LDH) Masterbatch Granulation: a. Pretreatment: LDH is treated with silane coupling agent KH-570 for surface modification to improve compatibility with EVA. Then, it is dried to remove moisture (LDH is hygroscopic). b. Blending and Extrusion: Modified LDH powder is premixed with EVA resin (VA content 28%) at a mass ratio of 5%. This is then melt-blended using a twin-screw extruder (temperature control: 120–150℃) at a speed of 100 rpm to avoid LDH decomposition due to high temperatures. The mixture is then air-dried, granulated, and sheared to prepare high-temperature resistant masterbatch (content 5%) with a particle size of 3 mm.

[0053] Example 6:

[0054] Hydrotalcite (LDH) Masterbatch Granulation: a. Pretreatment: LDH is treated with stearic acid for surface modification to improve compatibility with EVA. Then, it is dried to remove moisture (LDH is hygroscopic). b. Blending and Extrusion: Modified LDH powder is premixed with EVA resin (VA content 32%) at a mass ratio of 10%. This is then melt-blended using a twin-screw extruder (temperature control: 120–150℃) at a speed of 100 rpm to avoid LDH decomposition due to high temperatures. After air drying and granulation, it is sheared to prepare high-temperature resistant masterbatch (content 10%) with a particle size of 3 mm.

[0055] Example 7:

[0056] By weight, 100 parts of EVA particles, 0.6 parts of dicumyl peroxide, 0.4 parts of triallyl isocyanurate, 0.7 parts of ethoxylated trimethylolpropane triacrylate, 0.4 parts of bis(4-octylphenol) diphosphate, 0.5 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts of γ-methacryloyloxypropyltrimethoxysilane, and 4 parts of the nano-alumina masterbatch prepared in Example 1 were weighed out. The above raw materials were added to a high-speed mixer (800 rpm, 40 min) and mixed evenly. The mixture was then fed into a twin-screw extruder for co-extrusion, with the temperature range set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film was cut by traction and wound to obtain an EVA encapsulating film with a thickness of 0.5 mm.

[0057] Example 8:

[0058] By weight, 100 parts of EVA particles, 0.6 parts of dicumyl peroxide, 0.4 parts of triallyl isocyanurate, 0.7 parts of ethoxylated trimethylolpropane triacrylate, 0.4 parts of bis(4-octylphenol) diphosphate, 0.5 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts of γ-methacryloyloxypropyltrimethoxysilane, and 4 parts of the nano-alumina masterbatch prepared in Example 2 were weighed out. The above raw materials were added to a high-speed mixer (800 rpm, 40 min) and mixed evenly. The mixture was then fed into a twin-screw extruder for co-extrusion, with the temperature range set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film was cut by traction and wound to obtain an EVA encapsulating film with a thickness of 0.5 mm.

[0059] Example 9:

[0060] By weight, 100 parts of EVA particles, 0.6 parts of 2-ethylhexyl carbonate tert-butyl peroxide, 0.4 parts of trimethylolpropane triacrylate, 0.7 parts of trimethylolpropane trimethacrylate, 0.4 parts of butylated hydroxytoluene, 0.5 parts of mono(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts of γ-aminopropyltriethoxysilane, and 4 parts of the nano-silica masterbatch prepared in Example 3 were weighed. The above raw materials were added to a high-speed mixer (800 rpm, 40 min) and mixed evenly. Then the mixture was poured into a twin-screw extruder for co-extrusion. The temperature range was set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film was cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0061] Example 10:

[0062] By weight, 100 parts of EVA particles, 0.6 parts of 2-ethylhexyl carbonate tert-butyl peroxide, 0.4 parts of trimethylolpropane triacrylate, 0.7 parts of trimethylolpropane trimethacrylate, 0.4 parts of butylated hydroxytoluene, 0.5 parts of mono(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts of γ-aminopropyltriethoxysilane, and 4 parts of the nano-silica masterbatch prepared in Example 4 were weighed. The above raw materials were added to a high-speed mixer (800 rpm, 40 min) and mixed evenly. Then the mixture was poured into a twin-screw extruder for co-extrusion. The temperature range was set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film was cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0063] Example 11:

