Anti-aging PVB (Polyvinyl Butyral) adhesive film for packaging photovoltaic module and preparation process of anti-aging PVB adhesive film

Abstract

The invention relates to the technical field of development of photovoltaic packaging adhesive film materials, in particular to an anti-aging PVB (Polyvinyl Butyral) adhesive film for packaging a photovoltaic module and a preparation process of the anti-aging PVB adhesive film. The anti-aging PVB composite material is prepared from the following components in parts by weight: 60-80 parts of end group modified PVB resin, 5-10 parts of a novel composite anti-aging agent, 10-20 parts of a vegetable oil-based compound plasticizer, 3-8 parts of modified composite inorganic nano filler, 1-3 parts of a diepoxy group-containing cross-linking agent and 1-3 parts of an ultraviolet absorbent with a multi-conjugated structure, and all the components synergistically improve the performance. Through end group modification and special additives, the anti-aging, flexibility and heat resistance are improved, the binding power is enhanced, the preparation process is optimized, the efficiency is improved, the cost is reduced, the service life of a photovoltaic module is prolonged, the performance is guaranteed, and the development of the photovoltaic industry is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic encapsulation film material development, in particular to an anti-aging PVB film for photovoltaic module encapsulation and a preparation process thereof. Background Art

[0002] Against the backdrop of the global push for clean energy development, photovoltaic power generation, with its significant advantages such as being renewable and pollution-free, has become a key development direction in the energy sector. As the core component of a photovoltaic power generation system, the performance and service life of photovoltaic modules directly impact the efficiency and economic viability of the entire power generation system. The PVB film used to encapsulate photovoltaic modules plays a crucial role in this process. It not only isolates the photovoltaic cells from the external environment, preventing them from being corroded by moisture and oxygen, but also ensures excellent optical and adhesive properties to ensure the efficient and stable operation of the photovoltaic modules.

[0003] Traditional PVB film faces numerous challenges in practical application. Firstly, insufficient aging resistance is a prominent issue. PV modules are exposed to the combined effects of UV rays, high temperatures, and high humidity for extended periods. The molecular chains in conventional PVB film are susceptible to breakage and degradation under UV radiation, leading to a gradual decline in film performance, such as yellowing, brittleness, and weakened adhesion. This not only reduces the light transmittance of PV modules, impacting power generation efficiency, but can also cause delamination between the cell and the encapsulation material, severely shortening the module's lifespan. According to statistics, in areas with intense sunlight and complex climates, PV modules using traditional PVB film can experience a 15%-20% drop in power generation efficiency after 5-8 years.

[0004] Secondly, existing PVB films struggle to balance flexibility and heat resistance. At low temperatures, the film's lack of flexibility can lead to brittle cracking, compromising the integrity of the package. At high temperatures, the film can soften excessively and creep, causing deformation within the PV module, also adversely affecting power generation performance. For example, in winter in cold northern regions, some PV modules experience partial failure due to film cracking. In summer in hot southern regions, some modules experience cell displacement due to film creep.

[0005] Furthermore, traditional PVB films also have drawbacks when it comes to bonding to photovoltaic cells. Their adhesion is not stable and durable, and over time and due to environmental changes, the bond strength gradually decreases, increasing the risk of delamination in photovoltaic modules. Furthermore, during the preparation process of traditional films, some additives are not compatible with the PVB resin, leading to agglomeration and affecting the uniformity of the film's performance.

[0006] Furthermore, the rapid development of the photovoltaic industry has placed higher demands on the production efficiency and cost control of PVB films. Existing preparation processes are often complex, with long production cycles, resulting in high costs and limiting the further large-scale application of the photovoltaic industry. Therefore, the development of a new PVB film with excellent aging resistance, a good balance of flexibility and heat resistance, and long-lasting, stable adhesion, along with an efficient and cost-effective preparation process, is urgently needed. This is of great significance for improving the performance and service life of photovoltaic modules and promoting the sustainable development of the photovoltaic industry. Summary of the Invention

[0007] (1) Technical problems solved

[0008] In view of the deficiencies in the prior art, the present invention provides an anti-aging PVB film for photovoltaic module encapsulation and a preparation process thereof.

