High refractive index encapsulating adhesive film, its preparation method and application

Abstract

The application provides a high-refractive encapsulating adhesive film, a preparation method and application thereof. The high-refractive encapsulating adhesive film comprises the following components in parts by weight: 100 parts of a base resin, 0.1-20 parts of modified nano-silica, 0.1-10 parts of a crosslinking agent, 0.1-10 parts of an auxiliary crosslinking agent, 0.1-10 parts of a silane coupling agent and 0.1-10 parts of an ultraviolet light stabilizer. The encapsulating adhesive film provided by the application has high light refractive index and light transmittance, is suitable for preparing photovoltaic modules, and the photovoltaic module prepared therefrom has good reliability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photovoltaic modules, and particularly relates to a high-refractive-index encapsulating adhesive film and a preparation method and application thereof. BACKGROUND

[0002] A photovoltaic module, i.e., a solar cell panel, is one of core components of a solar photovoltaic power generation system, and is composed of pre-arranged crystalline silicon cells laminated between super-thin, transparent, high-strength glass and a sealing bottom layer. EVA (ethylene-vinyl acetate copolymer) has significant advantages in terms of sealing performance and adhesion, durability, optical properties and the like, and has become a commonly used encapsulating material for photovoltaic modules.

[0003] CN104356968A discloses a double-layer solar cell module encapsulating adhesive film composed of an EVA adhesive film outer layer and an EVA adhesive film inner layer. The EVA adhesive film outer layer comprises the following raw material substances: 100 parts of ethylene-vinyl acetate resin, 0.4-2.0 parts of peroxide crosslinking agent, 0.1-1.5 parts of tackifier, 0.01-0.5 parts of antioxidant, and 0.05-1.0 parts of modifier. The EVA adhesive film inner layer comprises the following raw material substances: 100 parts of ethylene-vinyl acetate resin, 0.4-2.0 parts of peroxide crosslinking agent. The encapsulating adhesive film provided by the technical solution has good adhesion and aging resistance, but the light incidence rate is low, and thus the photovoltaic module prepared therefrom has poor photoelectric conversion efficiency.

[0004] CN109401647A discloses an EVA encapsulating adhesive film modified by a fluorine compound. The EVA encapsulating adhesive film comprises the following components in weight parts: 100 parts of ethylene-vinyl acetate copolymer, 10-20 parts of reinforcing resin, 1-3 parts of crosslinking agent, 0.12-0.45 parts of antioxidant, 0.12-0.45 parts of ultraviolet light absorber, 0.08-0.4 parts of light stabilizer, 0.5-2.5 parts of silane coupling agent, 0.5-40 parts of fluorine-containing compound, 0.8-2 parts of tackifier, and 0.01-0.08 parts of modified processing aid. The preparation method of the EVA encapsulating adhesive film comprises the following steps: the above components are uniformly mixed by a mixer, and then are fed into a casting machine to be plasticized, extruded, stretched, drawn and wound to form an EVA adhesive film with a thickness of about 0.5 mm at 115℃. The EVA encapsulating adhesive film provided by the technical solution has good water vapor barrier property, hydrolysis resistance and insulation, but the light incidence rate is low, and thus the photovoltaic module prepared therefrom has poor photoelectric conversion efficiency.

[0005] CN103045112A discloses a kind of heat-conducting EVA encapsulation adhesive film for photovoltaic module and preparation method thereof.The encapsulation adhesive film includes the following raw material components by weight percentage:ethylene-vinyl acetate copolymer 47wt%-93.8wt%, heat-conducting filler 5wt%-40wt%, anti-aging auxiliary agent 0.1wt%-2wt%, crosslinking agent 0.5wt%-5wt%, tackifier 0.1wt%-1wt%, plasticizer 0.5wt%-5wt%;The heat-conducting filler is the mixture of inorganic filler whisker, chopped glass fiber and white inorganic filler powder.The technical solution, by introducing high-thermal-conductivity modified inorganic filler between low-thermal-conductivity organic macromolecules, the prepared encapsulation adhesive film has good thermal conductivity and light reflectivity, but its light incidence rate is low, and the photoelectric conversion efficiency of the prepared photovoltaic module is poor.

[0006] In the existing solar cell module, due to the large difference in refractive index between the solar cell and the encapsulating material, there is high reflection at the interface between the two, and the incident light cannot be efficiently utilized, so the solar cell module has low solar light utilization rate and low power output. At present, the optimization of the optical performance of the solar cell module mainly focuses on the solar cell or the outer glass front plate, such as using surface textured solar cell and coating with anti-reflection film to reduce the reflection of sunlight; for example, the uppermost layer of the module uses a glass front plate coated with an anti-reflection film, but the outermost anti-reflection layer needs to be protected by additional encapsulating material, which will increase the manufacturing cost of the module, and the structure of such a solar cell module is too complex.

[0007] Therefore, how to improve the refractive index of the encapsulating material and prepare an encapsulation adhesive film with high refractive index and high photoelectric conversion efficiency to improve the power generation efficiency of the photovoltaic module has become a technical problem to be solved. SUMMARY

[0008] In view of the deficiencies of the prior art, the purpose of the present application is to provide a high-refractive-index encapsulation adhesive film, its preparation method and application. In the present application, the optical refractive index of the encapsulation adhesive film is improved by designing the components of the high-refractive-index encapsulation adhesive film and using modified nano-silica, and the transmittance of incident light is also improved, so that the photovoltaic module prepared thereby has high photoelectric conversion efficiency.

