Packaging adhesive film and photovoltaic module

Abstract

The invention provides a packaging adhesive film and a photovoltaic module, the packaging adhesive film at least comprises a first adhesive film layer, a second adhesive film layer and a third adhesive film layer which are arranged in sequence, the content of an ultraviolet light absorber in the first adhesive film layer is different from the content of an ultraviolet light absorber in the third adhesive film layer, and the content of an ultraviolet light absorber in the second adhesive film layer is different from the content of an ultraviolet light absorber in the third adhesive film layer. And the second adhesive film layer is used for blocking the ultraviolet light absorber in the first adhesive film layer and / or the third adhesive film layer from diffusing. The contents of the ultraviolet absorbents in different adhesive film layers of the packaging adhesive film are different, and the adhesive film layers used for blocking diffusion of the ultraviolet absorbents are arranged among the different adhesive film layers including the ultraviolet absorbents. The ultraviolet light absorber is prevented from being in contact with other components which can generate chemical reaction or catalytic action with the ultraviolet light absorber in the packaging adhesive film, so that the adhesive film is prevented from yellowing, the service life of the adhesive film is prolonged, and meanwhile, the efficiency of the photovoltaic module is improved.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a packaging film and a photovoltaic module. Background Art

[0002] As conventional fossil fuels become increasingly depleted, solar energy is undoubtedly the cleanest, most widespread, and most promising alternative energy source available. Solar power generation devices, also known as solar cells or photovoltaic cells, can directly convert solar energy into electrical energy. Their power generation principle is based on the photovoltaic effect of a semiconductor PN junction.

[0003] Photovoltaic cells face numerous challenges in practical applications, a major one being UV-induced degradation. Taking heterojunction (HJT) cells and tunneling oxide passivated contact (TOPCon) cells as examples, UV light destroys the silicon-hydrogen (Si-H) bonds in the cells, leading to passivation failure and reduced cell efficiency. Conventional solutions include the use of UV-cutoff films containing UV absorbers. However, during the use and testing of films containing UV absorbers, it was found that these films are prone to yellowing. Summary of the Invention

[0004] Based on this, it is necessary to provide a packaging film and photovoltaic module to address the problems in the above background technology, which can at least prevent the film from yellowing and improve the service life of the film and the efficiency of the photovoltaic module.

[0005] To achieve the above-mentioned objectives and other related objectives, one aspect of the present application provides an encapsulation film, comprising at least a first film layer, a second film layer, and a third film layer arranged in sequence, wherein the content of the ultraviolet light absorber in the first film layer is different from the content of the ultraviolet light absorber in the third film layer, and the second film layer is used to block the diffusion of the ultraviolet light absorber in the first film layer and / or the third film layer.

[0006] In one embodiment, the third adhesive film layer is used to bond to the solar cell, the first adhesive film layer is arranged on the side of the second adhesive film layer away from the solar cell, and the content of the ultraviolet light absorber in the first adhesive film layer is greater than the content of the ultraviolet light absorber in the third adhesive film layer.

[0007] In one embodiment, the ultraviolet light absorber includes a functional group for absorbing ultraviolet light, and the functional group for absorbing ultraviolet light includes at least one of an o-hydroxybenzoate functional group, an azo functional group, a carbonyl functional group, and an imine functional group.

[0008] In one embodiment, the ultraviolet light absorber includes at least one of salicylic acid, benzotriazole, benzophenone, and triazine.

[0009] In one embodiment, the content of the ultraviolet absorber in the first film layer is greater than 90% of the total content of the ultraviolet absorber in the encapsulation film, and the content of the ultraviolet absorber in the third film layer is less than 10% of the total content of the ultraviolet absorber in the encapsulation film.

[0010] In one embodiment, the content of the ultraviolet light absorber in the first adhesive film layer is 100% of the total content of the ultraviolet light absorber in the encapsulation adhesive film, and the content of the ultraviolet light absorber in the third adhesive film layer is 0.

[0011] In one embodiment, the packaging film further includes an alkaline antacid.

[0012] In one embodiment, the alkaline antacid includes at least one of magnesium oxide, aluminum oxide, zinc oxide, barium sulfate, and titanium oxide.

[0013] In one embodiment, the third adhesive film layer is used to bond to the solar cell, the first adhesive film layer is arranged on the side of the second adhesive film layer away from the solar cell, and the content of alkaline antacid in the third adhesive film layer is greater than that in the first adhesive film layer.

[0014] In one embodiment, the content of the alkaline antacid in the third film layer is greater than 90% of the total content of the alkaline antacid in the encapsulating film, and the content of the alkaline antacid in the first film layer is less than 10% of the total content of the alkaline antacid in the encapsulating film.

