Weather-resistant light-transmitting EVA adhesive film and preparation method thereof

Abstract

The application discloses a weather-resistant light-transmitting EVA adhesive film and a preparation method thereof, and belongs to the technical field of photovoltaic packaging materials. The adhesive film is prepared by blending, extruding and casting with EVA resin as a base, Zr-Si-H functionalized grafting as a long-acting free radical capturing auxiliary agent, a crosslinking agent, a co-crosslinking agent, a coupling agent and a small amount of auxiliary antioxidant. The Zr-Si-H functionalized grafting can cyclically capture peroxide radicals and alkyl radicals generated in the service process of a photovoltaic module based on the reversible reaction characteristics of the Zr-H-Si three-center two-electron pyragostic bond, solves the long-term aging yellowing and mechanical property attenuation problems caused by the one-time consumption and easy migration and precipitation of the antioxidant of the traditional EVA adhesive film, can greatly extend the actual service life of the photovoltaic module, and is compatible with the traditional EVA adhesive film line in the production process, and is highly feasible in industrialization.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic encapsulation materials technology, and in particular to a weather-resistant, light-transmitting EVA film and its preparation method. Background Technology

[0002] Ethylene-vinyl acetate copolymer (EVA) films are currently the mainstream material for photovoltaic module encapsulation due to their excellent light transmittance, adhesion, flexibility, and electrical insulation. However, during long-term outdoor operation, photovoltaic modules are subjected to the combined effects of ultraviolet light, high temperature, high humidity, and oxygen. This causes the EVA molecular chains to break, generating alkyl free radicals, which further oxidize to generate peroxide free radicals, triggering a chain degradation reaction. This leads to yellowing of the film, decreased light transmittance, deterioration of mechanical properties, and adhesion failure, ultimately resulting in a significant reduction in the power output of the photovoltaic module.

[0003] Traditional EVA films typically contain hindered phenolic and phosphite antioxidants to inhibit aging and degradation. However, these antioxidants are single-use and lose their activity after capturing free radicals through irreversible reactions. They are generally depleted after 5-8 years of module service, leading to a sharp deterioration in the film's weather resistance. Furthermore, small-molecule antioxidants tend to migrate and precipitate within the film, reducing the module's adhesive strength, causing delamination and PID (Potential Inertia of Delamination) effects, and the precipitates can also contaminate the cell surface, further impacting the module's power generation efficiency.

[0004] To address the aforementioned issues, existing technologies have attempted to develop polymeric antioxidants or inorganic nano-UV-resistant additives. However, polymeric antioxidants still suffer from low free radical scavenging activity and poor compatibility with EVA; inorganic nano-additives, on the other hand, are prone to aggregation, leading to increased film haze and decreased light transmittance, and cannot fundamentally solve the problem of free radical chain degradation. Therefore, developing a novel weather-resistant EVA film with continuous free radical scavenging capabilities, high light transmittance, and good compatibility with EVA is of great significance for extending the lifespan of photovoltaic modules and reducing the levelized cost of electricity (LCOE). Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a weather-resistant, light-transmitting EVA film and its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention first proposes a weather-resistant, light-transmitting EVA film, the raw material composition of which, by weight, includes: EVA resin: 100 parts; Zr-Si-H functionalized graft: 0.8-1.5 parts; Crosslinking agent: 0.4-0.8 parts; Crosslinking agent: 0.2-0.6 parts; Coupling agent: 0.2-0.4 parts; Antioxidant supplement: 0.05-0.2 parts; This invention achieves a synergistic improvement in the long-term weather resistance and high light transmittance of EVA films based on the reversible cyclic free radical capture mechanism of Zr-H-Si three-center two-electron (3c2e) pyragostic bonds.

