Refractive index matching type anti-corrosion functional body, gradient refractive index interface layer precursor, adhesive film, and preparation method and application

Abstract

This invention provides a refractive index-matched anti-corrosion functional body, a gradient refractive index interface layer precursor, an encapsulant film, its preparation method, and its application, relating to the field of photovoltaic encapsulation materials technology. The refractive index-matched anti-corrosion functional body has a core-shell structure. Its core is a mesoporous silica nanosphere loaded with a pH-responsive slow-release anti-corrosion agent and grafted with a pH-sensitive polymer; its outer shell is a hydrophobic layer of a fluorinated acrylate copolymer. The gradient refractive index interface layer precursor comprises, from the inside out: a refractive index-matched anti-corrosion functional body, a mercaptosilane coupling agent grafted layer, a trifluoroethyl methacrylate copolymer layer, and a maleic anhydride-grafted ethylene-vinyl acetate copolymer layer. This invention solves the problem of the incompatibility between corrosion resistance and light transmittance. The encapsulant film exhibits excellent overall performance, maintaining high light transmittance and low haze while possessing excellent water vapor barrier capabilities, significantly extending its effective corrosion resistance lifespan.

Description

Technical Field

[0001] This invention relates to the field of solar photovoltaic encapsulation materials technology, specifically to a refractive index-matched corrosion-resistant functional body, a gradient refractive index interface layer precursor, an encapsulating film, its preparation method, and its application. In particular, it relates to a composite encapsulating film that combines ultra-high light transmittance with long-lasting corrosion resistance, suitable for encapsulating new high-efficiency battery modules such as N-type TOPCon and HJT. Background Technology

[0002] Ethylene-vinyl acetate copolymer (EVA) resin, as the mainstream matrix material for traditional photovoltaic encapsulation films, has an inherent structural defect during long-term humid and hot aging: the ethylene-vinyl acetate (VA) side chains are prone to hydrolysis. With the long-term effects of complex outdoor environments such as high temperature and humidity, and ultraviolet radiation, the vinyl acetate units in the EVA molecular chain gradually degrade and release free acetic acid. These acidic substances continuously corrode the silver grid lines and interconnecting solder ribbons on the surface of the solar cells, causing grid line corrosion, detachment, and increased contact resistance. Ultimately, this leads to significant power degradation in the photovoltaic modules, severely impacting their power generation efficiency and lifespan.

[0003] With the rapid popularization of new high-efficiency battery technologies such as N-type TOPCon and HJT, battery processes and electrode materials have become more refined. The electrode structures used, such as low-temperature silver paste and transparent conductive films, are highly sensitive to acidic substances. Even trace amounts of acetic acid can cause severe corrosion and interface failure. This has significantly increased the requirements for hydrolysis resistance, low acid precipitation, and high corrosion resistance in photovoltaic encapsulation systems. Traditional EVA films can no longer meet the needs of long-term reliable operation of new high-efficiency batteries. There is an urgent need to suppress hydrolysis and acid precipitation behavior at the source through formulation optimization and functional additive modification to ensure the stability and power generation performance of the module throughout its entire life cycle.

[0004] The refractive index of conventional metal oxides / hydroxides (MgO, CaO, ZnO, hydrotalcite, etc.) is approximately 1.7, which is significantly different from that of EVA resin (1.5). According to the Fresnel equation, when the refractive index difference is 0.2, the reflection loss at a single interface is approximately 0.5%; when the amount of functional agent added reaches 1%, the cumulative reflection loss at hundreds of interfaces can reach 5-8%, causing the transmittance to drop from 92% to below 85%.

[0005] CN102318080A discloses a sealing film for solar cells and a solar cell using the sealing film. The sealing film contains an ethylene vinyl acetate copolymer, a crosslinking agent, and an adsorbent. As an adsorbent, it contains 0.1 to 1.5 parts by mass of inorganic microparticles with a refractive index below 1.54, relative to 100 parts by mass of the ethylene vinyl acetate copolymer. However, the refractive index of this adsorbent differs significantly from that of the ethylene vinyl acetate copolymer matrix, being 1.7 and 1.5 respectively, resulting in poor optical matching. When its addition amount is high, it significantly exacerbates interfacial light scattering and light loss, causing a sharp decrease in the transmittance of the sealing film. Simultaneously, the adsorbent has a high surface energy, making it prone to agglomeration in the resin matrix and difficult to disperse uniformly, further deteriorating the optical properties and mechanical stability of the film.

[0006] CN113451423A discloses a method for fabricating a low-dimensional semiconductor opto-synaptic device based on the plasmon effect. From top to bottom, the device comprises an upper electrode pair, a metal nanoparticle layer, a low-dimensional semiconductor layer, an oxide layer, a substrate layer, and a bottom electrode, wherein the metal nanoparticle layer and the low-dimensional semiconductor layer are heterojunction layers. This method only provides protection for local structures such as electrodes, solder ribbons, or busbars, failing to provide effective protection for the main body of the solar cell. The overall protection coverage is incomplete, making it difficult to suppress the performance degradation of the solar cell itself. Furthermore, its multi-layer electrode and heterojunction layer structure has complex fabrication processes, requiring precise alignment, which is not conducive to large-scale production and application.

[0007] CN117343657A discloses a high-transmittance, corrosion-resistant photovoltaic encapsulating film and its preparation method. It employs a superhydrophobic material to hydrophobically modify the surface of a porous silicon nanocomposite oxide. The modified acid-resistant additive exhibits better compatibility with the EVA resin matrix. Due to the hydrophobic functional groups on its surface, it can effectively block water vapor, further reducing the film's water vapor transmission rate. However, this method only achieves water vapor barrier through hydrophobic modification, which only weakens the branched hydrolysis effect at its source, and its intrinsic acid corrosion resistance is very limited. Furthermore, the porous structure of the porous silicon nanocomposite oxide has poor refractive index matching with the EVA resin matrix, easily inducing light scattering and affecting the light transmittance and optical compatibility of the encapsulating film.

[0008] CN117153919A discloses a corrosion-resistant photovoltaic module and its preparation method. The preparation method includes: co-extruded a low melt index EVA resin material layer (melt index not greater than 10 g / 10 min) and a high melt index EVA resin material layer (melt index not less than 20 g / 10 min) at a thickness ratio of 1:0.1 to 1:10 to form a double-layer or multi-layer encapsulating film, thus obtaining the EVA photovoltaic encapsulating film; and applying an anti-corrosion coating to the busbars and solder strips of the photovoltaic cells. However, this method mainly relies on the viscosity difference between high and low melt index EVA resins to control interlayer flow and delamination structure, making it highly sensitive to fluctuations in raw material melt index, lamination temperature, pressure, and time, resulting in a narrow process control window. In actual mass production, problems such as interlayer mixing and uneven thickness easily occur, leading to poor stability in large-scale production and difficulty in ensuring batch consistency.

[0009] In view of this, the present invention is hereby proposed. Summary of the Invention

[0010] The purpose of this invention is to provide a refractive index-matched anti-corrosion functional body, a gradient refractive index interface layer precursor, a film, a preparation method, and an application. The aim is to solve the problem of how to achieve long-term (≥2000 h double 85 aging) anti-corrosion performance while maintaining ultra-high light transmittance (≥94%, haze <3%), without increasing the complexity of the process.

[0011] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a refractive index matching type anti-corrosion functional body, wherein the refractive index matching type anti-corrosion functional body has a core-shell structure; The core of the refractive index-matched anti-corrosion functional body includes mesoporous silica nanospheres, which are loaded with a pH-responsive slow-release anti-corrosion agent and grafted with a pH-sensitive polymer. The outer shell of the refractive index-matched corrosion-resistant functional body includes a hydrophobic layer of fluorinated acrylate copolymer.

[0012] Furthermore, the overall refractive index of the refractive index-matching anti-corrosion functional body is 1.48~1.52; the refractive index difference between the core and the outer shell is ≤0.03.

[0013] Furthermore, the mesoporous silica nanospheres have a particle size of 100~300 nm and a pore size of 5~35 nm.

[0014] Furthermore, the pH-responsive slow-release corrosion inhibitor is encapsulated in the mesoporous channels of the mesoporous silica nanospheres; the mass ratio of the pH-responsive slow-release corrosion inhibitor to the mesoporous silica nanospheres is 1:(2~5).

[0015] Furthermore, the pH-responsive slow-release corrosion inhibitor comprises nano-sized alkaline metal compounds, preferably any one or a combination of at least two of nano-Ca(OH)2, nano-Mg(OH)2, and nano-ZnO.

[0016] Furthermore, the pH-responsive slow-release corrosion inhibitor has a particle size of 10~30 nm.

[0017] Furthermore, the pH-sensitive polymer is grafted onto the mesoporous pore inlet of the mesoporous silica nanospheres; and the pH-sensitive polymer shrinks the open pores when pH < 5 and expands the closed pores when pH > 6; the grafting rate of the pH-sensitive polymer is 2~5 wt%.

[0018] Furthermore, the pH-sensitive polymer includes any one or a combination of at least two of polyacrylic acid, polymethacrylic acid, and polyacrylic acid-co-methyl methacrylate.

[0019] Furthermore, the weight-average molecular weight of the pH-sensitive polymer is 10,000 to 50,000.

[0020] Furthermore, the hydrophobic layer of the fluorinated acrylate copolymer is formed by copolymerization of fluorinated acrylate monomers and glycidyl methacrylate.

[0021] Furthermore, the fluorinated acrylate monomers include any one or a combination of at least two of trifluoroethyl methacrylate, hexafluorobutyl methacrylate, and perfluoroalkyl ethyl acrylate.

[0022] Furthermore, the mass ratio of the fluorinated acrylate monomer to glycidyl methacrylate is (60~95):(5~40).

[0023] Furthermore, the fluorine content in the hydrophobic layer of the fluorinated acrylate copolymer is 20~40 wt%.

[0024] Furthermore, the contact angle of the hydrophobic layer of the fluorinated acrylate copolymer is >110°.

[0025] Furthermore, the thickness of the hydrophobic layer of the fluorinated acrylate copolymer is 10~30 nm.

[0026] In a second aspect, the present invention provides a method for preparing a refractive index-matching anti-corrosion functional body as described in the first aspect, the method comprising: The mesoporous silica nanospheres were prepared by the sol-gel method. The pH-responsive slow-release corrosion inhibitor is introduced into the mesoporous silica nanospheres by vacuum impregnation to obtain mesoporous silica nanospheres loaded with the pH-responsive slow-release corrosion inhibitor. The core is obtained by grafting the pH-sensitive polymer onto mesoporous silica nanospheres via a carbodiimide chemical grafting reaction. The fluorinated acrylate copolymer hydrophobic layer is coated onto the surface of the core through emulsion polymerization to form a shell, thereby obtaining the refractive index-matched anti-corrosion functional body.

[0027] Furthermore, the method for preparing the kernel specifically includes the following steps: (a) A silicon source, a mesoporous template agent, a pH adjuster and a solvent are mixed, reacted and then calcined to obtain the mesoporous silica nanospheres; (b) The mesoporous silica nanospheres, pH-responsive slow-release corrosion inhibitor and solvent II are mixed and vacuum impregnated to allow the pH-responsive slow-release corrosion inhibitor to enter the mesoporous silica nanospheres, thereby obtaining mesoporous silica nanospheres loaded with pH-responsive slow-release corrosion inhibitor. (c) The mesoporous silica nanospheres loaded with pH-responsive slow-release corrosion inhibitor, pH-sensitive polymer, carbodiimide grafting agent and solvent are mixed and a grafting reaction is carried out to graft the pH-sensitive polymer onto the mesoporous silica nanospheres to obtain the core; (d) The core, fluorinated acrylate monomer, glycidyl methacrylate, initiator and solvent are mixed and subjected to emulsion polymerization to form a shell. The solvent is then removed to obtain the refractive index matching anti-corrosion functional body.

[0028] Further, in step (a), the silicon source includes tetraethyl orthosilicate; the mesoporous template agent includes hexadecyltrimethylammonium bromide; the pH adjuster includes ammonia; and the solvent is an aqueous ethanol solution.

[0029] Further, in step (a), the mass ratio of the silicon source, mesoporous template agent, pH adjuster and solvent is (10~20):(1~3):(4~8):(60~85).

[0030] Further, in step (a), the pH of the reaction is 8-12, the temperature of the reaction is 30-50°C, and the reaction time is 12-24 h.

[0031] Further, in step (a), the calcination temperature is 450~550℃ and the calcination time is 4~10 h.

[0032] Further, in step (b), the solvent two is ethanol.

[0033] Further, in step (b), the mass ratio of the mesoporous silica nanospheres, the pH-responsive slow-release corrosion inhibitor, and solvent II is (4~10):(1~2):(30~60).

[0034] Furthermore, in step (b), the vacuum impregnation time is 8 to 16 hours.

[0035] Further, in step (c), the carbodiimide grafting agent is a mixture of EDC-HCl and NHS; the solvent is ethanol and / or MES buffered aqueous solution.