[0009] (2) Technical solution

[0010] An anti-aging PVB film for photovoltaic module encapsulation is composed of the following components, calculated by weight: 60-80 parts of polyvinyl butyral (PVB) resin, with tert-butyl groups introduced at both ends of the PVB molecular chain. The structural formula of the polyvinyl butyral is:

[0011]

[0012] The modification reaction formula is:

[0013]

[0014] Wherein X is a halogen atom;

[0015] The anti-aging agent is 5-10 parts, consisting of a hindered amine light stabilizer containing nitroxide free radicals and a mercaptobenzimidazole antioxidant; the plasticizer is 10-20 parts, which is a new plasticizer based on vegetable oil, polyglycerol ricinoleate, and diisononyl phthalate, and the polyglycerol ricinoleate forms a weak hydrogen bond with the PVB resin; the inorganic nanofiller is 3-8 parts, which is a composite filler of nano-zinc oxide and nano-silicon dioxide, the surface of which is modified by a zwitterionic silane coupling agent, wherein the zwitterionic silane coupling agent is a compound of γ-aminopropyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane; the reaction formula of the zwitterionic silane coupling agent and nano-zinc oxide is:

[0016]

[0017] Crosslinking agent: 1-3 parts, which is an acrylic ester crosslinking agent bisphenol A diglycidyl ether acrylate, which undergoes a crosslinking reaction with the hydroxyl group in the PVB resin at 100-130°C. The reaction formula is:

[0018]

[0019] Ultraviolet absorber: 1-3 parts, which is a benzotriazole ultraviolet absorber 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole, which has an ultraviolet absorption efficiency of not less than 90% in the wavelength range of 280-400nm, and its conjugated structure can form a π-π stacking effect with the PVB molecular chain. The structural formula of the 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole is:

[0020]

[0021] Preferably, the glass transition temperature of the PVB resin after end group modification is reduced by 5-10° C., thereby improving the flexibility of the film in a low temperature environment.

[0022] Preferably, the thermal stability of the hindered amine light stabilizer containing nitroxide free radicals in the film is increased by 20%-30%, which can effectively extend the anti-aging life of the film.

[0023] Preferably, the acid value of the novel plant oil-based plasticizer is no higher than 5 mgKOH / g, ensuring the stability of the plasticizer and its compatibility with the PVB resin.

[0024] Preferably, the agglomeration rate of the nano-zinc oxide and nano-silicon dioxide composite filler whose surface is modified by a zwitterionic silane coupling agent in the PVB film is less than 5%, thereby ensuring the uniformity and stability of the film performance.

[0025] Preferably, the diepoxy-containing acrylate crosslinking agent reacts with the PVB resin at 120° C. for 60 minutes, and the crosslinking degree reaches 70%-80%, forming a stable and moderately crosslinked structure.

[0026] Preferably, the process for preparing an anti-aging PVB film for photovoltaic module encapsulation according to any of the above items comprises the following steps: raw material pretreatment: mixing nano zinc oxide and nano silicon dioxide in proportion, adding a zwitterionic silane coupling agent, and stirring in a high-speed stirrer at a speed of 1200-1800 r / min for 40-80 minutes to perform surface modification; performing purity testing and drying treatment on the new composite anti-aging agent, the new plasticizer based on vegetable oil, diisononyl phthalate, the diepoxy-containing acrylate crosslinker, and the benzotriazole ultraviolet absorber with a multi-conjugated structure;

[0027] End group modification: PVB resin is added to a reactor, and an appropriate amount of catalyst and tert-butylating agent are added. The reaction is carried out at 80-100°C and a stirring speed of 300-500 r / min for 2-4 hours to carry out end group modification. After the reaction is completed, the end group-modified PVB resin is obtained by precipitation, filtration, washing, drying and other steps;

[0028] Mixing: Add the end-group modified PVB resin into a high-speed mixer, and then add the treated anti-aging agent, plasticizer, modified composite filler, cross-linking agent and UV absorber in sequence. Mix at 90-110°C and 600-900r / min for 40-70 minutes to ensure that all ingredients are fully mixed.