[0015] In one embodiment, the content of the alkaline antacid in the third adhesive film layer is 100% of the total content of the alkaline antacid in the encapsulating adhesive film, and the content of the alkaline antacid in the first adhesive film layer is 0.

[0016] In one embodiment, the first adhesive film layer, the third adhesive film layer and the ultraviolet light absorber have the same polarity, and the second adhesive film layer and the ultraviolet light absorber have a different polarity.

[0017] In one embodiment, the first adhesive film layer, the third adhesive film layer, and the ultraviolet light absorber are polar substances, and the second adhesive film layer is a non-polar substance.

[0018] In one embodiment, main components of the first adhesive film layer and the third adhesive film layer include ethylene-vinyl acetate copolymer, and main component of the second adhesive film layer includes polyolefin elastomer.

[0019] In one embodiment, the raw material formula of the first adhesive film layer includes, by mass percentage: 93% to 96% ethylene-vinyl acetate copolymer, 0.5% to 3% ultraviolet light absorber, 0.5% to 1% antioxidant, 0.8% to 1% thermal stabilizer, 0.5% to 1.5% silane coupling agent, 0.5%-0.8% cross-linking agent, 0% to 0.5% tackifying resin, and 0% to 1.5% plasticizer.

[0020] In one embodiment, the raw material formula of the third adhesive film layer includes, by mass percentage: 93% to 96% ethylene-vinyl acetate copolymer, 1.5% to 2% alkaline antacid, 0.5% to 1% antioxidant, 0.8% to 1% thermal stabilizer, 0.5% to 1.5% silane coupling agent, 0.5% to 0.8% cross-linking agent, 0.5% to 0.8% tackifying resin, and 0% to 1.5% plasticizer.

[0021] In one embodiment, the raw material formula of the second adhesive film layer includes, by mass percentage: 93% to 97% polyolefin elastomer, 0.5% to 1% antioxidant, 0.8% to 1% heat stabilizer, 0.5% to 1.5% silane coupling agent, 0.5%-0.8% cross-linking agent, 0% to 0.5% tackifying resin, and 0% to 1.5% plasticizer.

[0022] Another aspect of the present application provides a photovoltaic module, comprising a front glass, a front adhesive film, a solar cell, a back adhesive film and a back plate arranged in sequence, wherein the front adhesive film and / or the back adhesive film comprises the encapsulation adhesive film in any of the above embodiments.

[0023] According to the encapsulation film and photovoltaic module provided by the present invention, by making the content of ultraviolet light absorber in different film layers of the encapsulation film different, and arranging a film layer for blocking the diffusion of ultraviolet light absorber between different film layers including ultraviolet light absorber, the ultraviolet light absorber is prevented from contacting with other components in the encapsulation film that may chemically react or catalyze the ultraviolet light absorber, thereby preventing the film from yellowing, improving the service life of the film, and at the same time improving the efficiency of the photovoltaic module. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to better describe and illustrate the embodiments and / or examples of the applications disclosed herein, reference may be made to one or more of the accompanying drawings. The additional details or examples used to describe the accompanying drawings should not be considered to limit the scope of the disclosed applications, the presently described embodiments and / or examples, and any of the best modes currently understood for these applications.

[0025] Figure 1 is a schematic structural diagram of a packaging film provided in one embodiment;

[0026] Figure 2 is a schematic structural diagram of another packaging film provided in an embodiment;

[0027] Figure 3 is a schematic structural diagram of another packaging film provided in an embodiment;

[0028] Figure 4 Schematic diagram of the structure of another packaging film provided in one embodiment;

[0029] Figure 5Schematic diagram of the structure of a photovoltaic module provided in one embodiment.

[0030] Description of reference numerals:

[0031] 100. Encapsulation film; 110. First film layer; 120. Second film layer; 130. Third film layer; 200. UV absorber; 300. Alkaline antacid; 400. Metal ions; 500. Photovoltaic module; 510. Front glass; 520. Front film; 530. Solar cell; 540. Back film; 550. Back sheet. DETAILED DESCRIPTION

[0032] To facilitate understanding of the present application, a more comprehensive description of the present application will be provided below with reference to the accompanying drawings. The drawings illustrate preferred embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the relevant listed items.

[0034] The purpose of the terms used herein is only to describe specific embodiments and is not intended to limit the present application. When used herein, the singular forms "a", "an", and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0035] It should be noted that the illustrations provided in this embodiment only illustrate the basic concept of the present application in a schematic manner. Although the illustrations only show components related to the present application and are not drawn according to the number, shape and size of components in actual implementation, the type, quantity and proportion of each component in actual implementation can be changed at will, and the component layout type may also be more complicated.