[0036] Further, in step (c), the mass ratio of the mesoporous silica nanospheres loaded with pH-responsive slow-release corrosion inhibitor, the pH-sensitive polymer, the carbodiimide grafting agent, and the solvent is (8~15):(0.2~0.7):(0.5~1.2):(40~70).

[0037] Furthermore, in step (c), the grafting reaction temperature is 20~55℃, and the grafting reaction time is 4~10 h.

[0038] Further, in step (d), the initiator is azobisisobutyramidine hydrochloride; the solvent is a mixed solution of ethanol and water; and so on.

[0039] Further, in step (d), the mass ratio of the core, fluorinated acrylate monomer, glycidyl methacrylate, initiator, and solvent is (5~12):(3~7):(0.4~2.1):(0.08~0.25):(40~80).

[0040] Further, in step (d), the temperature of the emulsion polymerization reaction is 50~80℃, and the time of the emulsion polymerization reaction is 4~12 h.

[0041] Thirdly, the present invention provides a gradient refractive index interface layer precursor, which comprises, from the inside out: an anti-corrosion functional body, a mercaptosilane coupling agent grafted layer, a trifluoroethyl methacrylate copolymer layer, and a maleic anhydride grafted ethylene-vinyl acetate copolymer layer. The corrosion-resistant functional body includes the refractive index-matching corrosion-resistant functional body as described in the first aspect.

[0042] Furthermore, the refractive index of the mercaptosilane coupling agent grafted layer is 1.51~1.53, the thickness of the trifluoroethyl methacrylate copolymer layer is 1.49~1.51, and the thickness of the maleic anhydride grafted ethylene-vinyl acetate copolymer layer is 1.48~1.50.

[0043] Furthermore, the thickness of the mercaptosilane coupling agent grafted layer is 2-5 nm, the thickness of the trifluoroethyl methacrylate copolymer layer is 5-10 nm, and the thickness of the maleic anhydride grafted ethylene-vinyl acetate copolymer layer is 5-15 nm.

[0044] Fourthly, the present invention provides a method for preparing a gradient refractive index interface layer precursor as described in the second aspect, the method comprising: (A) The refractive index matching anti-corrosion functional body is dispersed in an ethanol solution of mercaptosilane coupling agent and a grafting reaction is carried out to form a mercaptosilane coupling agent grafting layer on the surface of the refractive index matching anti-corrosion functional body, thereby obtaining reaction solution one; (B) Add trifluoroethyl methacrylate copolymer to the reaction solution one and cure it with ultraviolet light to form a trifluoroethyl methacrylate copolymer layer on the surface of the mercaptosilane coupling agent graft layer, thus obtaining reaction solution two. (C) Add maleic anhydride-grafted ethylene-vinyl acetate copolymer emulsion to the reaction solution II, and perform drying and curing treatment to form a maleic anhydride-grafted ethylene-vinyl acetate copolymer layer on the surface of the trifluoroethyl methacrylate copolymer layer, thereby obtaining the gradient refractive index interface layer precursor.

[0045] Further, in step (A), the mercaptosilane coupling agent is 3-mercaptopropyltrimethoxysilane.

[0046] Further, in step (A), the mass ratio of the refractive index matching anti-corrosion functional body, mercaptosilane coupling agent, and ethanol is (6~12):(0.3~0.8):(50~90).

[0047] Furthermore, in step (A), the grafting reaction temperature is 40~60℃, and the grafting reaction time is 4~8 h.

[0048] Further, in step (B), the mass ratio of the trifluoroethyl methacrylate copolymer to the anti-corrosion functional body is (1~3):(8~12).

[0049] Further, in step (B), the intensity of the UV curing is 5~20 mW / cm. 2 The UV curing time is 3~10 min.

[0050] Further, in step (C), the mass ratio of the maleic anhydride-grafted ethylene-vinyl acetate copolymer to the anti-corrosion functional body is (0.8~2.5):(8~12).

[0051] Further, in step (C), the solid content of the maleic anhydride-grafted ethylene-vinyl acetate copolymer emulsion is 15~30 wt%.

[0052] Further, in step (C), the temperature of the drying and curing treatment is 60~100℃, and the drying and curing time is 10~30 min.

[0053] Fifthly, the present invention provides an adhesive film, the adhesive film comprising, by weight, the following components: 100 parts of matrix resin, 1-8 parts of the refractive index matching anti-corrosion functional body described in the first aspect, 0.5-3 parts of the gradient refractive index interface layer precursor described in the second aspect, 0.5-2 parts of crosslinking agent, 0.3-1.5 parts of long-lasting anti-PID synergist, and 0.2-1 parts of light stabilizer.

[0054] Furthermore, the matrix resin includes an ethylene-vinyl acetate copolymer.

[0055] Furthermore, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 26~33 wt%, and the melt index of the ethylene-vinyl acetate is 15~25 g / 10min (190℃ / 2.16 kg).

[0056] Furthermore, the crosslinking agent includes peroxides and co-crosslinking agents.

[0057] Further, the peroxide includes any one or a combination of at least two of the following: 2-ethylhexyl carbonate tert-amyl peroxide, tert-butyl peroxycarbonate-2-ethylhexyl peroxide, 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, tert-butyl peroxide-3,5,5-trimethylhexanoate, benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, and di-tert-butyl peroxide.

[0058] Further, the crosslinking agent includes any one or a combination of at least two of the following: trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, triallyl isocyanurate, tetramethyltetravinylcyclotetrasiloxane, 4-acryloylmorpholine, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, neopentyl glycol (2)PO diacrylate, polyethylene glycol 200 diacrylate, EO (3) trimethylolpropane triacrylate, and 3(propoxy)propanetriol triacrylate.

[0059] Furthermore, the long-acting anti-PID synergist includes any one or a combination of at least two of nano-magnesium hydroxide, organic zinc carboxylate, borate corrosion inhibitor particles, zirconium phosphate, and zirconium hydrogen phosphate.

[0060] Furthermore, the light stabilizer includes hindered amines and ultraviolet absorbers.

[0061] Furthermore, the hindered amine includes any one or a combination of at least two of HALS-944, HALS-770, and HALS-622.

[0062] Furthermore, the ultraviolet absorber includes any one or a combination of at least two of UV-327, UV-531, UV329, UV328, and UV-1130.

[0063] Furthermore, the thickness of the adhesive film is 0.4~0.6 mm.

[0064] Sixthly, the present invention provides a method for preparing an adhesive film as described in the fifth aspect, the method comprising: The matrix resin, the refractive index-matched anti-corrosion functional body, the gradient refractive index interface layer precursor, the crosslinking agent, the long-lasting anti-PID synergist, and the light stabilizer are mixed in a certain proportion, melt-blended and granulated through a twin-screw extruder, then formed into a film through a casting extruder, cooled and shaped, and then wound up to obtain the adhesive film.

[0065] Furthermore, the granulation temperature is 100~140℃.

[0066] Furthermore, the temperature of the film-forming die head is 110~130℃.

[0067] In a seventh aspect, the present invention provides the application of the refractive index matching anti-corrosion functional body as described in the first aspect, or the gradient refractive index interface layer precursor as described in the second aspect, or the encapsulant film as described in the third aspect in the preparation of encapsulation materials for solar photovoltaic modules.

[0068] Furthermore, the solar photovoltaic module includes any one or a combination of at least two of N-type TOPCon cells, HJT cells, and PERC cells.

[0069] Compared with the prior art, the present invention has the following beneficial effects: (1) The core-shell structure refractive index matching anti-corrosion functional body provided by this invention fundamentally solves the industry pain point of the incompatibility between the optical performance and protective performance of traditional photovoltaic anti-corrosion fillers. The refractive index of traditional inorganic anti-corrosion fillers differs greatly from that of the encapsulating resin, which easily causes light scattering and interface reflection, seriously damaging the light transmittance of the encapsulating film. This invention achieves a high degree of matching between the overall refractive index of the functional body and the matrix resin through the precise structural design of the core mesoporous structure and the outer fluorinated copolymer hydrophobic layer, effectively eliminating optical loss and ensuring the excellent light transmittance of the encapsulating film. At the same time, this functional body constructs an anti-corrosion system that combines hydrophobic barrier and chemical anchoring, and with the pH intelligent response slow release mechanism, it can actively regulate the release state of anti-corrosion components according to changes in environmental acidity and alkalinity, avoiding the ineffective consumption of active components. Compared with traditional passive neutralizing fillers, its anti-corrosion persistence and stability are greatly improved, and it can block water vapor and lock acidic corrosive media for a long time, providing long-term protection for photovoltaic modules.

[0070] (2) The gradient refractive index interface layer precursor provided by this invention overcomes the shortcomings of existing technologies that only focus on the modification of the filler body and ignore the optical defects of the micro-interface. Even if the macroscopic refractive index of the filler and the matrix is ​​matched, the abrupt change in refractive index at the micro-interface will still cause light reflection loss, which restricts the improvement of the optical performance of the film. This precursor, through a three-layer gradient structure design, forms a continuously transitioning refractive index interface, completely eliminating the problem of abrupt change in refractive index at the interface, significantly reducing the optical loss caused by Fresnel reflection, and further optimizing the light transmission effect of the film. At the same time, the multi-layer composite structure can effectively improve the interfacial compatibility between the anti-corrosion functional body and the resin matrix, strengthen the interfacial bonding strength, and avoid defects such as interface peeling and micropores during the service of the film. It can not only prevent water vapor and acidic media from penetrating along the interfacial gaps and improve the overall protective stability, but also optimize the dispersibility of the filler and avoid the problem of agglomeration, providing interfacial protection for the long-term service of the film.

[0071] (3) The photovoltaic encapsulating film prepared by this invention, relying on self-developed functional components and a multi-component compound system, achieves a comprehensive upgrade in optical performance, corrosion resistance, and aging resistance. The film uses a multi-type resin compound matrix, combined with a refractive index-matched anti-corrosion functional body and a gradient refractive index interface layer precursor, supplemented by a multi-additive system of crosslinking, anti-PID, and light-stabilizing agents to form a synergistic composite protective structure. It retains the excellent processing and bonding performance of traditional encapsulating films, while completely solving many problems such as corrosion failure, optical attenuation, ion migration, and yellowing due to aging of traditional films. This film is suitable for various mainstream photovoltaic cell front and back encapsulation scenarios, and can effectively reduce power attenuation during long-term service of the module and eliminate failure problems such as corrosion spots on the cells. The overall preparation process is simple and highly controllable, suitable for large-scale mass production, and has extremely high practical value and market application prospects. Detailed Implementation

[0072] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0073] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0074] In a first aspect, the present invention provides a refractive index matching type anti-corrosion functional body, wherein the refractive index matching type anti-corrosion functional body has a core-shell structure; The core of the refractive index-matched anti-corrosion functional body includes mesoporous silica nanospheres, which are loaded with a pH-responsive slow-release anti-corrosion agent and grafted with a pH-sensitive polymer. The outer shell of the refractive index-matched corrosion-resistant functional body includes a hydrophobic layer of fluorinated acrylate copolymer.

[0075] It should be noted that the refractive index-matching anti-corrosion functional body has at least the following three advantages: (1) The core of resolving the contradiction between light transmission and corrosion resistance: This technology differs fundamentally from existing technologies, which suffer from a basic optical matching defect. The refractive index of commonly used corrosion-resistant metal oxides and hydroxides (including MgO, CaO, ZnO, and hydrotalcite) is approximately 1.7, a significant difference of 0.2 compared to the 1.5 refractive index of EVA resin, commonly used in photovoltaic encapsulation. According to Fresnel's law in optics, a 0.2 difference in refractive index leads to a single-interface reflection loss of approximately 0.5% when light travels from one medium to another. When the amount of anti-corrosion functional agent added reaches 1%, hundreds or even thousands of solid-liquid interfaces form within the film. The reflection loss from these interfaces accumulates, ultimately resulting in an overall reflection loss of 5-8%, directly causing the transmittance of the pure EVA film, originally approximately 92%, to plummet to below 85%. Even more challenging is that, in order to meet the corrosion resistance requirements of N-type battery modules, traditional technologies often require increasing the amount of metal oxide anti-acid agents added to 5-15%, which further exacerbates the interfacial optical loss, leading to a continuous decrease in light transmittance and a significant increase in haze. This has created a core technical bottleneck in the industry where corrosion resistance and light transmittance cannot be achieved simultaneously for a long time.

[0076] Based on this, this invention innovatively designs a core-shell structured organic-inorganic hybrid anti-corrosion microsphere to address this core technical challenge, thereby solving the problem of optical performance degradation caused by refractive index mismatch in traditional anti-acid agents. The refractive index-matched anti-corrosion functional body has a carefully designed multi-layered functional structure, and the mesoporous silica nanospheres are loaded with a pH-responsive slow-release anti-corrosion agent and grafted with a pH-sensitive polymer, laying the foundation for subsequent long-term anti-corrosion performance. The outer shell is a fluorinated acrylate copolymer layer, and its refractive index can be precisely controlled by adjusting the monomer composition and degree of polymerization of the copolymer. By precisely matching the particle size of the core with the thickness of the fluorinated acrylate copolymer layer, the overall refractive index of the microspheres is ultimately stabilized in the range of 1.49~1.51, achieving a high degree of compatibility with the 1.5 refractive index of the matrix resin (EVA resin) in the film.