[0007] The Zr-Si-H functionalized graft has polymethylhydrosiloxane-co-methyl methacrylate as the main chain and Zr-Si-H functional monomers as side links. The preparation method of the Zr-Si-H functional monomer specifically includes the following steps: S1: Under anhydrous and oxygen-free conditions, dimethylchlorosilane was slowly added dropwise to an anhydrous diethyl ether mixture of allylamine and triethylamine while stirring at 0°C. After the addition was complete, the temperature was raised to reflux for 6-8 hours. After the reaction was completed, the triethylamine hydrochloride was removed by filtration, and the filtrate was purified by atmospheric distillation to obtain allylbis(dimethylsilyl)amine. Allylamine (H2NCH2CH=CH2), as a bifunctional nucleophile, undergoes two SN2 nucleophilic substitution reactions in which the lone pair of electrons on its nitrogen atom attacks the electron-deficient silicon center of two molecules of dimethylchlorosilane (Me2SiHCl), gradually removing Cl. - The target secondary amine product is generated. Triethylamine (Et3N), as an organic base, quantitatively combines with the HCl generated in the reaction to form triethylamine hydrochloride precipitate.

[0008]

[0009] S2: Under argon protection at -78℃, a hexane solution of n-butyllithium was slowly added dropwise to an anhydrous tetrahydrofuran solution of allylbis(dimethylsilyl)amine. After reacting at this temperature for 1 hour, zirconium dichlorocerocene (Cp2ZrCl2) was added, and the mixture was naturally heated to room temperature for 12-16 hours. The lithium chloride precipitate was removed by filtration, and the solvent was removed by vacuum distillation. The crude product was recrystallized with a toluene / n-hexane mixed solvent to obtain a colorless crystalline Zr-Si-H functional monomer.

[0010] n-Butyllithium (n-BuLi), as a strong base, quantitatively abstracts an active hydrogen atom (pKa≈35) from the nitrogen atom of allylbis(dimethylsilyl)amine at a low temperature of -78°C, generating a lithium allylbis(dimethylsilyl)amine intermediate with strong nucleophilicity: The amine lithium intermediate, acting as a bidentate ligand precursor, attacks the electron-deficient Zr(IV) center (d) of zirconium dichlorodi ... 0 (Configuration), undergoes a nucleophilic substitution reaction, losing two molecules of LiCl precipitate to generate a neutral Zr-Si-H functional monomer:

[0011] Preferably, in S1, the molar ratio of dimethylchlorosilane to allylamine is (2.0-2.2):1, and the molar ratio of triethylamine to dimethylchlorosilane is (1.05-1.1):1; In S2, the molar ratio of n-butyllithium, allyl bis(dimethylsilyl)amine and zirconium dichlorodi ...

[0012] Preferably, the vinyl acetate content in the EVA resin is 26-30 wt%, and the melt index (MI, 190℃ / 2.16kg) is 20-30 g / 10min; The crosslinking agent is dicumyl peroxide; The crosslinking agent is trimethylolpropane triacrylate; The coupling agent is γ-methacryloxypropyltrimethoxysilane; The auxiliary antioxidant is hindered phenolic antioxidant 1010.

[0013] This invention also proposes a method for preparing the aforementioned weather-resistant and light-transmitting EVA film, comprising the following steps: A: Premix: Add EVA resin, Zr-Si-H functionalized graft, crosslinking agent, co-crosslinking agent, coupling agent and auxiliary antioxidant to a high-speed mixer and mix at 35-45℃ for 2-5 minutes to obtain a uniform mixture; B: Extrusion: Add the mixture to a twin-screw extruder, control the extrusion temperature gradient to 90-120℃ and the screw speed to 100-150rpm, and then convey it to the die after melt mixing; C: Casting film: The molten material is uniformly extruded through a T-die and cast onto a chrome-plated cooling roller for cooling and shaping. The temperature of the cooling roller is controlled at 20-30℃, and the film thickness is controlled at 0.40-0.50mm. D: Winding: After online thickness measurement and defect detection, the winding tension is controlled at 3-7 N / m to obtain the finished weather-resistant and light-transmitting EVA film.

[0014] Preferably, in step B, the temperature gradient of the twin-screw extruder is as follows: 90-100℃ in the feeding section, 100-110℃ in the melting section, 110-115℃ in the homogenization section, and 105-115℃ in the die head section.

