Encapsulation adhesive film for photovoltaic module, photovoltaic module

Abstract

This application relates to the field of photovoltaic module technology, specifically to encapsulating films for photovoltaic modules and photovoltaic modules themselves. The encapsulating film for photovoltaic modules of this application includes a film substrate and coated titanium dioxide and filler particles dispersed in the film substrate. The film substrate comprises a cross-linked ethylene-vinyl acetate copolymer with a cross-linking degree of 70%~85%. The coated titanium dioxide comprises a titanium dioxide substrate and an inorganic oxide layer coated on the surface of the titanium dioxide substrate. The inorganic oxide layer includes one or more of silicon oxide, aluminum oxide, and zirconium oxide. The filler particles include one or more of graphene oxide and metal oxides. The metal oxides include one or more of zinc oxide and aluminum oxide. The encapsulating film for photovoltaic modules provided by this application can suppress yellowing and discoloration, reduced reflectivity, and other phenomena that occur in the film, thereby helping to suppress the power degradation of the photovoltaic module.

Description

Technical Field

[0001] This application relates to the field of photovoltaic module technology, specifically to encapsulation films for photovoltaic modules and photovoltaic modules. Background Technology

[0002] With the increasing demand for high-reflectivity encapsulation materials in photovoltaic modules, white ethylene-vinyl acetate copolymer (EVA) films have been widely used in the encapsulation field. However, traditional EVA encapsulation films are prone to yellowing and discoloration, as well as reduced reflectivity, during use. This seriously affects the optical performance and structural stability of photovoltaic modules, and exacerbates power degradation. Summary of the Invention

[0003] Based on this, this application provides an encapsulating film for photovoltaic modules and a photovoltaic module. The encapsulating film for photovoltaic modules provided in this application can suppress phenomena such as yellowing and discoloration of the film and reduction in reflectivity, thereby helping to suppress the power degradation of the photovoltaic module.

[0004] A first aspect of this application provides an encapsulating film for photovoltaic modules, the encapsulating film comprising a film substrate and coated titanium dioxide and filler particles dispersed in the film substrate.

[0005] The film matrix comprises a cross-linked ethylene-vinyl acetate copolymer with a cross-linking degree of 70% to 85%; the coated titanium dioxide comprises a titanium dioxide matrix and an inorganic oxide layer coated on the surface of the titanium dioxide matrix, wherein the inorganic oxide layer comprises one or more of silicon oxide, aluminum oxide, and zirconium oxide; the filler particles comprise one or more of graphene oxide and metal oxides. The metal oxide comprises one or more of zinc oxide and aluminum oxide.

[0006] In some embodiments, the mass ratio of the film substrate to the coated titanium dioxide is 1:(0.05~0.15).

[0007] In some embodiments, the mass ratio of the film matrix to the filler particles is 1:(0.02~0.05).

[0008] In some embodiments, the mass ratio of the titanium oxide matrix to the inorganic oxide layer in the coated titanium oxide is 1:(0.03~0.1).

[0009] In some embodiments, the inorganic oxide layer includes a first inorganic oxide layer and a second inorganic oxide layer stacked together, wherein the mass ratio of the first inorganic oxide layer to the second inorganic oxide layer is 1:(1~3).

[0010] In some embodiments, the first inorganic oxide layer comprises silicon oxide. The second inorganic oxide layer comprises aluminum oxide.

[0011] In some embodiments, the filler particles comprise graphene oxide and metal oxide in a mass ratio of 1:(50~70).

[0012] In some embodiments, the encapsulating film further includes: a rare earth-based material; the rare earth-based material is dispersed in the film matrix; the mass ratio of the film matrix to the rare earth-based material is 1:(0.1~0.3).

[0013] In some embodiments, the rare earth-based material comprises Eu(dbm)3phen and Y2SiO5:Ce in a mass ratio of 1:(5~20). 3+ / Yb 3+ .

[0014] In some embodiments, the encapsulating film further includes an antioxidant and a light stabilizer; the antioxidant and the light stabilizer are dispersed in the film matrix, the mass ratio of the film matrix to the antioxidant is 1:(0.001~0.0012), and the mass ratio of the film matrix to the light stabilizer is 1:(0.001~0.008).

[0015] In some embodiments, the antioxidant comprises a hindered phenolic antioxidant and a phosphite antioxidant in a mass ratio of (1~3):1.

[0016] In some embodiments, the light stabilizer comprises a benzotriazole light stabilizer and a quenched excited-state molecule light stabilizer in a mass ratio of 1:(1~3).

[0017] A second aspect of this application provides a photovoltaic module, including a stacked encapsulation panel, solar cells, encapsulation film, and encapsulation backsheet; the encapsulation film includes the encapsulation film for photovoltaic modules described in any one of the first aspects of this application.

[0018] The encapsulating film for photovoltaic modules provided in this application has at least the following beneficial effects:

[0019] The encapsulating film provided in this application includes a cross-linked ethylene-vinyl acetate copolymer with a specific degree of cross-linking, and coated titanium dioxide and filler particles dispersed in the copolymer. The cross-linked ethylene-vinyl acetate copolymer with a specific degree of cross-linking enhances the stability of the main chain structure, inhibiting free radical-induced main chain breakage and β-fracture, thus weakening the formation of major yellowing chromophores such as conjugated double bonds at the source. Furthermore, the coated titanium dioxide, while retaining its high reflectivity, isolates its photocatalytic activity, thereby inhibiting film yellowing. In addition, the filler particles improve thermal conductivity and block water and oxygen permeation, reducing internal thermo-oxidative aging and water-oxygen-induced degradation, further lowering the risk of yellowing.

[0020] Therefore, in the encapsulating film for photovoltaic modules provided in this application, the filler particles, coated titanium dioxide, and cross-linked ethylene-vinyl acetate copolymer with a specific degree of cross-linking together form a multi-protection mechanism. It synergistically inhibits phenomena such as yellowing and reduced reflectivity of the encapsulating film by suppressing ultraviolet catalysis, reducing free radical generation, and blocking water and oxygen erosion, thereby significantly improving the long-term weather resistance of the encapsulating film and thus helping to suppress the power decay of photovoltaic modules. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating the reaction process of yellowing caused by photothermal and oxidative aging of encapsulating films used in photovoltaic modules.

