Photovoltaic backsheet and preparation method and application thereof

Abstract

The present application relates to a kind of photovoltaic back sheet and its preparation method and application, the photovoltaic back sheet includes the inner layer of back sheet, back sheet middle layer and back sheet outer layer sequentially stacked;The inner layer of back sheet includes the adhesion layer, functional layer and protective layer sequentially stacked;The protective layer is contacted with the back sheet middle layer.The photovoltaic back sheet of the present application splits into adhesion layer, functional layer and protective layer for the inner layer of back sheet, ensures the adhesion performance of back sheet adhesive film by the integrity of adhesion layer, provides comprehensive functional characteristics such as UV resistance by the uniform distribution of functional layer, provides additional environmental resistance in the back sheet middle layer by protective layer, ensures that the structure of component back does not directly expose in water vapor environment.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a photovoltaic backsheet, its preparation method, and its application. Background Technology

[0002] As a crucial component of photovoltaic modules, the functionality and environmental resistance of photovoltaic backsheets are of paramount importance. Currently, most photovoltaic backsheets have a two- or three-layer structure, with the middle substrate primarily composed of polyethylene terephthalate (PET), the outer layer providing environmental protection through a fluorinated film or coating, and the inner layer providing adhesion and UV resistance through a fluorinated coating or polymer film.

[0003] CN205122610U discloses a functional multilayer composite photovoltaic backsheet, which is composed of a weather-resistant outer layer A, a weather-resistant outer layer B, a middle base layer, an inner layer A, and an inner layer B stacked sequentially from top to bottom. The weather-resistant outer layer A, weather-resistant outer layer B, middle base layer, and inner layer A are all bonded together with a polymer adhesive. The inner layer B is a coating on the lower surface of the inner layer A. This disclosed photovoltaic backsheet, through structural design, adds two layers of weather-resistant polyolefin film, significantly improving the backsheet's water vapor barrier properties, thermal conductivity, and partial discharge resistance. The water vapor transmission rate of the backsheet is less than 1.0 g / m². 2 •d (infrared method), thermal conductivity between 3.0-5.0 W / M·K, relative tracking index test result greater than 400V (IEC level II), reflectivity (400-1100nm) greater than 85%, photovoltaic modules encapsulated using its disclosed backsheet are tested at 85℃, 85% humidity, and with an applied 1000V negative voltage for 96 hours, the maximum power degradation of the module does not exceed 1%.

[0004] CN102376805B discloses a solar cell backsheet and its preparation method. The disclosed backsheet comprises a glass fiber cloth substrate layer, a fluoropolymer resin film layer, two PET film layers, and two adhesive layers, arranged sequentially as follows: fluoropolymer resin film, PET film, adhesive layer, fluoropolymer resin film, glass fiber cloth, fluoropolymer resin film, adhesive layer, PET film, and fluoropolymer resin film. The disclosed backsheet, due to the use of multiple fluoropolymer resin films, significantly improves its weather resistance; the glass fiber cloth substrate imparts high pressure resistance, high strength, high modulus, and extremely high flame retardant properties; and the double-layer PET structure ensures extremely high water vapor barrier performance.

[0005] Currently, the inner coating of photovoltaic backsheets mainly consists of fluorocarbon (PEVE) coatings and titanium dioxide. Agglomerated titanium dioxide and PEVE coatings may have interstitial networks, which may lead to localized failures in adhesion and UV resistance. Furthermore, since PEVE coatings come from various raw material sources, simply mixing the slurry will further weaken the function of the inner coating.

[0006] In conclusion, it is crucial to develop a photovoltaic backsheet with excellent functional characteristics. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a photovoltaic backsheet, its preparation method, and its application, wherein the photovoltaic backsheet can still maintain functional integrity and uniformity even when the inner layer of the backsheet is thinned.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a photovoltaic backsheet, the photovoltaic backsheet comprising an inner backsheet layer, a middle backsheet layer and an outer backsheet layer stacked sequentially;

[0010] The inner layer of the back panel includes an adhesive layer, a functional layer, and a protective layer stacked sequentially.

[0011] The protective layer is in contact with the intermediate layer of the back plate.

[0012] The photovoltaic backsheet of this invention divides the inner layer of the backsheet into an adhesive layer, a functional layer, and a protective layer. Each layer functions independently and does not affect the others. The integrity of the adhesive layer ensures the adhesion performance of the backsheet film. The uniform distribution of the functional layer provides comprehensive functional characteristics. The protective layer provides additional environmental resistance inside the middle layer of the backsheet, ensuring that the back structure of the module is not directly exposed to the moisture environment. This ensures that even when the backsheet is very thin, the functionality of each layer remains complete and uniform.

