A high water-resistant solar cell backsheet and its preparation method

Abstract

This invention relates to the field of solar photovoltaic backsheet technology, specifically to a high water-blocking solar cell backsheet and its preparation method. The solar cell backsheet, from bottom to top, comprises a weather-resistant layer, a nanocomposite water-blocking layer, a substrate support layer, and an adhesive layer. The raw materials for preparing the nanocomposite water-blocking layer include nanomaterials, multilayer graphene, saturated aliphatic polyester polyol, and a curing agent. The nanomaterials include at least one of nano-silica, nano-clay, single-walled carbon nanotubes, multi-walled carbon nanotubes, nano-alumina, nano-boron carbide, nano-cellulose, nano-zinc oxide, nano-titanium oxide, and nano-molybdenum disulfide. This invention has the advantages of good water resistance and weather resistance, and a relatively simple preparation process.

Description

Technical Field

[0001] This invention relates to the field of solar photovoltaic backsheet technology, specifically to a high water-resistant solar cell backsheet and its preparation method. Background Technology

[0002] Traditional solar backsheets often employ technologies such as aluminum foil composites, PET thickening, or sputtering coatings to improve water-blocking performance. For example, aluminum foil composite technology reduces water vapor transmission through the barrier effect of metallic aluminum foil, but aluminum foil is prone to oxidation, has high cost, and increases the weight and thickness of the backsheet. While PET thickening technology is simple, its water-blocking effect is limited, with water vapor transmission typically exceeding 1.5 g / m³. 2 • 24-hour operation is insufficient to meet the needs of humid areas. Sputtering coating technology improves water resistance by depositing a water-blocking layer such as silicon oxide on the PET surface, but this layer is prone to peeling off after long-term aging, leading to a decline in performance.

[0003] Furthermore, the weather-resistant layer of traditional solar backsheets often uses a single material (such as PVDF or PET), which is prone to aging, yellowing, or performance degradation under long-term ultraviolet radiation and humid and hot environments. For example, while PVDF has good weather resistance, it is expensive and lacks sufficient mechanical properties; PET, on the other hand, has poor weather resistance and requires surface coating or modification to improve its performance. The manufacturing processes of existing high water-resistant backsheets are generally complex. For instance, aluminum foil lamination requires multiple layers, and sputtering technology requires expensive equipment and complex process control, resulting in high production costs and low efficiency. In addition, the use of aluminum foil or multi-layer composite structures in some traditional backsheets not only increases material usage but may also lead to recycling difficulties and environmental problems.

[0004] In recent years, with the rapid development of nanomaterials and composite technologies, the research direction of high water-resistant solar backsheets has gradually shifted towards nanocomposite coating technology. For example, Chinese Patent Publication No. CN107418316A discloses a solar reflective coating comprising the following raw materials in parts by weight: 20-40 parts fluororesin, 3-8 parts isocyanate, 0.5-2 parts dispersant, 10-30 parts titanium dioxide, 10-30 parts magnesium oxide, 1-3 parts graphene, 0.1-0.5 parts silane coupling agent, 1-5 parts nanocomposite powder, 1-2 parts silicon dioxide, and 10-20 parts butyl acetate. This coating has high reflectivity to sunlight and is suitable for use as a coating for solar photovoltaic module backsheets. However, this coating is mainly used to achieve high reflectivity and can only partially block the entry of water droplets; its water-resistant performance needs further improvement.