[0022] Figure 2 This is a schematic diagram of the structure of a photovoltaic module provided as an example in this application.

[0023] Explanation of reference numerals in the attached figures

[0024] 10 - Photovoltaic module; 100 - Encapsulation panel; 200 - Solar cell; 300 - Encapsulation film; 400 - Encapsulation backsheet. Detailed Implementation

[0025] The encapsulating film for photovoltaic modules and the photovoltaic module of this application are further described in detail below with reference to specific embodiments. This application can 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 complete understanding of the disclosure of this application.

[0026] The encapsulating film on the back of photovoltaic modules typically uses a cross-linked ethylene-vinyl acetate copolymer (EVA) film with high reflectivity. To further improve its reflectivity, traditional methods involve adding TiO2, a high-reflectivity filler, to the EVA film. However, after photovoltaic modules operate outdoors for extended periods, the EVA film undergoes photo-oxidative-thermal aging reactions, causing the white EVA film with added TiO2 to yellow and discolor. At this point, the film's reflectivity decreases significantly, leading to reduced light utilization and accelerated power attenuation in the photovoltaic module. Furthermore, the yellowing appearance also affects the module's aesthetics and long-term reliability.

[0027] In response, the inventors of this application have conducted a detailed study on the photo-oxidative-thermal aging reaction of the aforementioned EVA film through inventive work, and have improved the encapsulating film based on the aging mechanism. Specifically, see [link to relevant documentation]. Figure 1 This application discovers that when photovoltaic modules are exposed to prolonged outdoor ultraviolet radiation and high temperatures, cross-linked ethylene-vinyl acetate copolymers generate free radicals. Furthermore, the photocatalytic effect of titanium dioxide under ultraviolet light significantly accelerates the generation of free radicals and chain reactions. These free radicals react with oxygen to further generate peroxy free radicals. These peroxy free radicals further abstract hydrogen from the unbroken molecular chains of the cross-linked ethylene-vinyl acetate copolymer, initiating main chain breakage. At this point, the aging pathway of the cross-linked ethylene-vinyl acetate copolymer mainly consists of two pathways: the alkyl free radical pathway and the peroxy free radical pathway. In the alkyl free radical pathway, the main chain undergoes β-fracture, generating conjugated double bonds (-(C=C)). y The system, consisting of a γ-ray group, produces the primary chromophores that cause the material to yellow. The higher the value of γ, the darker the color of the film. In the peroxide free radical pathway, hydroperoxides are formed and further decompose to generate carboxylic acids, aldehydes, ketones, etc., which are secondary chromophores contributing to yellowing. These chromophores lead to the yellowing phenomenon in the encapsulating film.

[0028] In response to this, a first aspect of this application provides an encapsulating film for photovoltaic modules, the encapsulating film comprising a film substrate and coated titanium dioxide and filler particles dispersed in the film substrate.

[0029] The film matrix comprises a cross-linked ethylene-vinyl acetate copolymer with a cross-linking degree of 70%–85%. The coated titanium dioxide comprises a titanium dioxide matrix and an inorganic oxide layer coating the surface of the titanium dioxide matrix. The inorganic oxide layer comprises one or more of silicon oxide, aluminum oxide, and zirconium oxide. The filler particles comprise one or more of graphene oxide and metal oxides. The metal oxides comprise one or more of zinc oxide and aluminum oxide.

[0030] The encapsulating film provided in this application includes a cross-linked ethylene-vinyl acetate copolymer with a specific degree of cross-linking, and coated titanium dioxide and filler particles dispersed in the copolymer. The cross-linked ethylene-vinyl acetate copolymer with a specific degree of cross-linking enhances the stability of the main chain structure, inhibiting free radical-induced main chain breakage and β-fracture, thus weakening the formation of major yellowing chromophores such as conjugated double bonds at the source. Furthermore, the coated titanium dioxide, while retaining its high reflectivity, isolates its photocatalytic activity, thereby inhibiting film yellowing. In addition, the filler particles improve thermal conductivity and block water and oxygen permeation, reducing internal thermo-oxidative aging and water-oxygen-induced degradation, further lowering the risk of yellowing.

[0031] Therefore, in the encapsulating film for photovoltaic modules provided in this application, the filler particles, coated titanium dioxide, and cross-linked ethylene-vinyl acetate copolymer with a specific degree of cross-linking together form a multi-protection mechanism. It synergistically inhibits phenomena such as yellowing and reduced reflectivity of the encapsulating film by suppressing ultraviolet catalysis, reducing free radical generation, and blocking water and oxygen erosion, thereby significantly improving the long-term weather resistance of the encapsulating film and thus helping to suppress the power decay of photovoltaic modules.

[0032] This application discovers that selecting a cross-linked ethylene-vinyl acetate copolymer with a cross-linking degree of 70% to 85% provides a moderate cross-linking density of the molecular chains. This ensures both the processability and moldability of the film and the construction of a stable three-dimensional network structure. This effectively suppresses free radical-induced main chain breakage and β-fracture, reducing the generation of major chromophores such as conjugated double bonds, thus reducing film yellowing. As an example, the cross-linking degree of the cross-linked ethylene-vinyl acetate copolymer includes, but is not limited to, 70%, 73%, 75%, 78%, 80%, 82%, 82.5%, 83%, 83.5%, 84%, 84.5%, or 85%, or any two of the above values ​​as endpoints within a range.

[0033] In this application, the degree of crosslinking of the crosslinked ethylene-vinyl acetate copolymer can be obtained by referring to the xylene reflux extraction method described in GB / T 18474-2001. Furthermore, during the testing process, the reflux rate is controlled at 30 drops / min, and the extraction time is 8 hours.