[0077] In terms of core optical performance indicators, the refractive index-matching anti-corrosion functional body described in this invention achieves a revolutionary breakthrough in all aspects compared to traditional MgO / ZnO-based acid resistant agents. Regarding refractive index matching, traditional metal oxide acid resistant agents have a refractive index of approximately 1.7, differing from the EVA matrix by 0.2, while the refractive index of the hybrid microspheres in this invention is controlled at 1.49~1.51, differing from the EVA matrix by only 0.01~0.02, resulting in a 90% improvement in refractive index matching and significantly reducing the possibility of interfacial reflection from the root cause. Regarding single-interfacial reflection loss, the single-interfacial reflection loss between traditional materials and the EVA matrix is ​​0.5~0.8%, while the single-interfacial reflection loss of the hybrid microspheres in this invention is less than 0.2%, a reduction of over 60%. This advantage will be further amplified in high-addition scenarios, as the number of interfaces increases exponentially with the increase in functional body addition, making the cumulative difference in reflection loss even more significant. In practical applications, regarding light transmittance, when the amount of anti-corrosion functional agent added is 3%, the light transmittance of the film with traditional materials is only 87-89%, while the light transmittance of the film with the hybrid microspheres of this invention can reach 93-94.5%, an increase of 5 percentage points. This increase can be directly converted into a gain of 1.2-1.8% in the power generation of photovoltaic modules, resulting in significant economic benefits. Regarding haze control, traditional materials, due to refractive index mismatch and high surface energy leading to easy agglomeration, will cause a 6-10% increase in haze when added at 3%, severely affecting the appearance and optical performance of the module. However, the hybrid microspheres of this invention, due to their highly matched refractive index with the EVA matrix and fluorine-modified surface, exhibit excellent dispersibility in the EVA matrix. Adding 3% only increases the haze of the film by 1-2%, demonstrating excellent haze control and maintaining good transparency and appearance quality of the film.

[0078] The breakthrough improvement in optical performance mentioned above is based on the scientific application of the equivalent medium theory. This theory is one of the core theories in the field of composite material optics. Its core viewpoint is that when the size of the dispersed phase in a composite material is much smaller than the wavelength of the incident light, and the difference in refractive index between the dispersed phase and the continuous phase is less than 0.02, the composite system will macroscopically exhibit optical homogeneity, and the scattering loss of light passing through it can be ignored. This invention is based on this theory. Through the precise design of the core-shell structure, the difference between the overall refractive index of the microspheres and the EVA matrix is ​​strictly controlled within 0.02, so that the film system exhibits optical homogeneity on a macroscopic scale. This fundamentally eliminates the problem of optical performance degradation caused by refractive index mismatch in traditional acid-resistant agents, and successfully solves the technical problem of the incompatibility between corrosion resistance and light transmission that has plagued the photovoltaic encapsulation industry for many years.

[0079] (2) Corrosion resistance through a dual mechanism of hydrophobic barrier and chemical anchoring, surpassing the paradigm of passive neutralization: This differs fundamentally from existing technologies, which generally employ a single, passive neutralization approach. These technologies rely solely on the acid-base neutralization reaction between alkaline oxides and free acetic acid to alleviate corrosion. This approach neither blocks the water vapor intrusion pathway that leads to acetic acid production from EVA hydrolysis at its source, nor addresses the short corrosion resistance lifespan caused by the rapid, one-time consumption of alkaline oxides. For example, while CN117343657A introduces superhydrophobic modified porous silicon composite oxides, improving the water-blocking performance of the film to some extent, it only solves the water-blocking problem. Its acid resistance remains limited, and it does not involve refractive index matching technology, failing to address the industry-wide challenge of decreased light transmittance at high additive levels.

[0080] This invention breaks through the traditional passive neutralization technical paradigm and constructs a three-in-one synergistic anti-corrosion system that integrates physical barrier, chemical capture, and active neutralization. The anti-corrosion functional body simultaneously possesses three functional domains that cooperate with each other and are progressively enhanced. The hydrophobic barrier layer is composed of a perfluoroalkyl-grafted SiO2 shell. The low surface energy of the perfluoroalkyl chain results in a water contact angle greater than 120° on the microsphere surface, reducing the overall water vapor permeability of the film by 60%. This reduces the possibility of EVA hydrolysis producing acetic acid at the source, providing the first line of defense for the anti-corrosion functional body. The acid trapping site is an amino-functionalized mesoporous structure. The amino groups can react specifically with acetic acid molecules to generate stable ammonium salts, chemically locking the acetic acid molecules rather than simply physical adsorption, thus avoiding secondary corrosion caused by the re-release of acetic acid under high temperature and high humidity conditions. The slow-release neutralizer is a pH-responsive nanomaterial @mesoporous SiO2. It only slowly releases the active component for neutralization when the local pH value is below 5 and / or when there is a risk of acid erosion, avoiding the problem of excessive consumption of traditional alkaline oxides under normal conditions and significantly extending the effective life of the anti-corrosion function. Key data for core performance verification: After aging at high temperature and humidity of 85 for 1000 hours, the residual acid value inside the film of this invention is less than 30 ppm, which is far superior to the level of more than 80 ppm in the existing technology; the activity retention rate of the anti-corrosion functional group is more than 85%, which is more than 1.7 times that of the less than 50% of the existing technology.

[0081] (3) Intelligent responsive slow-release anti-corrosion mechanism, from "one-time consumption" to "on-demand supply": There is a fundamental difference from existing technologies: Existing technologies generally adopt a passive neutralization mode by directly adding alkaline oxides, and the corrosion inhibitor will react with acidic substances in the environment indiscriminately and continuously. Once it is consumed, it will become completely ineffective. In the high humidity and heat environment where photovoltaic modules are used for a long time, moisture intrusion will further accelerate the consumption of corrosion inhibitors, resulting in a generally short effective corrosion resistance life.

[0082] Based on this, this invention breaks through the limitations of traditional passive neutralization technology and innovatively proposes a pH-responsive intelligent slow-release design, constructing a dynamic anti-corrosion system that provides on-demand release and long-term protection: Nanoscale alkaline anti-corrosion agents are encapsulated within the internal pores of mesoporous silica nanospheres, and a pH-sensitive polymer is covalently grafted at the entrance of the mesoporous pores as a pH-sensitive switch material. The intelligent response mechanism is as follows: In normal service state (system pH close to neutral): the pH-sensitive polymer chains are extended, completely sealing the mesoporous pores, isolating the internal anti-corrosion agent from the external environment, and preventing premature consumption; In localized acid erosion state (system pH drops below the threshold): the pH-sensitive polymer chains undergo a conformational change, shrinking and collapsing to open the pores, allowing the internal anti-corrosion agent to be slowly released, precisely neutralizing localized free acetic acid; In acid erosion elimination state (system pH returns to the normal range): the pH-sensitive polymer chains re-extension, sealing the pores again, stopping the release of the anti-corrosion agent, and waiting for the next acid erosion trigger. This mechanism significantly extends the effective corrosion resistance lifespan of the film compared to conventional technologies; it also significantly improves the utilization rate of the anti-corrosion functional components; and it eliminates the need for excessive addition of corrosion inhibitors in pursuit of long-lasting effects, fundamentally avoiding the problem of decreased film transmittance caused by high addition levels. Key performance verification data: After double 85 aging tests, the effective corrosion resistance lifespan of the film is extended from the conventional 800 hours to over 2500 hours, the utilization rate of the anti-corrosion functional components increases from 30% to 85%, and the problem of decreased film transmittance caused by excessive addition of corrosion inhibitors is avoided.

[0083] In summary, the refractive index-matched anti-corrosion functional body provided by the first aspect of this invention solves the industry problem of a sharp drop in film transmittance and an increase in haze due to the refractive index mismatch between traditional metal oxide anti-acid agents and EVA resin, resulting in high addition amounts. It also overcomes the shortcomings of existing passive neutralization methods, such as rapid depletion of the functional body, short anti-corrosion lifespan, and insufficient water-blocking ability. This core-shell structure can precisely control the overall refractive index of the functional body, achieving a high degree of matching with the substrate, significantly reducing interfacial optical losses, and maintaining the excellent optical performance of the film. The fluorinated hydrophobic shell effectively blocks water vapor intrusion and reduces acetic acid generation. The pH-responsive design of the mesoporous core enables the on-demand release of anti-corrosion components, combined with chemical anchoring, greatly improving the utilization rate of the functional body and long-term anti-corrosion capability.

[0084] As an optional implementation, the overall refractive index of the refractive index-matching anti-corrosion functional body is 1.48~1.52, for example, it can be 1.48, 1.49, 1.50, 1.51, 1.52, etc.

[0085] As an optional implementation, the refractive index difference between the core and the shell is ≤0.03, for example, it can be 0.03, 0.025, 0.02, 0.015, 0.01, 0.05, 0, etc.

[0086] As an optional implementation, the refractive index difference between the refractive index-matching anti-corrosion functional body and the matrix resin in the base film is ≤0.02, for example, it can be 0.02, 0.015, 0.01, 0.05, 0, etc.

[0087] As an optional implementation, the mesoporous silica nanospheres have a particle size of 100~300 nm, for example, 100 nm, 120 nm, 140 nm, 150 nm, 160 nm, 180 nm, 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, etc.

[0088] As an optional implementation, the pore size of the mesoporous silica nanospheres is 5~35 nm, for example, it can be 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 35 nm, etc.

[0089] As an optional implementation, the pH-responsive slow-release corrosion inhibitor is encapsulated in the mesoporous channels of mesoporous silica nanospheres.

[0090] It should be noted that encapsulating the pH-responsive slow-release corrosion inhibitor in the mesoporous channels of mesoporous silica nanospheres can effectively solve the technical problems of traditional alkaline corrosion inhibitors, such as rapid one-time consumption, excessive waste under normal conditions, and short corrosion resistance life. In particular, the mesoporous channels provide physical protection for the corrosion inhibitor, preventing it from prematurely reacting with the environment and becoming ineffective. Combined with the pH-responsive mechanism, the active components are released on demand, significantly improving the utilization rate of the functional body and extending the long-term corrosion resistance period.

[0091] As an optional implementation, the mass ratio of the pH-responsive slow-release corrosion inhibitor to the mesoporous silica nanospheres is 1:(2~5), for example, it can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, etc.

[0092] As an optional implementation, the pH-responsive slow-release corrosion inhibitor includes nanoscale alkaline metal compounds.

[0093] As an optional implementation, the pH-responsive slow-release corrosion inhibitor includes any one or a combination of at least two of nano-Ca(OH)2, nano-Mg(OH)2, and nano-ZnO.

[0094] As an optional implementation, the pH-responsive slow-release corrosion inhibitor has a particle size of 10~30 nm, for example, it can be 10 nm, 12 nm, 14 nm, 15 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 25 nm, 26 nm, 28 nm, 30 nm, etc.

[0095] As an optional implementation, the pH-sensitive polymer is grafted onto the mesoporous pore inlet of the mesoporous silica nanospheres; and the pH-sensitive polymer shrinks the open pores when pH < 5 and expands the closed pores when pH > 6.

[0096] It should be noted that grafting the pH-sensitive polymer onto the mesoporous pore inlets of the mesoporous silica nanospheres solves the technical problems of indiscriminate and continuous release of traditional corrosion inhibitors, excessive consumption under normal conditions, low utilization of functional components, and short corrosion resistance lifespan. Simultaneously, it avoids the negative impact of premature corrosion inhibitor leakage on the optical and mechanical properties of the film. By grafting the pH-sensitive polymer onto the pore inlets to form a smart switch, the open pores only contract to release the active component when localized acid erosion occurs, and expand to close the pores under normal conditions to protect the internal corrosion inhibitor, achieving precise on-demand supply and significantly extending the long-lasting corrosion resistance period.

[0097] As an optional implementation, the grafting rate of the pH-sensitive polymer is 2 to 5 wt%, for example, it can be 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, etc.

[0098] As an optional implementation, the pH-sensitive polymer includes any one or a combination of at least two of polyacrylic acid, polymethacrylic acid, and polyacrylic acid-co-methyl methacrylate.

[0099] As an optional implementation, the weight-average molecular weight of the pH-sensitive polymer is 10,000 to 50,000, for example, it can be 10,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, etc.

[0100] As an optional implementation, the hydrophobic layer of the fluorinated acrylate copolymer is formed by copolymerization of fluorinated acrylate monomers and glycidyl methacrylate.

[0101] It should be noted that the hydrophobic layer of the fluorinated acrylate copolymer, formed by copolymerizing fluorinated acrylate monomers and glycidyl methacrylate, solves the technical problems of insufficient hydrophobic and water-blocking ability of traditional anti-corrosion functional materials, poor compatibility with EVA resin matrix, weak interfacial bonding, and difficulty in flexibly controlling the performance of single hydrophobic modified materials. By copolymerizing fluorinated acrylate monomers with glycidyl methacrylate, excellent hydrophobic and water-blocking properties are retained, while the interfacial bonding with the matrix is ​​enhanced through epoxy groups. A variety of fluorinated monomers are available, allowing for flexible control of hydrophobic effect and refractive index to meet different encapsulation requirements.