[0036] Solar cells face numerous challenges in practical applications, one of the main difficulties being UV-induced degradation. Taking heterojunction (HJT) cells and tunneling oxide passivated contact (TOPCon) cells as examples, UV light destroys the silicon-hydrogen (Si-H) bonds in the cells, causing passivation failure and reducing cell efficiency. Conventional solutions include the use of UV-cutoff films containing UV absorbers. After absorbing high-energy UV light, the UV absorbers undergo molecular structure changes to form a unique resonant state, releasing heat as they return to their initial state, thereby achieving light-to-heat conversion. However, during the use and testing of films containing UV absorbers, it was found that these films were prone to yellowing.

[0037] Research and analysis of films containing UV absorbers that yellow easily during use and testing have revealed that yellowing can occur due to chemical reactions between other components in the film and the UV absorber, or due to a catalytic effect on the UV absorber. Depending on the type of UV-absorbing functional group, the components that react or catalyze the UV absorber also vary. For example, when using a substance containing an o-hydroxybenzoate functional group as a UV absorber, the presence of alkaline substances in the film can cause yellowing. When using a substance containing an azo functional group as a UV absorber, the presence of metal ions in the film can also cause yellowing.

[0038] In view of the above problems, the present invention provides a packaging film, such as Figures 1 to 4 As shown, the encapsulation film 100 includes at least a first film layer 110, a second film layer 120 and a third film layer 130 arranged in sequence, wherein the content of the ultraviolet light absorber 200 in the first film layer 110 is different from the content of the ultraviolet light absorber 200 in the third film layer 130, and the second film layer 120 is used to block the diffusion of the ultraviolet light absorber 200 in the first film layer 110 and / or the third film layer 130.

[0039] In one embodiment, the ultraviolet light absorber 200 includes a functional group for absorbing ultraviolet light, and the functional group for absorbing ultraviolet light includes but is not limited to at least one of an o-hydroxybenzoate functional group (-OH and -COOR adjacent positions), an azo functional group (N=N), a carbonyl functional group (C=O), and an imine functional group (C=N).

[0040] In one embodiment, the UV absorber 200 includes but is not limited to salicylic acid (C7H6O3), benzotriazole (C6H5N3), benzophenone (C 13 H 10O), triazine (C3H3N3). Among them, salicylic acid (C7H6O3) includes o-hydroxybenzoate functional group (-OH and -COOR adjacent), benzotriazole (C6H5N3) includes azo functional group (N=N), benzophenone (C 13 H 10 O) includes a carbonyl functional group (C=O), and triazine (C3H3N3) includes an imine (C=N) functional group.

[0041] In one embodiment, different types of UV absorbers 200 can be used to absorb UV light of different wavelengths. For example, a first type of UV absorber absorbs long-wave ultraviolet (UVA) light with a wavelength of 315 nm to 400 nm, a second type of UV absorber absorbs medium-wave ultraviolet (UVB) light with a wavelength of 280 nm to 315 nm, and a third type of UV absorber absorbs short-wave ultraviolet (UVC) light with a wavelength of 100 nm to 280 nm.

[0042] In one embodiment, the encapsulating film 100 further includes a yellowing component that chemically reacts with or catalyzes the UV absorber 200, causing the encapsulating film 100 to yellow. Therefore, in the encapsulating film 100 provided herein, the UV absorber 200 and the yellowing component should be located in different film layers of the encapsulating film 100. In some cases, if both the UV absorber 200 and the yellowing component are essential or unavoidable components of the film layers, the content of the UV absorber 200 and the yellowing component in the film layers can be adjusted. For example, if the UV absorber 200 content in a film layer is high, the content of the yellowing component in that film layer can be reduced; if the UV absorber 200 content in a film layer is low, the content of the yellowing component in that film layer can be increased. Through these adjustments, the content of the UV absorber 200 and the yellowing component in the encapsulating film 100 as a whole can meet the requirements. After the above adjustment, the content of the ultraviolet light absorber 200 in the first film layer 110 of the packaging film 100 is different from the content of the ultraviolet light absorber 200 in the third film layer 130 .

[0043] In one embodiment, when the content of UV absorber 200 in first film layer 110 differs from the content of UV absorber 200 in third film layer 130, a film layer, namely, second film layer 120, is provided between first film layer 110 and third film layer 130 to block diffusion of UV absorber 200. According to the principle of like dissolves like, the first and third film layers 110, 130 must have the same polarity as the UV absorber 200, while the second film layer 120 must have a different polarity from the UV absorber 200. Because UV absorber 200 is a polar substance, in this embodiment, first film layer 110 and third film layer 130 must be made of a polar substance, such as ethylene-vinyl acetate copolymer (EVA), while second film layer 120 must be made of a non-polar substance, such as polyolefin elastomer (POE).