[0009] To achieve this purpose, the present application adopts the following technical solutions:

[0010] In a first aspect, the present application provides a high-refractive-index encapsulation adhesive film, which comprises the following components by weight:

[0011]

[0012] The application improves the refractive index of the encapsulating adhesive film and the transmittance of incident light by designing the components of the encapsulating adhesive film with high refractive index and using modified nano-silica, so that the photovoltaic module prepared has high photoelectric conversion efficiency.

[0013] In the application, the use of modified nano-silica improves the compatibility of nano-silica and the base resin, and the modified nano-silica can be uniformly dispersed in the base resin melt during the production of the adhesive film and form a stable and uniform "island" structure. During the preparation of the encapsulating adhesive film, the groups in the organic molecular chains on the surface of the modified nano-silica and the base resin and the crosslinking agent will undergo a curing and crosslinking reaction, so that the modified nano-silica is fixed between the molecular chains of the base resin. When part of the visible light irradiates the surface of the modified nano-silica in the photovoltaic module, the modified nano-silica can cause about 80% of the visible light to refract, which is much higher than the conventional 40%, so that the sunlight can pass through the glass. The light conversion efficiency of the encapsulating adhesive film provided by the application on the surface of the battery piece is increased by nearly 40% compared with the conventional adhesive film.

[0014] In addition, the polar end groups on the surface of the modified nano-silica chemically react with the base resin during the lamination process of the adhesive film, preventing the crystallization process of the base resin and reducing the crystallization rate of the base resin, thereby improving the light transmittance and further improving the light incidence and refractive index of the encapsulating adhesive film.

[0015] In the application, by controlling the weight fraction of the modified nano-silica within a specific range, the modified nano-silica can be uniformly dispersed in the encapsulating adhesive film, and an encapsulating adhesive film with high light refractive index can be prepared. If the content of the modified nano-silica is too small, the light refractive index of the encapsulating adhesive film prepared is low, and the photoelectric conversion efficiency of the photovoltaic module prepared is low. If the content of the modified nano-silica is too large, the dispersibility of the modified nano-silica in the encapsulating adhesive film is poor, and the refractive index of the encapsulating adhesive film prepared is also poor.

[0016] In the application, the weight fraction of the modified nano-silica can be 0.1 parts, 0.5 parts, 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, or 20 parts, etc.

[0017] The weight fraction of the crosslinking agent can be 0.1 parts, 0.5 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts, etc.

[0018] The weight fraction of the crosslinking agent can be 0.1 parts, 0.5 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts, etc.

[0019] The weight fraction of the silane coupling agent can be 0.1 part, 0.5 part, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts, etc.

[0020] The weight fraction of the ultraviolet light stabilizer can be 0.1 part, 0.5 part, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts, etc.

[0021] It should be noted that the high refractive index packaging adhesive film in the present application is a packaging adhesive film with a refractive index ≥1.499.

[0022] The following is a preferred technical solution of the present application, but not as a limitation on the technical solutions provided by the present application. Through the following preferred technical solution, the purpose and beneficial effects of the present application can be better achieved and realized.

[0023] As a preferred technical solution of the present application, the light transmittance of the base resin is ≥92%, for example, it can be 92%, 92.3%, 92.5%, 92.8%, 93%, 93.5%, or 94%, etc.

[0024] Preferably, the base resin comprises a cross-linkable polyolefin resin.

[0025] Preferably, the base resin is selected from ethylene-vinyl acetate copolymer and / or POE plastic.

[0026] It should be noted that the POE plastic is a thermoplastic elastomer obtained by in-situ polymerization of ethylene and octene using a metallocene catalyst.

[0027] Preferably, the mass percentage of vinyl acetate structural units in the ethylene-vinyl acetate copolymer is 28% to 33%, for example, it can be 28%, 28.5%, 29%, 29.5%, 30%, 30.5%, 31%, 31.5%, 32%, 32.5%, or 33%, etc., based on 100% of the mass of the ethylene-vinyl acetate copolymer.

[0028] Preferably, the melt index of the ethylene-vinyl acetate copolymer is 3 to 30 g / 10 min, for example, it can be 3 g / 10 min, 5 g / 10 min, 7 g / 10 min, 10 g / 10 min, 12 g / 10 min, 15 g / 10 min, 18 g / 10 min, 20 g / 10 min, 22 g / 10 min, 25 g / 10 min, 28 g / 10 min, or 30 g / 10 min, etc.

[0029] As a preferred technical solution of the present application, the modifier of the modified nano-silicon dioxide comprises the following raw material components in volume fraction:

[0030]

[0031] In the present application, the volume fraction of the silicon source can be 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts or 25 parts, etc.

[0032] The volume fraction of the surface modifier can be 5 parts, 7 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 23 parts or 25 parts, etc.

[0033] The volume fraction of the amino polymer can be 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts or 30 parts, etc.

[0034] The volume fraction of the mixed solvent can be 80 parts, 81 parts, 82 parts, 83 parts, 84 parts, 85 parts, 86 parts, 87 parts, 88 parts, 89 parts, 90 parts, 91 parts, 92 parts, 93 parts, 94 parts or 95 parts, etc.

[0035] Preferably, the silicon source is selected from tetraethyl orthosilicate and / or isopropyl silicate.

[0036] Preferably, the surface modifier is a compound containing non-polar end groups and polar end groups, the non-polar end groups are any one or a combination of at least two of siloxyl, methoxyl, methyl, vinyl or ethoxyl, and the polar end groups are selected from any one or a combination of at least two of amino, sulfide, phosphorus, carboxyl or epoxy groups.