[0102] As an optional implementation, the fluorinated acrylate monomer includes any one or a combination of at least two of trifluoroethyl methacrylate, hexafluorobutyl methacrylate, and perfluoroalkyl ethyl acrylate.

[0103] As an optional implementation, the mass ratio of the fluorinated acrylate monomer to glycidyl methacrylate is (60~95):(5~40), for example, it can be 60:40, 61.6:38.4, 63.2:36.8, 64.8:35.2, 66.4:33.6, 68:32, 69.6:30.4, 71.2:28.8, 72.8:27.2, 74.4:25.6, 76:24, 77.6:22.4, 79.2:20.8, 80.8:19.2, 82.4:17.6, 84:16, 85.6:14.4, 87.2:12.8, 88.8:11.2, 90.4:9.6, 92:8, 93.6:6.4, 95:5, etc.

[0104] As an optional implementation, the fluorine content in the hydrophobic layer of the fluorinated acrylate copolymer is 20~40 wt%, for example, it can be 20 wt%, 22 wt%, 24 wt%, 26 wt%, 28 wt%, 30 wt%, 32 wt%, 34 wt%, 36 wt%, 38 wt%, 40 wt%, etc.

[0105] As an optional implementation, the contact angle of the hydrophobic layer of the fluorinated acrylate copolymer is >110°, for example, it can be 110°, 112°, 114°, 116°, 118°, 120°, 125°, 130°, etc.

[0106] As an optional implementation, the thickness of the hydrophobic layer of the fluorinated acrylate copolymer is 10~30 nm, for example, it can be 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, etc.

[0107] In a second aspect, the present invention provides a method for preparing a refractive index-matching anti-corrosion functional body as described in the first aspect, the method comprising: The mesoporous silica nanospheres were prepared by the sol-gel method. The pH-responsive slow-release corrosion inhibitor is introduced into the mesoporous silica nanospheres by vacuum impregnation to obtain mesoporous silica nanospheres loaded with the pH-responsive slow-release corrosion inhibitor. The core is obtained by grafting the pH-sensitive polymer onto mesoporous silica nanospheres via a carbodiimide chemical grafting reaction. The fluorinated acrylate copolymer hydrophobic layer is coated onto the surface of the core through emulsion polymerization to form a shell, thereby obtaining the refractive index-matched anti-corrosion functional body.

[0108] It should be noted that the preparation method of the refractive index-matched anti-corrosion functional body described in the second aspect solves the technical problems in the existing anti-corrosion functional body preparation process, such as poor controllability of carrier pores, uneven loading of functional components, easy polymer detachment, and non-dense shell coating, and difficulty in accurately controlling the refractive index. The sol-gel method can prepare mesoporous silica carriers with uniform pore structure; vacuum impregnation achieves efficient and uniform loading of anti-corrosion agents and avoids surface agglomeration; carbodiimide chemical grafting ensures covalent bonding of pH-sensitive polymers, resulting in stable and long-lasting switching performance; emulsion polymerization can form a uniform and dense hydrophobic shell, while precisely controlling the shell thickness and refractive index; the preparation method has strong overall process controllability and can mass-produce core-shell functional bodies with complete structure and stable performance.

[0109] As an optional implementation, the kernel preparation method specifically includes the following steps: (a) A silicon source, a mesoporous template agent, a pH adjuster and a solvent are mixed, reacted and then calcined to obtain the mesoporous silica nanospheres; (b) The mesoporous silica nanospheres, pH-responsive slow-release corrosion inhibitor and solvent II are mixed and vacuum impregnated to allow the pH-responsive slow-release corrosion inhibitor to enter the mesoporous silica nanospheres, thereby obtaining mesoporous silica nanospheres loaded with pH-responsive slow-release corrosion inhibitor. (c) The mesoporous silica nanospheres loaded with pH-responsive slow-release corrosion inhibitor, pH-sensitive polymer, carbodiimide grafting agent and solvent are mixed and a grafting reaction is carried out to graft the pH-sensitive polymer onto the mesoporous silica nanospheres to obtain the core; (d) The core, fluorinated acrylate monomer, glycidyl methacrylate, initiator and solvent are mixed and subjected to emulsion polymerization to form a shell. The solvent is then removed to obtain the refractive index matching anti-corrosion functional body.

[0110] As an optional implementation, in step (a), the silicon source includes tetraethyl orthosilicate.

[0111] As an optional implementation, in step (a), the mesoporous template agent comprises hexadecyltrimethylammonium bromide.

[0112] As an optional implementation, in step (a), the pH adjuster includes ammonia.

[0113] As an optional implementation, in step (a), the solvent is an aqueous solution of ethanol.

[0114] As an optional implementation, in step (a), the mass ratio of the silicon source, mesoporous template agent, pH adjuster and solvent is (10~20):(1~3):(4~8):(60~85); Among them, "10~20" can be, for example, 10, 12, 14, 15, 16, 18, 20, etc.; Among them, "1~3" can be, for example, 1, 1.5, 2, 2.5, 3, etc.; Among them, "4~8" can be, for example, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, etc.; Among them, "60~85" can be, for example, 60, 65, 70, 75, 80, 85, etc.

[0115] As an optional implementation, in step (a), the pH of the reaction is 8 to 12, for example, 8, 9, 10, 11, 12, etc., the reaction temperature is 30 to 50°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, etc., and the reaction time is 12 to 24 h, for example, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h, etc.

[0116] As an optional implementation, in step (a), the calcination temperature is 450~550℃, for example, it can be 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, etc., and the calcination time is 4~10 h, for example, it can be 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, etc.

[0117] As an optional implementation, in step (b), the solvent two is ethanol.

[0118] As an optional implementation, in step (b), the mass ratio of the mesoporous silica nanospheres, the pH-responsive slow-release corrosion inhibitor, and solvent II is (4~10):(1~2):(30~60); Among them, "4~10" can be, for example, 4, 5, 6, 7, 8, 9, 10, etc.; Among them, "1~2" can be, for example, 1, 1.2, 1.4, 1.5, 1.6, 1.8, 2, etc.; Among them, "30~60" can be, for example, 30, 35, 40, 45, 50, 55, 60, etc.

[0119] As an optional implementation, in step (b), the vacuum impregnation time is 8 to 16 hours, for example, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, etc.

[0120] As an optional implementation, in step (c), the carbodiimide grafting agent is a mixture of EDC-HCl and NHS.

[0121] As an optional implementation, in step (c), the solvent three is ethanol and / or an aqueous solution of MES buffer.

[0122] As an optional implementation, in step (c), the mass ratio of the mesoporous silica nanospheres loaded with pH-responsive slow-release corrosion inhibitor, the pH-sensitive polymer, the carbodiimide grafting agent, and the solvent is (8~15):(0.2~0.7):(0.5~1.2):(40~70); Among them, "8~15" can be, for example, 8, 9, 10, 11, 12, 13, 14, 15, etc.; Among them, "0.2~0.7" can be, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, etc.; Among them, "0.5~1.2" can be, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, etc.

[0123] As an optional implementation, in step (c), the temperature of the grafting reaction is 20~55℃, for example, it can be 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, etc., and the grafting reaction time is 4~10 h, for example, it can be 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, etc.

[0124] As an optional implementation, in step (d), the initiator is azobisisobutyramidine hydrochloride.

[0125] As an optional implementation, in step (d), the solvent is a mixed solution of ethanol and water.

[0126] As an optional implementation, in step (d), the mass ratio of the core, fluorinated acrylate monomer, glycidyl methacrylate, initiator, and solvent is (5~12):(3~7):(0.4~2.1):(0.08~0.25):(40~80); Among them, "5~12" can be, for example, 5, 6, 7, 8, 9, 10, 11, 12, etc.; Among them, "3~7" can be, for example, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, etc.; Among them, "0.4~2.1" can be, for example, 0.5, 0.6, 0.8, 1, 1.2, 1.4, 1.5, 1.6, 1.8, 2.1, etc.; Among them, "0.08~0.25" can be, for example, 0.08, 0.1, 0.12, 0.15, 0.18, 0.2, 0.25, etc.; Among them, "40~80" can be, for example, 40, 45, 50, 55, 60, 65, 70, 75, 80, etc.

[0127] As an optional implementation, in step (d), the temperature of the emulsion polymerization reaction is 50~80℃, for example, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, etc., and the time of the emulsion polymerization reaction is 4~12 h, for example, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, etc.

[0128] Thirdly, the present invention provides a gradient refractive index interface layer precursor, which comprises, from the inside out: an anti-corrosion functional body, a mercaptosilane coupling agent grafted layer, a trifluoroethyl methacrylate copolymer layer, and a maleic anhydride grafted ethylene-vinyl acetate copolymer layer. The corrosion-resistant functional body includes the refractive index-matching corrosion-resistant functional body as described in the first aspect.

[0129] It should be noted that the gradient refractive index interface layer precursor has at least the following advantages: Although the anti-corrosion functional component and the resin matrix achieve macroscopic refractive index matching, abrupt changes in refractive index still exist at the interface between the two at the microscopic scale. This leads to a significant Fresnel reflection loss. Traditional anti-corrosion film technologies generally neglect this microscopic interface optical problem, resulting in the actual transmittance of the film consistently being lower than the theoretically calculated value, becoming a hidden bottleneck for further improving optical performance.

[0130] Based on this, the present invention constructs a three-layer continuously gradient refractive index transition layer between the corrosion-resistant functional component and the EVA resin matrix, completely eliminating abrupt changes in interfacial refractive index. This interfacial layer, from the inside out, consists of: an inner layer of mercaptosilane coupling agent grafted layer, forming covalent bonds with the functional component surface; a middle layer of fluorinated acrylate copolymer layer, serving as an intermediate bridge for refractive index transition; and an outer layer of EVA-g-MAH grafted layer, achieving molecular-level compatibility with the matrix resin. Through the continuous and gradual change in refractive index of the three layers from the functional component side to the matrix side, the traditional "step-like" refractive index interface is transformed into a "slope-like" gradient interface. Light passing through no longer experiences sudden reflection and refraction, but smoothly transitions from one medium to another, thereby reducing single-interface Fresnel reflection loss. Under the cumulative effect of millions of functional component-matrix interfaces within the film, the overall optical loss is significantly reduced. Specifically, this gradient refractive index interface layer eliminates abrupt interface changes through a gradual change in refractive index, reducing the reflection loss of light passing through the functional body-matrix interface from 0.5% to below 0.15%. The cumulative effect of multiple interfaces increases the overall transmittance by 2-3 percentage points.

[0131] As an optional implementation, the refractive index of the mercaptosilane coupling agent graft layer is 1.51~1.53, for example, it can be 1.51, 1.512, 1.514, 1.516, 1.518, 1.52, 1.522, 1.524, 1.526, 1.528, 1.53, etc.

[0132] As an optional implementation, the thickness of the trifluoroethyl methacrylate copolymer layer is 1.49~1.51, for example, it can be 1.49, 1.492, 1.494, 1.496, 1.498, 1.50, 1.502, 1.504, 1.506, 1.508, 1.51, etc.

[0133] As an optional implementation, the thickness of the maleic anhydride-grafted ethylene-vinyl acetate copolymer layer is 1.48~1.50, for example, it can be 1.48, 1.482, 1.484, 1.486, 1.488, 1.49, 1.492, 1.494, 1.496, 1.498, 1.50, etc.

[0134] As an optional implementation, the thickness of the mercaptosilane coupling agent graft layer is 2~5 nm, for example, it can be 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, etc.

[0135] As an optional embodiment, the thickness of the trifluoroethyl methacrylate copolymer layer is 5~10 nm, for example, it can be 5 nm, 5.5 nm, 6 nm, 6.5 nm, 7 nm, 7.5 nm, 8 nm, 8.5 nm, 9 nm, 9.5 nm, 10 nm, etc.

[0136] As an optional implementation, the thickness of the maleic anhydride-grafted ethylene-vinyl acetate copolymer layer is 5~15 nm, for example, it can be 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, etc.

[0137] Fourthly, the present invention provides a method for preparing a gradient refractive index interface layer precursor as described in the second aspect, the method comprising: (A) The refractive index matching type anti-corrosion functional body is dispersed in an ethanol solution of mercaptosilane coupling agent and grafted to obtain an anti-corrosion functional body reaction solution grafted with mercaptosilane coupling agent. (B) Add trifluoroethyl methacrylate copolymer to the reaction solution one and cure it with ultraviolet light to form a trifluoroethyl methacrylate copolymer layer on the surface of the mercaptosilane coupling agent graft layer, thus obtaining reaction solution two. (C) Add maleic anhydride-grafted ethylene-vinyl acetate copolymer emulsion to the reaction solution II, and perform drying and curing treatment to form a maleic anhydride-grafted ethylene-vinyl acetate copolymer layer on the surface of the trifluoroethyl methacrylate copolymer layer, thereby obtaining the gradient refractive index interface layer precursor.