[0029] Melt extrusion: Add the mixed materials into a twin-screw extruder and perform melt extrusion at a temperature of 160-190°C and a screw speed of 180-280 r / min. The aspect ratio of the extruder is 28:1-32:1.

[0030] Calendering: The extruded material is calendered through a calendering machine. The calendering temperature is controlled at 140-160°C and the linear speed of the calendering roller is 1.5-3.5 m / min to obtain a PVB film with a thickness of 0.4-0.7 mm.

[0031] Post-processing: The calendered PVB film is heat-treated in an oven at 90-110°C for 1.5-3.5 hours to fully carry out the cross-linking reaction and improve the performance stability of the film. It is then cooled to room temperature and rolled up for packaging.

[0032] Preferably, in the raw material pretreatment step, the mass ratio of nano zinc oxide to nano silicon dioxide is 2.5:1, and the amount of the zwitterionic silane coupling agent added is 3%-5% of the total mass of the composite filler.

[0033] Preferably, in the end group modification step, the catalyst is p-toluenesulfonic acid, and its amount is 0.5%-1% of the mass of the PVB resin.

[0034] Preferably, in the melt extrusion step, the temperature of each zone of the twin-screw extruder is set to: 160-170°C in zone 1, 170-180°C in zone 2, and 180-190°C in zone 3 to ensure that the material is fully melted and plasticized.

[0035] (3) Beneficial technical effects

[0036] Compared with the existing technology, the beneficial effects of the present invention are:

[0037] 1. By introducing tert-butyl groups at both ends of the PVB resin molecular chain, the flexibility and creep resistance of the molecular chain are enhanced, the glass transition temperature is lowered, and the film maintains good flexibility in low-temperature environments, reducing the risk of brittle cracking. In the new composite anti-aging agent, the hindered amine light stabilizer containing nitrogen oxide free radicals forms a covalent bond with the PVB molecular chain, greatly improving the stability of the anti-aging agent. Its ultraviolet absorption efficiency in the wavelength range of 280-400nm is not less than 90%, which can effectively resist ultraviolet damage to the film; the mercaptobenzimidazole antioxidant works synergistically to capture peroxyl free radicals, greatly extending the anti-aging life of the film. Accelerated aging tests have shown that the performance retention rate of this patented PVB film after 10 years of use in simulated outdoor environments is 30%-40% higher than that of traditional films, which can effectively ensure the long-term stable operation of photovoltaic modules and reduce power generation efficiency losses.

[0038] 2. A new plant-oil-based plasticizer forms weak hydrogen bonds with PVB resin, enhancing the plasticizing effect. Combined with diisononyl phthalate, the film maintains excellent flexibility and stability across various temperatures. At temperatures as low as -20°C, the film remains soft and bendable without cracking. Even at temperatures as high as 80°C, the film does not soften significantly and creep, ensuring the proper functioning of photovoltaic modules in diverse climates.

[0039] 3. A diepoxy-containing acrylate crosslinker reacts with the hydroxyl groups in the PVB resin to form a stable and moderately crosslinked three-dimensional network structure, enhancing the bond strength and durability between the film and the photovoltaic cell. Testing has shown that the initial bond strength of this patented film to the cell is 20%-30% higher than that of conventional films. The bond strength is also highly retained over long-term use, effectively reducing the risk of delamination in photovoltaic modules.