[0064] By mass, weigh 100 parts of EVA particles, 0.6 parts of tert-amyl peroxide (2-ethylhexyl) carbonate, 0.4 parts of trimethylolpropane trimethacrylate, 0.7 parts of propoxylated glycerol triacrylate, 0.4 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.5 parts of the polymer of succinic acid and (2,2,6,6-tetramethyl-4-piperidinyl) alcohol, 0.5 parts of vinyltriethoxysilane, and 4 parts of the hydrotalcite masterbatch prepared in Example 5. The above raw materials are added to a high-speed mixer (800 rpm, 40 min) in proportion and mixed evenly. Then the mixture is poured into a twin-screw extruder for co-extrusion. The temperature range is set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film is cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0065] Example 12:

[0066] By mass, weigh 100 parts of EVA particles, 0.6 parts of tert-amyl peroxide (2-ethylhexyl) carbonate, 0.4 parts of trimethylolpropane trimethacrylate, 0.7 parts of propoxylated glycerol triacrylate, 0.4 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.5 parts of the polymer of succinic acid and (2,2,6,6-tetramethyl-4-piperidinyl) alcohol, 0.5 parts of vinyltriethoxysilane, and 4 parts of the hydrotalcite masterbatch prepared in Example 6. The above raw materials are added to a high-speed mixer (800 rpm, 40 min) in proportion and mixed evenly. Then the mixture is poured into a twin-screw extruder for co-extrusion. The temperature range is set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film is cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0067] Example 13:

[0068] By mass fraction, weigh out 100 parts of EVA particles, 0.6 parts of dicumyl peroxide, 0.4 parts of triallyl isocyanurate, 0.7 parts of ethoxylated trimethylolpropane triacrylate, 0.4 parts of bis(4-octylphenol) diphosphate, 0.5 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts of γ-methacryloyloxypropyltrimethoxysilane, 2 parts of the nano-alumina masterbatch from Example 1, and 2 parts of the hydrotalcite masterbatch from Example 5. The above raw materials are added to a high-speed mixer (800 rpm, 40 min) in proportion and mixed evenly. Then the mixture is poured into a twin-screw extruder for co-extrusion. The temperature range is set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film is cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0069] Example 14:

[0070] By mass fraction, weigh out 100 parts of EVA particles, 0.6 parts of dicumyl peroxide, 0.4 parts of triallyl isocyanurate, 0.7 parts of ethoxylated trimethylolpropane triacrylate, 0.4 parts of bis(4-octylphenol) diphosphate, 0.5 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts of γ-methacryloyloxypropyltrimethoxysilane, 4 parts of the nano-alumina masterbatch from Example 2, and 4 parts of the hydrotalcite masterbatch from Example 6. The above raw materials are added to a high-speed mixer (800 rpm, 40 min) in proportion and mixed evenly. Then the mixture is poured into a twin-screw extruder for co-extrusion. The temperature range is set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film is cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0071] Example 15:

[0072] By mass fraction, weigh out 100 parts of EVA particles, 0.6 parts of dicumyl peroxide, 0.4 parts of triallyl isocyanurate, 0.7 parts of ethoxylated trimethylolpropane triacrylate, 0.4 parts of bis(4-octylphenol) diphosphate, 0.5 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts of γ-methacryloyloxypropyltrimethoxysilane, 2 parts of nano silica masterbatch from Example 3, and 2 parts of hydrotalcite masterbatch from Example 5. The above raw materials are added to a high-speed mixer (800 rpm, 40 min) in proportion and mixed evenly. Then the mixture is poured into a twin-screw extruder for co-extrusion. The temperature range is set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film is cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0073] Example 16:

[0074] By mass fraction, weigh out 100 parts of EVA particles, 0.6 parts of dicumyl peroxide, 0.4 parts of triallyl isocyanurate, 0.7 parts of ethoxylated trimethylolpropane triacrylate, 0.4 parts of bis(4-octylphenol) diphosphate, 0.5 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts of γ-methacryloyloxypropyltrimethoxysilane, 3 parts of the nano silica masterbatch from Example 4, and 3 parts of the hydrotalcite masterbatch from Example 6. The above raw materials are added to a high-speed mixer (800 rpm, 40 min) in proportion and mixed evenly. Then the mixture is poured into a twin-screw extruder for co-extrusion. The temperature range is set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film is cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0075] Example 17:

[0076] Weigh out the following components by weight: 100 parts EVA particles, 0.6 parts dicumyl peroxide, 0.4 parts triallyl isocyanurate, 0.7 parts ethoxylated trimethylolpropane triacrylate, 0.4 parts bis(4-octylphenol) diphosphate, 0.5 parts bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts γ-methacryloyloxypropyltrimethoxysilane, 2 parts of the nano-alumina masterbatch from Example 1, and 2 parts of the nano-silica masterbatch from Example 3. The above raw materials are added to a high-speed mixer (800 rpm, 40 min) in proportion and mixed evenly. Then the mixture is poured into a twin-screw extruder for co-extrusion. The temperature range is set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film is cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0077] Example 18:

[0078] Weigh out the following components by weight: 100 parts EVA particles, 0.6 parts dicumyl peroxide, 0.4 parts triallyl isocyanurate, 0.7 parts ethoxylated trimethylolpropane triacrylate, 0.4 parts bis(4-octylphenol) diphosphate, 0.5 parts bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts γ-methacryloyloxypropyltrimethoxysilane, 5 parts of the nano-alumina masterbatch from Example 2, and 5 parts of the nano-silica masterbatch from Example 4. The above raw materials are added to a high-speed mixer (800 rpm, 40 min) in proportion and mixed evenly. Then the mixture is poured into a twin-screw extruder for co-extrusion. The temperature range is set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film is cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0079] Example 19:

[0080] By mass fraction, weigh out 100 parts of EVA particles, 0.6 parts of dicumyl peroxide, 0.4 parts of triallyl isocyanurate, 0.7 parts of ethoxylated trimethylolpropane triacrylate, 0.4 parts of bis(4-octylphenol) diphosphate, 0.5 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts of γ-methacryloyloxypropyltrimethoxysilane, 2 parts of the nano alumina masterbatch from Example 1, 2 parts of the nano silica masterbatch from Example 3, and 2 parts of the hydrotalcite masterbatch from Example 5. The above raw materials are added to a high-speed mixer (800 rpm, 40 min) in proportion and mixed evenly. Then the mixture is poured into a twin-screw extruder for co-extrusion. The temperature range is set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film is cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0081] Example 20:

[0082] By mass fraction, weigh out 100 parts of EVA particles, 0.6 parts of dicumyl peroxide, 0.4 parts of triallyl isocyanurate, 0.7 parts of ethoxylated trimethylolpropane triacrylate, 0.4 parts of bis(4-octylphenol) diphosphate, 0.5 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts of γ-methacryloyloxypropyltrimethoxysilane, 4 parts of the nano alumina masterbatch from Example 2, 4 parts of the nano silica masterbatch from Example 4, and 4 parts of the hydrotalcite masterbatch from Example 6. The above raw materials are added to a high-speed mixer (800 rpm, 40 min) in proportion and mixed evenly. Then the mixture is poured into a twin-screw extruder for co-extrusion. The temperature range is set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film is cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0083] Example 21:

[0084] By mass fraction, weigh out 100 parts of EVA particles, 0.6 parts of dicumyl peroxide, 0.4 parts of triallyl isocyanurate, 0.7 parts of ethoxylated trimethylolpropane triacrylate, 0.4 parts of bis(4-octylphenol) diphosphate, 0.5 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts of γ-methacryloyloxypropyltrimethoxysilane, 6 parts of nano-alumina masterbatch from Example 1, 4 parts of nano-silica masterbatch from Example 3, and 2 parts of hydrotalcite masterbatch from Example 5. The above raw materials are added to a high-speed mixer (800 rpm, 40 min) in proportion and mixed evenly. Then the mixture is poured into a twin-screw extruder for co-extrusion. The temperature range is set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film is cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0085] Comparative Example 1:

[0086] Weigh out 100 parts by weight of EVA particles, 0.6 parts of dicumyl peroxide, 0.4 parts of triallyl isocyanurate, 0.7 parts of ethoxylated trimethylolpropane triacrylate, 0.4 parts of bis(4-octylphenol) diphosphate, 0.5 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and 0.5 parts of γ-methacryloyloxypropyltrimethoxysilane. Add the above raw materials to a high-speed mixer (800 rpm, 40 min) and mix thoroughly. Then, pour the mixture into a twin-screw extruder for co-extrusion, setting the temperature range as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, cut and wind the film to obtain an EVA encapsulating film with a thickness of 0.5 mm.