[0015] Preferably, in step A, the preparation method of the Zr-Si-H functionalized graft is as follows: polymethylhydrosiloxane-copoly-methyl methacrylate is dissolved in anhydrous toluene, Zr-Si-H functional monomers and Karstedt platinum catalyst are added, and the mixture is stirred at 70-90℃ for 6-10 h. After the reaction is completed, the mixture is cooled to room temperature, the reaction solution is poured into excess methanol to precipitate, the product is collected by filtration, and the product is dried under vacuum at 40℃ for 24 h to constant weight to obtain the Zr-Si-H functionalized graft.

[0016] Preferably, the polymethylhydrosiloxane-copolymer-methyl methacrylate (PHMS-co-PMMA) has a number average molecular weight of 8000-12000, wherein the content of methylhydrosiloxane units is 80-90 mol% and the content of methyl methacrylate units is 10-20 mol%; the molar ratio of the Zr-Si-H functional monomer to the Si-H bond in the polymethylhydrosiloxane-copolymer-methyl methacrylate (PHMS-co-PMMA) is (0.04-0.06):1; and the amount of the Karstedt platinum catalyst is 5-10 ppm based on platinum atoms.

[0017] Karstedt platinum catalyst (zero-valent platinum complex) catalyzes the hydrosilylation reaction between the Si-H bonds on the PHMS-co-PMMA backbone and the allyl double bonds on the functional monomer, achieving covalent grafting of functional units. The reaction mechanism follows the Chalk-Harrod cycle. Oxidative addition: The zero-valent platinum catalyst undergoes oxidative addition with the Si-H bond on PHMS to generate the Pt(II) intermediate, while simultaneously forming Pt-H and Pt-Si bonds.

[0018] Double bond coordination: The allyl double bond on the functional monomer coordinates to the Pt(II) center to form a π-complex.

[0019] Insertion reaction: Pt-H bonds cis-inserte into coordinated double bonds to generate Pt-C bonds, forming an intermediate containing a Pt-C-Si structure.

[0020] Reduction elimination: The Pt-C bond and the Pt-Si bond undergo reduction elimination to generate a stable Si-C covalent bond, while the zero-valent platinum catalyst is regenerated, completing the catalytic cycle.

[0021] By controlling the molar ratio of the functional monomer to the Si-H bonds in PHMS to (0.04-0.06):1, the grafting rate can be precisely controlled at 3-7 mol%, ensuring sufficient free radical scavenging activity while avoiding cross-linking gelation problems caused by bifunctional functional monomers. The introduced PMMA copolymer unit can adjust the solubility parameter of the grafted product (the difference in solubility parameter with EVA is <0.5 J). 1 / 2 / cm 3 / 2This achieves thermodynamic compatibility with the EVA matrix.

[0022] The breakthrough in weather resistance of this invention stems from the reversible reaction characteristics of the Zr-H-Si three-center two-electron pyragostic bond, and its electronic structure and reaction process are as follows: Zr(IV) is d 0 In the electron-deficient configuration, the empty 4d orbitals can laterally overlap with the σ bonding orbitals of adjacent Si-H bonds, forming delocalized three-center two-electron bonds. Electron cloud distribution: The electron cloud of the Si-H σ bond shifts towards the empty d orbitals of Zr, causing the H atom to carry a partial negative charge (approximately -0.19e). - Si atoms carry a partial positive charge (approximately +1.39e). - ).

[0023] Bond energy characteristics: The total bond energy of Zr-H-Si bond is about 33.4 kcal / mol, which is significantly lower than that of ordinary Si-H bond (about 76 kcal / mol) and Zr-H bond (about 60 kcal / mol). Therefore, H atom has higher reactivity and is easily taken by electron-deficient free radicals.

[0024] (with peroxy free radicals) (For example) Under UV / humid heat aging, the C-C bonds in the molecular chain of EVA film break to generate alkyl free radicals. , It reacts rapidly with oxygen to generate peroxide free radicals, which have stronger oxidizing power. This triggers a chain degradation of EVA.