[0044] Exemplarily, the third adhesive film layer 130 is used to bond to the solar cell, the first adhesive film layer 110 is arranged on the side of the second adhesive film layer 120 facing away from the solar cell, the content of the ultraviolet light absorber 200 in the first adhesive film layer 110 is greater than the content of the ultraviolet light absorber 200 in the third adhesive film layer 130, and the content of the yellowing component in the first adhesive film layer 110 is less than the content of the yellowing component in the third adhesive film layer 130.

[0045] In one embodiment, when the encapsulation film includes an ethylene-vinyl acetate copolymer (EVA) film layer, the EVA film layer decomposes in a hot and humid environment to produce acetic acid, which damages the solar cell electrodes and reduces cell efficiency. Therefore, an alkaline antacid 300 is added to the EVA film layer to neutralize the acetic acid generated in hot and humid environments. However, the alkaline antacid 300 is a yellowing component corresponding to the UV absorber 200, such as salicylic acid, which includes o-hydroxybenzoate functional groups (-OH and -COOR ortho-positions).

[0046] In one embodiment, when the encapsulating film 100 includes an EVA film layer, it is necessary to include both a UV absorber 200 and an alkaline antacid 300. To prevent the acetic acid produced by the decomposition of the EVA film layer in a hot and humid environment from damaging the solar cell, the alkaline antacid 300 is a necessary component in the third film layer 130 bonded to the solar cell. Therefore, the content of the UV absorber 200 in the third film layer 130 should be reduced. To ensure the overall UV cutoff effect of the encapsulating film 100, while minimizing the content of the UV absorber 200 in the third film layer 130, the content of the UV absorber 200 in the first film layer 110 is correspondingly increased, so that the total content of the UV absorber 200 in the encapsulating film 100 remains unchanged. Furthermore, because first adhesive layer 110 is positioned on the side of second adhesive layer 120 facing away from the solar cell, ultraviolet light first passes through first adhesive layer 110, then sequentially through second adhesive layer 120 and third adhesive layer 120, reaching the surface of the solar cell. By increasing the content of ultraviolet light absorber 200 in first adhesive layer 110, ultraviolet light (UV) is cut off when the UV light initially reaches first adhesive layer 110 of encapsulation film 100, thus preventing damage to second adhesive layer 120 and third adhesive layer 120.

[0047] A packaging film having the same content of ultraviolet absorber 200 in the first film layer 110 and the third film layer 130 is used as a comparative packaging film. Typically, the first film layer 110 and the third film layer 130 are produced using the same equipment / production line, and EVA film layers produced in the same batch can be used as both the first film layer 110 and the third film layer 130. Therefore, the first film layer 110 and the third film layer 130 have the same content of ultraviolet absorber 200 and the same content of alkaline antacid 300. A packaging film having different contents of ultraviolet absorber 200 in the first film layer 110 and the third film layer 130 according to an embodiment of the present invention is used as an improved packaging film. Optionally, the first film layer 110 and the third film layer 130 are produced using the same equipment / production line, but cannot be produced simultaneously. When producing the first adhesive film layer 110, the ultraviolet light absorber 200 is added and the alkaline antacid 300 is not added, so that the content of the ultraviolet light absorber 200 in the first adhesive film layer 110 is greater than 90% of the total content of the ultraviolet light absorber 200 in the encapsulating film 100, and the content of the alkaline antacid 300 is less than 10% of the total content of the alkaline antacid 300 in the encapsulating film 100. Figure 2 When producing the third adhesive film layer 130, the alkaline antacid 300 is added and the ultraviolet light absorber 200 is not added, so that the content of the alkaline antacid 300 in the third adhesive film layer is greater than 90% of the total content of the alkaline antacid 300 in the encapsulating film 100, and the content of the ultraviolet light absorber 200 is less than 10% of the total content of the ultraviolet light absorber 200 in the encapsulating film 100, as shown. Figure 2As shown. Optionally, the first adhesive film layer 110 and the third adhesive film layer 130 are produced using different equipment / production lines. When producing the first adhesive film layer 110, the ultraviolet light absorber 200 is added and the alkaline antacid 300 is not added, so that the content of the ultraviolet light absorber 200 in the first adhesive film layer 110 is 100% of the total content of the ultraviolet light absorber 200 in the encapsulating adhesive film 100, and the content of the alkaline antacid 300 in the first adhesive film layer 110 is 0, as shown. Figure 1 When producing the third adhesive film layer 130, the alkaline antacid 300 is added and the ultraviolet light absorber 200 is not added, so that the content of the alkaline antacid 300 in the third adhesive film layer 130 is 100% of the total content of the alkaline antacid 300 in the encapsulating adhesive film 100, and the content of the ultraviolet light absorber 200 in the third adhesive film layer 130 is 0, as shown. Figure 1 shown.