[0037] In the present application, the hydroxyl or ester groups generated by the hydrolysis of the non-polar end groups of the surface modifier chemically react with the hydroxyl groups on the surface of the nano-silica, forming stable chemical bonds, thereby completing the modification of the nano-silica, making the nano-silica have good compatibility with the matrix resin, and facilitating its better dispersion in the matrix resin.

[0038] In the present application, by controlling the content of the surface modifier within a specific range, the nano-silica can be fully modified, and then uniformly dispersed in the matrix resin. If the content of the surface modifier is too low, the compatibility of the modified silica with the matrix resin is poor; if the content of the surface modifier is too high, the aging performance of the finished product assembly will be affected.

[0039] Preferably, the surface modifier is selected from any one or a combination of at least two of γ-(2,3-epoxypropoxy) propyl trimethoxysilane, 3-glycidyl ether propyl triethoxysilane, mercaptopropyl methyl dimethoxysilane or aminopropyl triethoxysilane.

[0040] Preferably, the amino polymer is polyethyleneimine and / or polyacrylamide.

[0041] Preferably, the weight average molecular weight of the amino polymer is 5000-100000, for example, it can be 5000, 10000, 20000, 30000, 40000, 50000, 60000, 70000, 80000, 90000 or 100000, etc.

[0042] Preferably, the mixed solvent is a mixture of ethanol and water, and the volume ratio of ethanol to water is (8-10):1, for example, it can be 8:1, 8.2:1, 8.4:1, 8.6:1, 8.8:1, 9:1, 9.2:1, 9.4:1, 9.6:1, 9.8:1 or 10:1, etc.

[0043] Preferably, the raw materials for preparing the modified nano-silicon dioxide include the following components in the following volume fractions:

[0044]

[0045] As a preferred technical scheme of the present application, the modified nano-silicon dioxide is prepared by the following method, which comprises the following steps:

[0046] (A) mixing an amino polymer and a mixed solvent to obtain a mixture;

[0047] (B) adding a silicon source to the mixture obtained in step (A) to perform a hydrolysis reaction, thereby obtaining a nano-silicon dioxide suspension;

[0048] (C) reacting the nano-silicon dioxide suspension obtained in step (B) with a surface modifier to obtain the modified nano-silicon dioxide.

[0049] Preferably, the temperature for mixing in step (A) is 25-35°C (for example, it can be 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C or 35°C, etc.), and the time is 0.5-1h (for example, it can be 0.5h, 0.6h, 0.7h, 0.8h, 0.9h or 1h, etc.).

[0050] Preferably, the temperature for the hydrolysis reaction in step (B) is 60-70°C (for example, it can be 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C or 70°C, etc.), and the time is 3-5h (for example, it can be 3h, 3.5h, 4h, 4.5h or 5h, etc.).

[0051] Preferably, the temperature of the reaction in step (C) is 60-70°C (for example, it can be 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C or 70°C, etc.), and the time is 1.5-2.5h (for example, it can be 1.5h, 1.8h, 2h, 2.2h or 2.5h, etc.).

[0052] Preferably, after the reaction in step (C), a post-treatment step is further included.

[0053] Preferably, the post-treatment method includes centrifugation, drying and gasification crushing.

[0054] In the present application, the temperature of the drying is 100°C, and the time of the drying is 2h.

[0055] It should be noted that in the present application, the mixing method in step (A) is stirring, the adding method in step (B) is dropwise adding, and the hydrolysis reaction in step (B) and the reaction in step (C) are both carried out under stirring.

[0056] Preferably, the D 50 The particle size is ≤15nm, for example, it can be 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm or 15nm, etc.

[0057] In the present application, the preparation method of the modified nanosilica specifically includes the following steps:

[0058] (A) After stirring and mixing the amino polymer and the mixed solvent at 25-35°C for 0.5-1h, a mixture is obtained;

[0059] (B) After heating the mixture obtained in step (A) to 60-70°C, the silicon source is added dropwise into the mixture, a hydrolysis reaction is carried out for 3-5h, and a nanosilica suspension is obtained;

[0060] (C) At 60-70°C, the surface modifier is added into the nanosilica suspension obtained in step (B), a reaction is carried out for 1.5-2.5h, high-speed centrifugation is carried out, drying is carried out at 100°C for 2h, and gasification crushing is carried out, so that the D 50 modified nanosilica with a particle size of ≤15nm is obtained.

[0061] As a preferred technical solution of the present application, the crosslinking agent is selected from any one or a combination of at least two of triallyl isocyanurate, triallyl cyanurate, tripropyleneglycol trimethacrylate or trihydroxymethylpropane trimethacrylate.

[0062] Preferably, the co-crosslinking agent is selected from any one or a combination of at least two of 1,6-hexanediol diacrylate, ethoxylated trimethylolpropane trimethacrylate, trimethylolpropane trimethacrylate, triallyl isocyanurate, triallyl cyanurate, ethoxylated pentaerythritol tetraacrylate, ethylene glycol diacrylate or ethylene glycol dimethacrylate.

[0063] Preferably, the silane coupling agent is selected from any one or a combination of at least two of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane or vinyltris(β-methoxyethoxy)silane.

[0064] Preferably, the ultraviolet light stabilizer includes bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate.

[0065] As a preferred technical solution of the present application, the high-refractive encapsulation adhesive film further includes an initiator of 0.1-10 parts, for example, 0.1 parts, 0.5 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts, etc.