[0025] The Zr-H-Si bond of the present invention can be captured in the following three-step cyclic process. Completely terminate the chain reaction: Step 1: Free radical capture (consumption of active sites) Electron-deficient Attacking the electron-rich H atom in the Zr-H-Si bond, a hydrogen transfer reaction occurs, generating the stable hydroperoxide ROOH. Simultaneously, the Zr-H-Si bond undergoes homolytic cleavage, generating Zr-central radicals and Si-central radicals.

[0026] Step 2: Regeneration of active centers (reversible cycle) The generated Zr central radical possesses sufficient stability (thanks to the steric hindrance and electronic delocalization of the Cp ring) to rapidly abstract H atoms from adjacent Si-H bonds, reforming the Zr-H-Si active center:

[0027] The activation energy for this step is only 12.3 kcal / mol, which can be carried out rapidly at room temperature, achieving non-destructive regeneration of the active center.

[0028] Step 3: Termination of side reactions (breaking the chain reaction) The generated Si-centered free radicals have low reactivity and can combine with oxygen or another Si・ to form stable silicon-oxygen bonds (Si-O-Si) or silicon-silicon bonds (Si-Si), without initiating new chain degradation reactions.

[0029] This cycle can theoretically be repeated ≥10 times. 4 This method has a theoretical lifespan that is 3-5 times longer than traditional disposable antioxidant systems, fundamentally solving the problem of film weather resistance collapse caused by antioxidant depletion.

[0030] Compared with the prior art, the beneficial effects of the present invention are: 1. Existing hindered phenolic and phosphite antioxidants, widely used in the technology, are irreversibly consumed additives. Their mechanism of action involves a quantitative reaction between the active hydrogen on their molecules and free radicals. Each captured free radical consumes one antioxidant molecule, and the reaction products cannot restore their activity. Typically, they are completely depleted after 5-8 years of photovoltaic module service, leading to a sharp decline in the weather resistance of the encapsulant film. This invention, based on the reversible reaction characteristics of the Zr-H-Si three-center two-electron pyragostic bond, constructs a closed-loop mechanism of free radical capture and active center regeneration: after the active hydrogen in the Zr-H-Si bond is captured by a peroxy free radical, the generated Zr-center free radical can rapidly capture hydrogen atoms from adjacent Si-H bonds at room temperature, reforming the Zr-H-Si active center. This cycle can be repeated ≥10 times. 4 Secondly, its theoretical lifespan is 3-5 times that of traditional antioxidant systems, solving the industry problem of aging and yellowing of EVA films and degradation of mechanical properties after long-term service.

[0031] 2. In existing technologies, small-molecule antioxidants and UV absorbers, due to their low molecular weight (typically <1000), have high diffusion coefficients in the EVA matrix. During long-term service, they gradually migrate and precipitate to the surface of the encapsulant film. This not only leads to a decrease in the adhesion strength between the encapsulant film and the glass and backsheet, causing module delamination and PID effects, but the precipitates also contaminate the surface of the solar cells, reducing the module's power generation efficiency. While some high-molecular-weight antioxidants solve the migration problem, their poor compatibility with the EVA matrix easily leads to micron-level phase separation, resulting in a significant increase in film haze and a decrease in light transmittance. This invention grafts Zr-H-Si functional units onto the polymethylhydrosiloxane-co-methyl methacrylate backbone via covalent bonds, restricting the migration of functional units at the molecular level. Simultaneously, by adjusting the content of methyl methacrylate units in the backbone, the difference between the solubility parameter of the grafted material and that of the EVA matrix is ​​<0.5 J. 1 / 2 / cm 3 / 2 By controlling the phase separation size to below 10nm (far smaller than the wavelength of visible light), the synergy between stable immobilization of functional units and high light transmittance of the film was finally achieved.