[0034] In some examples, the mass ratio of the film substrate to the coated titanium dioxide is 1:(0.05~0.15). When the mass ratio of the film substrate to the coated titanium dioxide is within this range, it can maximize the reflectivity of the film while ensuring its mechanical properties and processability, and avoid the problem of reduced weather resistance caused by excessive filler. Furthermore, the mass ratio of the film substrate to the coated titanium dioxide includes, but is not limited to, 1:0.05, 1:0.08, 1:0.1, 1:0.12, or 1:0.15, or any two of the above values ​​as endpoints.

[0035] Because traditional titanium dioxide exhibits photocatalytic activity under ultraviolet irradiation, it can accelerate the degradation of the surrounding film substrate, generating free radicals. Therefore, this application coats the surface of the titanium dioxide substrate with one or more inorganic oxide layers, including silicon dioxide, aluminum oxide, and zirconium oxide. In this case, the inorganic oxide layer is a transparent or white material with strong absorption capacity in the ultraviolet region. It can shield the ultraviolet catalytic activity of titanium dioxide, block direct contact between titanium dioxide and cross-linked ethylene-vinyl acetate copolymer, thereby preventing the reactive oxygen species generated by titanium dioxide under photoexcitation from initiating free radical reactions in the EVA matrix, and inhibiting the decomposition of hydroperoxides and the formation of secondary chromophores such as carboxylic acids, aldehydes, and ketones. Simultaneously, it retains the high reflectivity advantage of titanium dioxide itself, synergistically improving the film's resistance to yellowing and optical reflectivity.

[0036] To achieve a balance between the anti-yellowing properties and optical performance of the encapsulating film, in some examples, the mass ratio of the titanium dioxide matrix to the inorganic oxide layer in the coated titanium dioxide is 1:(0.03~0.1). As examples, the mass ratio of the titanium dioxide matrix to the inorganic oxide layer in the coated titanium dioxide includes, but is not limited to, 1:0.03, 1:0.05, 1:0.052, 1:0.053, 1:0.055, 1:0.058, 1:0.06, 1:0.07, 1:0.08, 1:0.09, or 1:0.1, or any two of the above values ​​as endpoints within a range.

[0037] Further, in some examples, the inorganic oxide layer comprises a first inorganic oxide layer and a second inorganic oxide layer stacked together, wherein the mass ratio of the first inorganic oxide layer to the second inorganic oxide layer is 1:(1~3). In some examples, the first inorganic oxide layer comprises silicon oxide. The second inorganic oxide layer comprises aluminum oxide. As an example, the mass ratio of the first inorganic oxide layer to the second inorganic oxide layer includes, but is not limited to, 1:1, 1:1.5, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.32, 1:2.33, 1:2.34, 1:2.35, 1:2.4, 1:2.5, 1:2.8, or 1:3, or a range formed by any two of the above point values ​​as endpoint values.

[0038] The aforementioned coated titanium dioxide relies on an outer layer of alumina (second inorganic oxide layer) and an inner layer of silicon dioxide (first inorganic oxide layer). The first inorganic oxide layer exhibits excellent stability, tightly coating the titanium dioxide matrix, blocking its surface photocatalytic sites, and inhibiting the generation of reactive oxygen species and free radicals under ultraviolet excitation. This prevents the aging and degradation of the titanium dioxide-catalyzed cross-linked ethylene-vinyl acetate copolymer. Furthermore, the outer second inorganic oxide layer, with its high refractive index, enhances the shielding effect against ultraviolet light and improves the hydrophobicity and interfacial stability of the coated titanium dioxide surface. This reduces the penetration of small molecules such as water and oxygen into the interior, further delaying the yellowing of the film and enabling the encapsulating film to maintain high reflectivity and good appearance performance during long-term use.

[0039] As an example, the inorganic oxide layer includes a first inorganic oxide layer and a second inorganic oxide layer stacked together, and the coated titanium oxide is modified with an alkenyl-containing silane.

[0040] For example, alkenyl-containing silanes have one or more of the structures shown in formula (I): R1, R2, and R3 are each independently C1-C5 alkyl groups. "Alkyl" refers to a saturated hydrocarbon group containing a primary (normal) carbon atom, or a secondary carbon atom, or a tertiary carbon atom, or a quaternary carbon atom, or a combination thereof. Phrases containing this term, such as "C1-C5 alkyl," refer to alkyl groups containing 1-5 carbon atoms, and each time it appears, it can be independently C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl. Suitable examples include, but are not limited to: methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl (n-propyl, n-Pr, n-propyl, -CH2CH2CH3), 2-propyl (i-Pr, i-propyl, -CH(CH3)2), 1-butyl (n-butyl, n-Bu, n-butyl, -CH2CH2CH2CH3), 2-methyl-1-propyl (i-Bu, i-butyl, -CH2CH(CH3)2), 2) 2-Butyl (s-Bu, s-butyl, -CH(CH3)CH2CH3), tert-butyl (1,1-dimethylethyl, 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH3)3), 1-pentyl (n-pentyl, n-pentyl, -CH2CH2CH2CH2CH3) or 2-pentyl (-CH(CH3)CH2CH2CH3). Further, R1, R2 and R3 are each independently methyl or ethyl.

[0041] As an example, the inorganic oxide layer comprises a first inorganic oxide layer and a second inorganic oxide layer stacked together, wherein the mass ratio of the first inorganic oxide layer to the second inorganic oxide layer is 1:(1~3). The first inorganic oxide layer comprises silicon oxide. The second inorganic oxide layer comprises aluminum oxide. Furthermore, the types of coated titanium oxide modified with alkenyl-containing silanes include, but are not limited to, DAWN R-3195.

[0042] In some examples, the mass ratio of the film matrix to the filler particles is 1:(0.02~0.05). This application uses a composite of graphene oxide and metal oxide as filler particles. The two work together to improve thermal conductivity, reduce heat accumulation, and suppress the generation of free radicals in cross-linked ethylene-vinyl acetate copolymers caused by photothermal phenomena. They also form a dense, waterproof structure, inhibiting oxygen diffusion, thereby synergistically blocking the free radical chain aging reaction jointly induced by light, heat, and oxygen, reducing the formation of conjugated double bonds and carbonyl yellowing chromophores, and further improving the yellowing resistance and long-term outdoor weathering stability of the film. As examples, the mass ratio of the film matrix to the filler particles includes, but is not limited to, 1:0.02, 1:0.025, 1:0.028, 1:0.03, 1:0.032, 1:0.035, 1:0.038, 1:0.04, or 1:0.05, or any two of the above values ​​as endpoints.

