Encapsulation adhesive film, method of manufacturing the same, and photovoltaic module using the same

Abstract

The application relates to encapsulation adhesive film and a preparation method thereof, and a photovoltaic module using the encapsulation adhesive film, and belongs to the technical field of adhesive film for solar cells. The encapsulation adhesive film comprises an anti-ultraviolet surface layer and a bonding inner layer; the anti-ultraviolet surface layer comprises 100 parts of a base resin and 0.05-5 parts of an anti-ultraviolet filler in terms of weight parts; the anti-ultraviolet filler comprises composite particles with a core-shell structure, SiO2 is the core, and TiO2 is the shell; the shell is externally provided with a silane coupling agent modification layer; and the bonding inner layer contains a self-healing aid. The encapsulation adhesive film can long-term maintain stable optical performance, mechanical performance and interfacial bonding strength in a severe outdoor environment, and improves the overall reliability of the photovoltaic module.

Description

Technical Field

[0001] This invention relates to the field of encapsulant film technology for solar cells, specifically to an encapsulant film that combines UV protection, moisture barrier, adhesion, and stability, a method for preparing the same, and a photovoltaic module using the encapsulant film. Background Technology

[0002] The long-term reliability of photovoltaic modules largely depends on the stability of the encapsulating film. Currently, the mainstream encapsulating film materials mainly include ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), and polyvinyl butyral (PVB). Among them, EVA is the most widely used due to its low cost and mature technology, but it has the defect of insufficient weather resistance: in humid and hot environments, acetic acid migration is prone to occur, leading to a decrease in adhesion to the solar cells and potential corrosion problems; at the same time, it is sensitive to ultraviolet light and is prone to yellowing after long-term use, resulting in a decrease in light transmittance and module power.

[0003] To address these issues, existing technologies typically employ methods such as introducing tackifiers (e.g., phosphate esters) or grafting modification with silane coupling agents. However, these methods still have significant limitations: tackifiers are prone to decomposition during long-term aging, leading to a decline in adhesive performance; silane grafting systems are sensitive to moisture and require stringent processing conditions, increasing the difficulty of industrial production. Furthermore, current modification schemes often focus on improving a single property, making it difficult to achieve a good balance between UV resistance, humid heat resistance, long-term adhesive stability, and process applicability.

[0004] Therefore, as photovoltaic modules develop towards higher power and longer lifespan, there is an urgent need to develop a new type of encapsulating film with better overall performance, which can maintain stable optical performance and interfacial bonding strength in harsh outdoor environments for a long time, thereby improving the overall reliability of photovoltaic modules. Summary of the Invention

[0005] This application improves the composition of the encapsulating film to solve the aforementioned technical problems. One objective of this invention is to provide an encapsulating film; another is to provide a method for preparing the encapsulating film; and a third is to provide a solar cell using the encapsulating film, thereby simultaneously improving the film's optical stability, mechanical strength, and adhesion durability, and solving problems such as yellowing, aging, and adhesion degradation in existing encapsulating films.

[0006] The specific technical solution is explained below:

[0007] An encapsulating film, the encapsulating film comprising an anti-UV outer layer and an adhesive inner layer;

[0008] By weight, the UV-resistant outer layer comprises 100 parts of matrix resin and 0.05 to 5 parts of UV-resistant filler;

[0009] The UV-resistant filler includes composite particles with a core-shell structure, wherein the composite particles have a core formed of SiO2 and a shell formed of at least TiO2 covering the core;

[0010] The composite particles have a silane coupling agent modification layer on their outer shell;

[0011] The adhesive inner layer includes a self-healing agent.

[0012] In the above embodiments, an inorganic UV-resistant filler with bifunctional components is introduced into the UV-resistant outer layer. SiO2 possesses excellent dispersibility and transparency, significantly improving the mechanical strength and interfacial bonding of the resin system. TiO2 exhibits broad-band UV absorption and photostable properties, effectively shielding UV light with wavelengths of 300-400 nm and reducing polymer chain degradation. By combining the two through sol-gel and in-situ encapsulation methods to form a core-shell structure of SiO2 core-TiO2 shell, both the optical transparency of SiO2 and the material's excellent UV resistance are preserved. Specifically, the SiO2 core-TiO2 shell structure prevents TiO2 agglomeration and light blocking while retaining the high transparency of SiO2. When TiO2 is used as the core, TiO2 particles are prone to agglomeration (strong surface polarity). Even if coated with a SiO2 shell, the size of the agglomerated core may still exceed the wavelength of visible light, causing strong light scattering. Furthermore, the light-shielding property of the TiO2 core cannot be completely covered by the SiO2 shell, which will lead to a significant decrease in the light transmittance of the system (usually below 88%), and it will be unable to retain optical transparency.

[0013] Self-healing agents can construct a recombinant physical cross-linked network during resin aging, which can repair microcracks at the bonding interface, giving the encapsulating film excellent bonding toughness, stress relief and self-healing ability, thereby extending the service life of the film.