[0087] Comparative Example 2:

[0088] Weigh out 100 parts by weight of EVA particles, 0.6 parts by weight of 2-ethylhexyl tert-butyl carbonate, 0.4 parts by weight of trimethylolpropane triacrylate, 0.7 parts by weight of trimethylolpropane trimethacrylate, 0.4 parts by weight of dibutylhydroxytoluene, 0.5 parts by weight of mono(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and 0.5 parts by weight of γ-aminopropyltriethoxysilane. Add the above raw materials to a high-speed mixer (800 rpm, 40 min) and mix thoroughly. Then, pour the mixture into a twin-screw extruder for co-extrusion. Set the temperature range as follows: 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, cut and wind the film to obtain an EVA encapsulating film with a thickness of 0.5 mm.

[0089] Comparative Example 3:

[0090] Weigh out the following components by weight: 100 parts EVA particles, 0.6 parts dicumyl peroxide, 0.4 parts triallyl isocyanurate, 0.7 parts ethoxylated trimethylolpropane triacrylate, 0.4 parts bis(4-octylphenol) diphosphate, 0.5 parts bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 0.5 parts γ-methacryloyloxypropyltrimethoxysilane, 2 parts ungranulated nano-alumina powder, 2 parts nano-silica powder, and 2 parts hydrotalcite powder. The above raw materials are added to a high-speed mixer (800 rpm, 40 min) in proportion and mixed evenly. Then the mixture is poured into a twin-screw extruder for co-extrusion. The temperature range is set as 80℃ (zone 1) → 110℃ (zone 2) → 130℃ (zone 3) → 120℃ (die). After casting, embossing, and cooling to form a film, the film is cut by traction and wound up to obtain an EVA encapsulation film with a thickness of 0.5 mm.

[0091] Mechanical properties, light transmittance, peel strength, high temperature resistance, damp heat stability, and high temperature baking were tested on the film samples of Examples 7-21 and Comparative Examples 1-3, respectively. The lamination process was 145 degrees Celsius vacuum for 6 minutes and lamination for 10 minutes, using a solar cell module laminator.

[0092] The aforementioned EVA encapsulation film was then used to prepare photovoltaic modules.

[0093] The specific test results are shown in Table 1.

[0094] Table 1

[0095]

[0096]

[0097]

[0098] Specifically, the test results show that the high-temperature resistant and weather-resistant EVA film prepared by this invention basically meets the requirements of solar photovoltaic modules for encapsulants. The EVA film prepared in this invention has clear high-temperature resistance and high weather resistance performance indicators. After the raw materials are granulated, the addition of high-temperature resistant masterbatch in Examples 13-16 and 19-21, with the synergistic effect of hydrotalcite masterbatch and two other masterbatches, gives the encapsulating film high-temperature resistance and good weather resistance: after aging at 85℃ for 1000 hours, the tensile properties are good (GB / T 528-2009); the light transmittance can still maintain ≥90% (GB / T 2410-2008). Crosslinking degree: ≥85% (xylene extraction method); damp heat stability: at 85℃ / 85%RH for 1000 hours, the yellowing index ΔYI < 2 (ASTM E313); no bubbles appear after high-temperature baking. Comparative Examples 1 and 2 show that, compared to traditional EVA, the high-temperature resistant and weather-resistant EVA film exhibits a yellowing index ΔYI < 2 after humid heat aging and 1000 hours at 150 degrees Celsius, with a good appearance and no bubbles. Comparative Example 3 shows that without special granulation treatment, the high-temperature resistant powder cannot achieve the goal of a high-temperature resistant and weather-resistant film. Furthermore, its synthesis method is simple and suitable for large-scale production.

[0099] In summary, this high-temperature resistant and high-weather resistant EVA encapsulation film for photovoltaic modules and its preparation method improve the compatibility with EVA particles and avoid agglomeration by pre-dispersing the surface of the high-temperature resistant nanofiller after surface modification. Subsequently, different types of high-temperature resistant fillers are subjected to differentiated extrusion granulation, which avoids both resin degradation and filler structural decomposition. The cross-linking degree of the encapsulation film is improved during the extrusion of the high-temperature resistant masterbatch and EVA resin. In addition, the synergistic effect of hydrotalcite and SiO2 / Al2O3 is used to form physical cross-linking points, thereby achieving long-lasting weather resistance and high-temperature resistance of the EVA encapsulation film.