[0048] In one embodiment, the thickness of the first adhesive film layer 110 and the thickness of the third adhesive film layer 130 may be the same (eg, Figure 1 and Figure 2 ), or they can be different (as shown in Figure 3 As shown). The thickness of the first adhesive film layer 110 ranges from 50 μm to 200 μm, such as 50 μm, 80 μm, 150 μm, and 200 μm. The thickness of the third adhesive film layer 130 is greater than or equal to the thickness of the first adhesive film layer 110. Figure 1 and Figure 2 In the embodiment shown, the thickness of the third adhesive film layer 130 is equal to the thickness of the first adhesive film layer 110. Figure 3 In the embodiment shown, the thickness of the third adhesive film layer 130 is greater than the thickness of the first adhesive film layer 110. The thickness of the third adhesive film layer 130 ranges from 100 μm to 200 μm, for example, 100 μm, 150 μm, or 200 μm. Figures 1 to 3 As shown, the thickness of the second adhesive film layer 120 is greater than the thickness of the first adhesive film layer 110 and the third adhesive film layer 130. The thickness of the second adhesive film layer 120 ranges from 150 μm to 250 μm, such as 150 μm, 190 μm, and 250 μm.

[0049] In one embodiment, the raw material formulation of the first adhesive film layer 110 includes ethylene-vinyl acetate copolymer (EVA), a UV absorber 200, an antioxidant, a heat stabilizer, a silane coupling agent, and a crosslinking agent. Optionally, the raw material formulation of the first adhesive film layer 110 also includes a tackifying resin and / or a plasticizer. The UV absorber 200 includes, but is not limited to, salicylic acid. Antioxidants include, but are not limited to, phenolic antioxidants and phosphite antioxidants. Heat stabilizers include, but are not limited to, phosphite heat stabilizers, fatty acid salt heat stabilizers, epoxy compound heat stabilizers, and hindered amine heat stabilizers. Silane coupling agents include, but are not limited to, methacryloxysilane coupling agents, vinyl silane coupling agents, and epoxy silane coupling agents. Crosslinking agents include, but are not limited to, olefin crosslinking agents, peroxide crosslinking agents, and silane crosslinking agents. Tackifying resins include, but are not limited to, terpene resins, petroleum resins, styrene copolymer resins, and phenolic resins. Plasticizers include phthalate plasticizers, epoxy compound plasticizers, polyester plasticizers, etc.

[0050] In one embodiment, the raw material formula of the first adhesive film layer 110 includes, by mass percentage: ethylene vinyl acetate copolymer (EVA) 93%~96%, for example, 93%, 94.5%, and 96%; ultraviolet light absorber 2000 0.5%~3%, for example, 0.5%, 2%, and 3%; antioxidant 0.5%~1%, for example, 0.5%, 0.8%, and 1%; thermal stabilizer 0.8%~1%, for example, 0.8%, 0.9%, and 1%; silane coupling agent 0.5%~1.5%, for example, 0.5%, 1%, and 1.5%; crosslinking agent 0.5%-0.8%, for example, 0.5%, 0.6%, and 0.8%; tackifying resin 0~0.5%, for example, 0%, 0.3%, and 0.5%; plasticizer 0~1.5%, for example, 0%, 0.5%, and 1.5%.

[0051] In one embodiment, the raw material formula of the third adhesive film layer 130 includes ethylene-vinyl acetate copolymer (EVA), an alkaline antacid 300, an antioxidant, a thermal stabilizer, a silane coupling agent, and a crosslinking agent. Optionally, the raw material formula of the third adhesive film layer 130 also includes a tackifying resin and / or a plasticizer. The alkaline antacid 300 includes, but is not limited to, at least one of magnesium oxide, aluminum oxide, zinc oxide, barium sulfate, and titanium oxide.

[0052] In one embodiment, the raw material formula of the third adhesive film layer 130 includes, by mass percentage: ethylene-vinyl acetate copolymer (EVA) 93%~96%, for example, 93%, 94.5%, and 96%; alkaline antacid 300 1.5%~2%, for example, 1.5%, 1.8%, and 2%; antioxidant 0.5%~1%, for example, 0.5%, 0.8%, and 1%; thermal stabilizer 0.8%~1%, for example, 0.8%, 0.9%, and 1%; silane coupling agent 0.5%~1.5%, for example, 0.5%, 1%, and 1.5%; cross-linking agent 0.5%-0.8%, for example, 0.5%, 0.6%, and 0.8%; tackifying resin 0~0.5%, for example, 0%, 0.3%, and 0.5%; and plasticizer 0~1.5%, for example, 0%, 0.5%, and 1.5%.