[0005] Furthermore, the introduction of in-situ polymerization technology and co-extrusion process further simplifies the backsheet preparation process and reduces production costs. Chinese Patent Publication No. CN117774465A discloses a multi-layer co-extruded solar backsheet and its processing technology, including a backsheet body comprising an outer weather-resistant layer, a first adhesive layer, a structural reinforcement layer, a second adhesive layer, and an inner weather-resistant layer. The bottom end of the outer weather-resistant layer is bonded to the top end of the first adhesive layer, the bottom end of the first adhesive layer is bonded to the top end of the structural reinforcement layer, the bottom end of the structural reinforcement layer is bonded to the top end of the second adhesive layer, and the bottom end of the second adhesive layer is bonded to the top end of the inner weather-resistant layer. This process transforms the previous method of separately producing four materials and then compounding them into a single production step, shortening the cycle. The integrated molding results in strong interlayer adhesion, improving interlayer peel strength and reducing the likelihood of delamination and detachment, ensuring the long-term weather resistance of the solar cell backsheet. It avoids the use of solvent-based adhesives, eliminating solvent evaporation and preventing environmental pollution. Costs are reduced, and economic benefits increase. However, this backsheet primarily achieves partial water resistance through multi-layer bonding and physical methods, and its water-blocking performance needs further improvement.

[0006] Chinese Patent Publication No. CN113437170A discloses a flexible encapsulation composite film for solar cell backsheets, comprising an outer protective film, an inorganic intermediate film, and a flexible bottom film stacked sequentially from top to bottom. The flexible bottom film is composed of the following raw materials in parts by weight: 20-30 parts diisobutyl nitrile; 12-16 parts polyol; and 1-3 parts graphene oxide. This composite film is prepared by layering organic layers with inorganic layers and organic layers. The outer protective film provides external protection, the inorganic intermediate film provides water and oxygen barrier properties, and graphene oxide is used to graft and modify polyurethane, overcoming the defects of polyurethane. This results in a corrosion-resistant, high-strength, and water- and oxygen-barrier flexible encapsulation composite film. However, its water resistance, weather resistance, and mechanical properties need further improvement.

[0007] Existing technologies are mainly developed for passivated emitter back surface cells (PERC cells), which cannot meet the requirements of tunnel oxide passivated contact cell (Topcon) technology, intrinsic thin film heterojunction cell (HJT technology) and perovskite technology for water blocking and weather resistance. They also have many shortcomings in terms of fabrication process and environmental friendliness.

[0008] Therefore, there is an urgent need to develop a high water resistance solar backsheet to solve the above problems and meet market demand. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a high water-blocking solar cell backsheet with good water resistance and weather resistance, and a simple manufacturing process, as well as its manufacturing method. This invention utilizes the principle of tightly packed nanomaterials within multilayer graphene to increase the pathway for water vapor to pass through the nanocomposite water-blocking layer, thereby achieving better water-blocking performance. Simultaneously, the weather-resistant layer ensures the long-term usability of the material, and the adhesive layer provides excellent bonding with the substrate support layer. The product manufacturing process of this invention is simple and suitable for mass production.

[0010] This invention is achieved through the following technical solutions:

[0011] The first aspect of the present invention provides a high water-resistant solar cell backsheet, wherein the structure of the solar cell backsheet, from bottom to top, comprises a weather-resistant layer, a nanocomposite water-resistant layer, a substrate support layer, and an adhesive layer;

[0012] The raw materials for preparing the nanocomposite water-blocking layer include nanomaterials, multilayer graphene, saturated aliphatic polyester polyols, and curing agents.

[0013] The nanomaterials include at least one of nano-silica, nano-clay, single-walled carbon nanotubes, multi-walled carbon nanotubes, nano-alumina, nano-boron carbide, nano-cellulose, nano-zinc oxide, nano-titanium oxide, and nano-molybdenum disulfide.

[0014] The weather-resistant layer of this invention is used to resist environmental erosion such as ultraviolet rays and humid heat; the nanocomposite water-blocking layer is used to enhance the water-blocking performance of the backsheet; the substrate support layer is used to provide mechanical support and insulation performance; and the adhesive layer is used to bond with the battery cells and other encapsulation materials.

[0015] The multilayer graphene described in this invention typically has a lateral dimension ranging from submicron to tens of micrometers (0.5µm-10µm being the most common), while the number of layers is mostly concentrated in 5-10 layers.