[0040] 4. The method of the present invention is relatively simple to operate and improves production efficiency by precisely controlling the parameters of each step. For example, optimization of the raw material pretreatment, mixing, and melt extrusion steps shortens the production cycle and reduces production costs, facilitating large-scale industrial production and promoting the further development of the photovoltaic industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a flow chart for preparing an anti-aging PVB film for photovoltaic module encapsulation proposed by the present invention;

[0042] Figure 2 3. It is a comparison chart of initial bonding strength and bonding strength retention after aging of the embodiment and the comparative example;

[0043] Figure 3 is a comparative chart of ultraviolet transmittance of the embodiment and the comparative example;

[0044] Figure 4 It is a line comparison chart of the production efficiency of the embodiment and the comparative example;

[0045] Figure 5 This is the nuclear magnetic resonance spectrum of the product of the reaction between bisphenol A diglycidyl ether acrylate and the hydroxyl group in PVB resin. DETAILED DESCRIPTION

[0046] Example 1

[0047] Raw material pretreatment: 2 parts nano-zinc oxide and 1 part nano-silicon dioxide were mixed, and a zwitterionic silane coupling agent (γ-aminopropyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane in a ratio of 1.5:1) was added, accounting for 4% of the total weight of the composite filler. The mixture was stirred in a high-speed blender at 1500 rpm for 60 minutes to produce a modified composite filler. A novel composite anti-aging agent (a nitroxide-containing hindered amine light stabilizer and a mercaptobenzimidazole antioxidant in a weight ratio of 2.5:1) was added, along with a novel vegetable oil-based plasticizer (polyglycerol ricinoleate), diisononyl phthalate, a diepoxy-containing acrylate crosslinker (bisphenol A diglycidyl ether acrylate), and a multi-conjugated benzotriazole UV absorber (2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole) for purity testing and drying.

[0048] End-group modification: 60 parts of PVB resin were added to a reactor, along with 0.8% p-toluenesulfonic acid catalyst and an appropriate amount of a tert-butylating agent. The mixture was reacted at 90°C and stirred at 400 rpm for 3 hours. After the reaction, the end-group-modified PVB resin was obtained through precipitation, filtration, washing, and drying. The modification rate was 8%.

[0049] Mixing: Add the end-group modified PVB resin into a high-speed mixer, and add in sequence 5 parts of treated anti-aging agent, 15 parts of plasticizer (polyglycerol ricinoleate and diisononyl phthalate compounded in a weight ratio of 3.5:1), 5 parts of modified composite filler, 2 parts of cross-linking agent and 2 parts of ultraviolet absorber, and mix at 100°C and 700r / min for 50 minutes to ensure that all ingredients are fully mixed.

[0050] Melt extrusion: Add the mixed materials into a twin-screw extruder, set the temperature of zone 1 to 165°C, the temperature of zone 2 to 175°C, the temperature of zone 3 to 185°C, the screw speed to 220 r / min, the aspect ratio to 30:1, and perform melt extrusion.

[0051] Calendering: The extruded material is calendered by a calendering machine. The calendering temperature is controlled at 150°C and the linear speed of the calendering roller is 2.5 m / min to obtain a PVB film with a thickness of 0.5 mm.

[0052] Post-processing: The calendered PVB film is heat-treated in an oven at 100°C for 2.5 hours to allow the cross-linking reaction to proceed fully, then cooled to room temperature and rolled up for packaging.

[0053] Example 2

[0054] Raw material pretreatment: Mix 2.5 parts of nano-zinc oxide with 1 part of nano-silicon dioxide, add 3% of the total weight of the composite filler in a zwitterionic silane coupling agent (γ-aminopropyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane in a ratio of 2:1), and stir in a high-speed blender at 1200 rpm for 80 minutes to obtain a modified composite filler. Other raw material preparations were the same as in Example 1.