[0066] Preferably, the initiator is selected from any one or a combination of at least two of t-butyl peroxy-2-ethylhexanoate, dibenzoyl peroxide, di-t-butyl peroxide isopropyl benzene, 2,5-di-t-butyl peroxy-2,5-dimethylhexane or t-amyl peroxy-2-ethylhexyl carbonate.

[0067] Preferably, the high-refractive encapsulation adhesive film further includes a lubricant of 0.1-2 parts, for example, 0.1 parts, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts or 2 parts, etc.

[0068] Preferably, the lubricant includes silicone master granules.

[0069] As a preferred technical solution of the present application, the thickness of the encapsulation adhesive film is 0.2-1 mm, for example, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1 mm, etc.

[0070] In a second aspect, the present application provides a preparation method of the high-refractive encapsulation adhesive film as described in the first aspect, including the following steps:

[0071] (1) mixing the components of the high-refractive encapsulation adhesive film to obtain a mixture;

[0072] (2) melt-extruding, casting stretching and rolling the mixture obtained in step (1) to obtain the encapsulation adhesive film.

[0073] As a preferred technical solution of the present application, the mixing time is 1.5-3h, for example, it can be 1.5h, 2h, 2.5h or 3h, etc.

[0074] Preferably, the mixing temperature is 45-55℃, for example, it can be 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃ or 55℃, etc.

[0075] Preferably, the melt-extruding temperature is 60-100℃, for example, it can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃, etc.

[0076] In the present application, the preparation method of the high-refractive encapsulation adhesive film specifically comprises the following steps:

[0077] (1) mixing the components of the high-refractive encapsulation adhesive film at 45-55℃ for 1.5-3h to obtain a mixture;

[0078] (2) melt-extruding the mixture obtained in step (1) at 60-100℃, then casting stretching and rolling to obtain a high-refractive encapsulation adhesive film with a thickness of 0.2-1mm.

[0079] In a third aspect, the present application provides a use of the high-refractive encapsulation adhesive film as described in the first aspect in a photovoltaic module.

[0080] Compared with the prior art, the present application has the following beneficial effects:

[0081] In the present application, through the design of the components of the encapsulation adhesive film, the use of modified nano-silica and the control of its content within a specific range, as well as the control of the amount of surface modifier within a specific range, the prepared encapsulation adhesive film has good optical and mechanical properties, the optical refractive index is ≥1.499, specifically 1.499-1.513, the transmittance at a wavelength of 280-380nm is ≥85%, specifically 85.3-90%, the transmittance at a wavelength of 380-1100nm is ≥92%, specifically 92.5-93.8%. After the ultraviolet accelerated aging performance test, the change of yellow index is ≤1.0, after the damp-heat aging performance test, the change of yellow index is ≤0.5, and the peeling strength with glass is >88N / cm, specifically 88.5-131.7N / cm. DETAILED DESCRIPTION

[0082] For the purpose of understanding the present application, the present application is illustrated by the following examples. It should be apparent to those skilled in the art that the examples are merely for the purpose of understanding the present application and should not be considered as specific limitations to the present application.

[0083] The sources of some components in the examples and comparative examples are as follows:

[0084] POE: melt index 3-20 g / 10 min;

[0085] Polyethyleneimine: CAS: 9002-98-6; light yellow viscous liquid, number average molecular weight about 60000;

[0086] Polyacrylamide: white powder, CAS: 9003-05-8, number average molecular weight about 150000.

[0087] Example 1

[0088] The present example provides a high refractive index packaging adhesive film and a preparation method thereof, the high refractive index packaging adhesive film comprises the following components in parts by weight:

[0089] 100 parts of ethylene-vinyl acetate copolymer, 15 parts of modified nano-silica, 5 parts of triallyl isocyanurate, 4 parts of 1,6-hexanediol diacrylate, 6 parts of γ-aminopropyl triethoxysilane, 8 parts of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 5 parts of peroxide-2-ethylhexanoic acid tert-butyl ester and 1 part of silicone master particle; the mass percentage content of vinyl acetate structural unit in the ethylene-vinyl acetate copolymer is 30%;

[0090] The raw materials for preparing the modified nano-silica include the following raw material components in parts by volume: tetraethyl orthosilicate 18 parts, aminopropyl triethoxysilane 15 parts, polyethyleneimine 20 parts and mixed solvent 90 parts; the mixed solvent is composed of ethanol and water in a volume ratio of 9:1;

[0091] The preparation method of the modified nano-silica specifically comprises the following steps:

[0092] (A) stirring and mixing polyethyleneimine and mixed solvent at 30°C for 0.5h to obtain a mixture;

[0093] (B) after warming the mixture obtained in step (A) to 65°C, adding tetraethyl orthosilicate dropwise into the mixture, carrying out hydrolysis reaction for 4h to obtain a nano-silica suspension;

[0094] (C) at 65°C, adding aminopropyl triethoxysilane into the nano-silica suspension obtained in step (B), after reaction for 2h, carrying out high-speed centrifugation, drying at 100°C for 2h, and then carrying out gasification and crushing to obtain D 50Modified nano-silica with a particle size of 10 nm.

[0095] The preparation method of the high-refractive encapsulating adhesive film is as follows:

[0096] (1) The components of the high-refractive encapsulating adhesive film are mixed at 50℃ for 2h to obtain a mixture;

[0097] (2) The mixture obtained in step (1) is melt-extruded at 80℃, and then subjected to casting stretching and winding to obtain a high-refractive encapsulating adhesive film with a thickness of 0.5mm.