[0043] In some examples, the mass ratio of graphene oxide to metal oxide is 1:(50~70). In the formulation of the filler particles, graphene oxide is secondary, and metal oxide is primary. This allows the encapsulating film to fully utilize its thermal conductivity, water and oxygen barrier properties, and aging inhibition effects, while also ensuring good compatibility with the film matrix. It avoids problems such as film darkening and uneven dispersion caused by excessive graphene oxide, achieving a balance between weather resistance, optical performance, and mechanical properties. As examples, the mass ratio of graphene oxide to metal oxide includes, but is not limited to, 1:50, 1:55, 1:58, 1:59, 1:60, 1:61, 1:62, 1:65, or 1:70, or any two of the above values ​​as endpoints within a range.

[0044] In some examples, the encapsulating film further includes a rare earth-based material. The rare earth-based material is dispersed within the film matrix. The mass ratio of the film matrix to the rare earth-based material is 1:(0.1~0.3). As examples, the mass ratio of the film matrix to the rare earth-based material includes, but is not limited to, 1:0.1, 1:0.15, 1:0.18, 1:0.19, 1:0.2, 1:0.21, 1:0.22, 1:0.25, 1:0.28, or 1:0.3, or a range formed by any two of the above values ​​as endpoints.

[0045] In some of these examples, rare earth-based materials include Eu(dbm)3phen and Y2SiO5:Ce in a mass ratio of 1:(5~20). 3+ / Yb 3+ This application discovers that the above-mentioned rare earth-based material formulation can achieve graded utilization of ultraviolet light, which can reduce the yellowing and aging of the film caused by ultraviolet light, and convert harmful ultraviolet energy into effective light that can be absorbed by the battery, thereby achieving a dual improvement in weather resistance and photoelectric performance.

[0046] As an example, Eu(dbm)3phen and Y2SiO5:Ce 3+ / Yb 3+ The mass ratio includes, but is not limited to, 1:5, 1:8, 1:9, 1:10, 1:12, 1:14, 1:16, 1:18 or 1:20, or any two of the above point values ​​as endpoint values ​​within the range.

[0047] In some examples, the encapsulating film further includes antioxidants and light stabilizers; the antioxidants and light stabilizers are dispersed in the film matrix. The mass ratio of the film matrix to the antioxidant is 1:(0.001~0.0012). The mass ratio of the film matrix to the light stabilizer is 1:(0.001~0.008).

[0048] As an example, the mass ratio of the film matrix to the antioxidant includes, but is not limited to, 1:0.001, 1:0.0011, or 1:0.0012, or any two of the above point values ​​as endpoints.

[0049] In some examples, the antioxidants include hindered phenolic antioxidants and phosphite antioxidants in a mass ratio of (1~3):1. This application has found that the combination of hindered phenolic antioxidants and phosphite antioxidants in the antioxidants allows the hindered phenolic antioxidants, as the primary antioxidant, to effectively capture free radicals, while the phosphite antioxidants, as secondary antioxidants, can decompose hydroperoxides, thus blocking the aging chain reaction at different stages and significantly improving the thermo-oxidative stability and anti-yellowing ability of the film. As an example, the mass ratio of hindered phenolic antioxidants to phosphite antioxidants includes, but is not limited to, 1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.8:1, 2:1, 2.5:1, or 3:1, or any two of the above values ​​within a range defined by endpoint values.

[0050] Furthermore, the types of hindered phenolic antioxidants include, but are not limited to, one or more of 2,6-di-tert-butyl-p-cresol, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene.

[0051] Phosphite antioxidants include, but are not limited to, one or more of tris(2,4-di-tert-butylphenyl) phosphite and triisooctyl phosphite.

[0052] In some examples, the light stabilizer comprises a benzotriazole light stabilizer and a quencher of excited-state molecules in a mass ratio of 1:(1~3). The benzotriazole light stabilizer and the quencher of excited-state molecules work synergistically to efficiently absorb ultraviolet light and reduce energy excitation while rapidly quenching excited-state polymer molecules and oxygen, thus doubly blocking the generation of free radicals induced by photoaging and further enhancing the film's resistance to ultraviolet yellowing. The mass ratio of the benzotriazole light stabilizer to the quencher of excited-state molecules includes, but is not limited to, 1:1, 1:1.4, 1:1.5, 1:1.6, 1:2, 1:2.5, or 1:3, or any two of the above values ​​as endpoints within a range.

[0053] As an example, the mass ratio of the film matrix to the light stabilizer includes, but is not limited to, 1:0.001, 1:0.002, 1:0.003, 1:0.004, 1:0.005, 1:0.006, 1:0.007 or 1:0.008, or any two of the above point values ​​as endpoints.

[0054] As an example, light stabilizers include benzotriazole light stabilizers and quenched excited-state molecular light stabilizers in a mass ratio of 1:(1~3). The mass ratio of benzotriazole light stabilizers to quenched excited-state molecular light stabilizers includes, but is not limited to, 1:1, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.8, 1:2, 1:2.5, or 1:3, or any two of the above values ​​as endpoints.

[0055] Furthermore, the types of benzotriazole light stabilizers include, but are not limited to, one or more of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole UV-320, UV-326 and 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole UV-328.

[0056] The types of light stabilizers that quench excited-state molecules include, but are not limited to, one or more of nickel chelate UV-1084 and nickel chelate UV-2002.

[0057] This application also provides a method for preparing an encapsulating film for photovoltaic modules, comprising the following steps: providing raw materials for preparing an encapsulating film for photovoltaic modules, mixing, extruding, molding, and curing the raw materials to prepare an encapsulating film for photovoltaic modules.