[0053] In one embodiment, the raw material formula of the second adhesive film layer 120 includes polyolefin elastomer (POE), antioxidant, heat stabilizer, silane coupling agent and crosslinking agent. Optionally, the raw material formula of the second adhesive film layer 120 also includes tackifying resin and / or plasticizer.

[0054] In one embodiment, the raw material formula of the second film layer 120 includes, by mass percentage: polyolefin elastomer (POE) 93%~97%, for example, 93%, 94.5%, 97%; antioxidant 0.5%~1%, for example, 0.5%, 0.8%, 1%; heat stabilizer 0.8%~1%, for example, 0.8%, 0.9%, 1%; silane coupling agent 0.5%~1.5%, for example, 0.5%, 1%, 1.5%; cross-linking agent 0.5%-0.8%, for example, 0.5%, 0.6%, 0.8%; tackifying resin 0~0.5%, for example, 0%, 0.3%, 0.5%; plasticizer 0~1.5%, for example, 0%, 0.5%, 1.5%.

[0055] In one embodiment, a yellowing test is performed on the encapsulating film 100 composed of the first adhesive film layer 110, the second adhesive film layer 120, and the third adhesive film layer 130 to obtain a yellowing index of the encapsulating film 100. Specifically, a spectrophotometer is used to measure the transmittance of the encapsulating film 100 at wavelengths λ = 445 nm, 555 nm, and 600 nm. The yellowing index Y = (T600 - T445) / T555, and the yellowing index change ΔYn = Yn - Y0, where Yn represents the yellowing index value after aging for n hours, and Y0 represents the yellowing index value before aging.

[0056] In one embodiment, the content of the ultraviolet absorber 200 in the comparative encapsulating film is a, the content of the alkaline antacid 300 is b, the content of the ultraviolet absorber 200 in the first film layer is 50% a, the content of the ultraviolet absorber 200 in the third film layer is 50% a, the content of the alkaline antacid 300 in the first film layer is 50% b, and the content of the alkaline antacid 300 in the third film layer is 50% b. The content of the ultraviolet absorber 200 in the improved encapsulating film is a, the content of the alkaline antacid 300 is b, the content of the ultraviolet absorber 200 in the first film layer is 100% a, the content of the ultraviolet absorber 200 in the third film layer is 0, the content of the alkaline antacid 300 in the first film layer is 0, and the content of the alkaline antacid 300 in the third film layer is 100% b. The comparative encapsulating film and the improved encapsulating film were subjected to a yellowing test, and the test results are shown in Table 1.

[0057] Table 1 Comparison of yellowing index of encapsulation film and improved encapsulation film

[0058]

[0059] In one embodiment, referring to Figure 4 As shown, when the film layer of the encapsulation film 100 is bonded to the solar cell, the metal ions 400 of the solar cell diffuse into the film layer. However, the metal ions 400 are benzotriazole (C6H5N3) including an azo functional group (N=N), benzophenone (C6H5N3) including a carbonyl functional group (C=O), and 13 H 10 O), including the corresponding yellowing component of the ultraviolet light absorber 200 such as triazine (C3H3N3) with imine (C=N) functional group.

[0060] In one embodiment, when the third adhesive film layer 130 is bonded to the solar cell, in order to avoid the formation of benzotriazole (C6H5N3) including an azo functional group (N=N), benzophenone (C6H5N3) including a carbonyl functional group (C=O), 13 H 10 O), and ultraviolet light absorbers 200, such as triazine (C3H3N3) containing imine (C=N) functional groups, come into contact with metal ions 400 diffused into the third adhesive film layer 130. Therefore, the content of ultraviolet light absorbers 200 in the third adhesive film layer 130 should be reduced. To ensure the overall UV blocking effect of the encapsulating film 100, while minimizing the content of ultraviolet light absorbers 200 in the third adhesive film layer 130, the content of ultraviolet light absorbers 200 in the first adhesive film layer 110 should be increased accordingly, so that the total content of ultraviolet light absorbers 200 in the encapsulating film 100 remains unchanged.

[0061] In one embodiment, referring to Figure 4As shown, when producing the first adhesive film layer 110, the ultraviolet absorber 200 is added, so that the content of the ultraviolet absorber 200 in the first adhesive film layer 110 is greater than 90%, or even 100%, of the total content of the ultraviolet absorber 200 in the encapsulating film 100. When producing the third adhesive film layer 130, no ultraviolet absorber 200 is added, so that the content of the ultraviolet absorber 200 in the third adhesive film layer 130 is less than 10%, or even 0%, of the total content of the ultraviolet absorber 200 in the encapsulating film 100.