[0098] Example 2

[0099] The present embodiment provides a high-refractive encapsulating adhesive film and a preparation method thereof, and the high-refractive encapsulating adhesive film comprises the following components by weight:

[0100] 100 parts of ethylene-vinyl acetate copolymer, 10 parts of modified nano-silica, 8 parts of trimethylolpropane trimethacrylate, 0.1 part of trimethylolpropane trimethacrylate, 8 parts of γ-aminopropyltrimethoxysilane, 10 parts of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 2 parts of dibenzoyl peroxide and 2 parts of silicone masterbatch; the mass percentage content of vinyl acetate structural units in the ethylene-vinyl acetate copolymer is 28%;

[0101] The preparation raw material of the modified nano-silica comprises the following raw component by volume: 15 parts of tetraethyl orthosilicate, 10 parts of aminopropyltriethoxysilane, 25 parts of polyethyleneimine and 90 parts of mixed solvent; the mixed solvent is composed of ethanol and water in a volume ratio of 8:1;

[0102] The preparation method of the modified nano-silica specifically comprises the following steps:

[0103] (A) The polyethyleneimine and the mixed solvent are stirred and mixed at 25℃ for 1h to obtain a mixture;

[0104] (B) The mixture obtained in step (A) is heated to 60℃, and then the tetraethyl orthosilicate is added dropwise into the mixture to perform hydrolysis reaction for 5h to obtain a nano-silica suspension;

[0105] (C) At 60℃, the aminopropyltriethoxysilane is added into the nano-silica suspension obtained in step (B), and then the reaction is performed for 2h, followed by high-speed centrifugation, drying at 100℃ for 2h, and then gasification and crushing to obtain D 50 Modified nano-silica with a particle size of 15 nm.

[0106] The preparation method of the high-refractive encapsulating adhesive film is as follows:

[0107] (1) mixing each component of the high-refractive encapsulating adhesive film at 50℃ for 2h to obtain a mixture;

[0108] (2) melt-extruding the mixture obtained in step (1) at 100℃, then performing cast stretching and winding to obtain a high-refractive encapsulating adhesive film with a thickness of 1mm.

[0109] Example 3

[0110] The present embodiment provides a high-refractive encapsulating adhesive film and a preparation method thereof, the high-refractive encapsulating adhesive film comprising the following components in parts by weight:

[0111] 100 parts of POE plastic, 12 parts of modified nano-silica, 3 parts of triallyl cyanurate, 5 parts of ethylene glycol diacrylate, 0.1 part of vinyl triethoxy silane, 1 part of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 7 parts of bis-tert-butyl peroxyisopropyl benzene, and 0.1 part of silicone master batch;

[0112] The raw materials for preparing the modified nano-silica comprise the following raw material components in parts by volume: 20 parts of isopropyl silicate, 20 parts of γ-(2,3-epoxypropoxy) propyl trimethoxysilane, 18 parts of polyethyleneimine, and 88 parts of mixed solvent; the mixed solvent is composed of ethanol and water in a volume ratio of 10:1;

[0113] The preparation method of the modified nano-silica specifically comprises the following steps:

[0114] (A) stirring and mixing the polyethyleneimine and the mixed solvent at 35℃ for 0.5h to obtain a mixture;

[0115] (B) warming the mixture obtained in step (A) to 70℃, then adding isopropyl silicate dropwise into the mixture, and performing hydrolysis reaction for 3h to obtain a nano-silica suspension;

[0116] (C) adding γ-(2,3-epoxypropoxy) propyl trimethoxysilane into the nano-silica suspension obtained in step (B) at 70℃, and performing reaction for 2h, then performing high-speed centrifugation, drying at 100℃ for 2h, and performing gasification and crushing to obtain D 50 modified nano-silica with a particle size of 7nm.

[0117] The preparation method of the high-refractive encapsulating adhesive film is as follows:

[0118] (1) mixing each component of the high-refractive encapsulating adhesive film at 55℃ for 3h to obtain a mixture;

[0119] (2) After melt extrusion of the mixture obtained in step (1) at 60℃, cast stretching and winding are performed to obtain a high-refractive encapsulating adhesive film with a thickness of 0.8 mm.

[0120] Example 4

[0121] The present embodiment provides a high-refractive encapsulating adhesive film and a preparation method thereof. The high-refractive encapsulating adhesive film comprises the following components in weight percentage:

[0122] 100 parts of ethylene-vinyl acetate copolymer, 8 parts of modified nano-silica, 10 parts of trihydroxymethylpropane triacrylate, 2 parts of ethylene glycol diacrylate, 10 parts of vinyl trimethoxysilane, 5 parts of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 6 parts of 2,5-di-tert-butyl peroxy-2,5-dimethylhexane, and 0.8 parts of silicone master batch; the mass percentage of vinyl acetate structural units in the ethylene-vinyl acetate copolymer is 33%;

[0123] The preparation raw material of the modified nano-silica comprises the following raw material components in volume percentage: 25 parts of isopropyl silicate, 18 parts of mercaptopropyl methyl dimethoxysilane, 15 parts of polyacrylamide, and 80 parts of mixed solvent; the mixed solvent is composed of ethanol and water in a volume ratio of 9:1;

[0124] The preparation method of the modified nano-silica specifically comprises the following steps:

[0125] (A) After stirring and mixing the polyacrylamide and the mixed solvent at 30℃ for 1 h, a mixture is obtained;

[0126] (B) After heating the mixture obtained in step (A) to 65℃, isopropyl silicate is added dropwise into the mixture, and a hydrolysis reaction is performed for 5 h to obtain a nano-silica suspension;

[0127] (C) At 65℃, mercaptopropyl methyl dimethoxysilane is added into the nano-silica suspension obtained in step (B), and a reaction is performed for 2 h. After high-speed centrifugation, drying at 100℃ for 2 h, and gasification crushing, D 50 modified nano-silica with a particle size of 8 nm is obtained.