[0014] Meanwhile, the surface of untreated SiO2-TiO2 composite particles contains a large number of hydroxyl groups, which are highly polar and prone to agglomeration and have poor compatibility with the matrix resin. Therefore, this embodiment modifies the surface of the composite particles by silane coupling to give the surface of the composite particles good organic affinity and reactivity, forming hydrogen bonds and van der Waals interactions with the matrix resin, thereby achieving high dispersibility of the composite particles in the matrix resin and strong bonding of the UV-resistant outer surface layer interface.

[0015] Furthermore, due to the addition of inorganic particles, the UV-resistant outer layer also has excellent water vapor barrier properties, which can delay the aging of the encapsulating film.

[0016] In a further embodiment, the encapsulating film includes a resin intermediate layer located between the UV-resistant outer layer and the adhesive inner layer; the resin intermediate layer contains more than 60% matrix resin.

[0017] In the above embodiments, the UV-resistant outer layer, the resin intermediate layer, and the adhesive inner layer can form a three-layer composite structure to achieve functional zoning: the outer layer is UV-resistant, the intermediate layer is highly transparent, and the inner layer is highly adhesive, taking into account both the optical and structural properties of the encapsulating film.

[0018] The UV-resistant outer layer has excellent water vapor barrier properties, protecting the resin intermediate layer and the adhesive inner layer and delaying their aging caused by water vapor. The resin intermediate layer, as the matrix, ensures high light transmittance, low haze, and low yellowing, while also serving as a structural support layer to synergistically enhance the overall mechanical stability of the film.

[0019] In a further embodiment, the adhesive inner layer comprises, by weight, 100 parts of matrix resin and 0.1 to 5 parts of self-healing agent; and / or, the self-healing agent is selected from prepolymers containing ureidopyrimidinone structural units.

[0020] In a further embodiment, the adhesive inner layer comprises 1 to 3 parts by weight of a self-healing agent.

[0021] In a further embodiment, the self-healing agent is selected from one or more of ureidopyrimidinone-terminated polycaprolactone prepolymers, ureidopyrimidinone-terminated polyether prepolymers, and ureidopyrimidinone-terminated polybutadiene prepolymers.

[0022] In a preferred embodiment, the UV-resistant outer layer comprises 1 to 3 parts by weight of UV-resistant filler.

[0023] In a further embodiment, the UV-resistant filler is a particle with a D50 particle size of 5-20 nm.

[0024] In a further preferred embodiment, the UV-resistant filler is a particle with a D50 particle size of 10-15 nm.

[0025] In a preferred embodiment, the mass ratio of SiO2 to TiO2 is 1:(0.2~0.8); in a more preferred embodiment, the mass ratio of SiO2 particles to TiO2 particles is 1:(0.3~0.5).

[0026] In the above technical solution:

[0027] When the particle size of the UV-resistant filler is too large, it is easy to generate light scattering because the particle size is close to the wavelength of visible light, which affects the photoelectric conversion efficiency of the photovoltaic module. At the same time, it makes the particles easy to agglomerate and cannot be uniformly dispersed in the resin matrix, resulting in stress concentration points inside the film, a decrease in mechanical properties such as tensile strength and elongation at break, and easy cracking.

[0028] When the particle size of the UV-resistant filler is too small, the specific surface area of ​​the particles becomes too large, the number of surface hydroxyl groups increases sharply, the polarity is enhanced, and severe agglomeration is likely to occur. Moreover, the agglomerates are difficult to disperse through melt blending, which instead leads to an increase in defects inside the film.

[0029] When the mass ratio of SiO2 to TiO2 is too high, the proportion of TiO2 is too low, which makes it unable to effectively absorb ultraviolet light. When the film is exposed to ultraviolet radiation for a long time, the resin matrix is ​​prone to photo-oxidative degradation, resulting in yellowing, embrittlement, and a significant reduction in its UV aging resistance. At the same time, the resin degradation caused by ultraviolet light will damage the internal structure of the film and reduce its hydrolytic stability, making it prone to delamination and decreased bonding strength in humid and hot environments. Furthermore, when photovoltaic modules are used outdoors for a long time, the aging of the film is accelerated, which will lead to cell oxidation, reduced module power generation efficiency, and even module failure.

[0030] When the mass ratio of SiO2 to TiO2 is too small, the excessive proportion of TiO2 leads to a significant decrease in the visible light transmittance of the encapsulant film, affecting the photoelectric conversion efficiency of the photovoltaic module. Furthermore, excessive TiO2 is prone to agglomeration, which disrupts the internal uniformity of the encapsulant film, resulting in a decrease in mechanical properties such as tensile strength and elongation at break. At the same time, agglomerates are prone to becoming stress concentration points, making the encapsulant film susceptible to cracking. In addition, the unit price of TiO2 is higher than that of SiO2, and excessive addition will significantly increase the production cost of the encapsulant film, reducing the product's market competitiveness.

[0031] In a preferred embodiment, the matrix resin is selected from one or more of ethylene-vinyl acetate copolymer, polyolefin elastomer, polyvinyl butyral, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, and ethylene-butyl acrylate copolymer.