[0055] End group modification: 70 parts of PVB resin were added to a reactor, and 0.5% of the mass of the PVB resin was added as a p-toluenesulfonic acid catalyst and an appropriate amount of a tert-butylating agent. The mixture was reacted at 80°C and a stirring speed of 300 r / min for 4 hours to obtain a PVB resin with an end group modification rate of 5%.

[0056] Mixing: Add the end-group modified PVB resin into a high-speed mixer, and add 7 parts of treated anti-aging agent, 12 parts of plasticizer (polyglycerol ricinoleate and diisononyl phthalate in a weight ratio of 3:1), 4 parts of modified composite filler, 1.5 parts of cross-linking agent and 1.5 parts of ultraviolet absorber in sequence, and mix at 90°C and 600r / min for 70 minutes.

[0057] Melt extrusion: twin-screw extruder zone 1 temperature 160 ° C, zone 2 temperature 170 ° C, zone 3 temperature 180 ° C, screw speed 180 r / min, aspect ratio 28:1.

[0058] Calendering molding: calendering temperature 140 ° C, calendering roller linear speed 1.5 m / min, to obtain a PVB film with a thickness of 0.4 mm.

[0059] Post-treatment: heat treatment in an oven at 90°C for 3.5 hours, cooling and winding.

[0060] Example 3

[0061] Raw material pretreatment: Mix 3 parts of nano-zinc oxide with 1 part of nano-silicon dioxide, add 5% of the total weight of the composite filler in a zwitterionic silane coupling agent (γ-aminopropyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane in a 1:1 ratio), and stir in a high-speed blender at 1800 rpm for 40 minutes to obtain a modified composite filler. Other raw material preparations were the same as in Example 1.

[0062] End group modification: 80 parts of PVB resin were added to a reactor, and 1% of the mass of the PVB resin was added as a p-toluenesulfonic acid catalyst and an appropriate amount of a tert-butylating agent. The mixture was reacted at 100°C and a stirring speed of 500 r / min for 2 hours to obtain a PVB resin with an end group modification rate of 10%.

[0063] Mixing: Add the end-group modified PVB resin into a high-speed mixer, and add 10 parts of treated anti-aging agent, 20 parts of plasticizer (polyglycerol ricinoleate and diisononyl phthalate in a weight ratio of 4:1), 8 parts of modified composite filler, 3 parts of cross-linking agent and 3 parts of ultraviolet absorber in sequence, and mix at 110°C and 900r / min for 40 minutes.

[0064] Melt extrusion: twin-screw extruder zone 1 temperature 170 ° C, zone 2 temperature 180 ° C, zone 3 temperature 190 ° C, screw speed 280 r / min, aspect ratio 32:1.

[0065] Calendering: Calendering temperature 160°C, calendering roller speed 3.5m / min, to obtain a PVB film with a thickness of 0.7mm. Post-treatment: Heat treatment in an oven at 110°C for 1.5 hours, cooling and winding.

[0066] Comparative Example

[0067] This film is made using a traditional PVB film production method. The PVB resin is not end-group modified, and standard anti-aging agents, plasticizers, and cross-linking agents are used. UV absorbers with multi-conjugated structures and modified composite inorganic nanofillers are omitted. During the production process, the PVB resin is directly mixed with additives, followed by melt extrusion, calendaring, and post-processing.

[0068] Performance testing and result analysis

[0069] According to the performance test results, Examples 1-3 show significant differences from the comparative PVB films. Example 1 has an initial bonding strength of 12 N / cm, a retention rate of 90% after aging, and a UV transmittance of 5%. No brittle cracking occurs at -20°C, and no obvious creep is observed at a high temperature of 80°C. Example 2 has an initial bonding strength of 11 N / cm, an aging retention rate of 88%, and a UV transmittance of 6%. It also has good low-temperature flexibility and high-temperature heat resistance. Example 3 has the best performance, with an initial bonding strength of 13 N / cm, an aging retention rate of 92%, and a UV transmittance of only 4%. It is stable under extreme temperature conditions. In contrast, the comparative film has an initial bonding strength of only 8 N / cm, a retention rate of 60% after aging, a UV transmittance of as high as 15%, and brittle cracking occurs in low-temperature tests, and obvious creep occurs in high-temperature environments. The test data fully demonstrates that the PVB films of Examples 1-3 are significantly superior to traditional comparative products in terms of bonding performance, weather resistance, and temperature adaptability.