[0128] The preparation method of the high-refractive encapsulating adhesive film is as follows:

[0129] (1) After mixing the components of the high-refractive encapsulating adhesive film at 45℃ for 3 h, a mixture is obtained;

[0130] (2) After melt extrusion of the mixture obtained in step (1) at 70℃, cast stretching and winding are performed to obtain a high-refractive encapsulating adhesive film with a thickness of 0.2 mm.

[0131] Example 5

[0132] The present example provides a high refractive index packaging adhesive film and a preparation method thereof, which is different from example 1 in that the high refractive index packaging adhesive film comprises the following components in parts by weight:

[0133] 100 parts of ethylene-vinyl acetate copolymer, 17 parts of modified nano-silica, 0.1 part of trimethylolpropane trimethacrylate, 10 parts of triallyl cyanurate, 3 parts of γ-glycidoxypropyltrimethoxysilane, 2 parts of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 10 parts of 2,5-di-tert-butyl peroxy-2,5-dimethylhexane, and 1.6 parts of silicone master batch;

[0134] The preparation raw material of the modified nano-silica comprises the following raw material components in parts by volume: tetraethyl orthosilicate 25 parts, 3-glycidoxypropyl triethoxysilane 18 parts, polyacrylamide 15 parts, and mixed solvent 80 parts;

[0135] The other conditions are the same as those in example 1.

[0136] Example 6

[0137] The present example provides a high refractive index packaging adhesive film and a preparation method thereof, which is different from example 1 in that the preparation raw material of the modified nano-silica contains 5 parts by volume of aminopropyl triethoxysilane, and the other conditions are the same as those in example 1.

[0138] Example 7

[0139] The present example provides a high refractive index packaging adhesive film and a preparation method thereof, which is different from example 1 in that the preparation raw material of the modified nano-silica contains 25 parts by volume of aminopropyl triethoxysilane, and the other conditions are the same as those in example 1.

[0140] Example 8

[0141] The present example provides a high refractive index packaging adhesive film and a preparation method thereof, which is different from example 1 in that the preparation raw material of the modified nano-silica contains 3 parts by volume of aminopropyl triethoxysilane, and the other conditions are the same as those in example 1.

[0142] Example 9

[0143] The present example provides a high refractive index packaging adhesive film and a preparation method thereof, which is different from example 1 in that the preparation raw material of the modified nano-silica contains 30 parts by volume of aminopropyl triethoxysilane, and the other conditions are the same as those in example 1.

[0144] Example 10

[0145] The present embodiment provides a high refractive index packaging adhesive film and a preparation method thereof, which is different from the embodiment 1 only in that the amino propyl triethoxysilane is replaced by a surface modifier containing only non-polar end groups, vinyl triethoxysilane, in the preparation raw material of the modified nano-silica, and other conditions are the same as those in the embodiment 1.

[0146] Embodiment 11

[0147] The present embodiment provides a high refractive index packaging adhesive film and a preparation method thereof, which is different from the embodiment 1 only in that the amino propyl triethoxysilane is replaced by a surface modifier containing only non-polar end groups, vinyl triethoxysilane, in the preparation raw material of the modified nano-silica, and other conditions are the same as those in the embodiment 1.

[0148] Embodiment 12

[0149] The present embodiment provides a high refractive index packaging adhesive film and a preparation method thereof, which is different from the embodiment 1 only in that the weight fraction of the modified nano-silica is 0.1 part, and other conditions are the same as those in the embodiment 1.

[0150] Embodiment 13

[0151] The present embodiment provides a high refractive index packaging adhesive film and a preparation method thereof, which is different from the embodiment 1 only in that the weight fraction of the modified nano-silica is 20 parts, and other conditions are the same as those in the embodiment 1.

[0152] Comparative Example 1

[0153] The present comparative example provides a packaging adhesive film and a preparation method thereof, which is different from the embodiment 1 only in that the high refractive index packaging adhesive film does not contain modified nano-silica, and other conditions are the same as those in the embodiment 1.

[0154] Comparative Example 2

[0155] The present comparative example provides a packaging adhesive film and a preparation method thereof, which is different from the embodiment 1 only in that the weight fraction of the modified nano-silica is 30 parts, and other conditions are the same as those in the embodiment 1.

[0156] Comparative Example 3

[0157] The present comparative example provides a packaging adhesive film and a preparation method thereof, which is different from the embodiment 1 only in that the modified nano-silica is replaced by nano-silica (D 50 10 nm), and other conditions are the same as those in the embodiment 1.

[0158] The performance of the packaging adhesive films provided in the above embodiments and comparative examples is tested, and the testing method is as follows:

[0159] Optical refractive index: tested according to the Test Procedure for Refractive Index and Thickness Tester of Optical Thin Film in GJB 8687-2015;

[0160] Transmittance: measured according to ISO 9050-2003;

[0161] Ultraviolet accelerated aging performance: the change of yellow index of the encapsulation adhesive film provided by the above examples and comparative examples was measured according to IEC 61215;

[0162] Hygrothermal aging performance: after the encapsulation adhesive film provided by the above examples and comparative examples was placed in a condition of 85℃ and 85% relative humidity for 2000h, whether delamination d or corrosion occurred was observed, and the change of yellow index and the peeling strength were measured according to the standard of IEC 61215.