[0032] In a further embodiment, the silane coupling agent modification layer is a bifunctional silane coupling agent modification layer, wherein the bifunctional silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0033] The necessity of bifunctional groups lies in the fact that one end can form a chemical bond with the hydroxyl groups on the surface of inorganic particles, while the other end can react or physically entangle with the organic resin matrix, thereby significantly improving particle dispersibility, interfacial bonding strength, and overall material performance.

[0034] In a further embodiment, the UV-resistant outer layer, the adhesive inner layer, and the resin intermediate layer each independently include one or more of a crosslinking agent, a co-crosslinking agent, a UV absorber, and a dispersant.

[0035] The crosslinking agent comprises 0.1 to 1.5 parts by weight; the co-crosslinking agent comprises 0.1 to 1.5 parts by weight; the ultraviolet absorber comprises 0.1 to 1.5 parts by weight; and the dispersant comprises 0.1 to 1.5 parts by weight.

[0036] Specifically, but not limitingly, the crosslinking agent is selected from any one or more of the following: dicumyl peroxide, tert-butyl peroxide-2-ethylhexanoate, di-tert-butyl peroxide, azobisisobutyronitrile, benzoyl peroxide, tert-amyl peroxide, tert-butyl peroxide, 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane, tert-butyl peroxyisopropyl carbonate, tert-amyl peroxide acetate, tert-amyl peroxide-(2-ethylhexyl)carbonate, tert-butyl peroxide-3,5,5-trimethylhexanoate, 1,1-di-tert-butylperoxide-cyclohexane, 2,2-bis(tert-butyl peroxide), tert-butyl peroxyvalerate, 1,1-bis(tert-amylperoxy)cyclohexane, and 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane.

[0037] The crosslinking agent is selected from triethylamine, dimethylaminoethanol, methyl ethyl ketone oxime, cyclohexanone oxime, diphenylthiourea, tri(2-hydroxyethyl)isocyanurate triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate, ethoxylated trimethylolpropane triacrylate, propionyl glycerol triacrylate, ethoxylated glycerol triacrylate, propionyl glycerol triacrylate, bis(trimethylolpropane) The following are any one or more of the following: propane tetraacrylate, bis(trimethylolpropane tetramethacrylate), pentaerythritol tetraacrylate, 2,4,6-tris(2-propenyloxy)-1,3,5-triazine, tricyclodecanedimethyl diacrylate, neopentyl glycol diacrylate, bisphenol A diacrylate, bisphenol A dimethacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate.

[0038] The ultraviolet absorber is selected from 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 4-methoxy-2-hydroxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-benzoyloxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-5-chlorobenzophenone, bis-(2-methoxy-4-hydroxy-5-benzoyl) The first one or more of the following: phenylmethane, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-5'-aminophenyl)benzotriazole, and 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole.

[0039] The dispersant is selected from any one or more of EVA wax, polyethylene wax, Span 80, and Tween 80.

[0040] The method for preparing the encapsulating film according to any of the above technical solutions includes the following steps:

[0041] S1: Obtain SiO2-TiO2 composite particle precursor, wherein SiO2 forms the core and TiO2 forms the shell covering the core;

[0042] S2: The composite particle precursor is surface modified with a silane coupling agent to obtain surface-silanized SiO2-TiO2 composite particles;

[0043] S3: Premix the raw materials corresponding to each layer separately;

[0044] S4: Melt-blend the premixed raw materials of each layer separately;

[0045] S5: The raw materials after melt blending of each layer are used to prepare a composite film by three-layer co-extrusion casting;

[0046] S6: The composite film is subjected to electron beam irradiation to form an encapsulation film with a three-dimensional mesh structure.

[0047] In this preparation method, electron beam irradiation is used to form a stable three-dimensional network structure within the composite film. The electron beam irradiation dose is controlled to achieve effective cross-linking of the matrix resin while preserving the molecular structural integrity of the self-healing agent. The three-dimensional network structure formed by electron beam irradiation provides a "supporting framework," which, combined with the "dynamic hydrogen bond physical network" provided by the self-healing agent, constitutes an ideal structure that combines rigidity and flexibility, ensuring both the dimensional stability of the encapsulation film and its reliability for long-term use.

[0048] In a further embodiment, the electron beam irradiation power is 100~300 keV and the irradiation duration is 10~60 s.

[0049] A photovoltaic module having an encapsulating film as described or prepared in any of the above technical solutions.

[0050] In summary, the technical solution described in this invention has the following main beneficial effects:

[0051] Compared with existing technologies, the bifunctional inorganic UV-resistant filler introduced in the technical solution of this invention can improve the UV resistance of the film and the interfacial adhesion of the UV-resistant outer layer, as well as improve the water vapor barrier and delay the aging of the film.

[0052] Meanwhile, the introduced self-healing agent enables the self-healing of microcracks during the aging process of the adhesive film, thus extending the service life of the adhesive film.