[0058] As an example, the raw materials for preparing the encapsulating film for photovoltaic modules include ethylene-vinyl acetate copolymer, coated titanium dioxide, and filler particles. Further, the raw materials for preparing the encapsulating film for photovoltaic modules also include a crosslinking agent. Understandably, the ethylene-vinyl acetate copolymer is cured and crosslinked under the action of the crosslinking agent to form a crosslinked ethylene-vinyl acetate copolymer. For example, the crosslinking agent includes, but is not limited to, one or more of tert-butyl peroxycarbonate-2-ethylhexyl ester (TBEC), tert-butyl peroxy-2-ethylhexanoate, and tert-butyl peroxy-2-valerate.

[0059] As an example, the melt index of the ethylene-vinyl acetate copolymer at 190°C / 2.16 kg is 3 g / 10 min to 15 g / 10 min.

[0060] Furthermore, the raw materials for preparing the encapsulating film for photovoltaic modules also include: rare earth-based materials, antioxidants, and light stabilizers. Understandably, the above-mentioned raw materials are mixed, extruded, molded, and cured to prepare the encapsulating film for photovoltaic modules. The mass fraction of each raw material can be selected according to the mass fraction of the components in the encapsulating film. In addition, to increase the compatibility of the components in the raw materials, a silane coupling agent is also included. The types of silane coupling agents include, but are not limited to, one or more of γ-methacryloyloxypropyltrimethoxysilane KH-570 and γ-aminopropyltriethoxysilane KH-550. Further, the mass fraction of the silane coupling agent in the raw materials is 0.1% to 1%.

[0061] See Figure 2 In a second aspect, a photovoltaic module 10 is provided, comprising a stacked encapsulation panel 100, a solar cell 200, an encapsulation film 300, and an encapsulation backplate 400; the encapsulation film includes the photovoltaic module encapsulation film of any one of the first aspects of this application.

[0062] When the encapsulating film provided in this application is applied to photovoltaic modules, testing shows that after DH1000h of damp heat aging, the encapsulating film exhibits no whitening or bubble defects, with only slight wrinkles of 30-40mm. This indicates that the encapsulating film effectively prevents yellowing and possesses excellent appearance stability. It does not exhibit delamination, whitening, or bubbling failure under long-term damp heat conditions, significantly improving the long-term weather resistance reliability of photovoltaic modules.

[0063] The following detailed embodiments illustrate this application in more detail. It should also be understood that the following embodiments are for further explanation only and should not be construed as limiting the scope of protection of this application. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of this application fall within the scope of protection of this application. The specific process parameters, etc., in the following embodiments are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the range based on the description herein, and are not necessarily limited to the specific values ​​in the embodiments below.

[0064] Example 1

[0065] Example 1 provides an encapsulating film for photovoltaic modules, wherein the encapsulating film comprises the following components by weight: 100 parts of film matrix, 10 parts of coated titanium dioxide, 3 parts of filler particles, 20 parts of rare earth-based material, 0.1 parts of antioxidant, and 0.1 parts of light stabilizer. The film matrix comprises a cross-linked ethylene-vinyl acetate copolymer, the degree of cross-linking of which is shown in Table 2. The coated titanium dioxide is DAWN R-3195. The coated titanium dioxide comprises a titanium dioxide matrix and a first inorganic oxide layer and a second inorganic oxide layer sequentially coated on the surface of the titanium dioxide matrix. The first inorganic oxide layer is silicon dioxide, and the second inorganic oxide layer is aluminum oxide. The mass ratio of the titanium dioxide matrix to the sum of the masses of silicon dioxide and aluminum oxide is 1:0.053, and the mass ratio of silicon dioxide to aluminum oxide is 1:2.33. Furthermore, the above-mentioned coated titanium dioxide is treated with vinyltriethoxysilane... Modification. The filler particles are graphene oxide. The rare earth-based material is Y₂SiO₅:Ce. 3+ / Yb 3+ The antioxidant is 2,6-di-tert-butyl-p-cresol (a hindered phenolic antioxidant). The light stabilizer is benzotriazole-based light stabilizer UV-320.

[0066] The preparation steps of the above-mentioned photovoltaic module encapsulation film are as follows: (1) Raw material preparation: ethylene-vinyl acetate copolymer particles with a melt index of 3g / 10min~15g / 10min at 190℃ / 2.16kg are selected as the matrix resin. Coated titanium dioxide, filler particles, rare earth-based materials, antioxidants and light stabilizers are provided in parts by mass. Crosslinking agent tert-butyl percarbonate-2-ethylhexyl ester (TBEC) and silane coupling agent γ-methacryloyloxypropyltrimethoxysilane (KH-570) are also provided. In the preparation of raw materials, the mass fraction of silane coupling agent is 0.1%~0.3%.

[0067] (2) Mixing: Add the above matrix resin to a high-speed mixer and mix at room temperature for 20 min to 60 min. Then add crosslinking agent and coupling agent and mix for 30 min to obtain intermediate mixture. Then add coated titanium dioxide, filler particles, rare earth-based materials, antioxidant and light stabilizer to the intermediate mixture and mix to obtain mixture.

[0068] (3) Extrusion: The mixture is fed into the extruder hopper, heated (about 80~100℃), melted and plasticized, and dispersed into a uniform melt by the strong shearing action of the screw.

[0069] (4) Molding: The above melt is extruded and molded using a calendering method.

[0070] (5) Slitting and Packaging: Before the film-forming product is rolled up, it undergoes electron radiation pre-crosslinking treatment to make the crosslinking degree of ethylene-vinyl acetate copolymer ≤10%, and then it is slitting and packaging.

[0071] (6) Preparation of photovoltaic modules: The encapsulation panel, the pre-crosslinked intermediate after slitting and packaging, the cell, the pre-crosslinked intermediate after slitting and packaging, and the encapsulation backsheet are stacked and then put into a laminator for lamination. The lamination temperature is 150℃ and the lamination time is 15min~20min. After that, an encapsulation film is formed between the cell and the encapsulation backsheet, and an encapsulation film is formed between the encapsulation panel and the cell.