[0013] Preferably, the thickness of the inner layer of the backplate is 5-14μm, such as 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, etc.

[0014] Preferably, the thickness of the intermediate layer of the backplate is 250-300μm, such as 260μm, 270μm, 280μm, 290μm, etc.

[0015] Preferably, the thickness of the outer layer of the backplate is 20-25 μm, such as 21 μm, 22 μm, 23 μm, 24 μm, etc.

[0016] Preferably, the thickness of the functional layer is 2-5 μm, such as 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, etc., more preferably 3-5 μm, and even more preferably 4 μm.

[0017] The thickness of the functional layer described in this invention is 2-5 μm. Within this range, the functional layer can be guaranteed to function completely and uniformly. A thickness of 3-5 μm can better guarantee the complete and uniform function of the functional layer.

[0018] Preferably, the thickness of the protective layer is 1-5 μm, such as 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, etc., and more preferably 3-5 μm.

[0019] The thickness of the protective layer described in this invention is 1-5 μm. A thickness within this range ensures that the protective layer functions completely and uniformly. A thickness within the range of 3-5 μm further ensures that the protective layer functions completely and uniformly.

[0020] Preferably, the thickness of the adhesive layer is 2-4 μm, such as 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm, etc.

[0021] The thickness of the adhesive layer described in this invention is 2-4 μm. Within this range, the adhesive layer can be made to function completely and uniformly. If the thickness is too thin, it is prone to cracking due to the influence of the intermediate layer. If the thickness is too thick, the adhesive performance will decrease to some extent.

[0022] Preferably, the adhesive layer is made of at least one or a combination of two of polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PTFE), or phosphite. Typical but non-limiting combinations include: a combination of PTFE and PTFE, a combination of PTFE and phosphite, a combination of PTFE, PTFE, and phosphite, etc. In this invention, phosphite can be used as an antioxidant.

[0023] Preferably, the material of the functional layer includes at least one or a combination of two of titanium dioxide, zinc oxide, zirconium oxide, aluminum oxide, or triazine-based ultraviolet absorbers. Typical but non-limiting combinations include: a combination of titanium dioxide and zinc oxide, a combination of zinc oxide, zirconium oxide, and aluminum oxide, and a combination of titanium dioxide, zinc oxide, zirconium oxide, aluminum oxide, and triazine-based ultraviolet absorbers.

[0024] Preferably, the material of the protective layer includes at least one or a combination of two of polychlorotrifluoroethylene, polytetrafluoroethylene and its derivatives or acrylic resin, wherein typical but non-limiting combinations include: a combination of polychlorotrifluoroethylene and polytetrafluoroethylene, a combination of polychlorotrifluoroethylene, polytetrafluoroethylene and polytetrafluoroethylene derivatives, a combination of polychlorotrifluoroethylene, polytetrafluoroethylene, acrylic resin and polytetrafluoroethylene derivatives, etc.

[0025] Preferably, the material of the intermediate layer of the back panel includes polyethylene terephthalate.

[0026] Preferably, the material of the outer layer of the backplate includes polyvinylidene fluoride.

[0027] In a second aspect, the present invention provides a method for preparing the photovoltaic backsheet described in the first aspect, the method comprising the following steps:

[0028] The raw materials for preparing the protective layer, functional layer, and adhesive layer are dissolved in a solvent to form protective layer slurry, functional layer slurry, and adhesive layer slurry, respectively.

[0029] The protective layer material, functional layer slurry, and adhesive layer slurry are then sequentially coated onto the intermediate layer of the back panel, and each coating is dried afterward to form a protective layer, functional layer, and adhesive layer that are sequentially stacked on the intermediate layer of the back panel, thus obtaining the inner layer of the back panel.

[0030] Then, the inner backsheet layer and the middle backsheet layer, which are stacked sequentially, are placed on the outer backsheet layer to obtain the photovoltaic backsheet.

[0031] or

[0032] First, the middle layer of the backsheet is set on the outer layer of the backsheet, and then the inner layer of the backsheet is set according to the above process to obtain the photovoltaic backsheet.

[0033] Preferably, the middle layer of the back panel is corona treated before the inner layer of the back panel is installed.

[0034] Preferably, the drying temperatures of the protective layer material, the functional layer slurry, and the adhesive layer slurry are each independently 70-150°C, for example 80°C, 100°C, 120°C, 140°C, etc.