[0053] Furthermore, the three-layer composite structure of the UV-resistant outer layer, resin intermediate layer, and adhesive inner layer achieves functional zoning, which, in conjunction with the three-dimensional network structure formed by electron beam irradiation, enhances both the optical and structural properties of the film.

[0054] Further or more detailed beneficial effects will be described in conjunction with specific embodiments in the detailed implementation. Detailed Implementation

[0055] The present invention will be further explained in conjunction with the embodiments:

[0056] The core technical problem faced by the technical solutions of this application's embodiments stems from the inventor's accurate understanding of the prior art. Therefore, how to maintain the overall reliability of photovoltaic modules in harsh outdoor environments for a long time is a technical problem that the inventor urgently needs to solve.

[0057] It should be noted that the embodiments do not constitute a limitation on the scope of protection of the claims of this invention. All technical solutions that can be reasonably expected by those skilled in the art based on the technical concepts provided / proved by the embodiments should be covered within the scope of protection of the claims of this invention.

[0058] In the implementation method:

[0059] The testing methods for each parameter are as follows:

[0060] Total transmittance test: A UV-Vis spectrophotometer was used, and the test was conducted according to GB / T 2410 regarding the test method for transmittance of transparent plastics. The encapsulating film was prepared into a 50 mm × 50 mm square sample, and the total transmittance in the 380–1100 nm wavelength range was tested. Three parallel samples were tested for each sample, and the average value was taken as the total transmittance of that sample.

[0061] Yellowing Index Test: The yellowing index (YI) of the samples was tested using a colorimeter according to GB / T 2409, Test Method for Yellowing Index of Plastics. The encapsulation film samples were tested before and after UV aging, and the yellowing index ΔYI was recorded. The sample size was 50 mm × 50 mm, with three parallel samples in each group, and the average value was taken.

[0062] Peel strength test: According to GB / T 2790 peel strength test method, the encapsulating film was laminated to the photovoltaic glass / backsheet to form a standard specimen of 25 mm × 150 mm. A universal tensile testing machine was used to perform a 180° peel test at a tensile speed of 100 mm / min. Three parallel specimens were tested in each group, and the average value was taken after removing outliers. The unit is N / cm.

[0063] Tensile strength test: Tensile properties are tested according to GB / T1040-1992, type II specimen, tensile speed 500 mm / min.

[0064] Self-healing efficiency test: Scratches were made on the surface of the adhesive film with a scalpel, and then it was placed in an environment of 80 ℃ for 4 hours, after which its tensile strength was tested. The calculation method is: tensile strength of the adhesive film after self-healing / initial tensile strength of the adhesive film × 100%.

[0065] The specific implementation examples are detailed below:

[0066] In the example:

[0067] The preparation method of core-shell structured composite particles composed of SiO2 / TiO2 in inorganic UV-resistant fillers is as follows:

[0068] S1: Prepare particulate raw materials according to the mass ratio of SiO2 and TiO2, wherein SiO2 is particles with a D50 particle size of 10~15 nm and TiO2 is particles with a D50 particle size of 5~20 nm; add ethanol and deionized water (volume ratio 4:1) to a constant temperature reactor, stir evenly, and slowly add tetraethyl orthosilicate, react at room temperature for 1.5 h to generate SiO2 core particles (SiO2 core); under stirring conditions, slowly add tetrabutyl titanate (or titanium isopropanol) solution to the system, maintain pH=8.5±0.5, control the hydrolysis rate of TiO2 precursor, so that it is deposited in situ on the SiO2 surface to form a uniform shell (TiO2 shell); after the reaction is completed, age for 12 h, centrifuge, wash with ethanol 3 times, and vacuum dry at 60 ℃ to obtain SiO2-TiO2 composite particulate precursor.

[0069] S2: KH-550 (γ-aminopropyltriethoxysilane) silane coupling agent was added to 50 mL of a mixed solution of ethanol-water (95:5 volume ratio) at 4 wt% of the composite particle precursor. The pH was adjusted to 5±0.5 (using glacial acetic acid), and the mixture was stirred for 30 min for pre-hydrolysis to convert some -Si-O-CH3 into -Si-OH to form an active intermediate. The SiO2-TiO2 composite particle precursor was dispersed in the above modified solution and ultrasonically dispersed for 20 min. Then, the mixture was stirred at 70±5℃ for 2.5 h to allow the -Si-OH in the silane molecule to undergo a condensation reaction with the hydroxyl groups on the particle surface, generating stable -Si-O-Si- covalent bonds. After the reaction was completed, the mixture was centrifuged and repeatedly washed with ethanol and deionized water to remove unreacted silane coupling agent and byproducts. Then, it was dried in a vacuum oven at 70 ℃ for 8 h to obtain surface-silanized SiO2-TiO2 composite particles.

[0070] The preparation method of the composite film includes the following steps:

[0071] S3: Premix the raw materials of each layer of the encapsulating film under dry conditions;

[0072] S4: The premixed raw materials of each layer are melt-blended separately using a twin-screw extruder to ensure uniform dispersion of the composite particles and interfacial bonding with the matrix resin. The melt-blending temperature is controlled in stages: 100~115℃ for the feeding section, 110~125℃ for the compression section, 120~130℃ for the metering section, and 120~130℃ for the die head. The twin-screw extruder speed is 180~280 r / min, preferably 220~260 r / min.