[0100] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing an EVA encapsulating film, characterized in that, Includes the following steps: (1) Granulation of alumina masterbatch: Nano alumina is modified with titanate coupling agent or polyethylene glycol, then premixed with liquid paraffin at a mass ratio of 20-40:60-80, then blended with EVA particles, extruded at 130-160℃, air-dried, granulated and sheared to prepare alumina masterbatch. (2) Granulation of silica masterbatch: The surface of nano silica is hydrophobically treated and premixed with EVA particles at a mass ratio of 10-20:80-90. Then it is blended with EVA particles, extruded at low temperature at 100-130℃, air-dried, granulated and sheared to obtain silica masterbatch. (3) Granulation of hydrotalcite masterbatch: Nano-hydrotalcite is modified with silane coupling agent or stearic acid, then dried, premixed with EVA particles at a mass ratio of 10-30:70-90, then blended with EVA particles, extruded at 120-150℃, air-dried, granulated and sheared to prepare hydrotalcite masterbatch. (4) Mix EVA particles with high-temperature resistant masterbatch and additives evenly, extrude and knead at 110-120°C, and obtain EVA encapsulation film through casting, embossing and cooling. The content of nano-alumina in the alumina masterbatch is 5%-10%; The content of nano-silica in the silica masterbatch is 5%-10%; The content of nano-hydrotalcite in the hydrotalcite masterbatch is 5%-10%; The high-temperature resistant masterbatch comprises, by weight parts: 2 parts alumina masterbatch and 2 parts hydrotalcite masterbatch; or 4 parts alumina masterbatch and 4 parts hydrotalcite masterbatch; or 2 parts alumina masterbatch, 2 parts silica masterbatch, and 2 parts hydrotalcite masterbatch; or 4 parts alumina masterbatch, 4 parts silica masterbatch, and 4 parts hydrotalcite masterbatch; or 6 parts alumina masterbatch, 4 parts silica masterbatch and 2 parts hydrotalcite masterbatch; The mass fractions of each component in which EVA particles, high-temperature resistant masterbatch, and additives are uniformly mixed are as follows: 100 portions of EVA particles; The additive comprises the following parts by weight: Crosslinking agent 0.4-0.8 parts, co-crosslinking agent 0.4-0.8 parts, UV curing agent 0.7-1 part, antioxidant 0.4-1 part, light stabilizer 0.1-1 part, silane coupling agent 0.2-0.8 parts.

2. The preparation method according to claim 1, characterized in that, The EVA particles contain 5% to 40% VA, have a melt index of 0.1 to 40 g / 10 min at 120°C, a melting point of 50 to 90°C, and a light transmittance of not less than 90%.

3. The preparation method according to claim 1, characterized in that, The crosslinking agent includes at least one of the following: tert-butyl peroxide-2-ethylhexyl carbonate, tert-amyl peroxide-2-ethylhexyl carbonate, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl peroxide-2-ethylhexanoate, tert-butyl peroxide, benzoyl peroxide, and dicumyl peroxide. The co-crosslinking agent includes at least one of triallyl isocyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, 1,6-hexanediol diacrylate, γ-(methacryloyloxy)propyltrimethoxysilane, and N,N′-m-phenylbismaleimide.

4. The preparation method according to claim 1, characterized in that, The UV curing agent includes at least one of ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, propoxylated glycerol triacrylate, and neopentyl glycol polymethyl ethylene oxide diacrylate.

5. The preparation method according to claim 1, characterized in that, The antioxidants include at least one of bis(4-octylphenol) diphosphate, butylated hydroxytoluene, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and tris[2,4-di-tert-butylphenyl] phosphite. The light stabilizer is a hindered amine light stabilizer, including at least one of the following: bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, mono(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and a polymer of succinic acid and (2,2,6,6-tetramethyl-4-piperidinyl) alcohol.

6. The preparation method according to claim 1, characterized in that, The silane coupling agent includes at least one of γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, or vinyltri(β-methoxyethoxy)silane.

7. An EVA encapsulating film, characterized in that, Prepared by the method according to any one of claims 1-6 Furthermore, the yellowing index ΔYI of the EVA encapsulation film is <2 after 1000h at 85℃ / 85%RH. The yellowing index ΔYI of the EVA encapsulation film is less than 2 after 1000 hours at 150°C.

8. A photovoltaic module, characterized in that, Includes the EVA encapsulation film as described in claim 7.

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