[0016] In one embodiment of the present invention, the raw materials for preparing the nanocomposite water-blocking layer include the following components by weight:

[0017] 10-25 parts of nanomaterials;

[0018] 2-5 parts of multilayer graphene;

[0019] 65-90 parts of saturated aliphatic polyester polyol;

[0020] 5-10 parts of curing agent.

[0021] In this invention, saturated aliphatic polyester polyol and curing agent are used to prepare aliphatic polyurethane resin, which mainly provides a carrier for nanomaterials and multilayer graphene.

[0022] In one embodiment of the present invention, the curing agent is selected from hexamethylene diisocyanate trimer.

[0023] In one embodiment of the present invention, the saturated aliphatic polyester polyol is prepared by polycondensation reaction of a dicarboxylic acid and a diol.

[0024] The saturated aliphatic polyester polyol of this invention can be a commercially available product or can be prepared in-house; there are no particular limitations. Specifically, it is prepared by esterification and polycondensation of a diacid and a diol under the action of a catalyst. The catalyst can be selected from tetraisopropyl titanate. A stabilizer can also be added during the above reaction process; the stabilizer can be selected from triphenyl phosphite.

[0025] In a preferred embodiment of the present invention, the dicarboxylic acid has 2-10 carbon atoms, more preferably 6-10.

[0026] In one embodiment of the present invention, the dicarboxylic acid is at least one of adipic acid and sebacic acid.

[0027] In a preferred embodiment of the present invention, the number of carbon atoms in the diol is 2-10, more preferably 2-4.

[0028] In one embodiment of the present invention, the diol is at least one selected from ethylene glycol, 1,2-propanediol, and 1,4-butanediol.

[0029] In one embodiment of the present invention, the thickness of the weather-resistant layer is 5-20 μm, preferably 5-10 μm.

[0030] In one embodiment of the present invention, the thickness of the nanocomposite water-blocking layer is 10-50 μm, preferably 10-20 μm.

[0031] In one embodiment of the present invention, the thickness of the substrate support layer is 100-800μm, preferably 100-300μm.

[0032] In one embodiment of the present invention, the thickness of the adhesive layer is 5-15 μm.

[0033] In one embodiment of the present invention, the weather-resistant layer is composed of a fluorine-containing coating.

[0034] Preferably, the components of the fluorinated coating include fluorinated resin, polyester resin and acrylic resin.

[0035] In addition to the resin components mentioned above, the fluorinated coatings generally also contain solvents and curing agents. The commonly used solvent is ethyl acetate, and the commonly used curing agent is aliphatic polyisocyanate trimer.

[0036] In one embodiment of the present invention, the substrate support layer comprises a single or multiple film layer made of at least one material selected from polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyethylene, polypropylene and polyimide.

[0037] In one embodiment of the present invention, the adhesive layer comprises at least one of polyurethane adhesive and acrylate adhesive.

[0038] Preferably, the polyurethane adhesive is selected from one or more of polyether-type PU adhesives, polyester-type PU adhesives, polycarbonate-type PU adhesives, UV-curable polyurethane acrylates, and self-healing PU adhesives.

[0039] Preferably, the acrylate adhesive is selected from one or more of the following: UV-curable acrylate adhesives, two-component acrylate structural adhesives, and silicone-modified acrylate adhesives.

[0040] A second aspect of the present invention provides a method for preparing the above-mentioned high water resistance solar cell backsheet, comprising the following steps:

[0041] (1) Disperse nanomaterials and multilayer graphene in a ketone organic solvent to form a nano-mixed suspension; add saturated aliphatic polyester polyol and curing agent to the nano-mixed suspension and mix evenly to obtain a nano-composite water-blocking coating.

[0042] (2) The nanocomposite water-blocking coating is applied to the surface of the substrate support layer and cured to form a nanocomposite water-blocking layer on the surface of the substrate support layer;

[0043] (3) Coat the surface of the nanocomposite water-blocking layer with the components of the weather-resistant layer, remove the solvent from the components of the weather-resistant layer, and cure to form the weather-resistant layer;

[0044] (4) Apply the components of the adhesive layer to one side of the substrate support layer and the nanocomposite water-blocking layer, and cure to obtain the final product.