[0032] 3. Existing weather-resistant modifications typically employ simple compounding schemes of UV absorbers and antioxidants, which have significant limitations: On the one hand, organic UV absorbers themselves undergo photolysis, gradually losing their UV shielding ability, and the photolysis products may become new free radical initiators, accelerating EVA aging; on the other hand, inorganic UV nano-auxiliaries are prone to aggregation and can only shield UV light, failing to eliminate already generated free radicals, resulting in limited protective effects. The Zr-H-Si functionalized graft of this invention possesses two protective functions simultaneously: the empty 4d orbitals of the Zr(IV) center can absorb high-energy UV light of 300-350 nm and convert it into harmless heat energy, reducing the direct excitation and breakage of EVA molecular chains at the source; simultaneously, the Zr-H-Si active centers can rapidly capture already generated alkyl and peroxide free radicals, interrupting the chain degradation reaction of EVA. These two functions work synergistically; UV shielding reduces the amount of free radicals generated, and free radical capture eliminates residual active species, significantly reducing the aging rate of the EVA film compared to a single protective system. Attached Figure Description

[0033] Figure 1 The image shows the nuclear magnetic resonance (NMR) image of the Zr-Si-H functional monomer proposed in this invention. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0035] General experimental conditions: All examples and comparative examples used the same preparation process and testing standards: Preparation process: Premix (40℃, 3min) → Twin-screw extrusion (temperature gradient: 95℃ / 105℃ / 112℃ / 110℃, screw speed 120rpm) → Casting film (cooling roller 25℃, thickness 0.45mm) → Winding; Test standards: Visible light transmittance / haze (GB / T2410-2008), yellowing index ΔYI (IEC61730-2), glass peel strength (GB / T2790-1995), volume resistivity (IEC60093), free radical scavenging activity retention rate (ESR spin trapping method, double 85 aging for 1000h), migration (observation of surface precipitates after hot pressing at 85℃ for 1000h); Example: Example 1 (Zr-Si-H graft addition amount 0.8 parts): Raw material composition (parts by weight): 100 parts of EVA resin (VA 28%, MI=25), 0.8 parts of Zr-Si-H functionalized graft, 0.6 parts of DCP, 0.4 parts of TMPTA, 0.3 parts of KH-570, and 0.1 parts of antioxidant 1010.

[0036] Zr-Si-H graft parameters: PHMS-co-PMMA backbone (Mn=10000, methylhydrosiloxane 85mol%, PMMA 15mol%), grafting rate 4mol%.

[0037] Example 2 (Zr-Si-H graft added in amounts of 1.2 parts): Raw material composition (parts by weight): 100 parts of EVA resin (VA 28%, MI=25), 1.2 parts of Zr-Si-H functionalized graft, 0.6 parts of DCP, 0.4 parts of TMPTA, 0.3 parts of KH-570, and 0.1 parts of antioxidant 1010.

[0038] Zr-Si-H graft parameters: same as in Example 1.

[0039] Example 3 (Zr-Si-H graft added in amounts of 1.5 parts): Raw material composition (parts by weight): 100 parts of EVA resin (VA 28%, MI=25), 1.5 parts of Zr-Si-H functionalized graft, 0.6 parts of DCP, 0.4 parts of TMPTA, 0.3 parts of KH-570, and 0.1 parts of antioxidant 1010.

[0040] Zr-Si-H graft parameters: same as in Example 1.

[0041] The following comparison model was also set: Comparative Example 1 (blank control, without antioxidant adjuvant) Raw material composition (parts by weight): 100 parts of EVA resin (VA 28%, MI=25), 0.6 parts of DCP, 0.4 parts of TMPTA, and 0.3 parts of KH-570.

[0042] Comparative Example 2 (Traditional Small Molecule Antioxidant System) Raw material composition (parts by weight): 100 parts of EVA resin (VA 28%, MI=25), 0.4 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 0.6 parts of DCP, 0.4 parts of TMPTA, and 0.3 parts of KH-570.

[0043] Comparative Example 3 (Direct addition of Zr-Si-H small molecule functional monomers) Raw material composition (parts by weight): 100 parts of EVA resin (VA 28%, MI=25), 0.12 parts of Zr-Si-H functional monomer (equivalent to the molar amount of active center in Example 2), 0.6 parts of DCP, 0.4 parts of TMPTA, 0.3 parts of KH-570, and 0.1 parts of antioxidant 1010.