[0138] It should be noted that the preparation method of the gradient refractive index interface layer precursor described in this invention solves the technical problems of abrupt refractive index changes, large Fresnel reflection losses, weak interfacial bonding, easy delamination defects, and inability to form a continuous gradient refractive index transition region in traditional functional-matrix interfaces. This stepwise preparation method achieves a strong bond between the inner layer and the functional body and provides reaction sites through covalent grafting of mercaptosilane; ultraviolet light curing rapidly forms a uniform intermediate transition layer, precisely controlling the refractive index gradient; finally, molecular-level compatibility between the outer layer and the matrix is ​​achieved through EVA graft emulsion coating. The overall process is continuous and controllable, requiring no multiple separation and purification steps, and can batch-produce structurally complete and stable three-layer gradient refractive index interface layers, significantly reducing interfacial optical losses.

[0139] As an optional implementation, in step (A), the mercaptosilane coupling agent is 3-mercaptopropyltrimethoxysilane.

[0140] As an optional implementation, in step (A), the mass ratio of the refractive index matching anti-corrosion functional body, mercaptosilane coupling agent, and ethanol is (6~12):(0.3~0.8):(50~90); Among them, "6~12" can be, for example, 6, 7, 8, 9, 10, 11, 2, etc.; Among them, "0.3~0.8" can be, for example, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, etc.; Among them, "50~90" can be, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, etc.

[0141] As an optional implementation, in step (A), the temperature of the grafting reaction is 40~60℃, for example, 40℃, 45℃, 50℃, 55℃, 60℃, etc., and the grafting reaction time is 4~8 h, for example, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, etc.

[0142] As an optional implementation, in step (B), the mass ratio of the trifluoroethyl methacrylate copolymer to the anti-corrosion functional body is (1~3):(8~12); Among them, "1~3" can be, for example, 1, 1.5, 2, 2.5, 3, etc.; Among them, "8~12" can be, for example, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, etc.

[0143] As an optional implementation, in step (B), the intensity of the UV curing is 5~20 mW / cm². 2 For example, it could be 5 mW / cm 2 6 mW / cm 2 8 mW / cm 2 10 mW / cm 2 12 mW / cm 2 14 mW / cm 2 16 mW / cm 2 18 mW / cm 2 20 mW / cm 2 The UV curing time is 3 to 10 minutes, for example, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc.

[0144] As an optional implementation, in step (C), the mass ratio of the maleic anhydride-grafted ethylene-vinyl acetate copolymer to the anti-corrosion functional body is (0.8~2.5):(8~12); Among them, "0.8~2.5" can be, for example, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, etc.; Among them, "8~12" can be, for example, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, etc.

[0145] As an optional implementation, in step (C), the solid content of the maleic anhydride-grafted ethylene-vinyl acetate copolymer emulsion is 15~30 wt%, for example, it can be 15 wt%, 16 wt%, 18 wt%, 20 wt%, 22 wt%, 24 wt%, 25 wt%, 26 wt%, 28 wt%, 30 wt%, etc.

[0146] As an optional implementation, in step (C), the temperature of the drying and curing treatment is 60~100℃, for example, it can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, etc., and the drying and curing treatment time is 10~30min, for example, it can be 10 min, 15 min, 20 min, 25 min, 30 min, etc.

[0147] Fifthly, the present invention provides an adhesive film, the adhesive film comprising, by weight, the following components: 100 parts of matrix resin, 1-8 parts of the refractive index matching anti-corrosion functional body described in the first aspect, 0.5-3 parts of the gradient refractive index interface layer precursor described in the second aspect, 0.5-2 parts of crosslinking agent, 0.3-1.5 parts of long-lasting anti-PID synergist, and 0.2-1 parts of light stabilizer.

[0148] It should be noted that this invention addresses three common industry bottlenecks in existing anti-corrosion film technologies: the inability to simultaneously achieve corrosion resistance and light transmittance, short-term effectiveness followed by long-term failure, and passive neutralization rather than active blocking. It proposes a systematic and disruptive technological solution. Compared with existing technologies, the core innovative breakthroughs of this invention are reflected in the following four aspects: (1) Design of dual mechanism of hydrophobic barrier and chemical anchoring: Breaking through the limitations of the existing single acid neutralization, the synergistic anti-corrosion mechanism of physical hydrophobic barrier and chemical bonding lock is used to block the dual paths of water vapor intrusion and acetic acid corrosion from the source.

[0149] (2) Refractive index matching type anti-corrosion functional body: It solves the industry problem of severe mismatch between the refractive index of traditional metal oxide anti-acid agents (refractive index of about 1.7) and EVA resin (refractive index of 1.5). It designs organic-inorganic hybrid anti-corrosion microspheres with refractive index that can be precisely controlled in the range of 1.48~1.52, which fundamentally avoids the problem of decreased light transmittance and increased haze of the film under high addition.

[0150] (3) Gradient refractive index interface layer technology: A continuous and gradual gradient refractive index transition zone is constructed between the anti-corrosion functional body and the resin matrix, which reduces the Fresnel reflection loss at the interface by more than 60%, and achieves that the light transmittance of the film is still maintained above 94% even when the amount of anti-corrosion functional body added is 1~5%.

[0151] (4) Intelligent response acid capture mechanism: It abandons the defective mode of instant neutralization and rapid depletion of traditional metal oxides and designs a pH-responsive slow-release anti-corrosion agent. It only releases the active components precisely when the local acid concentration exceeds the standard, achieving a long-term anti-corrosion effect. After 2000 h of aging, the acid value inside the film is still below 30 ppm.

[0152] As an optional embodiment, the matrix resin in the adhesive film is 100 parts by weight.

[0153] As an optional implementation, the refractive index matching type anti-corrosion functional body described in the first aspect is in the film in parts by weight of 1 to 8, for example, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, etc.

[0154] As an optional implementation, in the adhesive film, the weight fraction of the gradient refractive index interface layer precursor described in the second aspect is 0.5 to 3 parts, for example, it can be 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, 3 parts, etc.

[0155] As an optional implementation, the crosslinking agent in the adhesive film is 0.5 to 2 parts by weight, for example, 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, etc.

[0156] As an optional implementation, the long-acting anti-PID synergist in the film is 0.3 to 1.5 parts by weight, for example, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.5 parts, etc.

[0157] As an optional implementation, the light stabilizer in the film is 0.2 to 1 part by weight, for example, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, etc.

[0158] It should be noted that the specific composition and ratio of the encapsulant film solves the technical problems in traditional photovoltaic encapsulant film formulations, such as the difficulty in balancing corrosion resistance, light transmittance, and mechanical properties, poor synergy among components, and optical degradation or functional deficiencies caused by imbalances in the amount added. This formulation, based on the matrix resin, precisely controls the optimal addition range of each functional component: the corrosion-resistant functional component balances long-term protection and optical performance; the gradient refractive index precursor further reduces interfacial reflection loss; the crosslinking agent ensures the crosslinking strength and processing compatibility of the encapsulant film; and the anti-PID synergist and light stabilizer synergistically improve the long-term reliability of the module. The synergistic effect of each component achieves a comprehensive balance of ultra-transparency, long-term corrosion resistance, and high weather resistance in the encapsulant film.

[0159] As an optional embodiment, the matrix resin includes ethylene-vinyl acetate copolymer (EVA).

[0160] As an optional embodiment, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 26~33 wt%, for example, it can be 26 wt%, 26.5 wt%, 27 wt%, 27.5 wt%, 28 wt%, 28.5 wt%, 29 wt%, 29.5 wt%, 30 wt%, 30.5 wt%, 31 wt%, 31.5 wt%, 32 wt%, 32.5 wt%, 33 wt%, etc.

[0161] As an optional implementation, the melt index of the ethylene-vinyl acetate is 15~25 g / 10 min (190℃ / 2.16 kg), for example, it can be 15 g / 10 min, 16 g / 10 min, 17 g / 10 min, 18 g / 10 min, 19 g / 10 min, 20 g / 10 min, 21 g / 10 min, 22 g / 10 min, 23 g / 10 min, 24 g / 10 min, 25 g / 10 min, etc.

[0162] As an optional implementation, the crosslinking agent includes peroxides and co-crosslinking agents.

[0163] As an optional embodiment, the peroxide includes any one or a combination of at least two of the following: 2-ethylhexyl carbonate tert-amyl peroxide, tert-butyl peroxycarbonate-2-ethylhexyl peroxide, 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, tert-butyl peroxide-3,5,5-trimethylhexanoate, benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, and di-tert-butyl peroxide.

[0164] As an optional implementation, the co-crosslinking agent includes any one or a combination of at least two of the following: trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, triallyl isocyanurate, tetramethyltetravinylcyclotetrasiloxane, 4-acryloylmorpholine, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, neopentyl glycol (2)PO diacrylate, polyethylene glycol 200 diacrylate, EO (3) trimethylolpropane triacrylate, and 3(propoxy)propanetriol triacrylate.

[0165] As an optional implementation, the long-acting anti-PID synergist includes any one or a combination of at least two of nano-magnesium hydroxide, organic zinc carboxylate, borate corrosion inhibitor particles, zirconium phosphate, and zirconium hydrogen phosphate.

[0166] As an optional implementation, the light stabilizer includes hindered amines and ultraviolet absorbers.

[0167] As an optional implementation, the hindered amine includes any one or a combination of at least two of HALS-944, HALS-770, and HALS-622.

[0168] As an optional implementation, the ultraviolet absorber includes any one or a combination of at least two of UV-327, UV-531, UV329, UV328, and UV-1130.

[0169] As an optional implementation, the thickness of the adhesive film is 0.4~0.6 mm, for example, it can be 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, etc.

[0170] Sixthly, the present invention provides a method for preparing an adhesive film as described in the fifth aspect, the method comprising: The matrix resin, the refractive index-matched anti-corrosion functional body, the gradient refractive index interface layer precursor, the crosslinking agent, the long-lasting anti-PID synergist, and the light stabilizer are mixed in a certain proportion, melt-blended and granulated through a twin-screw extruder, then formed into a film through a casting extruder, cooled and shaped, and then wound up to obtain the adhesive film.

[0171] As an optional implementation, the granulation temperature is 100~140℃, for example, it can be 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, etc.

[0172] As an optional implementation, the temperature of the film-forming die head is 110~130℃, for example, it can be 110℃, 112℃, 114℃, 116℃, 118℃, 120℃, 122℃, 124℃, 126℃, 128℃, 130℃, etc.

[0173] In a seventh aspect, the present invention provides the application of the refractive index matching anti-corrosion functional body as described in the first aspect, or the gradient refractive index interface layer precursor as described in the second aspect, or the encapsulant film as described in the third aspect in the preparation of encapsulation materials for solar photovoltaic modules.

[0174] As an optional implementation, the solar photovoltaic module includes any one or a combination of at least two of N-type TOPCon cells, HJT cells, and PERC cells.

[0175] It should be noted that the encapsulating film described herein is used in the encapsulation of photovoltaic modules, specifically for the front and / or back encapsulation of N-type TOPCon, HJT, or PERC cells. This encapsulating film is widely adaptable to the front and back encapsulation of mainstream photovoltaic cells such as N-type TOPCon, HJT, and PERC, solving the pain point that traditional encapsulating films cannot simultaneously meet the high light transmittance requirements and stringent corrosion resistance demands of high-efficiency cells. Its ultra-high light transmittance and low haze characteristics maximize the utilization of incident light, significantly improving the power generation efficiency of both sides of bifacial modules; its long-lasting corrosion resistance effectively inhibits the corrosion of cell electrodes by acetic acid generated from EVA hydrolysis, significantly reducing the module power degradation rate. Simultaneously, the film's excellent processing performance and universal adaptability allow for direct compatibility with existing module production lines without additional equipment modifications, contributing to the large-scale application of high-efficiency photovoltaic modules and significantly reducing the cost per kilowatt-hour of photovoltaic power generation.

[0176] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0177] Example 1 This embodiment provides a refractive index-matched anti-corrosion functional body, a gradient refractive index interface layer precursor, and an adhesive film.

[0178] (I) Refractive index-matched corrosion-resistant functional body and its preparation method: (I-1) Specific structure of refractive index matching type anti-corrosion functional body: The refractive index-matched anti-corrosion functional body has a core-shell structure; the core of the refractive index-matched anti-corrosion functional body includes mesoporous silica nanospheres, which are loaded with a pH-responsive slow-release anti-corrosion agent and grafted with a pH-sensitive polymer; the overall refractive index of the refractive index-matched anti-corrosion functional body is 1.50; the refractive index difference between the core and the shell is 0.02; the refractive index difference between the refractive index-matched anti-corrosion functional body and EVA resin is 0.01. The mesoporous silica nanospheres have an average particle size of 200 nm and an average pore size of 15 nm. The pH-responsive slow-release corrosion inhibitor is encapsulated within the mesoporous channels of the mesoporous silica nanospheres. The mass ratio of the pH-responsive slow-release corrosion inhibitor to the mesoporous silica nanospheres is 1:3.5. The pH-responsive slow-release corrosion inhibitor is nano-sized Ca(OH)₂ with an average particle size of 10 nm. The pH-sensitive polymer is polyacrylate-co-methyl methacrylate (weight average molecular weight 30,000), grafted onto the inlet of the mesoporous channels of the mesoporous silica nanospheres. The pH-sensitive polymer shrinks open channels when pH < 5 and expands closed channels when pH > 6. The grafting rate of the pH-sensitive polymer is 3.5 wt%. The fluorinated acrylate copolymer hydrophobic layer is formed by copolymerizing 80 parts of trifluoroethyl methacrylate and 20 parts of glycidyl methacrylate; wherein the fluorine content in the fluorinated acrylate copolymer hydrophobic layer is 30 wt%, the contact angle is 119°, and the thickness is 20 nm.