[0070] Comprehensive data table of performance of PVB films of Examples and Comparative Examples:

[0071] project Example 1 Example 2 Example 3 Comparative Example Initial bond strength (N / cm) 12 11 13 8 Bond strength retention rate after aging (%) 90 88 92 60 UV transmittance (%) 5 6 4 15 -20℃ low temperature flexibility No brittle cracks No brittle cracks No brittle cracks There is brittle cracking 80℃ high temperature heat resistance No obvious creep No obvious creep No obvious creep There is obvious creep

[0072] Conclusion: This table visually demonstrates the differences between the Example and Comparative Example PVB adhesive films in several key performance indicators. The Example outperforms the Comparative Example in terms of bond strength, aging resistance, UV shielding, and high- and low-temperature performance, highlighting the performance advantages of the PVB adhesive films of this invention.

[0073] Comparison table of cost and production efficiency of PVB films of Examples and Comparative Examples:

[0074] project Example 1 Example 2 Example 3 Comparative Example Raw material cost (yuan / square meter) 20 22 21 25 Production cycle (hours) 10 11 10.5 15 Production efficiency improvement (%) 30 25 28 0

[0075] Conclusion: This table compares the cost and production efficiency of the Examples and Comparative Examples. The Examples have lower raw material costs than the Comparative Examples, significantly shorten the production cycle, and significantly improve production efficiency, demonstrating the economic and production advantages of the present invention.

[0076] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An anti-aging PVB film for photovoltaic module encapsulation, characterized in that: The invention is composed of the following components by weight: polyvinyl butyral (PVB) resin: 60-80 parts, and the two ends of the PVB molecular chain are modified to introduce tert-butyl groups. The structural formula of the polyvinyl butyral is: The modification reaction formula is: Wherein X is a halogen atom; The anti-aging agent is 5-10 parts, consisting of a hindered amine light stabilizer containing nitroxide free radicals and a mercaptobenzimidazole antioxidant; the plasticizer is 10-20 parts, which is a new plasticizer based on vegetable oil, polyglycerol ricinoleate, and diisononyl phthalate, and the polyglycerol ricinoleate forms a weak hydrogen bond with the PVB resin; the inorganic nanofiller is 3-8 parts, which is a composite filler of nano-zinc oxide and nano-silicon dioxide, the surface of which is modified by a zwitterionic silane coupling agent, wherein the zwitterionic silane coupling agent is a compound of γ-aminopropyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane; the reaction formula of the zwitterionic silane coupling agent and nano-zinc oxide is: Crosslinking agent: 1-3 parts, which is an acrylic ester crosslinking agent bisphenol A diglycidyl ether acrylate, which undergoes a crosslinking reaction with the hydroxyl group in the PVB resin at 100-130°C. The reaction formula is: Ultraviolet absorber: 1-3 parts, which is a benzotriazole ultraviolet absorber 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole, which has an ultraviolet absorption efficiency of not less than 90% in the wavelength range of 280-400nm, and its conjugated structure can form a π-π stacking effect with the PVB molecular chain. The structural formula of the 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole is:

2. The anti-aging PVB film for photovoltaic module encapsulation according to claim 1, characterized in that: The glass transition temperature of the PVB resin after the end group modification is reduced by 5-10° C., thereby improving the flexibility of the film in a low-temperature environment.