[0073] S5: A composite structure film is prepared by three-layer co-extrusion casting technology, wherein the outer layer is an anti-UV outer layer containing inorganic anti-UV fillers, the middle layer is a resin layer, and the inner layer is an adhesive inner layer containing self-healing agents; wherein the casting machine temperature is: segmented temperature control at the die head, 110~125 ℃ for the outer layer die head, 105~120 ℃ for the middle layer die head, and 110~125 ℃ for the inner layer die head; casting speed is 1.5~3.5 m / min, preferably 2.0~3.0 m / min;

[0074] S6: The prepared composite film is cross-linked by electron beam irradiation to form a stable three-dimensional network structure. The electron beam irradiation dose is controlled to achieve effective cross-linking of the matrix resin while preserving the molecular structural integrity of the dynamic hydrogen bond network additive, thus obtaining the encapsulating film. The electron beam irradiation power is 100~300 keV, preferably 150~250 keV; the irradiation duration is 10~60 s, preferably 20~40 s.

[0075] Example 1:

[0076] This embodiment relates to an encapsulating film, which is composed of an anti-UV outer layer, a resin intermediate layer, and an adhesive inner layer;

[0077] The total thickness of the encapsulating film described in this embodiment is 0.5 mm, of which the thickness of the UV-resistant outer layer is about 0.1 mm, the thickness of the resin intermediate layer is about 0.3 mm, and the thickness of the adhesive inner layer is about 0.1 mm.

[0078] More specifically, by weight:

[0079] The UV-resistant outer layer comprises: 100 parts of matrix resin (POE, Dow 8688), 2.5 parts of UV-resistant filler, 0.5 parts of crosslinking agent dicumyl peroxide, 1.5 parts of co-crosslinking agent triethylamine, 0.3 parts of UV absorber 2-hydroxy-4-methoxybenzophenone, and 0.1 parts of dispersant EVA wax; wherein the UV-resistant filler is surface-silanized SiO2-TiO2 composite particles (D50 particle size of 10 nm) prepared according to the above steps S1 and S2, wherein the mass ratio of SiO2 to TiO2 is 1:0.4.

[0080] The resin intermediate layer components include: 100 parts of matrix resin (POE, Dow 8688), 0.5 parts of crosslinking agent dicumyl peroxide, 1.5 parts of co-crosslinking agent triethylamine, and 0.3 parts of UV absorber 2-hydroxy-4-methoxybenzophenone.

[0081] The adhesive inner layer comprises: 100 parts of matrix resin (POE, Dow 8688), 1.5 parts of polyether prepolymer capped with ureidopyrimidinone as a self-healing agent, 0.5 parts of dicumyl peroxide as a crosslinking agent, 1.5 parts of triethylamine as a co-crosslinking agent, and 0.3 parts of 2-hydroxy-4-methoxybenzophenone as a UV absorber.

[0082] The above-mentioned raw materials are prepared according to the steps described above: S3 premixing, S4 melt blending (segmented temperature control 110 / 120 / 125 / 125 ℃, rotation speed 240 r / min), S5 three-layer co-extrusion casting (outer die head 120 ℃, resin die head 115 ℃, inner die head 120 ℃, casting speed 2.5 m / min), and S6 electron beam irradiation (power 200 keV, duration 30 s).

[0083] Example 2:

[0084] The only difference from Example 1 is that:

[0085] The mass ratio of SiO2 to TiO2 is 1:0.2.

[0086] Example 3:

[0087] The only difference from Example 1 is that:

[0088] The mass ratio of SiO2 to TiO2 is 1:0.8.

[0089] Example 4:

[0090] The only difference from Example 1 is that:

[0091] The mass ratio of SiO2 to TiO2 is 1:0.3.

[0092] Example 5:

[0093] The only difference from Example 1 is that:

[0094] The mass ratio of SiO2 to TiO2 is 1:0.5.

[0095] Example 6:

[0096] The only difference from Example 1 is that:

[0097] The D50 particle size of the UV-resistant filler is 15 nm.

[0098] Example 7:

[0099] The only difference from Example 1 is that:

[0100] The D50 particle size of the UV-resistant filler is 10 nm.

[0101] Example 8:

[0102] The only difference from Example 1 is that:

[0103] The D50 particle size of the UV-resistant filler is 20 nm.

[0104] Example 9:

[0105] The only difference from Example 1 is that:

[0106] The D50 particle size of the UV-resistant filler is 5 nm.

[0107] Example 10:

[0108] The only difference from Example 1 is that:

[0109] The number of parts by weight of the UV-resistant filler is 1 part.

[0110] Example 11:

[0111] The only difference from Example 1 is that:

[0112] The amount of UV-resistant filler is 3 parts by weight.