[0179] (I-2) Preparation method of refractive index matching type corrosion-resistant functional body: (a) 15 parts of tetraethyl orthosilicate, 2 parts of hexadecyltrimethylammonium bromide, 6 parts of ammonia (25 vol%) and 77 parts of aqueous ethanol (60 vol%) were mixed and reacted at 40 °C for 18 h in a system with pH 10. The solvent was removed to obtain the precursor, which was then calcined at 500 °C for 6 h to obtain the mesoporous silica nanospheres. (b) Mix 7 parts of the mesoporous silica nanospheres, 2 parts of nano-sized Ca(OH)2 and 45 parts of ethanol, and vacuum impregnate for 12 h to allow the pH-responsive slow-release corrosion inhibitor to enter the mesoporous silica nanospheres, thereby obtaining mesoporous silica nanospheres loaded with pH-responsive slow-release corrosion inhibitor. (c) 10 parts of the aforementioned pH-responsive slow-release corrosion inhibitor-loaded mesoporous silica nanospheres, 0.45 parts of polyacrylate-co-methyl methacrylate, and 0.8 parts of carbodiimide grafting agent (EDC) A HCl and NHS complex system (EDC:NHS mass ratio 2:1) was mixed with 55 parts of solvent trioxide (0.1 mol / L MES buffered ethanol aqueous solution, pH=5.0) and grafted onto mesoporous silica nanospheres at 30°C for 6 h to obtain the core. (d) Mix 8 parts of the core, 5 parts of trifluoroethyl methacrylate, 1.25 parts of glycidyl methacrylate, 0.15 parts of initiator (AIBA azobisisobutyramidine hydrochloride), and 60 parts of solvent (a mixture of deionized water and anhydrous ethanol, with a water-to-ethanol volume ratio of 1:1), and carry out emulsion polymerization at 72 °C for 9 h to form a shell. Remove the solvent to obtain the refractive index-matched anti-corrosion functional body.

[0180] (II) Precursor for gradient refractive index interface layer and its preparation method: (II-1) Structure of the gradient refractive index interface layer precursor: The gradient refractive index interface layer precursor comprises, from the inside out: the refractive index-matching anti-corrosion functional body described in (I) above, a mercaptosilane coupling agent grafted layer, a trifluoroethyl methacrylate copolymer layer, and a maleic anhydride-grafted ethylene-vinyl acetate copolymer layer; the refractive index of the mercaptosilane coupling agent grafted layer is 1.52, the thickness of the trifluoroethyl methacrylate copolymer layer is 1.50, the thickness of the maleic anhydride-grafted ethylene-vinyl acetate copolymer layer is 1.49; the thickness of the mercaptosilane coupling agent grafted layer is 3.5 nm, the thickness of the trifluoroethyl methacrylate copolymer layer is 7.5 nm, and the thickness of the maleic anhydride-grafted ethylene-vinyl acetate copolymer layer is 10 nm.

[0181] (II-2) Preparation method of gradient refractive index interface layer precursor: (A) Dissolve 0.5 parts of mercaptosilane coupling agent (3-mercaptopropyltrimethoxysilane MPTMS) in 60 parts of ethanol to obtain an ethanol solution of mercaptosilane coupling agent; then, disperse 9 parts of the refractive index matching type anti-corrosion functional body described in (I) above in 60.5 parts of the ethanol solution of mercaptosilane coupling agent, and carry out a grafting reaction at 50°C for 4.5 h to form a mercaptosilane coupling agent graft layer on the surface of the refractive index matching type anti-corrosion functional body to obtain reaction solution one; (B) Add 2 parts of trifluoroethyl methacrylate copolymer (weight-average molecular weight 35,000) to the reaction solution, 12 mW / cm 2 The mixture is cured under ultraviolet light for 5 minutes to form a trifluoroethyl methacrylate copolymer layer on the surface of the mercaptosilane coupling agent grafted layer, thus obtaining reaction solution two. (C) Add 1.6 parts of maleic anhydride-grafted ethylene-vinyl acetate copolymer (weight average molecular weight of 80,000) emulsion to the reaction solution II. The solid content of the maleic anhydride-grafted ethylene-vinyl acetate copolymer emulsion is 22 wt%. After drying and curing for 20 min, a maleic anhydride-grafted ethylene-vinyl acetate copolymer layer is formed on the surface of the trifluoroethyl methacrylate copolymer layer to obtain the gradient refractive index interface layer precursor.

[0182] (III) Adhesive film and its preparation method: (III-1) Composition of the film: The film comprises the following components by weight: 100 parts of ethylene-vinyl acetate copolymer, 4.5 parts of the refractive index matching anti-corrosion functional body described in (I) above, 1.5 parts of the gradient refractive index interface layer precursor described in (II) above, 1 part of crosslinking agent, 1 part of long-lasting anti-PID synergist, and 0.5 parts of light stabilizer. The ethylene-vinyl acetate copolymer contains 28 wt% vinyl acetate, and the melt index of the ethylene-vinyl acetate copolymer is 25 g / 10 min (190℃ / 2.16 kg). The crosslinking agent comprises a peroxide (tert-butyl peroxycarbonate-2-ethylhexyl ester) and a co-crosslinking agent (traceryl isocyanurate) in a mass ratio of 1:1. The long-lasting anti-PID synergist is (nano zinc borate). The light stabilizer comprises a hindered amine (light stabilizer 770) and a UV absorber (UV-328) in a mass ratio of 1:2. The thickness of the adhesive film is 0.5 mm.

[0183] (III-2) Preparation method of adhesive film: The matrix resin, the refractive index matching anti-corrosion functional agent described in (I) above, the gradient refractive index interface layer precursor described in (II) above, the crosslinking agent, the long-lasting anti-PID synergist, and the light stabilizer are mixed in the above proportions, melt-blended and granulated by a twin-screw extruder (120°C), and then formed into a film by a casting extruder (120°C). After cooling and shaping, the film is wound up to obtain the adhesive film.

[0184] Example 2 This embodiment provides a refractive index-matched anti-corrosion functional body, a gradient refractive index interface layer precursor, and a film. The only difference from Example 1 is that the pH-responsive slow-release anti-corrosion agent is replaced with an equal mass and particle size of nano-Mg(OH)2; the pH-sensitive polymer is replaced with an equal mass and molecular weight of polyacrylic acid; and the fluorinated acrylate monomer is replaced with an equal mass of hexafluorobutyl methacrylate. All other steps are completely consistent with Example 1.

[0185] Example 3 This embodiment provides a refractive index-matched anti-corrosion functional body, a gradient refractive index interface layer precursor, and a film. The only difference from Example 1 is that the pH-responsive slow-release anti-corrosion agent is replaced with an equal mass and particle size of nano-ZnO; the pH-sensitive polymer is replaced with an equal mass and molecular weight of polymethacrylic acid; and the fluorinated acrylate monomer is replaced with an equal mass of perfluoroalkyl ethyl acrylate. All other steps are completely consistent with Example 1.

[0186] Example 4 This embodiment provides a refractive index-matched anti-corrosion functional body, a gradient refractive index interface layer precursor, and a film. The only difference from Embodiment 1 is that the mass ratio of the pH-responsive slow-release anti-corrosion agent to the mesoporous silica nanospheres is 1:2, and the grafting rate of the pH-sensitive polymer is 5 wt%; the other steps are completely consistent with Embodiment 1.

[0187] Example 5 This embodiment provides a refractive index-matched anti-corrosion functional body, a gradient refractive index interface layer precursor, and a film. The only difference from Embodiment 1 is that the mass ratio of the pH-responsive slow-release anti-corrosion agent to the mesoporous silica nanospheres is 1:5, and the grafting rate of the pH-sensitive polymer is 2 wt%; the other steps are completely consistent with Embodiment 1.

[0188] Example 6 This embodiment provides a refractive index-matched anti-corrosion functional body, a gradient refractive index interface layer precursor, and a film. The only difference from Embodiment 1 is that the thickness of the hydrophobic layer of the fluorinated acrylate copolymer is 10 nm; the other steps are completely the same as in Embodiment 1.

[0189] Example 7 This embodiment provides a refractive index-matched anti-corrosion functional body, a gradient refractive index interface layer precursor, and a film. The only difference from Embodiment 1 is that the thickness of the hydrophobic layer of the fluorinated acrylate copolymer is 15 nm; the other steps are completely the same as in Embodiment 1.

[0190] Example 8 This embodiment provides a refractive index-matched anti-corrosion functional body, a gradient refractive index interface layer precursor, and a film. The only difference from Embodiment 1 is that the thickness of the mercaptosilane coupling agent grafted layer is 2 nm, the thickness of the trifluoroethyl methacrylate copolymer layer is 5 nm, and the thickness of the maleic anhydride grafted ethylene-vinyl acetate copolymer layer is 5 nm; the other steps are completely consistent with Embodiment 1.

[0191] Example 9 This embodiment provides a refractive index-matched anti-corrosion functional body, a gradient refractive index interface layer precursor, and a film. The only difference from Embodiment 1 is that the thickness of the mercaptosilane coupling agent grafted layer is 5 nm, the thickness of the trifluoroethyl methacrylate copolymer layer is 10 nm, and the thickness of the maleic anhydride grafted ethylene-vinyl acetate copolymer layer is 15 nm; the other steps are completely consistent with Embodiment 1.

[0192] Example 10 This embodiment provides a refractive index-matching anti-corrosion functional body, a gradient refractive index interface layer precursor, and a film. The only difference from Embodiment 1 is that the film, by weight, comprises the following components: 100 parts of matrix resin, 1 part of the refractive index-matching anti-corrosion functional body provided in Embodiment 1, 3 parts of the gradient refractive index interface layer precursor provided in Embodiment 1, 0.5 parts of crosslinking agent, 1.5 parts of long-lasting anti-PID synergist, and 0.2 parts of light stabilizer; all other steps are completely consistent with Embodiment 1.

[0193] Example 11 This embodiment provides a refractive index-matching anti-corrosion functional body, a gradient refractive index interface layer precursor, and a film. The only difference from Embodiment 1 is that the film, by weight, comprises the following components: 100 parts of matrix resin, 8 parts of the refractive index-matching anti-corrosion functional body provided in Embodiment 1, 0.5 parts of the gradient refractive index interface layer precursor provided in Embodiment 1, 2 parts of crosslinking agent, 0.3 parts of long-lasting anti-PID synergist, and 1 part of light stabilizer; all other steps are completely consistent with Embodiment 1.

[0194] Example 12 This embodiment provides a refractive index-matched anti-corrosion functional body, a gradient refractive index interface layer precursor, and a film. The only difference from Embodiment 1 is that the crosslinking agent is replaced with an equal mass of dicumyl peroxide (DCP), the long-lasting anti-PID synergist is replaced with an equal mass of zinc carboxylate complex, and the light stabilizer is replaced with an equal mass of light stabilizer 622; the other steps are completely consistent with Embodiment 1.

[0195] Comparative Example 1 This comparative example provides a film that differs from Example 1 only in that it no longer adds a refractive index-matching anti-corrosion functional body and a gradient refractive index interface layer precursor; instead, it directly adds 6 parts of the mesoporous silica nanospheres prepared in Example 1; the other steps are completely consistent with Example 1.

[0196] Comparative Example 2 This comparative example provides an anti-corrosion functional body, an interface layer precursor, and a film. The only difference from Example 1 is that the anti-corrosion functional body no longer supports nano-sized Ca(OH)2, and the corresponding interface layer precursor also lacks this component; the other steps are completely consistent with Example 1.

[0197] Comparative Example 3 This comparative example provides an anti-corrosion functional body, an interface layer precursor, and a film. The only difference from Example 1 is that the anti-corrosion functional body is no longer grafted with polyacrylic acid-co-methyl methacrylate, and the corresponding interface layer precursor also lacks this component; the other steps are completely consistent with Example 1.

[0198] Comparative Example 4 This comparative example provides an anti-corrosion functional body, an interface layer precursor, and a film. The only difference from Example 1 is that the anti-corrosion functional body is no longer coated with a hydrophobic layer of fluorinated acrylate copolymer, and the corresponding interface layer precursor also lacks this component; the other steps are completely consistent with Example 1.

[0199] Comparative Example 5 This comparative example provides a refractive index-matched anti-corrosion functional body, an interface layer precursor, and a film. The only difference from Example 1 is that the interface layer precursor does not contain a mercaptosilane coupling agent graft layer; the other steps are completely consistent with Example 1.

[0200] Comparative Example 6 This comparative example provides a refractive index-matched anti-corrosion functional body, an interface layer precursor, and a film. The only difference from Example 1 is that the interface layer precursor does not contain a trifluoroethyl methacrylate copolymer layer; the other steps are completely consistent with Example 1.