[0072] Example 2

[0073] Example 2 provides an encapsulating film for photovoltaic modules, wherein the encapsulating film comprises the following components by weight: 100 parts of film matrix, 10 parts of coated titanium dioxide, 3 parts of filler particles, 20 parts of rare earth-based material, 0.1 parts of antioxidant, and 0.1 parts of light stabilizer. The film matrix comprises a cross-linked ethylene-vinyl acetate copolymer, the degree of cross-linking of which is shown in Table 2. The coated titanium dioxide comprises a titanium dioxide matrix and a first inorganic oxide layer sequentially coated on the surface of the titanium dioxide matrix, the first inorganic oxide layer being silicon dioxide. The mass ratio of the titanium dioxide matrix to the silicon dioxide is 1:0.053. The filler particles are graphene oxide. The rare earth-based material is Y₂SiO₅:Ce. 3+ / Yb 3+ The antioxidant is 2,6-di-tert-butyl-p-cresol (a hindered phenolic antioxidant). The light stabilizer is benzotriazole-based light stabilizer UV-320.

[0074] The preparation steps of the encapsulating film for the photovoltaic modules are the same as in Example 1.

[0075] Example 3

[0076] Example 3 provides an encapsulating film for photovoltaic modules, wherein the encapsulating film comprises the following components by weight: 100 parts of film matrix, 10 parts of coated titanium dioxide, 3 parts of filler particles, 20 parts of rare earth-based material, 0.1 parts of antioxidant, and 0.1 parts of light stabilizer. The film matrix comprises a cross-linked ethylene-vinyl acetate copolymer, the degree of cross-linking of which is shown in Table 2. The coated titanium dioxide is DAWN R-3195. The coated titanium dioxide comprises a titanium dioxide matrix and a first inorganic oxide layer and a second inorganic oxide layer sequentially coated on the surface of the titanium dioxide matrix. The first inorganic oxide layer is silicon dioxide, and the second inorganic oxide layer is aluminum oxide. The mass ratio of the titanium dioxide matrix to the sum of the masses of silicon dioxide and aluminum oxide is 1:0.053, and the mass ratio of silicon dioxide to aluminum oxide is 1:2.33. Furthermore, the above-mentioned coated titanium dioxide is treated with vinyltriethoxysilane... Modification. The filler particles consist of graphene oxide and zinc oxide in a mass ratio of 1:59. The rare earth-based material is Y₂SiO₅:Ce. 3+ / Yb 3+ The antioxidant is 2,6-di-tert-butyl-p-cresol (a hindered phenolic antioxidant). The light stabilizer is benzotriazole-based light stabilizer UV-320.

[0077] The preparation steps of the encapsulating film for the photovoltaic modules are the same as in Example 1.

[0078] Example 4

[0079] Example 4 provides an encapsulating film for photovoltaic modules, wherein the encapsulating film comprises the following components by weight: 100 parts of film matrix, 10 parts of coated titanium dioxide, 3 parts of filler particles, 20 parts of rare earth-based material, 0.1 parts of antioxidant, and 0.1 parts of light stabilizer. The film matrix comprises a cross-linked ethylene-vinyl acetate copolymer, the degree of cross-linking of which is shown in Table 2. The coated titanium dioxide is DAWN R-3195. The coated titanium dioxide comprises a titanium dioxide matrix and a first inorganic oxide layer and a second inorganic oxide layer sequentially coated on the surface of the titanium dioxide matrix. The first inorganic oxide layer is silicon dioxide, and the second inorganic oxide layer is aluminum oxide. The mass ratio of the titanium dioxide matrix to the sum of the masses of silicon dioxide and aluminum oxide is 1:0.053, and the mass ratio of silicon dioxide to aluminum oxide is 1:2.33. Furthermore, the above-mentioned coated titanium dioxide is treated with vinyltriethoxysilane... Modification. The filler particles consist of graphene oxide and zinc oxide in a mass ratio of 1:59. The rare earth-based material consists of rare earth complexes Eu(dbm)3phen and Y2SiO5:Ce in a mass ratio of 1:9. 3+ / Yb 3+The antioxidant is 2,6-di-tert-butyl-p-cresol (a hindered phenolic antioxidant). The light stabilizer is benzotriazole-based light stabilizer UV-320.

[0080] The preparation steps of the encapsulating film for the photovoltaic modules are the same as in Example 1.

[0081] Example 5

[0082] Example 5 provides an encapsulating film for photovoltaic modules, wherein the encapsulating film comprises the following components by weight: 100 parts of film matrix, 10 parts of coated titanium dioxide, 3 parts of filler particles, 20 parts of rare earth-based material, 0.1 parts of antioxidant, and 0.1 parts of light stabilizer. The film matrix comprises a cross-linked ethylene-vinyl acetate copolymer, the degree of cross-linking of which is shown in Table 2. The coated titanium dioxide is DAWN R-3195. The coated titanium dioxide comprises a titanium dioxide matrix and a first inorganic oxide layer and a second inorganic oxide layer sequentially coated on the surface of the titanium dioxide matrix. The first inorganic oxide layer is silicon dioxide, and the second inorganic oxide layer is aluminum oxide. The mass ratio of the titanium dioxide matrix to the sum of the masses of silicon dioxide and aluminum oxide is 1:0.053, and the mass ratio of silicon dioxide to aluminum oxide is 1:2.33. Furthermore, the above-mentioned coated titanium dioxide is treated with vinyltriethoxysilane... Modification. The filler particles consist of graphene oxide and zinc oxide in a mass ratio of 1:59. The rare earth-based material consists of a rare earth complex and Eu(dbm)3phen and Y2SiO5:Ce in a mass ratio of 1:9. 3+ / Yb 3+ The antioxidants include 2,6-di-tert-butyl-p-cresol (a hindered phenolic antioxidant) and tris(2,4-di-tert-butylphenyl) phosphite (a phosphite antioxidant) in a mass ratio of 1.5:1. The light stabilizer is benzotriazole UV-320.

[0083] The preparation steps of the encapsulating film for the photovoltaic modules are the same as in Example 1.