[0163] The performance test results of the encapsulation adhesive film provided by the above examples and comparative examples are shown in Table 1 below:

[0164] Table 1

[0165]

[0166]

[0167] From the content of Table 1, it can be known that, by designing the components of the encapsulation adhesive film, further by using modified nano-silica and controlling the content of the modified nano-silica in a specific range, and by controlling the amount of the surface modifier in a specific range, the encapsulation adhesive film prepared has good optical performance and good mechanical performance, the optical refractive index is ≥1.499, specifically 1.499-1.513, the transmittance under the wavelength of 280-380nm is ≥85%, specifically 85.3-90%, the transmittance under the wavelength of 380-1100nm is ≥92%, specifically 92.5-93.8%. After the ultraviolet accelerated aging performance test, the change of yellow index is ≤1.0, and after the hygrothermal aging performance test, the change of yellow index is ≤0.5, and the peeling strength with glass is >88N / cm, specifically 88.5-131.7N / cm.

[0168] Compared with Example 1, if the amount of the surface modifier is too small when preparing the modified nano-silica (Example 8), the optical refractive index and the transmittance of the encapsulation adhesive film prepared are low, and the mechanical performance is poor; if the amount of the surface modifier is too large when preparing the modified nano-silica (Example 9), the comprehensive performance of the encapsulation adhesive film prepared is poor.

[0169] Compared with Example 1, if the surface modifier is a compound containing only non-polar end groups when preparing the modified nanosilica (Example 10) or if the surface modifier is a compound containing only polar end groups when preparing the modified nanosilica (Example 11), the properties of the encapsulant film prepared are poorer.

[0170] Compared with Example 1, if the content of the modified nanosilica is too low, even without adding the modified nanosilica (Comparative Example 1) or the content of the modified nanosilica is too high (Comparative Example 2) or using nanosilica instead of the modified nanosilica (Comparative Example 3), the properties of the encapsulant film prepared are poorer.

[0171] The encapsulant films provided by the examples and comparative examples are used to prepare photovoltaic modules with PERC cell pieces, glass, back sheets, etc., and the modules are subjected to reliability tests according to the international standard IEC 61215. Among them, the reliability test contents include the power loss of the module after 200 kw / h under ultraviolet light (UV200), the power loss of the module after the wet and frozen test of the module (HF10), the power loss of the module after 2000 h of the wet and heat test of the module (DH2000), the power loss of the module after the thermal cycle test of the module (TC200), and the power loss of the module after applying a voltage of -1500 V for 192 h under high temperature and high humidity (PID9192). The test results are shown in Table 2 below.

[0172] Table 2

[0173]

[0174]

[0175] As can be seen from the content of Table 2, by designing the components of the encapsulant film, further by using the modified nanosilica and controlling its content in a specific range, and by controlling the mass ratio of the modifier and the nanosilica in a specific range, the encapsulant film prepared has good optical properties and good mechanical properties, and the photovoltaic module prepared therefrom has good reliability, with the power attenuation of the module after 200 kw / h under ultraviolet light (UV200) ≤1.6%, specifically 0.7-1.6%, the power attenuation of the module after the wet and frozen test of the module (HF10) ≤0.9%, specifically 0.4-0.9%, the power attenuation of the module after 2000 h of the wet and heat test of the module (DH2000) ≤2.1%, specifically 1.0-2.1%, the power attenuation of the module after the thermal cycle test of the module (TC200) ≤1.1%, specifically 0.5-1.1%, and the power attenuation of the module after applying a voltage of -1500 V for 192 h under high temperature and high humidity (PID9192) ≤1.6%, specifically 1.1-1.6%.

[0176] Compared with Example 1, if the amount of the surface modifier is too small (Example 8) or too large (Example 9) when preparing the modified nanosilica, the reliability of the photovoltaic module prepared is poor.

[0177] Compared with Example 1, if the surface modifier is a compound containing only non-polar end groups (Example 10) or if the surface modifier is a compound containing only polar end groups (Example 11) when preparing the modified nanosilica, the reliability of the photovoltaic module prepared is poor.

[0178] Compared with Example 1, if the amount of the modified nanosilica is too small, even without the modified nanosilica (Comparative Example 1) or the amount of the modified nanosilica is too large (Comparative Example 2) or nanosilica is used instead of the modified nanosilica (Comparative Example 3), the reliability of the photovoltaic module prepared is poor.

[0179] In summary, by designing the components of the encapsulating adhesive film, further by using the modified nanosilica and controlling the content of the modified nanosilica in a specific range, and controlling the amount of the surface modifier in a specific range, the encapsulating adhesive film prepared has good optical properties and good mechanical properties. The photovoltaic module prepared by assembling has good reliability.