3. The anti-aging PVB film for photovoltaic module encapsulation according to claim 1, characterized in that: The hindered amine light stabilizer containing nitrogen oxide free radicals can improve the thermal stability of the adhesive film by 20%-30%, thereby effectively extending the anti-aging life of the adhesive film.

4. The anti-aging PVB film for photovoltaic module encapsulation according to claim 1, characterized in that: The acid value of the novel plant oil-based plasticizer is no higher than 5 mgKOH / g, thereby ensuring the stability of the plasticizer and its compatibility with the PVB resin.

5. The anti-aging PVB film for photovoltaic module encapsulation according to claim 1, characterized in that: The agglomeration rate of the nano zinc oxide and nano silicon dioxide composite filler whose surface is modified by a zwitterionic silane coupling agent in the PVB film is lower than 5%, thereby ensuring the uniformity and stability of the film performance.

6. The anti-aging PVB film for photovoltaic module encapsulation according to claim 1, characterized in that: The diepoxy-containing acrylate crosslinking agent reacts with the PVB resin at 120° C. for 60 minutes, and the crosslinking degree reaches 70%-80%, forming a stable and moderately crosslinked structure.

7. A process for producing an anti-aging PVB film for photovoltaic module encapsulation according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: raw material pretreatment: mixing nano zinc oxide and nano silicon dioxide in proportion, adding a zwitterionic silane coupling agent, and stirring in a high-speed stirrer at a speed of 1200-1800 r / min for 40-80 minutes to perform surface modification; performing purity testing and drying treatment on a new composite anti-aging agent, a new plasticizer based on vegetable oil, diisononyl phthalate, an acrylate crosslinking agent containing a diepoxy group, and a benzotriazole ultraviolet absorber with a multi-conjugated structure; End group modification: PVB resin is added to a reactor, and an appropriate amount of catalyst and tert-butylating agent are added. The reaction is carried out at 80-100°C and a stirring speed of 300-500 r / min for 2-4 hours to carry out end group modification. After the reaction is completed, the end group-modified PVB resin is obtained by precipitation, filtration, washing, drying and other steps; Mixing: Add the end-group modified PVB resin into a high-speed mixer, and then add the treated anti-aging agent, plasticizer, modified composite filler, cross-linking agent and UV absorber in sequence. Mix at 90-110°C and 600-900r / min for 40-70 minutes to ensure that all ingredients are fully mixed. Melt extrusion: Add the mixed materials into a twin-screw extruder and perform melt extrusion at a temperature of 160-190°C and a screw speed of 180-280 r / min. The aspect ratio of the extruder is 28:1-32:

1. Calendering: The extruded material is calendered through a calendering machine. The calendering temperature is controlled at 140-160°C and the linear speed of the calendering roller is 1.5-3.5 m / min to obtain a PVB film with a thickness of 0.4-0.7 mm. Post-processing: The calendered PVB film is heat-treated in an oven at 90-110°C for 1.5-3.5 hours to fully carry out the cross-linking reaction and improve the performance stability of the film. It is then cooled to room temperature and rolled up for packaging.

8. The process for preparing an anti-aging PVB film for photovoltaic module encapsulation according to claim 7, characterized in that: In the raw material pretreatment step, the mass ratio of nano zinc oxide to nano silicon dioxide is 2.5:1, and the added amount of the zwitterionic silane coupling agent is 3%-5% of the total mass of the composite filler.

9. The process for preparing an anti-aging PVB film for photovoltaic module encapsulation according to claim 7, characterized in that: In the end group modification step, the catalyst is p-toluenesulfonic acid, and its usage is 0.5%-1% of the mass of the PVB resin.

10. The process for preparing an anti-aging PVB film for photovoltaic module encapsulation according to claim 7, characterized in that: In the melt extrusion step, the temperature of each zone of the twin-screw extruder is set to: 160-170°C in zone 1, 170-180°C in zone 2, and 180-190°C in zone 3 to ensure that the material is fully melted and plasticized.

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