[0045] As one embodiment of the present invention, the nanocomposite water-blocking layer can be prepared by in-situ polymerization technology, layer-by-layer self-assembly technology, sol-gel method, microemulsion polymerization and plasma-assisted polymerization.

[0046] In one embodiment of the present invention, in step (1), nanomaterials and multilayer graphene are dispersed in a ketone organic solvent and uniformly dispersed by ultrasonic treatment or high-speed shearing and stirring to form a stable nano-mixed suspension; saturated aliphatic polyester polyol and curing agent are added to the nano-mixed suspension and stirred continuously at a certain speed under constant temperature conditions to ensure that the components are fully mixed and form a uniform system, thereby obtaining a nano-composite water-blocking coating.

[0047] In one embodiment of the present invention, the ketone organic solvent in step (1) is at least one of acetone and butanone.

[0048] The mass ratio of the ketone organic solvent to the nanomaterial in step (1) is 3-6:2-5.

[0049] In step (2), a thermosetting process is selected according to the characteristics of the system. The coated substrate support layer is placed in an oven at 50-80℃ for 48-72h for heat treatment, which promotes the reaction between the hexamethylene diisocyanate trimer curing agent and the saturated aliphatic polyester polyol to form a dense cross-linked network and finally form a nanocomposite water-blocking layer on the surface of the substrate support layer.

[0050] As one embodiment of the present invention, the curing process parameters in step (3) are 50-80℃ for 48-72 hours.

[0051] As one embodiment of the present invention, the method for removing the solvent from the components of the weather-resistant layer in step (3) is to remove the solvent by heating at 100-180°C for 2-4 minutes.

[0052] As one embodiment of the present invention, the curing process parameters in step (4) are 50-80℃ for 48-72h.

[0053] The beneficial effects of this invention are:

[0054] This invention optimizes the composition of the nanocomposite water-blocking layer. The dense network structure of the water-blocking layer, composed of nanomaterials, multilayer graphene, and aliphatic polyurethane resin (obtained from saturated aliphatic polyester polyol and curing agent), significantly reduces water vapor transmission rate and improves the water-blocking performance of the solar panel. Tests show that the water vapor transmission rate is less than 0.1 g / m³. 2 • 24h. While reducing the water vapor transmission rate of the backsheet, this method also improves the mechanical properties of the backsheet. Due to the addition of multilayer graphene materials, the mechanical properties of the solar backsheet are significantly improved. In particular, the high tensile strength and impact resistance of the backsheet make it more suitable for complex climatic environments.

[0055] Furthermore, this invention offers significant cost and efficiency advantages in its manufacturing process. Specifically, the technology employs a solution coating process, requiring only conventional stirring and coating equipment to complete production, eliminating the need for expensive vacuum coating or high-temperature, high-pressure equipment. The entire process comprises only three standardized steps: material mixing, substrate coating, and curing. It is simple to operate, easy to control in terms of quality, and requires no external environmental control. This simplified manufacturing process meets the photovoltaic industry's urgent need for large-scale, low-cost manufacturing, significantly improving production efficiency and being environmentally friendly. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the structure of a high water-resistant solar backsheet according to the present invention.

[0057] Figure 2 This is a schematic diagram of a traditional solar backsheet structure without a nanocomposite water-blocking layer.

[0058] Among them, 1-weather-resistant layer, 2-nano-composite water-blocking layer, 3-matrix support layer, and 4-adhesive layer. Detailed Implementation

[0059] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as a result. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0060] A solar cell backsheet has a structure consisting of, from bottom to top, a weather-resistant layer (1), a nanocomposite water-blocking layer (2), a substrate support layer (3), and an adhesive layer (4), as shown in the figure. Figure 1 As shown, the specific preparation methods are described in Examples 1 and 2.

[0061] The multilayer graphene used in the various embodiments of the present invention was purchased from Changzhou Sixth Element Materials Technology Co., Ltd., model SE1230.