[0035] Thirdly, the present invention provides an application of the photovoltaic backsheet described in the first aspect in a solar cell.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The photovoltaic backsheet of the present invention divides the inner layer of the backsheet into an adhesive layer, a functional layer and a protective layer. The integrity of the adhesive layer ensures the adhesive performance of the backsheet film. The uniform distribution of the functional layer provides comprehensive functions such as UV resistance. The protective layer provides additional environmental resistance in the middle layer of the backsheet, ensuring that the back structure of the module is not directly exposed to the moisture environment. Even with the thinning of the inner layer of the backsheet, the integrity and uniformity of the functions can still be guaranteed.

[0038] (2) By controlling the distribution of the inner layers of the backsheet and functionally differentiating the inner layers, this invention ensures that, within a given size range, the inner layers of the backsheet possess complete adhesive properties, improved UV resistance, and enhanced environmental tolerance. When the thickness of the protective layer is adjusted to within the range of 1-5 μm and the thickness of the adhesive layer is within the range of 2-4 μm, the adhesive force is greater than 60 N / cm, the mechanical property retention rate is greater than 50%, and there are no abnormalities at double IEC, demonstrating excellent adhesion, UV resistance, and environmental tolerance. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the photovoltaic backsheet structure described in Example 1;

[0040] Figure 2 This is a schematic diagram of the manufacturing process of the inner layer of the photovoltaic backsheet described in Example 1;

[0041] Among them, 1-inner layer of back panel; 2-middle layer of back panel; 3-outer layer of back panel; 101-protective layer; 102-functional layer; 103-adhesive layer. Detailed Implementation

[0042] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0043] Example 1

[0044] This embodiment provides a photovoltaic backsheet, the structure of which is as follows: Figure 1 As shown, the photovoltaic backsheet is composed of an inner backsheet layer 1, a middle backsheet layer 2, and an outer backsheet layer 3 stacked sequentially.

[0045] The inner layer of the back panel includes an adhesive layer 103, a functional layer 102 and a protective layer 101 stacked in sequence.

[0046] The protective layer is in contact with the intermediate layer of the back plate.

[0047] The adhesive layer has a thickness of 2 μm and is prepared from polytetrafluoroethylene.

[0048] The functional layer has a thickness of 4 μm and is prepared from titanium dioxide and triazine-based ultraviolet absorber 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexyloxy-phenol in a mass ratio of 1:1.

[0049] The protective layer has a thickness of 4 μm and is prepared from polychlorotrifluoroethylene.

[0050] The middle layer of the backplate is made of PET and has a thickness of 275μm.

[0051] The outer layer of the backplate is made of polyvinylidene fluoride film with a thickness of 20 μm.

[0052] The above-mentioned method for preparing a photovoltaic backsheet includes the following steps:

[0053] (1) The raw materials for the preparation of the protective layer, functional layer and adhesive layer are dissolved in the solvent trifluorochloroethylene to form the protective layer slurry, functional layer slurry and adhesive layer slurry respectively;

[0054] (2) The intermediate layer of the backsheet, i.e., the PET substrate, is then subjected to corona treatment. The protective layer material, functional layer slurry, and adhesive layer slurry are sequentially coated onto the corona-treated intermediate layer of the backsheet, and dried after each coating at temperatures of 70℃, 70℃, and 150℃ respectively, forming a protective layer, functional layer, and adhesive layer sequentially stacked on the intermediate layer of the backsheet. The adhesive layer is further cured to obtain the inner layer of the backsheet. The process flow diagram is shown below. Figure 2 As shown;

[0055] (3) Then, the inner layer and the middle layer of the backsheet, which are stacked in sequence, are placed on the outer layer of the backsheet to obtain the photovoltaic backsheet.

[0056] Example 2

[0057] This embodiment provides a photovoltaic backsheet, which is composed of an inner backsheet layer, a middle backsheet layer and an outer backsheet layer stacked in sequence.

[0058] The inner layer of the back panel includes an adhesive layer, a functional layer, and a protective layer stacked sequentially.

[0059] The protective layer is in contact with the intermediate layer of the back plate.

[0060] The adhesive layer has a thickness of 4 μm and is prepared from polychlorotrifluoroethylene and phosphite antioxidant in a mass ratio of 20:1.

[0061] The functional layer has a thickness of 2 μm and is prepared from zirconium oxide, zinc oxide and triazine-based ultraviolet absorber 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexyloxy-phenol in a mass ratio of 1:1:1.

[0062] The protective layer has a thickness of 1 μm and is prepared from acrylic resin.

[0063] The middle layer of the backplate is made of PET and has a thickness of 275 μm.

[0064] The outer layer of the backsheet is made of polyvinylidene fluoride film with a thickness of 20 μm.