[0044] Comparative Example 4 (Zr-Si-H graft addition was insufficient, 0.5 parts) Raw material composition (parts by weight): 100 parts of EVA resin (VA 28%, MI=25), 0.5 parts of Zr-Si-H functionalized graft, 0.6 parts of DCP, 0.4 parts of TMPTA, 0.3 parts of KH-570, and 0.1 parts of antioxidant 1010.

[0045] Comparative Example 5 (Zr-Si-H graft addition was too high, 2.0 parts) Raw material composition (parts by weight): 100 parts of EVA resin (VA 28%, MI=25), 2.0 parts of Zr-Si-H functionalized graft, 0.6 parts of DCP, 0.4 parts of TMPTA, 0.3 parts of KH-570, and 0.1 parts of antioxidant 1010.

[0046] Comparative Example 6 (graft without PMMA compatibility unit) Raw material composition (parts by weight): 100 parts of EVA resin (VA 28%, MI=25), 1.2 parts of pure PHMS-based Zr-Si-H graft, 0.6 parts of DCP, 0.4 parts of TMPTA, 0.3 parts of KH-570, and 0.1 parts of antioxidant 1010.

[0047] Performance testing:

[0048] Data Analysis: Examples 1-3 all exhibited excellent overall performance, with Example 2 (1.2 parts added) balancing weather resistance, optical performance, and cost, making it the optimal solution. As the amount of graft material added increased, weather resistance gradually improved, but haze slightly increased, verifying the rationality of the 0.8-1.5 parts addition range of this invention.

[0049] Comparative Example 1: The pure EVA film has extremely poor aging performance. After 2000 hours of aging with double 85, it yellows severely and loses almost all of its mechanical properties, indicating that EVA itself has insufficient aging resistance.

[0050] Comparative Example 2: The traditional antioxidant system showed acceptable performance in the early stages, but after 1000 hours, the free radical scavenging activity was only 23%, and after 2000 hours, the yellowing index and peel strength dropped significantly, reflecting the inherent defect of being a one-time consumption system.

[0051] Comparative Example 3: The small molecule functional monomers showed better weather resistance than the traditional system in the early stages, but after 1000 hours, due to severe migration and precipitation, the activity retention rate was only 18%, and the peel strength dropped sharply, proving that polymer grafting is the key to solving the migration problem.

[0052] Comparative Example 4: Insufficient addition resulted in an insufficient number of active centers. After aging with Double 85 for 2000 hours, the yellowing index and peel strength were significantly worse than those of the Example, verifying the necessity of the lower limit of the present invention.

[0053] Comparative Example 5: Excessive addition caused the graft to agglomerate, the initial light transmittance decreased to 90.8%, the haze increased to 1.3%, and the cost increased, which verified the rationality of the upper limit of the present invention.

[0054] Comparative Example 6: Grafts without PMMA compatibility units have poor compatibility with EVA, resulting in micron-level phase separation. The initial haze is as high as 3.5%, and the transmittance is only 88.2%, proving that compatibility design is the core to achieving high transmittance.

[0055] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A weather-resistant, light-transmitting EVA film, characterized in that, By weight, the raw material composition includes: EVA resin: 100 parts; Zr-Si-H functionalized graft: 0.8-1.5 parts; Crosslinking agent: 0.4-0.8 parts; Crosslinking agent: 0.2-0.6 parts; Coupling agent: 0.2-0.4 parts; Antioxidant supplement: 0.05-0.2 parts; The Zr-Si-H functionalized graft has polymethylhydrosiloxane-co-methyl methacrylate as the main chain and Zr-Si-H functional monomers as side links. The preparation method of the Zr-Si-H functional monomer specifically includes the following steps: S1: Under anhydrous and oxygen-free conditions, dimethylchlorosilane was slowly added dropwise to an anhydrous diethyl ether mixture of allylamine and triethylamine while stirring at 0°C. After the addition was complete, the temperature was raised to reflux for 6-8 hours. After the reaction was completed, the triethylamine hydrochloride was removed by filtration, and the filtrate was purified by atmospheric distillation to obtain allylbis(dimethylsilyl)amine. S2: Under argon protection at -78℃, a hexane solution of n-butyllithium was slowly added dropwise to an anhydrous tetrahydrofuran solution of allylbis(dimethylsilyl)amine. After reacting at this temperature for 1 hour, zirconium dichlorocerocene was added, and the temperature was naturally raised to room temperature for 12-16 hours. The lithium chloride precipitate was removed by filtration, and the solvent was removed by vacuum distillation. The crude product was recrystallized with a toluene / n-hexane mixed solvent to obtain a colorless crystalline Zr-Si-H functional monomer.