[0084] Example 6

[0085] Example 6 provides an encapsulating film for photovoltaic modules, wherein the encapsulating film comprises the following components by weight: 100 parts of film matrix, 10 parts of coated titanium dioxide, 3 parts of filler particles, 20 parts of rare earth-based material, 0.1 parts of antioxidant, and 0.1 parts of light stabilizer. The film matrix comprises a cross-linked ethylene-vinyl acetate copolymer, the degree of cross-linking of which is shown in Table 2. The coated titanium dioxide is DAWN R-3195. The coated titanium dioxide comprises a titanium dioxide matrix and a first inorganic oxide layer and a second inorganic oxide layer sequentially coated on the surface of the titanium dioxide matrix. The first inorganic oxide layer is silicon dioxide, and the second inorganic oxide layer is aluminum oxide. The mass ratio of the titanium dioxide matrix to the sum of the masses of silicon dioxide and aluminum oxide is 1:0.053, and the mass ratio of silicon dioxide to aluminum oxide is 1:2.33. Furthermore, the above-mentioned coated titanium dioxide is treated with vinyltriethoxysilane... Modification. The filler particles consist of graphene oxide and zinc oxide in a mass ratio of 1:59. The rare earth-based material consists of a rare earth complex and Eu(dbm)3phen and Y2SiO5:Ce in a mass ratio of 1:9. 3+ / Yb 3+ Antioxidants include 2,6-di-tert-butyl-p-cresol (hindered phenolic antioxidant) and tris(2,4-di-tert-butylphenyl) phosphite (phosphite antioxidant) in a mass ratio of 1.5:1. Light stabilizers include benzotriazole light stabilizer UV-320 in a mass ratio of 1:1.5 and nickel chelate light stabilizer UV-1084, which quenches excited-state molecules.

[0086] The preparation steps of the encapsulating film for the photovoltaic modules are the same as in Example 1.

[0087] Example 7

[0088] Composition of each component of the encapsulating film for photovoltaic modules: Example 7 is basically the same as Example 1, the main difference being that Example 7 does not include rare earth-based materials, antioxidants and light stabilizers, and the film matrix in Example 7 is 120.2 parts.

[0089] The preparation steps of the encapsulating film for photovoltaic modules are as follows: Example 7 is basically the same as Example 1, the main difference being that Example 7 does not include rare earth-based materials, antioxidants and light stabilizers, and the film substrate in Example 7 is 120.2 parts.

[0090] Comparative Example 1

[0091] The composition of each component of the encapsulating film for photovoltaic modules is the same as in Example 1.

[0092] In Comparative Example 1, the preparation steps of the encapsulating film for photovoltaic modules are as follows: (1) Raw material preparation: ethylene-vinyl acetate copolymer particles with a melt index of 3g / 10min~15g / 10min at 190℃ / 2.16kg are selected as the matrix resin. Coated titanium dioxide, filler particles, rare earth-based materials, antioxidants and light stabilizers are provided in parts by mass. Crosslinking agent tert-butyl percarbonate-2-ethylhexyl ester (TBEC) and silane coupling agent γ-methacryloyloxypropyltrimethoxysilane (KH-570) are also provided.

[0093] (2) Mixing: Add the above matrix resin to a high-speed mixer and mix at room temperature for 20 min to 60 min. Then add crosslinking agent and coupling agent and mix for 30 min to obtain intermediate mixture. Then add coated titanium dioxide, filler particles, rare earth-based materials, antioxidant and light stabilizer to the intermediate mixture and mix to obtain mixture.

[0094] (3) Extrusion: The mixture is fed into the extruder hopper, heated (about 80~100℃), melted and plasticized, and dispersed into a uniform melt by the strong shearing action of the screw.

[0095] (4) Molding: The above melt is extruded and molded using a calendering method.

[0096] (5) Slitting and Packaging: Before the film-forming product is rolled up, it undergoes electron radiation pre-crosslinking treatment to make the crosslinking degree of ethylene-vinyl acetate copolymer ≤10%, and then it is slitting and packaging.

[0097] (6) Preparation of photovoltaic modules: The encapsulation panel, the pre-crosslinked intermediate after cutting and packaging, the cell, the pre-crosslinked intermediate after cutting and packaging, and the encapsulation back sheet are stacked and then put into a laminator for lamination. The lamination temperature is 130℃ and the lamination time is 5min. After lamination, an encapsulation film is formed between the cell and the encapsulation back sheet, and an encapsulation film is formed between the encapsulation panel and the cell.

[0098] Comparative Example 2

[0099] Comparative Example 2 provides an encapsulating film for photovoltaic modules, wherein the encapsulating film comprises the following components by weight: 100 parts of film matrix, 10 parts of titanium dioxide, 3 parts of filler particles, 20 parts of rare earth-based material, 0.1 parts of antioxidant, and 0.1 parts of light stabilizer. The film matrix comprises a cross-linked ethylene-vinyl acetate copolymer with a cross-linking degree of 83.5%. The titanium dioxide is not coated. The filler particles are graphene oxide. The rare earth-based material is Y₂SiO₅:Ce. 3+ / Yb 3+ The antioxidant is 2,6-di-tert-butyl-p-cresol (a hindered phenolic antioxidant). The light stabilizer is benzotriazole-based light stabilizer UV-320.

[0100] The preparation steps of the encapsulating film for the photovoltaic modules are the same as in Example 1.

[0101] The mass fractions of each component in the encapsulating films of the above embodiments and comparative examples are shown in Table 1.

[0102] Table 1

[0103]

[0104] Test case

[0105] Taking the encapsulation film formed between the solar cell and the encapsulation backsheet as an example, the crosslinking degree of the crosslinked ethylene-vinyl acetate copolymer in the encapsulation film was tested according to the method described in GB / T 18474-2001. During the test, the reflux rate was controlled at 30 drops / min and the extraction time was 8 hours. The photovoltaic module was subjected to a temperature of 85±2℃ and a humidity of 85±5%RH for 3000 hours, and the wrinkles and bubbles in the encapsulation film after DH3000 hours were observed. The corresponding test results are shown in Table 2 below. Furthermore, the yellowing value of the above encapsulation film was also tested. Before DH3000 hours, the initial yellowness b1 value of the encapsulation film was tested using a colorimeter to characterize its initial background color. After DH3000 hours, the yellowness b2 value of the encapsulation film was tested using a colorimeter. Based on the b1 and b2 values, the yellowing value Δb was calculated, Δb=b2-b1.