[0065] The above-mentioned method for preparing a photovoltaic backsheet includes the following steps:

[0066] (1) The raw materials for the preparation of the protective layer, functional layer and adhesive layer are dissolved in the solvent trifluorochloroethylene to form the protective layer slurry, functional layer slurry and adhesive layer slurry respectively;

[0067] (2) The back panel intermediate layer, i.e., the PET substrate, is then subjected to corona treatment. The protective layer material, functional layer slurry and adhesive layer slurry are sequentially coated onto the corona-treated back panel intermediate layer. After each coating, the material is dried at temperatures of 70°C, 70°C and 150°C, respectively, to form a protective layer, a functional layer and an adhesive layer that are sequentially stacked on the back panel intermediate layer. The adhesive layer is then further cured to obtain the back panel inner layer.

[0068] (3) Then, the inner layer and the middle layer of the backsheet, which are stacked in sequence, are placed on the outer layer of the backsheet to obtain the photovoltaic backsheet.

[0069] Example 3

[0070] This embodiment provides a photovoltaic backsheet, which is composed of an inner backsheet layer, a middle backsheet layer and an outer backsheet layer stacked in sequence.

[0071] The inner layer of the back panel includes an adhesive layer, a functional layer, and a protective layer stacked sequentially.

[0072] The protective layer is in contact with the intermediate layer of the back plate.

[0073] The adhesive layer has a thickness of 2 μm and is prepared from polychlorotrifluoroethylene.

[0074] The functional layer has a thickness of 5 μm and is prepared from aluminum oxide.

[0075] The protective layer has a thickness of 5 μm and is prepared from polytetrafluoroethylene.

[0076] The middle layer of the backplate is made of PET and has a thickness of 300μm.

[0077] The outer layer of the backplate is made of polyvinylidene fluoride film with a thickness of 23 μm.

[0078] The above-mentioned method for preparing a photovoltaic backsheet includes the following steps:

[0079] (1) The raw materials for the preparation of the protective layer, functional layer and adhesive layer are dissolved in the solvent trifluorochloroethylene to form the protective layer slurry, functional layer slurry and adhesive layer slurry respectively;

[0080] (2) The back panel intermediate layer, i.e., the PET substrate, is then subjected to corona treatment. The protective layer material, functional layer slurry and adhesive layer slurry are sequentially coated onto the corona-treated back panel intermediate layer. After each coating, the material is dried at temperatures of 70°C, 70°C and 150°C, respectively, to form a protective layer, a functional layer and an adhesive layer that are sequentially stacked on the back panel intermediate layer. The adhesive layer is then further cured to obtain the back panel inner layer.

[0081] (3) Then, the inner layer and the middle layer of the backsheet, which are stacked in sequence, are placed on the outer layer of the backsheet to obtain the photovoltaic backsheet.

[0082] Examples 4-5

[0083] The difference between Examples 4 and 5 and Example 1 is that the thickness of the functional layer is 2 μm (Example 4) and 5 μm (Example 5), respectively, while the rest is the same as Example 1.

[0084] Examples 6-7

[0085] The difference between Examples 6 and 7 and Example 1 is that the thickness of the adhesive layer is 1 μm (Example 6) and 5 μm (Example 7), respectively, while the rest is the same as Example 1.

[0086] Comparative Example 1

[0087] The difference between this comparative example and Example 1 is that the inner layer of the backsheet is not layered, and the photovoltaic backsheet includes an inner backsheet layer, a middle backsheet layer and an outer backsheet layer stacked in sequence.

[0088] The raw materials for preparing the inner layer of the backplate are a mixture of the raw materials for preparing the adhesive layer, functional layer and protective layer in Example 1.

[0089] The above-mentioned method for preparing a photovoltaic backsheet includes the following steps:

[0090] The raw materials for preparing the inner backsheet layer are dissolved in a solvent to form an inner backsheet layer slurry. The middle backsheet layer, i.e., the PET substrate, is then corona treated. The inner backsheet layer slurry is coated onto the corona-treated middle backsheet layer and dried at 150°C for further curing to form the inner backsheet layer placed on the middle backsheet layer.

[0091] Then, the inner backsheet layer and the middle backsheet layer, which are stacked sequentially, are placed on the outer backsheet layer to obtain the photovoltaic backsheet.

[0092] Performance testing

[0093] The photovoltaic backsheets described in Examples 1-7 and Comparative Example 1 were subjected to the following tests:

[0094] (1) Adhesive performance: Tested according to GB / T 2792-2014 Test method for peel strength of adhesive tape;

[0095] (2) UV resistance: Performed in accordance with IEC62788-1 and GBT 1040.1-2006 Determination of tensile properties of plastics Part 1: General;

[0096] (3) Environmental tolerance: In accordance with IEC62788-1 and IEC 61215.