[0062] The specific preparation process of the saturated aliphatic polyester polyol used in the embodiments of this invention is as follows: 146g of adipic acid (AA), 86g of 1,2-propanediol (PG), 0.07g of tetraisopropyl titanate catalyst, and 0.69g of triphenyl phosphite stabilizer are added sequentially while dry nitrogen gas is introduced. The temperature is raised to 150°C and reacted for 3 hours. The temperature is then raised to 180°C and the reaction continues for another 2 hours. When the water output reaches more than 95% of the theoretical value and the acid value drops to a certain range (<30mgKOH / g), the system pressure is slowly reduced to approximately 5000Pa (50mbar), and the reaction continues under low vacuum while maintaining the temperature at 200°C. When the acid value and viscosity reach the predetermined indicators (acid value ≤2mgKOH / g, viscosity 1000-2000cps), the reaction is complete. Heating and stirring are stopped, the vacuum is broken, and nitrogen gas is introduced into the reactor to atmospheric pressure to obtain the desired saturated aliphatic polyester polyol.

[0063] Example 1

[0064] (1) Add 10g of nano-silica and 2g of multilayer graphene to 100mL of acetone, then sonicate at 500W for 30min to disperse it in acetone, then add 83g of saturated aliphatic polyester polyol and 5g of hexamethylene diisocyanate trimer curing agent, and use constant temperature magnetic stirring to completely dissolve the resin in the acetone system.

[0065] (2) Surface activation of 200 μm thick biaxially oriented PET film was performed using a corona treatment device (energy 2.5 W·min / m). 2 As a substrate support layer, the mixed solution in (1) is coated on the surface of a 200μm thick PET film. The curing temperature is 60℃ and the curing time is 48h to form a 15μm thick nanocomposite water-blocking layer.

[0066] (3) After the preparation of the nanocomposite water-blocking layer is completed, a precision slit extrusion coating process is used to uniformly coat the fluorine-containing coating (Changzhou Weston Adhesive Materials Co., Ltd., WSD-1556) on the surface of the activated nanocomposite water-blocking layer at a linear speed of 10±0.2m / min. The solvent is removed by heating at 180℃ for 2min. The curing temperature is 60℃ and the curing time is 72h, finally forming a dense weather-resistant layer.

[0067] (4) After the preparation of the nanocomposite water-blocking layer and the fluorinated resin weather-resistant layer is completed, a high-precision transfer coating process is used to uniformly coat the other side of the PET film with a 10±0.5μm thick two-component polyurethane adhesive (Anzo Chemical Co., Ltd., brand Y2600). During the coating process, the linear speed is maintained at 10±0.5m / min, the curing temperature is 60℃, and the time is 72h. Finally, a high-performance adhesive layer is formed, and the preparation of the back sheet is completed.

[0068] The backsheet material obtained in Example 1 was subjected to water vapor transmission rate and interlayer peel strength tests. The initial test results are shown in Table 1. After aging for 3000 h of DH damp heat test (85℃, 85RH%) and 72 h of PCT pressure cooker test (121℃, 100% relative humidity, 2 atmospheres), the test results of water vapor transmission rate and interlayer peel strength of the backsheet are shown in Tables 2 and 3.

[0069] Example 2

[0070] (1) Add 15g of nano-silica and 3g of multilayer graphene to 150mL of acetone, then sonicate at 500W for 30min to disperse it in acetone, then add 70g of saturated aliphatic polyester polyol and 7g of hexamethylene diisocyanate trimer curing agent prepared in advance, and use constant temperature magnetic stirring to completely dissolve the resin in the acetone system.

[0071] (2) Surface activation of 200 μm thick biaxially oriented PET film was performed using a corona treatment device (energy 3.5 W·min / m). 2 As a substrate support layer, the mixed solution in (1) is coated on the surface of a 200μm thick PET film. The curing temperature is 60℃ and the curing time is 48h to form a 50μm thick nanocomposite water-blocking layer with a three-dimensional interpenetrating network structure.