[0106] Table 2

[0107]

[0108] In Table 2 above, "bubbles after DH3000h" refers to circular or elliptical cavities, micro-voids, and interlayer defoaming defects that appear inside the encapsulating film after photovoltaic modules have undergone 3000h of humid heat aging at 85℃ and 85%RH. As can be seen from Table 2, the encapsulating films of Comparative Examples 1 and 2 have severe bubbles, and their yellowing values ​​are all higher than those of the embodiments in this application. Therefore, the encapsulating films provided by Comparative Examples 1 and 2 have poor yellowing resistance.

[0109] In the above embodiments, Embodiment 1 and Embodiment 2 are basically the same, the main difference being that the two use different coated titanium dioxide. As can be seen from the comparison between the two, this application uses a first inorganic oxide layer and a second inorganic oxide layer to coat titanium dioxide, which is more conducive to improving the yellowing resistance of the encapsulation film.

[0110] Example 1 and Example 3 are basically the same, the main difference being that Example 3 uses graphene oxide and zinc oxide as filler particles in combination. As can be seen from Table 2, in Example 3, due to the synergistic effect of graphene oxide and zinc oxide, it can effectively block water vapor and ultraviolet light, inhibit the wet heat degradation and molecular chain breakage of the film, and significantly reduce the yellowing value after DH3000h aging.

[0111] Examples 3 and 4 are basically the same, the main difference being the different rare earth-based materials used. A comparison shows that Example 4 uses the rare earth complex Eu(dbm)3phen and Y2SiO5:Ce. 3+ / Yb 3+ As rare earth-based materials, the combination of the two can reduce the damage of ultraviolet light to the molecular chains of the encapsulating film, while inhibiting the oxidative degradation and hydrolysis reactions during the humid heat aging process, thereby resulting in a lower yellowing value of the encapsulating film after DH3000h aging.

[0112] Examples 4 and 5 are essentially the same, the main difference being the different antioxidants used. Examples 5 and 6 are essentially the same, the main difference being the different light stabilizers used. A comparison of the above examples shows that using a combination of hindered phenolic antioxidants and phosphite antioxidants as the antioxidants, and a combination of benzotriazole light stabilizers and quenched excited-state molecular light stabilizers as the light stabilizers, with these components working synergistically, is more effective in inhibiting the oxidative breakage and degradation of the molecular chains in the film during long-term humid heat aging, significantly reducing the yellowing value after DH3000h aging.

[0113] Example 1 and Example 7 are basically the same, the main difference being that Example 7 does not include rare earth-based materials, antioxidants and light stabilizers. As can be seen from Table 2, Example 7 can improve yellowing resistance compared to Comparative Example 1 and Comparative Example 2, but its effect is slightly worse than that of Example 1.

[0114] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0115] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. An encapsulant film for a photovoltaic module, characterized by, The encapsulating film includes an encapsulating film matrix and coated titanium dioxide and filler particles dispersed in the encapsulating film matrix; The film matrix comprises a cross-linked ethylene-vinyl acetate copolymer with a cross-linking degree of 70% to 85%; the coated titanium dioxide comprises a titanium dioxide matrix and an inorganic oxide layer coated on the surface of the titanium dioxide matrix, wherein the inorganic oxide layer comprises one or more of silicon oxide, aluminum oxide, and zirconium oxide; the filler particles comprise one or more of graphene oxide and metal oxides; and the metal oxides comprise one or more of zinc oxide and aluminum oxide.

2. The encapsulant film for photovoltaic modules according to claim 1, wherein The mass ratio of the adhesive film substrate to the coated titanium dioxide is 1:(0.05~0.15); and / or, The mass ratio of the film matrix to the filler particles is 1:(0.02~0.05).

3. The encapsulant film for photovoltaic modules according to claim 1, wherein In the coated titanium oxide, the mass ratio of the titanium oxide matrix to the inorganic oxide layer is 1:(0.03~0.1).

4. The encapsulant film for photovoltaic modules according to claim 1, wherein The inorganic oxide layer includes a first inorganic oxide layer and a second inorganic oxide layer stacked together, and the mass ratio of the first inorganic oxide layer to the second inorganic oxide layer is 1:(1~3). The first inorganic oxide layer includes silicon oxide, and the second inorganic oxide layer includes aluminum oxide.

5. The encapsulant film for photovoltaic modules according to claim 1, wherein The filler particles comprise graphene oxide and metal oxide in a mass ratio of 1:(50~70).

6. The encapsulant film for photovoltaic modules according to any one of claims 1 to 5, wherein The encapsulating film further includes: a rare earth-based material; the rare earth-based material is dispersed in the film matrix; the mass ratio of the film matrix to the rare earth-based material is 1:(0.1~0.3).

7. The encapsulant film for photovoltaic modules according to claim 6, wherein The rare earth-based material includes Eu(dbm)3phen and Y2SiO5:Ce in a mass ratio of 1:(5-20) 3+ / Yb 3+ .

8. The encapsulant film for photovoltaic modules according to any one of claims 1 to 5, wherein The encapsulating film further includes an antioxidant and a light stabilizer; the antioxidant and the light stabilizer are dispersed in the film matrix, the mass ratio of the film matrix to the antioxidant is 1:(0.001~0.0012), and the mass ratio of the film matrix to the light stabilizer is 1:(0.001~0.008).

9. The encapsulating film for photovoltaic modules according to claim 8, characterized in that, The antioxidants include hindered phenolic antioxidants and phosphite antioxidants in a mass ratio of (1~3):

1.

10. The encapsulating film for photovoltaic modules according to claim 8, characterized in that, The light stabilizer includes benzotriazole light stabilizers and quenched excited-state molecular light stabilizers in a mass ratio of 1:(1~3).

11. A photovoltaic module, characterized in that, It includes a stacked encapsulation panel, solar cells, encapsulating film, and encapsulation backplate; the encapsulating film includes the encapsulating film for photovoltaic modules as described in any one of claims 1 to 10.

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