[0201] Comparative Example 7 This comparative example provides a refractive index-matched anti-corrosion functional body, an interface layer precursor, and a film. The only difference from Example 1 is that the interface layer precursor does not contain a maleic anhydride-grafted ethylene-vinyl acetate copolymer layer; the other steps are completely consistent with Example 1.

[0202] Comparative Example 8 This comparative example provides a gradient refractive index interface layer precursor and a film. The only difference from Example 1 is that the refractive index matching anti-corrosion functional body described in (I) is no longer added to the film, and the content of the gradient refractive index interface layer precursor described in (II) is increased to 6 parts; the other steps are completely consistent with Example 1.

[0203] Comparative Example 9 This comparative example provides a refractive index matching type anti-corrosion functional body and film. The only difference from Example 1 is that the gradient refractive index interface layer precursor described in (II) above is no longer added to the film, and the content of the refractive index matching type anti-corrosion functional body described in (I) above is increased to 6 parts; the other steps are completely consistent with Example 1.

[0204] Test Example 1 Test samples: adhesive films provided in Examples 1-12 and comparative examples 1-9.

[0205] Test method: (1) Transmittance (%) (380~1100 nm): GB / T 2410-2008.

[0206] (2) Haze (%): GB / T 2410-2008.

[0207] (3) Water vapor transmission rate (g / m 2 •day): GB / T 26253-2010.

[0208] (4) Acid value (ppm) after 1000 h of aging with double 85: T / CPIA 0073—2024 Test method for acid content in encapsulation film for photovoltaic modules.

[0209] The specific test results are shown in Table 1: Table 1

[0210] As shown in Table 1, the film prepared by the present invention from the refractive index-matched anti-corrosion functional body and the gradient refractive index interface layer precursor has a light transmittance of 92.5-94.0%, a haze of 2.5-4.0%, and a water vapor transmission rate of 15 g / m. 2 The acid value is below 30 ppm after 1000 hours of aging with dual 85 coatings. This fully demonstrates that the present invention, through the synergistic innovation of a refractive index-matched anti-corrosion functional body and a gradient refractive index interface layer, has successfully solved the long-standing core technical challenge in the photovoltaic encapsulation film field of "the incompatibility between corrosion resistance and light transmittance." The film exhibits comprehensive and excellent performance, maintaining ultra-high light transmittance and extremely low haze while possessing excellent water vapor barrier capabilities, reducing the possibility of acetic acid production from EVA hydrolysis at the source. After rigorous high-temperature and high-humidity aging tests, the acid value inside the film remains at an extremely low level, significantly extending the effective lifespan of corrosion resistance. All key performance indicators comprehensively surpass the existing technology level, verifying the scientific nature and advancement of the technical solution of the present invention, and providing reliable material support for the long-term stable operation of high-efficiency photovoltaic modules.

[0211] Test Example 2 Test samples: adhesive films provided in Examples 1-12 and comparative examples 1-9.

[0212] Test method: (1) Initial power: GB / T 6495.1-2021.

[0213] (2) Power after aging of 2000 h with dual 85: GB / T 2423.3-2016, GB / T 9535-2023, GB / T 6495.1-2021.

[0214] (3) EL testing: IEC 61730-2-2023 "Safety qualification of photovoltaic modules - Part 2 Test requirements".

[0215] The specific test results are shown in Table 2: Table 2

[0216] As shown in Table 2, the initial output power of the module is 1.2-1.8% higher than that of the comparative packages. This gain mainly comes from the excellent optical performance of the encapsulant film. After 2000 hours of high temperature and humidity aging at 85°C, the module power decay rate is less than 3%, far superior to the 4-10% decay level of the comparative packages. In addition, electroluminescence (EL) detection shows that there are no obvious black spots of cell corrosion after aging, which fully verifies the excellent long-term anti-corrosion protection capability of the encapsulant film of this invention. This fully demonstrates that the significant improvement in the initial output power of the module fully verifies the optical gain effect brought by the ultra-high light transmittance and low haze design of the encapsulant film of this invention; the extremely low power decay rate after aging strongly proves the reliability and stability of the intelligent response long-term anti-corrosion mechanism; and the result of no obvious black spots of cell corrosion in the EL detection more intuitively confirms the all-round long-term protection of the cell electrodes by the encapsulant film. This invention completely solves the common industry problem of rapid power decay caused by corrosion during long-term service of traditional EVA encapsulant films, providing a solid material foundation for the long-term stable operation of high-efficiency photovoltaic modules.

[0217] A comparison of Examples 1 and 2-3 shows that after changing the pH-controlled corrosion inhibitor and fluorinated monomer in different systems, the optical and anti-corrosion properties of the film fluctuated slightly but remained at a high level overall. Light transmittance, haze, moisture barrier properties, and aging acid value all remained within excellent ranges. The initial power of the corresponding encapsulated components decreased slightly, while the aging power decay increased slightly. The EL only showed slight uneven brightness, without fatal defects such as grid line corrosion or delamination. This indicates that all three types of alkaline corrosion inhibitors and fluorinated monomers are suitable for the system, and the combination of nano-calcium hydroxide and trifluoroethyl methacrylate exhibits the best overall performance.

[0218] A comparison of Examples 1 and 4-5 shows that after adjusting the ratio of the slow-release corrosion inhibitor to silica and changing the grafting rate of the pH-sensitive polymer, the light transmittance of the film decreased slightly, the haze and water vapor barrier performance deteriorated slightly, and the aging acid value increased slightly. The initial power of the supporting components decreased slightly, the aging degradation increased slightly, and only slight edge dark spots appeared, without serious defects such as grid line corrosion or delamination. Both formulation schemes can achieve basic long-term protection, and the combination of moderate load and grafting rate provides better overall optical and corrosion protection balance.

[0219] A comparison of Examples 1 and 6-7 shows that reducing the thickness of the fluorinated hydrophobic outer shell slightly reduces the light transmittance of the film, weakens its haze and water vapor barrier capabilities, and slightly increases the acid value of the system after aging. The corresponding initial power of the photovoltaic module decreases slightly, while the power degradation during long-term aging increases, and slight dark areas appear in the EL image. However, no serious failure problems such as grid line corrosion or interface delamination occur. The thickness of the fluorinated layer directly affects the hydrophobic and water-blocking effects and optical matching; the originally set thickness can balance the advantages of both light transmittance and long-term corrosion protection.

[0220] Compared with Examples 8-9, after adjusting the overall thickness of the three-layer gradient interface layer, the light transmittance, water vapor barrier, and acid resistance of the film showed slight fluctuations. A thinner interface layer resulted in better optical uniformity and higher uniformity of the module's EL brightness. A thicker interface layer improved interface compatibility, but increased haze, decreased water vapor barrier effect, accelerated power decay over long-term aging, and increased likelihood of edge dark spots on the module. There is an optimal range for the gradient layer thickness; a moderate layer thickness can balance optical loss and interface protection.

[0221] Comparing Examples 10 and 11, after changing the addition ratio of the two core functional components, the optical properties and resistance to damp heat and corrosion of the film only fluctuated slightly. Reducing the anti-corrosion functional component and increasing the gradient interface precursor resulted in better light transmission, but slightly weakened corrosion resistance; conversely, haze increased slightly and aging acid value increased slightly. The corresponding component power attenuation was not significantly different, and there were no obvious corrosion defects. Both ratios can be used stably, and the combination of moderate additions can balance optical gain and long-term corrosion resistance.

[0222] Comparing Example 1 and Example 12, after changing the types of crosslinking, anti-PID, and light-stabilizing additives, the film's light transmittance, haze, water vapor barrier properties, and aging acid value only fluctuated slightly, with little difference in overall performance. The initial power of the matching photovoltaic module decreased slightly, while the long-term aging power degradation increased slightly. No serious defects such as corrosion spots or delamination were observed in the EL (photovoltaic film). This indicates that the additive replacement system in Example 1 has good compatibility, and all alternative additives can meet basic usage requirements. The original additive combination has a greater advantage in terms of overall balance between optical properties and weather resistance / corrosion protection.

[0223] Compared with Comparative Example 1, Example 1, which only filled with mesoporous silica without the composite core-shell functional body, showed significantly reduced light transmittance, significantly increased haze, and poorer water vapor barrier performance. After aging, the acid value of the system was significantly higher. The initial output power of the encapsulated component was low, and the power decay was severe after long-term aging. EL detection revealed large-area blackening of the grid lines and delamination / microcracks. This confirms that the refractive matching slow-release anti-corrosion core-shell structure of this invention can simultaneously achieve high light transmittance and long-term acid suppression and corrosion protection, overcoming the shortcomings of traditional inorganic fillers that cannot simultaneously achieve both optical and protective properties.

[0224] Compared with Comparative Example 2, after removing the internal slow-release corrosion inhibitor, the optical properties of the encapsulant film deteriorated slightly, the water vapor barrier decreased slightly, and the aging acid value increased significantly. The corresponding photovoltaic module experienced significantly accelerated power degradation over long-term aging, with EL analysis showing large-area corrosion and blackening of the main grid, and interface delamination defects. This demonstrates that the alkaline slow-release component loaded in the core is the key to acid suppression and corrosion prevention. Without this pH-responsive neutralization system, it is impossible to continuously neutralize the acetic acid produced by EVA hydrolysis, making it difficult to provide long-term protection for the battery grid lines.

[0225] Compared with Comparative Example 3, after removing the pH-sensitive polymer at the pore inlet, the film's light transmittance and haze only slightly deteriorated, but the aging acid value increased significantly. After long-term humid heat aging, the power attenuation of the supporting components increased dramatically, and obvious corrosion channels were visible around the solder ribbon in the EL (electrochemical) image. The lack of a pH-responsive switch structure resulted in premature and indiscriminate consumption of the internal corrosion inhibitor, preventing the timely release to neutralize acidic substances and significantly shortening the anti-corrosion effectiveness. This confirms that the polymer is a key structure for achieving long-term slow-release protection.

[0226] Compared with Comparative Example 4, after removing the outer fluorinated hydrophobic shell layer, the water vapor barrier performance of the film significantly decreased, the aging acid value significantly increased, and the optical performance slightly deteriorated. The corresponding components experienced accelerated power decay over long-term aging, and large areas of dark spots appeared in the EL (electroluminescent substrate), making it easier for water vapor to penetrate and cause corrosion. The fluorinated copolymer hydrophobic layer can construct a low surface energy barrier, reducing water vapor penetration and inhibiting acetic acid formation at the source, while also helping to improve filler dispersibility. It is an important structure that balances water barrier and optical performance; its absence would significantly weaken the overall protective capability.

[0227] Compared with Comparative Example 5, after removing the mercaptosilane graft layer, the haze of the film increased significantly, the water vapor barrier capacity decreased, and the aging acid value increased substantially. The initial power of the module decreased, the long-term aging degradation intensified, and dark spots appeared at the edges of the EL. The silane layer acts as a bridging transition, firmly binding the anti-corrosion microspheres and establishing the starting point for the refractive index gradient. After its removal, the interface exhibits abrupt refractive changes, the filler compatibility deteriorates, water vapor and acidic media easily penetrate along the interface, and the optical and anti-corrosion properties deteriorate simultaneously.

[0228] Compared with Comparative Example 6, Example 1, without the intermediate trifluoroethyl methacrylate transition layer, showed increased film haze, poorer water vapor barrier properties, and a significantly higher aging acid value. The initial power of the module decreased, long-term aging degradation worsened, and localized uneven light scattering and slight darkening of the grid lines appeared at the interface. This layer, acting as a bridge between the refractive index gradients, eliminates abrupt optical changes at the interface and buffers dielectric stress. Its absence increases light loss, and water vapor and acidic media diffuse more easily along the interface, resulting in simultaneous damage to both optical and long-term protective performance.

[0229] Compared with Comparative Example 7, after removing the outer maleic anhydride-grafted EVA transition layer, the haze of the film increased, the water vapor barrier effect weakened, and the aging acid value increased significantly. The initial output of the corresponding component decreased, the long-term power decay increased, and the EL exhibited edge delamination and slight corrosion defects. This outer layer structure improves the compatibility between the functional component and the matrix resin and perfects the refractive index gradient system. Its absence leads to a decrease in interfacial bonding, allowing water vapor and acetic acid to easily penetrate along the gaps, resulting in a simultaneous decline in optical performance and long-term corrosion resistance.

[0230] Compared with Comparative Example 8, Example 1, with only the addition of a gradient interface precursor and no refractive matching anti-corrosion core, showed decreased film transmittance, significantly increased haze, and greatly weakened water vapor barrier and acid suppression capabilities. The initial power of the encapsulated component was low, and the long-term aging degradation was significant, with multiple dark spots appearing at the interface in the EL. Lacking a core-shell body with a loaded slow-release anti-corrosion agent, the system lacked the core function of long-term neutralization of acidic substances, and relying solely on the interface transition layer could not achieve excellent anti-corrosion effects; both optical matching and anti-corrosion performance showed significant shortcomings.