[0072] (3) After the preparation of the nanocomposite water-blocking layer is completed, a precision slit extrusion coating process is used to uniformly coat the fluorinated coating (Changzhou Weston Adhesive Materials Co., Ltd., WSD-1556) on the surface of the activated nanocomposite water-blocking layer at a linear speed of 10±0.2m / min. The solvent is removed by heating at 120℃ for 4min. The curing temperature is 80℃ and the curing time is 48h, finally forming a dense weather-resistant layer.

[0073] (4) After the preparation of the nanocomposite water-blocking layer and the fluorinated resin weather-resistant layer is completed, a high-precision transfer coating process is used to uniformly coat the other side of the PET film with a 10±0.5μm thick two-component polyurethane adhesive (Anzo Chemical Co., Ltd., brand Y2600). During the coating process, the linear speed is maintained at 10±0.5m / min, the curing temperature is 60℃, and the time is 72h. Finally, a high-performance adhesive layer is formed, and the preparation of the back sheet is completed.

[0074] The backsheet material obtained in Example 2 was subjected to water vapor transmission rate and interlayer peel strength tests. The initial test results are shown in Table 1. After aging for 3000 h of DH damp heat test (85℃, 85RH%) and 72 h of PCT pressure cooker test (121℃, 100% relative humidity, 2 atmospheres), the test results of water vapor transmission rate and interlayer peel strength of the backsheet are shown in Tables 2 and 3.

[0075] Comparative Example 1

[0076] The only difference from Example 2 is the composition of the nanocomposite water-blocking layer, which does not contain nano-silica, but the thickness of the nanocomposite water-blocking layer remains unchanged, and all other conditions are the same.

[0077] Comparative Example 2

[0078] The only difference from Example 2 is the composition of the nanocomposite water-blocking layer, which does not contain multilayer graphene, but the thickness of the nanocomposite water-blocking layer remains unchanged, and all other conditions are the same.

[0079] Comparative Example 3

[0080] The only difference from Example 2 is the composition of the nanocomposite water-blocking layer. It does not contain aliphatic polyurethane resin and its raw material components, but the thickness of the nanocomposite water-blocking layer remains unchanged, and all other conditions are the same.

[0081] Comparative Example 4

[0082] The only difference from Example 2 is that it does not contain a nanocomposite water-blocking layer; the specific structure is as follows: Figure 2 As shown.

[0083] Comparative Example 5

[0084] The only difference from Example 2 is the composition of the nanocomposite water-blocking layer. It does not contain nano-silica, and the amount of multilayer graphene is increased to 18g. All other conditions are the same.

[0085] Comparative Example 6

[0086] The only difference from Example 2 is the composition of the nanocomposite water-blocking layer. It does not contain multilayer graphene, and the amount of nano silica is increased to 18g. All other conditions are the same.

[0087] Comparative Example 7

[0088] The only difference from Example 2 is that the ratio of nano-silica and multilayer graphene in the nanocomposite water-blocking layer is different, which is 1:1. The total amount of both remains the same, that is, 9g of nano-silica and 9g of multilayer graphene. All other conditions are the same.

[0089] Table 1 Comparison of initial value data between the examples and comparative examples.

[0090]

[0091] Table 2 Comparison of DH 3000h data between the examples and comparative examples.

[0092]

[0093] Table 3 Comparison of PCT data between the examples and comparative examples after 72 hours.

[0094]

[0095] The solar backsheet of this invention adopts a multi-layer composite structure design. The nano-composite water-blocking layer, through a unique in-situ polymerization process, uniformly disperses nano-silica and multi-layer graphene within an aliphatic polyurethane resin matrix, forming a dense three-dimensional barrier network that reduces water vapor permeability to as low as 0.10 g / m². 2 The water-blocking performance is improved by more than 5 times compared to traditional backsheets (Comparative Example 4) with a capacity of less than 100 m³ / day. Simultaneously, the solar backsheet of this invention exhibits superior mechanical properties, with a tensile strength exceeding 80 MPa and an elongation at break exceeding 200%, enabling long-term use under extreme climatic conditions. The manufacturing process of this invention achieves continuous and large-scale production through optimized coating parameters and curing conditions. This technology not only solves the industry problem of rapid performance degradation of existing backsheets in humid environments but also offers lower costs.