[0062] In one embodiment, the raw material formulation of the first adhesive film layer 110 includes ethylene-vinyl acetate copolymer (EVA), ultraviolet light absorber 200, an antioxidant, a heat stabilizer, a silane coupling agent, and a crosslinking agent. Optionally, the raw material formulation of the first adhesive film layer 110 also includes a tackifying resin and / or a plasticizer. The raw material formulation of the third adhesive film layer 130 includes ethylene-vinyl acetate copolymer (EVA), an antioxidant, a heat stabilizer, a silane coupling agent, and a crosslinking agent. Optionally, the raw material formulation of the third adhesive film layer 130 also includes a tackifying resin and / or a plasticizer. The raw material formulation of the second adhesive film layer 120 includes a polyolefin elastomer (POE), an antioxidant, a heat stabilizer, a silane coupling agent, and a crosslinking agent. Optionally, the raw material formulation of the second adhesive film layer 120 also includes a tackifying resin and / or a plasticizer.

[0063] In one embodiment, the thickness of the first adhesive film layer 110 ranges from 50 μm to 200 μm, such as 50 μm, 80 μm, 150 μm, and 200 μm. The thickness of the third adhesive film layer 130 is greater than or equal to the thickness of the first adhesive film layer 110, and the thickness of the third adhesive film layer 130 ranges from 100 μm to 200 μm, such as 100 μm, 150 μm, and 200 μm. The thickness of the second adhesive film layer 120 is greater than the thickness of the first adhesive film layer 110 and the third adhesive film layer 130, and the thickness of the second adhesive film layer 120 ranges from 150 μm to 250 μm, such as 150 μm, 190 μm, and 250 μm.

[0064] The present invention also provides a photovoltaic assembly 500, such as Figure 5 As shown, the embodiment includes a front glass 510, a front film 520, a solar cell 530, a back film 540, and a back sheet 550, which are arranged in sequence. The front film 520 and / or the back film 540 include the encapsulation film 100 in the above embodiment. The encapsulation film 100 includes at least a first film layer 110, a second film layer 120, and a third film layer 130, which are arranged in sequence. The content of the ultraviolet light absorber 200 in the first film layer 110 is different from the content of the ultraviolet light absorber 200 in the third film layer 130. The second film layer 120 is used to prevent the diffusion of the ultraviolet light absorber 200 in the first film layer 110 and / or the third film layer 130.

[0065] In one embodiment, the encapsulating film 100 is used to encapsulate solar cells 530. The first film layer 110 is bonded to the front glass 510 and / or the backplane 550, and the third film layer 130 is bonded to the solar cells 530. The content of the ultraviolet light absorber 200 in the first film layer 110 is greater than the content of the ultraviolet light absorber 200 in the third film layer 130. For example, the content of the ultraviolet light absorber 200 in the first film layer 110 is greater than 90%, or even 100%, of the total content of the ultraviolet light absorber 200 in the encapsulating film 100; and the content of the ultraviolet light absorber 200 in the third film layer 130 is less than 10%, or even 0%, of the total content of the ultraviolet light absorber 200 in the encapsulating film 100.

[0066] In one embodiment, a comparative photovoltaic module using the comparative encapsulant film described in the above embodiment and an improved photovoltaic module using the improved encapsulant film described in the above embodiment were subjected to a PID (potential induced degradation) test under conditions of 85°C, 85% RH, and an applied voltage of -1500 V. The test results are shown in Table 2.

[0067] Table 2 Comparison of power attenuation of photovoltaic modules and improved photovoltaic modules

[0068]

[0069] According to the encapsulation film and photovoltaic module provided by the present invention, by making the content of ultraviolet light absorber in different film layers of the encapsulation film different, and arranging a film layer for blocking the diffusion of ultraviolet light absorber between different film layers including ultraviolet light absorber, the ultraviolet light absorber is prevented from contacting with other components in the encapsulation film that may chemically react or catalyze the ultraviolet light absorber, thereby preventing the film from yellowing, improving the service life of the film, and at the same time improving the efficiency of the photovoltaic module.

[0070] Please note that the above embodiments are for illustrative purposes only and are not intended to limit the present application.

[0071] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0072] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the scope of the present application, and such modifications and improvements are all within the scope of protection of the present application.

Claims

1. A packaging film, characterized in that: The invention comprises at least a first adhesive film layer, a second adhesive film layer and a third adhesive film layer which are arranged in sequence, wherein the content of the ultraviolet light absorber in the first adhesive film layer is different from the content of the ultraviolet light absorber in the third adhesive film layer, and the second adhesive film layer is used to block the diffusion of the ultraviolet light absorber in the first adhesive film layer and / or the third adhesive film layer.