[0113] Example 12:

[0114] The only difference from Example 1 is that:

[0115] One part by weight is the self-healing aid.

[0116] Implementation 13:

[0117] The only difference from Example 1 is that:

[0118] The self-healing aid is 3 parts by weight.

[0119] Example 14:

[0120] The only difference from Example 1 is that:

[0121] By weight:

[0122] The UV-resistant outer layer comprises: 100 parts of ethylene-vinyl acetate copolymer (Zhejiang Petrochemical, V6110M), 0.05 parts of UV-resistant filler, 0.5 parts of crosslinking agent benzoyl peroxide, 1.5 parts of co-crosslinking agent diphenylthiourea, 0.3 parts of UV absorber 2-hydroxy-5-chlorobenzophenone, and 0.1 parts of dispersant EVA wax; wherein the UV-resistant filler is SiO2-TiO2 composite particles (D50 particle size of 10 nm) with surface silanization prepared according to the above steps S1 and S2, wherein the mass ratio of SiO2 to TiO2 is 1:0.4.

[0123] The resin intermediate layer components include: 100 parts of ethylene-vinyl acetate copolymer (Zhejiang Petrochemical, V6110M), 0.5 parts of crosslinking agent benzoyl peroxide, 1.5 parts of co-crosslinking agent diphenylthiourea, and 0.3 parts of ultraviolet absorber 2-hydroxy-5-chlorobenzophenone.

[0124] The adhesive inner layer comprises: 100 parts of ethylene-vinyl acetate copolymer (Zhejiang Petrochemical, V6110M), 0.1 parts of polycaprolactone prepolymer capped with ureidopyrimidinone as a self-healing agent, 0.5 parts of benzoyl peroxide as a crosslinking agent, 1.5 parts of diphenylthiourea as a co-crosslinking agent, and 0.3 parts of 2-hydroxy-5-chlorobenzophenone as a UV absorber. The silane coupling agent modification layer is made of γ-aminopropyltriethoxysilane.

[0125] Example 15:

[0126] The only difference from Example 1 is that:

[0127] By weight:

[0128] The UV-resistant outer layer comprises: 100 parts of ethylene-vinyl acetate copolymer (Zhejiang Petrochemical, V6110M), 5 parts of UV-resistant filler, 0.5 parts of crosslinking agent dicumyl peroxide, 1.5 parts of co-crosslinking agent triethylamine, 0.3 parts of UV absorber 2-hydroxy-4-methoxybenzophenone, and 0.1 parts of dispersant EVA wax; wherein the UV-resistant filler is SiO2-TiO2 composite particles (D50 particle size of 10nm) with surface silanization prepared according to the above steps S1 and S2, wherein the mass ratio of SiO2 to TiO2 is 1:0.4.

[0129] The resin intermediate layer components include: 100 parts of ethylene-vinyl acetate copolymer (Zhejiang Petrochemical, V6110M), 0.5 parts of crosslinking agent dicumyl peroxide, 1.5 parts of co-crosslinking agent triethylamine, and 0.3 parts of ultraviolet absorber 2-hydroxy-4-methoxybenzophenone.

[0130] The adhesive inner layer comprises: 100 parts of ethylene-vinyl acetate copolymer (Zhejiang Petrochemical, V6110M), 5 parts of self-healing ureidopyrimidinone-terminated polybutadiene prepolymer, 0.5 parts of crosslinking agent dicumyl peroxide, 1.5 parts of co-crosslinking agent triethylamine, and 0.3 parts of UV absorber 2-hydroxy-4-methoxybenzophenone. The silane coupling agent modification layer is made of vinyltrimethoxysilane.

[0131] Comparative Example 1:

[0132] The only difference from Example 1 is that:

[0133] The encapsulating film of this comparative example contains only the same adhesive inner layer as in Example 1, but does not contain the UV-resistant outer layer and the resin intermediate layer.

[0134] Comparative Example 2:

[0135] The only difference from Example 1 is that:

[0136] The encapsulating film in this comparative example contains only the UV-resistant outer layer, the same as in Example 1, but does not contain the adhesive inner layer or the resin intermediate layer.

[0137] Comparative Example 3:

[0138] The only difference from Example 1 is that:

[0139] Composite particles with opposite core-shell structures on the outer surface of the UV-resistant material are prepared as follows:

[0140] S1: The ratio of SiO2 to TiO2, the D50 particle size of SiO2, and the D50 particle size of TiO2 are the same as in Example 1. Ethanol and deionized water (volume ratio 4:1) are added to a constant-temperature reactor, stirred evenly, and then tetrabutyl titanate is slowly added dropwise. Acetic acid solution (1 mol / L, 1% of solution mass) is added dropwise, and the reaction is carried out at room temperature for 1.5 h to generate TiO2 core particles (TiO2 cores). After filtration and drying, TiO2 core particles are obtained. Then, the obtained TiO2 core particles are further dispersed in ethanol and deionized water (volume ratio 4:1), and the pH is adjusted to 9.0 using ammonia as a catalyst. Tetraethyl orthosilicate is slowly added to the system under stirring conditions to cause it to condense on the TiO2 surface to form a shell layer. After the reaction is completed, the mixture is aged for 12 h, centrifuged, washed three times with ethanol, and dried under vacuum at 60 °C to obtain the TiO2-SiO2 composite particle precursor.