[0096] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A high water-resistant solar cell backsheet, characterized in that, The structure of the solar cell backsheet, from bottom to top, consists of a weather-resistant layer, a nanocomposite water-blocking layer, a substrate support layer, and an adhesive layer. The raw materials for preparing the nanocomposite water-blocking layer include nanomaterials, multilayer graphene, saturated aliphatic polyester polyols, and curing agents. The nanomaterials include at least one of nano-silica, nano-clay, single-walled carbon nanotubes, multi-walled carbon nanotubes, nano-alumina, nano-boron carbide, nano-cellulose, nano-zinc oxide, nano-titanium oxide, and nano-molybdenum disulfide. The raw materials for preparing the nanocomposite water-blocking layer, by weight, include the following components: 10-25 parts of nanomaterials; 2-5 parts of multilayer graphene; 65-90 parts of saturated aliphatic polyester polyol; 5-10 parts of curing agent; The saturated aliphatic polyester polyol is prepared by polycondensation reaction of diacid and diol.

2. The high water resistance solar cell backsheet according to claim 1, characterized in that, The thicknesses of the weather-resistant layer, the nanocomposite water-blocking layer, the matrix support layer, and the adhesive layer are 5-20μm, 10-50μm, 100-800μm, and 5-15μm, respectively.

3. The high water resistance solar cell backsheet according to claim 1, characterized in that, The weather-resistant layer is composed of a fluorinated coating; and / or the substrate support layer comprises a single or multilayer film layer made of at least one of polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyethylene, polypropylene and polyimide; and / or the adhesive layer comprises at least one of polyurethane adhesive and acrylate adhesive.

4. The high water resistance solar cell backsheet according to claim 3, characterized in that, The components of the fluorinated coating include fluorinated resin, polyester resin and acrylic resin.

5. The high water resistance solar cell backsheet according to claim 3, characterized in that, The polyurethane adhesive is selected from one or more of polyether-type polyurethane adhesives, polyester-type polyurethane adhesives, polycarbonate-type polyurethane adhesives, UV-curable polyurethane acrylates, and self-healing polyurethane adhesives; the acrylate adhesive is selected from one or more of UV-curable acrylate adhesives, two-component acrylate structural adhesives, and silicone-modified acrylate adhesives.

6. The high water resistance solar cell backsheet according to claim 1, characterized in that, The dicarboxylic acid has 2-10 carbon atoms, and the diol has 2-10 carbon atoms; the curing agent is selected from hexamethylene diisocyanate trimer.

7. The high water resistance solar cell backsheet according to claim 1, characterized in that, The multilayer graphene has 5-10 layers and a lateral dimension of 0.5-10 μm.

8. A method for preparing a high water-resistant solar cell backsheet according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Disperse nanomaterials and multilayer graphene in a ketone organic solvent to form a nano-mixed suspension; add saturated aliphatic polyester polyol and curing agent to the nano-mixed suspension and mix evenly to obtain a nano-composite water-blocking coating. (2) The nanocomposite water-blocking coating is applied to the surface of the substrate support layer and cured to form a nanocomposite water-blocking layer on the surface of the substrate support layer; (3) Coating the components of the weather-resistant layer onto the surface of the nanocomposite water-blocking layer, removing the solvent from the components, and curing to form the weather-resistant layer; (4) Apply the components of the adhesive layer to one side of the substrate support layer and the nanocomposite water-blocking layer, and cure to obtain the final product.

9. The preparation method according to claim 8, characterized in that, The curing environment temperature in step (2) is 50-80℃ and the time is 48-72h; the curing environment temperature in step (3) is 60-90℃ and the time is 48-72h; the curing environment temperature in step (4) is 50-80℃ and the time is 48-72h.

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