2. The packaging film according to claim 1, wherein The third adhesive film layer is used to bond to the solar cell. The first adhesive film layer is arranged on the side of the second adhesive film layer away from the solar cell. The content of the ultraviolet light absorber in the first adhesive film layer is greater than that in the third adhesive film layer.

3. The packaging film according to claim 1, wherein The ultraviolet light absorber includes a functional group for absorbing ultraviolet light, and the functional group for absorbing ultraviolet light includes at least one of an o-hydroxybenzoate functional group, an azo functional group, a carbonyl functional group, and an imine functional group.

4. The packaging film according to claim 3, characterized in that The ultraviolet light absorber includes at least one of salicylic acid, benzotriazole, benzophenone and triazine.

5. The packaging film according to claim 2, wherein: The content of the ultraviolet absorber in the first adhesive film layer is greater than 90% of the total content of the ultraviolet absorber in the encapsulation adhesive film, and the content of the ultraviolet absorber in the third adhesive film layer is less than 10% of the total content of the ultraviolet absorber in the encapsulation adhesive film.

6. The packaging film according to claim 2, characterized in that The content of the ultraviolet light absorber in the first adhesive film layer is 100% of the total content of the ultraviolet light absorber in the packaging adhesive film, and the content of the ultraviolet light absorber in the third adhesive film layer is 0.

7. The packaging film according to claim 1, wherein: The packaging film also includes an alkaline antacid.

8. The packaging film according to claim 7, wherein: The alkaline antacid includes at least one of magnesium oxide, aluminum oxide, zinc oxide, barium sulfate, and titanium oxide.

9. The packaging film according to claim 7, wherein: The third adhesive film layer is used to bond to the solar cell. The first adhesive film layer is arranged on the side of the second adhesive film layer away from the solar cell. The content of alkaline antacid in the third adhesive film layer is greater than that in the first adhesive film layer.

10. The packaging film according to claim 9, characterized in that The content of the alkaline antacid in the third film layer is greater than 90% of the total content of the alkaline antacid in the packaging film, and the content of the alkaline antacid in the first film layer is less than 10% of the total content of the alkaline antacid in the packaging film.

11. The packaging film according to claim 9, wherein The content of the alkaline antacid in the third adhesive film layer is 100% of the total content of the alkaline antacid in the packaging adhesive film, and the content of the alkaline antacid in the first adhesive film layer is 0.

12. The packaging film according to claim 1, wherein The first adhesive film layer, the third adhesive film layer and the ultraviolet light absorber have the same polarity, and the second adhesive film layer and the ultraviolet light absorber have a different polarity.

13. The packaging film according to claim 12, wherein: The first adhesive film layer, the third adhesive film layer and the ultraviolet light absorber are polar substances, and the second adhesive film layer is a non-polar substance.

14. The packaging film according to claim 1 or 13, characterized in that: The main components of the first adhesive film layer and the third adhesive film layer include ethylene-vinyl acetate copolymer, and the main component of the second adhesive film layer includes polyolefin elastomer.

15. The packaging film according to claim 1, wherein The raw material formula of the first adhesive film layer includes, by mass percentage: ethylene-vinyl acetate copolymer 93%~96%, ultraviolet light absorber 0.5%~3%, antioxidant 0.5%~1%, heat stabilizer 0.8%~1%, silane coupling agent 0.5%~1.5%, cross-linking agent 0.5%-0.8%, tackifying resin 0~0.5%, and plasticizer 0~1.5%.

16. The packaging film according to claim 1, wherein The raw material formula of the third adhesive film layer includes, by mass percentage: 93%~96% ethylene-vinyl acetate copolymer, 1.5%~2% alkaline antacid, 0.5%~1% antioxidant, 0.8%~1% heat stabilizer, 0.5%~1.5% silane coupling agent, 0.5%-0.8% cross-linking agent, 0~0.5% tackifying resin, and 0~1.5% plasticizer.

17. The packaging film according to claim 1, wherein The raw material formula of the second film layer includes, by mass percentage: 93% to 97% polyolefin elastomer, 0.5% to 1% antioxidant, 0.8% to 1% heat stabilizer, 0.5% to 1.5% silane coupling agent, 0.5%-0.8% cross-linking agent, 0% to 0.5% tackifying resin, and 0% to 1.5% plasticizer.

18. A photovoltaic module, characterized in that: The invention comprises a front glass, a front adhesive film, a solar cell, a back adhesive film and a back plate arranged in sequence, wherein the front adhesive film and / or the back adhesive film comprises the encapsulation adhesive film according to any one of claims 1 to 17.

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