[0141] S2: Add 4 wt% of KH-550 silane coupling agent to 50 mL of an ethanol-water (95:5 volume ratio) mixture, adjust the pH to 5±0.5 (using glacial acetic acid), and stir for 30 min for pre-hydrolysis to convert some -Si-O-CH3 into -Si-OH to form an active intermediate. Disperse the above composite particle precursor in the modified solution, ultrasonically disperse for 20 min, and then stir at 70±5 ℃ for 2.5 h to allow the -Si-OH in the silane molecules to condense with the hydroxyl groups on the particle surface, generating stable -Si-O-Si- covalent bonds. After the reaction is complete, centrifuge the mixture, wash repeatedly with ethanol and deionized water to remove unreacted silane coupling agent and byproducts, and then dry in a vacuum oven at 70 ℃ for 8 h to obtain surface-silanized composite particles.

[0142] Comparative Example 4:

[0143] The only difference from Example 1 is that:

[0144] The UV-resistant filler is not modified with a silane coupling agent, which means that step S2 in Example 1 is omitted.

[0145] Comparative Example 5:

[0146] The only difference from Example 1 is that:

[0147] It contains only a resin intermediate layer.

[0148] The performance parameters of the encapsulating films prepared in Examples 1-15 are shown in Table 1 below:

[0149] Table 1 Performance parameters of the encapsulating films prepared in Examples 1-15

[0150] serial number Light transmittance (%) Yellowing index ΔYI after 1000h of ultraviolet irradiation Peel strength (N / cm) Tensile strength (MPa) Self-healing efficiency (%) of repair at 80℃ for 4 hours Example 1 92.2 0.54 198 9.4 89 Example 2 92.1 0.68 178 8.3 85 Example 3 91.9 0.72 189 7.8 82 Example 4 92.8 0.54 192 9.1 87 Example 5 92.6 0.55 191 9.1 88 Example 6 92.7 0.55 183 9.3 88 Example 7 92.6 0.54 182 9.3 88 Example 8 91.9 0.72 171 8.2 83 Example 9 91.8 0.71 171 8.3 82 Example 10 92.2 0.61 197 9.2 86 Example 11 92.3 0.6 192 9.1 87 Example 12 92.1 0.62 178 8.9 85 Example 13 91.2 0.62 176 9.2 86 Example 14 92.8 0.78 192 9.3 83 Example 15 91.2 0.59 175 8.2 86

[0151] As can be seen from Table 1, the encapsulating films prepared in Examples 1 to 15 all have relatively high performance parameters;

[0152] Example 1 demonstrates excellent overall performance, proving the synergistic effect of the three-layer structure (UV-resistant outer layer, resin intermediate layer, and adhesive inner layer) and the optimized process.

[0153] In Examples 2 through 15, by changing the mass ratio of SiO2 to TiO2, the D50 particle size of the UV-resistant filler, the amount of UV-resistant filler, and the amount of self-healing agent, excellent optical properties, mechanical properties, and yellowing resistance, as well as a good self-healing effect, can be achieved simultaneously. This improves the optical stability, mechanical strength, and adhesion durability of the adhesive film, demonstrating the superior effectiveness of this approach.

[0154] in:

[0155] Examples 4 and 5 show that when the SiO2 / TiO2 mass ratio is within the preferred range of 1:0.3 to 1:0.5, the film exhibits higher light transmittance (92.6 to 92.8%) and lower yellowing index (ΔYI 0.54 to 0.55), while also showing better mechanical properties (peel strength of approximately 192 N / cm and tensile strength of approximately 9.1 MPa), proving that this ratio is the preferred ratio in terms of balancing UV resistance and optical transparency.

[0156] Examples 6 and 7 show that when the particle size of the UV-resistant filler is within the preferred range of 10-15 nm, the film also achieves high light transmittance (92.6-92.7%), low yellowing (ΔYI 0.54-0.55), and high mechanical strength (tensile strength 9.3 MPa), proving that this particle size range can effectively avoid particle agglomeration and light scattering.

[0157] The performance parameters of the encapsulating films prepared in Comparative Examples 1-5 are shown in Table 2 below:

[0158] Table 2. Performance parameters of the encapsulating films prepared in steps 1-5.

[0159] serial number Light transmittance (%) Yellowing index ΔYI after 1000h of ultraviolet irradiation Peel strength (N / cm) Tensile strength (MPa) Self-healing efficiency (%) of repair at 80℃ for 4 hours Comparative Example 1 89.2 2.3 168 6.2 80 Comparative Example 2 91.8 0.52 68 6.8 0 Comparative Example 3 85.2 1.82 158 5.4 82 Comparative Example 4 89.3 2.1 162 5.3 81 Comparative Example 5 90.2 1.9 152 7.5 0

[0160] As can be seen from Table 2, the performance parameters of the encapsulating films prepared in Comparative Examples 1-5 are lower than those in the Examples.