2. The weather-resistant, light-transmitting EVA film according to claim 1, characterized in that, In S1, the molar ratio of dimethylchlorosilane to allylamine is (2.0-2.2):1, and the molar ratio of triethylamine to dimethylchlorosilane is (1.05-1.1):

1. In S2, the molar ratio of n-butyllithium, allyl bis(dimethylsilyl)amine and zirconium dichlorodi ...

3. The weather-resistant, light-transmitting EVA film according to claim 1, characterized in that, The EVA resin contains 26-30 wt% vinyl acetate and has a melt index (MI, 190℃ / 2.16kg) of 20-30 g / 10 min. The crosslinking agent is dicumyl peroxide; The crosslinking agent is trimethylolpropane triacrylate; The coupling agent is γ-methacryloxypropyltrimethoxysilane; The auxiliary antioxidant is hindered phenolic antioxidant 1010.

4. A method for preparing a weather-resistant, light-transmitting EVA film as described in any one of claims 1-3, characterized in that, Includes the following steps: A: Premix: Add EVA resin, Zr-Si-H functionalized graft, crosslinking agent, co-crosslinking agent, coupling agent and auxiliary antioxidant to a high-speed mixer and mix at 35-45℃ for 2-5 minutes to obtain a uniform mixture; B: Extrusion: Add the mixture to a twin-screw extruder, control the extrusion temperature gradient to 90-120℃ and the screw speed to 100-150rpm, and then convey it to the die after melt mixing; C: Casting film: The molten material is uniformly extruded through a T-die and cast onto a chrome-plated cooling roller for cooling and shaping. The temperature of the cooling roller is controlled at 20-30℃, and the film thickness is controlled at 0.40-0.50mm. D: Winding: After online thickness measurement and defect detection, the winding tension is controlled at 3-7 N / m to obtain the finished weather-resistant and light-transmitting EVA film.

5. The method for preparing the weather-resistant, light-transmitting EVA film according to claim 4, characterized in that, In section B, the temperature gradient of the twin-screw extruder is specifically as follows: 90-100℃ in the feeding section, 100-110℃ in the melting section, 110-115℃ in the homogenization section, and 105-115℃ in the die head section.

6. The method for preparing the weather-resistant, light-transmitting EVA film according to claim 4, characterized in that, In section A, the preparation method of the Zr-Si-H functionalized graft is as follows: polymethylhydrosiloxane-copoly-methyl methacrylate is dissolved in anhydrous toluene, Zr-Si-H functional monomers and Karstedt platinum catalyst are added, and the reaction is stirred at 70-90℃ for 6-10h. After the reaction is completed, the mixture is cooled to room temperature, the reaction solution is poured into excess methanol to precipitate, the product is collected by filtration, and the product is dried under vacuum at 40℃ for 24h to constant weight to obtain the Zr-Si-H functionalized graft.

7. The method for preparing the weather-resistant, light-transmitting EVA film according to claim 6, characterized in that, The polymethylhydrosiloxane-copolymer-methyl methacrylate has a number average molecular weight of 8000-12000, wherein the content of methylhydrosiloxane units is 80-90 mol% and the content of methyl methacrylate units is 10-20 mol%; the molar ratio of the Zr-Si-H functional monomer to the Si-H bond in the polymethylhydrosiloxane-copolymer-methyl methacrylate is (0.04-0.06):1; and the amount of the Karstedt platinum catalyst is 5-10 ppm based on platinum atoms.

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