[0180] The applicant declares that the detailed process flow of the present application is illustrated by the above examples, but the present application is not limited to the above detailed process flow, that is, it does not mean that the present application must rely on the above detailed process flow to be implemented. It should be understood by those skilled in the art that any improvement on the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A high refractive index encapsulating film, characterized in that, The high refractive index encapsulating film comprises the following components in parts by weight: 100 parts of matrix resin; 0.1-20 parts of modified nano-silica; Crosslinking agent 0.1~10 parts; Crosslinking agent 0.1~10 parts; 0.1 to 10 parts of silane coupling agent; 0.1 to 10 parts of UV stabilizer; The matrix resin is selected from ethylene-vinyl acetate copolymer and / or POE plastic; The raw materials for preparing the modified nano-silica include the following raw material components in parts by volume: 12-25 parts of silicon source; 5-25 parts of surface modifier; 15-30 parts of amino polymer; Mixed solvent 80-95 parts; The modified nano-silica was prepared by the following method, which includes the following steps: (A) The amino polymer and the mixed solvent are mixed to obtain a mixture; (B) Add the silicon source to the mixture obtained in step (A) and carry out a hydrolysis reaction to obtain a nano silica suspension; (C) The nano-silica suspension obtained in step (B) is reacted with a surface modifier to obtain the modified nano-silica; The surface modifier is selected from any one or a combination of at least two of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, mercaptopropylmethyldimethoxysilane or aminopropyltriethoxysilane. The amino polymer is polyethyleneimine and / or polyacrylamide.

2. The high refractive index encapsulating film according to claim 1, characterized in that, The light transmittance of the matrix resin is ≥92%.

3. The high refractive index encapsulating film according to claim 1, characterized in that, Based on the mass of the ethylene-vinyl acetate copolymer as 100%, the mass percentage of vinyl acetate structural units in the ethylene-vinyl acetate copolymer is 28% to 33%.

4. The high refractive index encapsulating film according to claim 1, characterized in that, The melt index of the ethylene-vinyl acetate copolymer is 3~30 g / 10min.

5. The high refractive index encapsulating film according to claim 1, characterized in that, The silicon source is selected from tetraethyl orthosilicate and / or isopropyl orthosilicate.

6. The high refractive index encapsulating film according to claim 1, characterized in that, The weight-average molecular weight of the amino polymer is 5,000 to 100,000.

7. The high refractive index encapsulating film according to claim 1, characterized in that, The mixed solvent is a mixture of ethanol and water, and the volume ratio of ethanol to water is (8~10):

1.

8. The high refractive index encapsulating film according to claim 1, characterized in that, The raw materials for preparing the modified nano-silica include the following components in parts by volume: 15-20 parts of silicon source; 10-20 parts of surface modifier; 18-25 parts of amino polymer; 90 parts of mixed solvent.

9. The high refractive index encapsulating film according to claim 1, characterized in that, The mixing temperature in step (A) is 25~35℃, and the time is 0.5~1 h.

10. The high refractive index encapsulating film according to claim 1, characterized in that, The hydrolysis reaction in step (B) is carried out at a temperature of 60-70°C for 3-5 hours.

11. The high refractive index encapsulating film according to claim 1, characterized in that, The reaction in step (C) is carried out at a temperature of 60-70°C for 2 hours.

12. The high refractive index encapsulating film according to claim 1, characterized in that, The reaction described in step (C) also includes a post-processing step.

13. The high refractive index encapsulating film according to claim 12, characterized in that, The post-processing methods include centrifugation, drying, and gasification pulverization.

14. The high refractive index encapsulating film according to claim 1, characterized in that, The modified nano-silica D 50 Particle size ≤15 nm.

15. The high refractive index encapsulating film according to claim 1, characterized in that, The crosslinking agent is selected from any one or a combination of at least two of triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, or trimethylolpropane trimethacrylate.

16. The high refractive index encapsulating film according to claim 1, characterized in that, The co-crosslinking agent is selected from any one or a combination of at least two of the following: 1,6-hexanediol diacrylate, ethoxylated trimethylolpropane trimethacrylate, trimethylolpropane trimethacrylate, triallyl isocyanurate, triallyl cyanurate, ethoxylated pentaerythritol tetraacrylate, ethylene glycol diacrylate, or ethylene glycol dimethacrylate.

17. The high refractive index encapsulating film according to claim 1, characterized in that, The silane coupling agent is selected from any one or a combination of at least two of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, or vinyltri(β-methoxyethoxy)silane.

18. The high refractive index encapsulating film according to claim 1, characterized in that, The UV stabilizer includes bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

19. The high refractive index encapsulating film according to claim 1, characterized in that, The high refractive index encapsulating film also includes 0.1 to 10 parts of initiator.

20. The high refractive index encapsulating film according to claim 19, characterized in that, The initiator is selected from any one or a combination of at least two of the following: tert-butyl peroxide-2-ethylhexanoate, benzoyl peroxide, bis-tert-butylperoxyisopropylbenzene, 2,5-di-tert-butylperoxide-2,5-dimethylhexane, or tert-amyl peroxide-2-ethylhexyl carbonate.

21. The high refractive index encapsulating film according to claim 1, characterized in that, The high refractive index encapsulating film also includes 0.1 to 2 parts of lubricant.

22. The high refractive index encapsulating film according to claim 1, characterized in that, The thickness of the encapsulating film is 0.2~1 mm.

23. A method for preparing a high refractive index encapsulating film as described in any one of claims 1-22, characterized in that, The preparation method includes the following steps: (1) After mixing the components of the high refractive index encapsulating film, a mixture is obtained; (2) The mixture obtained in step (1) is melt-extruded, cast, stretched and wound to obtain the encapsulation film.

24. The preparation method according to claim 23, characterized in that, The mixing time is 1.5 to 3 hours.

25. The preparation method according to claim 23, characterized in that, The mixing temperature is 45~55℃.

26. The preparation method according to claim 23, characterized in that, The temperature of the melt extrusion is 60~100℃.

27. The application of a high refractive index encapsulating film as described in any one of claims 1-22 in a photovoltaic module.

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