[0161] in:

[0162] Comparative Examples 1 and 2 show that a single functional layer alone cannot achieve ideal overall performance. Comparative Example 1 (containing only the adhesive inner layer) has poor UV aging resistance (yellowing index ΔYI as high as 2.3) due to the lack of the UV-resistant outer layer. Comparative Example 2 (containing only the UV-resistant outer layer) has poor interfacial adhesion performance (peel strength 68 N / cm) and self-healing ability due to the lack of the adhesive inner layer and self-healing agent. This proves that the adhesive layer containing the self-healing agent is a necessary feature to achieve high adhesion and self-healing.

[0163] Comparative Example 3 (with the opposite core-shell structure) shows that changes in the core-shell structure of SiO2 and TiO2 lead to poorer dispersibility, which in turn results in decreased mechanical properties, optical properties, and resistance to yellowing.

[0164] Comparative Example 4 (without silane coupling agent modification) shows that surface silanization treatment plays an important role in improving filler dispersion and enhancing interfacial bonding.

[0165] Comparative Example 5 (resin intermediate layer only) shows that although the single resin intermediate layer has high light transmittance, its UV resistance and yellowing resistance are poor, and it does not have self-healing properties. The three-layer composite structure has a significant synergistic effect.

[0166] In the description of this specification, the references to terms such as "embodiment," "basic embodiment," "preferred embodiment," "other embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0167] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0168] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An encapsulating film, characterized in that: The encapsulating film includes an anti-UV outer layer and an adhesive inner layer; By weight, the UV-resistant outer layer comprises 100 parts of matrix resin and 0.05 to 5 parts of UV-resistant filler; The UV-resistant filler includes composite particles with a core-shell structure, wherein the composite particles have a core formed of SiO2 and a shell formed of at least TiO2 covering the core; The composite particles have a silane coupling agent modification layer on their outer shell; The adhesive inner layer includes a self-healing agent.

2. The encapsulating film according to claim 1, characterized in that: The encapsulating film also includes a resin intermediate layer; The resin intermediate layer is located between the UV-resistant outer layer and the adhesive inner layer.

3. The encapsulating film according to claim 1, characterized in that: By weight, the adhesive inner layer comprises 100 parts of matrix resin and 0.1 to 5 parts of self-healing agent; the self-healing agent is selected from prepolymers containing ureidopyrimidinone structural units; Preferably, the adhesive inner layer includes 1 to 3 parts of a self-healing agent, wherein the self-healing agent is selected from one or more of ureidopyrimidinone-terminated polycaprolactone prepolymer, ureidopyrimidinone-terminated polyether prepolymer, and ureidopyrimidinone-terminated polybutadiene prepolymer.

4. The encapsulating film according to claim 1, characterized in that: The UV-resistant outer layer comprises 1 to 3 parts by weight of UV-resistant filler; And / or, the UV-resistant filler is composed of particles with a D50 particle size of 5-20 nm; Preferably, the UV-resistant filler is composed of particles with a D50 particle size of 10-15 nm.

5. The encapsulating film according to claim 1, characterized in that: The mass ratio of SiO2 to TiO2 is 1:(0.2~0.8); preferably 1:(0.3~0.5).

6. The encapsulating film according to claim 1, characterized in that: The matrix resin is selected from one or more of the following: ethylene-vinyl acetate copolymer, polyolefin elastomer, polyvinyl butyral, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, and ethylene-butyl acrylate copolymer. And / or the silane coupling agent modification layer is a bifunctional silane coupling agent modification layer, wherein the bifunctional silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and vinyltrimethoxysilane.

7. The encapsulating film according to claim 2, characterized in that: The UV-resistant outer layer, the adhesive inner layer, and the resin intermediate layer each independently include one or more of the following: crosslinking agent, co-crosslinking agent, UV absorber, and dispersant.

8. The method for preparing the encapsulating film according to any one of claims 1 to 7, characterized in that... It includes the following steps: S1: Obtain a SiO2-TiO2 composite particle precursor, wherein SiO2 forms a core and TiO2 forms a shell covering the core; S2: The composite particle precursor is surface modified with a silane coupling agent to obtain surface-silanized SiO2-TiO2 composite particles; S3: Premix the raw materials corresponding to each layer separately; S4: Melt-blend the premixed raw materials of each layer separately; S5: The raw materials after melt blending of each layer are used to prepare a composite film by three-layer co-extrusion casting; S6: The composite film is subjected to electron beam irradiation to form an encapsulation film with a three-dimensional mesh structure.

9. The method for preparing the encapsulating film according to claim 10, characterized in that: The electron beam irradiation power is 100~300 keV, and the irradiation duration is 10~60 s.

10. A photovoltaic module, characterized in that: The photovoltaic module includes the encapsulating film according to any one of claims 1 to 9 or the encapsulating film prepared by the preparation method according to claim 10 or 11.