[0097] The above tests were performed multiple times at different locations on the photovoltaic backsheet in each example, and the results were similar. The average test results are summarized in Table 1.

[0098] Table 1

[0099]

[0100] Analysis of the data in Table 1 shows that, by controlling the distribution of the inner layers of the backsheet and functionally differentiating them, this invention achieves complete adhesive performance, improved UV resistance, and enhanced environmental tolerance within a given size range. When the thickness of the protective layer is adjusted to 1-5 μm and the adhesive layer thickness to 2-4 μm, the adhesive force exceeds 60 N / cm, the mechanical property retention rate exceeds 50%, and there are no abnormalities at double IEC, demonstrating excellent adhesion, UV resistance, and environmental tolerance.

[0101] Analysis of Comparative Example 1 and Example 1 shows that the performance of Comparative Example 1 is not as good as that of Example 1, proving that the photovoltaic backsheet with the inner layer of the backsheet divided into an adhesive layer, a functional layer and a protective layer has better performance than the traditional hybrid coating.

[0102] Analysis of Examples 6-7 and Example 1 shows that the performance of Examples 6-7 is not as good as that of Example 1, proving that the photovoltaic backsheet with a thickness of 2-4 μm is better.

[0103] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A photovoltaic backsheet, characterized in that, The photovoltaic backsheet includes an inner backsheet layer, a middle backsheet layer, and an outer backsheet layer stacked sequentially; the middle backsheet layer is made of polyethylene terephthalate, and the outer backsheet layer is made of polyvinylidene fluoride. The inner layer of the back panel includes an adhesive layer, a functional layer, and a protective layer stacked sequentially; the adhesive layer is made of at least one or a combination of two of polytetrafluoroethylene, polychlorotrifluoroethylene, or phosphite; the functional layer is made of at least one or a combination of two of titanium dioxide, zinc oxide, zirconium oxide, aluminum oxide, or triazine UV absorbers; and the protective layer is made of at least one or a combination of two of polychlorotrifluoroethylene, polytetrafluoroethylene and its derivatives, or acrylic resin. The protective layer is in contact with the intermediate layer of the back plate; The thickness of the inner layer of the backplate is 5-14 μm; The thickness of the functional layer is 2-5 μm, and the thickness of the protective layer is 1-5 μm.

2. The photovoltaic backsheet according to claim 1, characterized in that, The thickness of the intermediate layer of the backplate is 250-300μm.

3. The photovoltaic backsheet according to claim 1, characterized in that, The thickness of the outer layer of the backplate is 20-25 μm.

4. The photovoltaic backsheet according to claim 1, characterized in that, The thickness of the adhesive layer is 2-4 μm.

5. A method for preparing a photovoltaic backsheet according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: The raw materials for preparing the protective layer, functional layer, and adhesive layer are dissolved in a solvent to form protective layer slurry, functional layer slurry, and adhesive layer slurry, respectively. The protective layer slurry, functional layer slurry, and adhesive layer slurry are then sequentially applied to the intermediate layer of the back sheet, and each application is dried to form a protective layer, a functional layer, and an adhesive layer that are sequentially stacked on the intermediate layer of the back sheet, thus obtaining the inner layer of the back sheet. Then, the inner backsheet layer and the middle backsheet layer, which are stacked sequentially, are placed on the outer backsheet layer to obtain the photovoltaic backsheet. or First, the intermediate layer of the backsheet is placed on the outer layer of the backsheet. Then, the raw materials for preparing the protective layer, functional layer, and adhesive layer are dissolved in a solvent to form protective layer slurry, functional layer slurry, and adhesive layer slurry, respectively. Then, the protective layer slurry, functional layer slurry, and adhesive layer slurry are sequentially coated onto the intermediate layer of the backsheet, and each coating is dried afterward to form a protective layer, functional layer, and adhesive layer that are sequentially stacked on the intermediate layer of the backsheet, thus obtaining the inner layer of the backsheet and the photovoltaic backsheet.

6. The preparation method according to claim 5, characterized in that, The middle layer of the backplate is corona treated before the inner layer of the backplate is installed.

7. The preparation method according to claim 5, characterized in that, The drying temperatures of the protective layer slurry, functional layer slurry, and adhesive layer slurry are each independently 70-150℃.

8. The application of a photovoltaic backsheet according to any one of claims 1-4 in a solar cell.

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