[0231] Compared with Comparative Example 9, Example 1, which only added corrosion-resistant core-shell microspheres without a gradient refractive index interface layer, showed a significant increase in film haze, and a simultaneous deterioration in water vapor barrier and acid resistance. The initial power of the module decreased, and long-term aging degradation was more pronounced. Slight corrosion of the EL grid lines and poor interface compatibility were observed. The gradient interface layer can eliminate abrupt refractive changes between the microspheres and the resin, strengthening interfacial bonding. The absence of this structure leads to additional light loss, and water vapor and acid easily penetrate along the interfacial gaps, resulting in a significant decrease in both optical and long-term protective performance.

[0232] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A refractive index-matching anti-corrosion functional body, characterized in that, The refractive index-matching anti-corrosion functional body has a core-shell structure; The core of the refractive index-matched anti-corrosion functional body includes mesoporous silica nanospheres, which are loaded with a pH-responsive slow-release anti-corrosion agent and grafted with a pH-sensitive polymer. The outer shell of the refractive index-matched corrosion-resistant functional body includes a hydrophobic layer of fluorinated acrylate copolymer.

2. The refractive index-matching anti-corrosion functional body according to claim 1, characterized in that, The overall refractive index of the refractive index-matched corrosion-resistant functional body is 1.48~1.52; the refractive index difference between the core and the outer shell is ≤0.03; Preferably, the mesoporous silica nanospheres have a particle size of 100~300 nm and a pore size of 5~35 nm; Preferably, the pH-responsive slow-release corrosion inhibitor is encapsulated in the mesoporous channels of mesoporous silica nanospheres; the mass ratio of the pH-responsive slow-release corrosion inhibitor to the mesoporous silica nanospheres is 1:(2~5); Preferably, the pH-responsive slow-release corrosion inhibitor comprises a nano-sized alkaline metal compound, preferably any one or a combination of at least two of nano-Ca(OH)2, nano-Mg(OH)2, and nano-ZnO; Preferably, the particle size of the pH-responsive slow-release corrosion inhibitor is 10~30 nm; Preferably, the pH-sensitive polymer is grafted onto the mesoporous pore inlet of the mesoporous silica nanospheres; and the pH-sensitive polymer shrinks the open pores when pH < 5 and expands the closed pores when pH > 6; the grafting rate of the pH-sensitive polymer is 2~5 wt% Preferably, the pH-sensitive polymer includes any one or a combination of at least two of polyacrylic acid, polymethacrylic acid, and polyacrylic acid-co-methyl methacrylate; Preferably, the weight-average molecular weight of the pH-sensitive polymer is 10,000 to 50,000; Preferably, the hydrophobic layer of the fluorinated acrylate copolymer is formed by copolymerization of fluorinated acrylate monomers and glycidyl methacrylate; Preferably, the fluorinated acrylate monomers include any one or a combination of at least two of trifluoroethyl methacrylate, hexafluorobutyl methacrylate, and perfluoroalkyl ethyl acrylate; Preferably, the mass ratio of the fluorinated acrylate monomer to glycidyl methacrylate is (60~95):(5~40); Preferably, the fluorine content in the hydrophobic layer of the fluorinated acrylate copolymer is 20-40 wt%. Preferably, the contact angle of the hydrophobic layer of the fluorinated acrylate copolymer is >110°; Preferably, the thickness of the hydrophobic layer of the fluorinated acrylate copolymer is 10~30 nm.

3. A method for preparing a refractive index-matching corrosion-resistant functional body according to claim 1 or 2, characterized in that, The preparation method includes: The mesoporous silica nanospheres were prepared by the sol-gel method. The pH-responsive slow-release corrosion inhibitor is introduced into the mesoporous silica nanospheres by vacuum impregnation to obtain mesoporous silica nanospheres loaded with the pH-responsive slow-release corrosion inhibitor. The core is obtained by grafting the pH-sensitive polymer onto mesoporous silica nanospheres via a carbodiimide chemical grafting reaction. The fluorinated acrylate copolymer hydrophobic layer is coated onto the surface of the core through emulsion polymerization to form a shell, thereby obtaining the refractive index-matched anti-corrosion functional body.

4. The method for preparing the refractive index-matching anti-corrosion functional body according to claim 3, characterized in that, The preparation method of the refractive index-matched anti-corrosion functional body specifically includes the following steps: (a) A silicon source, a mesoporous template agent, a pH adjuster and a solvent are mixed, reacted and then calcined to obtain the mesoporous silica nanospheres; (b) The mesoporous silica nanospheres, pH-responsive slow-release corrosion inhibitor and solvent II are mixed and vacuum impregnated to allow the pH-responsive slow-release corrosion inhibitor to enter the mesoporous silica nanospheres, thereby obtaining mesoporous silica nanospheres loaded with pH-responsive slow-release corrosion inhibitor. (c) The mesoporous silica nanospheres loaded with pH-responsive slow-release corrosion inhibitor, pH-sensitive polymer, carbodiimide grafting agent and solvent are mixed and a grafting reaction is carried out to graft the pH-sensitive polymer onto the mesoporous silica nanospheres to obtain the core; (d) The core, fluorinated acrylate monomer, glycidyl methacrylate, initiator and solvent are mixed and emulsion polymerized to form a shell. The solvent is removed to obtain the refractive index matching anti-corrosion functional body. Preferably, in step (a), the silicon source comprises tetraethyl orthosilicate; the mesoporous template agent comprises hexadecyltrimethylammonium bromide; the pH adjuster comprises ammonia; and the solvent is an aqueous ethanol solution. Preferably, in step (a), the mass ratio of the silicon source, mesoporous template agent, pH adjuster and solvent is (10~20):(1~3):(4~8):(60~85); Preferably, in step (a), the pH of the reaction is 8-12, the temperature is 30-50°C, and the reaction time is 12-24h. Preferably, in step (a), the calcination temperature is 450~550℃ and the calcination time is 4~10 h; Preferably, in step (b), the solvent two is ethanol; Preferably, in step (b), the mass ratio of the mesoporous silica nanospheres, the pH-responsive slow-release corrosion inhibitor, and solvent II is (4~10):(1~2):(30~60); Preferably, in step (b), the vacuum impregnation time is 8-16 h; Preferably, in step (c), the carbodiimide grafting agent is a mixture of EDC-HCl and NHS; the solvent is ethanol and / or MES buffered aqueous solution; Preferably, in step (c), the mass ratio of the mesoporous silica nanospheres loaded with the pH-responsive slow-release corrosion inhibitor, the pH-sensitive polymer, the carbodiimide grafting agent, and the solvent is (8~15):(0.2~0.7):(0.5~1.2):(40~70); Preferably, in step (c), the temperature of the grafting reaction is 20~55℃, and the grafting reaction time is 4~10 h; Preferably, in step (d), the initiator is azobisisobutyramidine hydrochloride; and the solvent is a mixed solution of ethanol and water. Preferably, in step (d), the mass ratio of the core, fluorinated acrylate monomer, glycidyl methacrylate, initiator, and solvent is (5~12):(3~7):(0.4~2.1):(0.08~0.25):(40~80); Preferably, in step (d), the temperature of the emulsion polymerization reaction is 50~80℃, and the time of the emulsion polymerization reaction is 4~12h.

5. A gradient refractive index interface layer precursor, characterized in that, The gradient refractive index interface layer precursor comprises, from the inside out: an anti-corrosion functional body, a mercaptosilane coupling agent grafted layer, a trifluoroethyl methacrylate copolymer layer, and a maleic anhydride grafted ethylene-vinyl acetate copolymer layer. The corrosion-resistant functional body includes the refractive index-matching corrosion-resistant functional body as described in claim 1 or 2.

6. The gradient refractive index interface layer precursor according to claim 5, characterized in that, The refractive index of the mercaptosilane coupling agent grafted layer is 1.51~1.53, the thickness of the trifluoroethyl methacrylate copolymer layer is 1.49~1.51, and the thickness of the maleic anhydride grafted ethylene-vinyl acetate copolymer layer is 1.48~1.

50. Preferably, the thickness of the mercaptosilane coupling agent grafted layer is 2-5 nm, the thickness of the trifluoroethyl methacrylate copolymer layer is 5-10 nm, and the thickness of the maleic anhydride grafted ethylene-vinyl acetate copolymer layer is 5-15 nm.

7. A method for preparing a gradient refractive index interface layer precursor according to claim 5 or 6, characterized in that, The preparation method includes: (A) The refractive index matching anti-corrosion functional body is dispersed in an ethanol solution of mercaptosilane coupling agent and a grafting reaction is carried out to form a mercaptosilane coupling agent grafting layer on the surface of the refractive index matching anti-corrosion functional body, thereby obtaining reaction solution one; (B) Add trifluoroethyl methacrylate copolymer to the reaction solution one and cure it with ultraviolet light to form a trifluoroethyl methacrylate copolymer layer on the surface of the mercaptosilane coupling agent graft layer, thus obtaining reaction solution two. (C) Add maleic anhydride-grafted ethylene-vinyl acetate copolymer emulsion to the reaction solution II, and perform drying and curing treatment to form a maleic anhydride-grafted ethylene-vinyl acetate copolymer layer on the surface of the trifluoroethyl methacrylate copolymer layer, thereby obtaining the gradient refractive index interface layer precursor. Preferably, in step (A), the mercaptosilane coupling agent is 3-mercaptopropyltrimethoxysilane; Preferably, in step (A), the mass ratio of the refractive index-matching anti-corrosion functional body, the mercaptosilane coupling agent, and ethanol is (6~12):(0.3~0.8):(50~90); Preferably, in step (A), the temperature of the grafting reaction is 40~60℃, and the grafting reaction time is 4~8 h; Preferably, in step (B), the mass ratio of the trifluoroethyl methacrylate copolymer to the anti-corrosion functional body is (1~3):(8~12); Preferably, in step (B), the intensity of the UV curing is 5~20 mW / cm. 2 The UV curing time is 3~10 minutes; Preferably, in step (C), the mass ratio of the maleic anhydride-grafted ethylene-vinyl acetate copolymer to the anti-corrosion functional body is (0.8~2.5):(8~12); Preferably, in step (C), the solid content of the maleic anhydride-grafted ethylene-vinyl acetate copolymer emulsion is 15-30 wt%. Preferably, in step (C), the drying and curing temperature is 60~100℃ and the drying and curing time is 10~30 min.

8. A film, characterized in that, The adhesive film comprises the following components by weight: 100 parts of matrix resin, 1-8 parts of the refractive index matching anti-corrosion functional body as described in claim 1 or 2, 0.5-3 parts of the gradient refractive index interface layer precursor as described in claim 5 or 6, 0.5-2 parts of crosslinking agent, 0.3-1.5 parts of long-lasting anti-PID synergist, and 0.2-1 parts of light stabilizer; Preferably, the matrix resin comprises an ethylene-vinyl acetate copolymer; Preferably, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 26-33 wt%, and the melt index of the ethylene-vinyl acetate is 15-25 g / 10min (190℃ / 2.16 kg). Preferably, the crosslinking agent includes peroxide and co-crosslinking agent; The peroxide includes any one or a combination of at least two of the following: 2-ethylhexyl carbonate tert-amyl peroxide, tert-butyl peroxycarbonate-2-ethylhexyl peroxide, 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, tert-butyl peroxide-3,5,5-trimethylhexanoate, benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, and di-tert-butyl peroxide. The co-crosslinking agent includes any one or a combination of at least two of the following: trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, triallyl isocyanurate, tetramethyltetravinylcyclotetrasiloxane, 4-acryloylmorpholine, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, neopentyl glycol (2)PO diacrylate, polyethylene glycol 200 diacrylate, EO (3) trimethylolpropane triacrylate, and 3(propoxy)glycerol triacrylate. Preferably, the long-lasting anti-PID synergist includes any one or a combination of at least two of nano-magnesium hydroxide, organic zinc carboxylate, borate corrosion inhibitor particles, zirconium phosphate, and zirconium hydrogen phosphate; Preferably, the light stabilizer comprises a hindered amine and an ultraviolet absorber; The hindered amine includes any one or a combination of at least two of HALS-944, HALS-770, and HALS-622; the ultraviolet absorber includes any one or a combination of at least two of UV-327, UV-531, UV329, UV328, and UV-1130. Preferably, the thickness of the adhesive film is 0.4~0.6 mm.

9. A method for preparing an adhesive film according to claim 8, characterized in that, The method for preparing the adhesive film includes: The matrix resin, the refractive index matching anti-corrosion functional body, the gradient refractive index interface layer precursor, the crosslinking agent, the long-lasting anti-PID synergist, and the light stabilizer are mixed in proportion, melt-blended and granulated by a twin-screw extruder, then formed into a film by a casting extruder, cooled and shaped, and then wound up to obtain the adhesive film. Preferably, the granulation temperature is 100~140℃; Preferably, the temperature of the film-forming die head is 110~130℃.

10. The application of the refractive index matching anti-corrosion functional body according to claim 1 or 2, or the gradient refractive index interface layer precursor according to claim 5 or 6, or the encapsulant film according to claim 8 in the preparation of solar photovoltaic module encapsulation materials; Preferably, the solar photovoltaic module includes any one or a combination of at least two of N-type TOPCon cells, HJT cells, and PERC cells.

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