Photovoltaic backboard and preparation method thereof, and photovoltaic module

Abstract

The invention relates to the technical field of solar cells, and mainly provides a photovoltaic backboard and a preparation method thereof, and a photovoltaic module. The photovoltaic backboard comprises a composite fiber layer and a base body layer which are sequentially arranged in a stacked mode. Wherein the composite fiber layer comprises a resin matrix, and continuous fibers and short fibers which are dispersed in the resin matrix. According to the technical scheme, the photovoltaic backboard is light in weight and has good mechanical property, mechanical property, wear resistance, chemical stability and environmental aging resistance.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a photovoltaic backplane and a preparation method thereof, and a photovoltaic module. Background Art

[0002] The photovoltaic backsheet is an important component of the photovoltaic module. It is located on the back of the photovoltaic module and plays a role in protecting and supporting the photovoltaic cells. The main function of the photovoltaic backsheet is to isolate the internal and external environments of the module, ensure electrical insulation, and enable the photovoltaic module to operate outdoors for a long time. Therefore, the performance of the photovoltaic backsheet (for example, weight, strength and stability) directly affects the performance and service life of the photovoltaic module.

[0003] In the prior art, some photovoltaic lightweight modules use transparent backboards or highly transparent fluorine films as packaging materials, which have low strength and are difficult to meet the requirements of the impact resistance (hail resistance) performance of photovoltaic modules. Some photovoltaic lightweight modules use a substrate layer and a honeycomb core layer structure to replace the design of the backboard and aluminum frame, and use an adhesive layer or an adhesive film layer to achieve the connection and composite between the substrate layer and the honeycomb core layer. However, the application of this composite structure in photovoltaic modules will cause bubbling, debonding, deformation and creeping during subsequent lamination, and the strength of this photovoltaic module is low and the support is poor.

[0004] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the invention

[0005] The present application provides a photovoltaic backsheet and a preparation method thereof, and a photovoltaic module to solve or alleviate the above technical problems. The photovoltaic backsheet in the technical solution of the present application is not only light in weight, but also has good mechanical properties, mechanical properties, wear resistance, chemical stability and environmental aging resistance.

[0006] In a first aspect, an embodiment of the present application provides a photovoltaic backsheet, comprising: a composite fiber layer and a substrate layer stacked in sequence; The composite fiber layer includes a resin matrix, and continuous fibers and short fibers dispersed in the resin matrix.

[0007] Optionally, the continuous fiber includes one or more of glass fiber, carbon fiber, aramid fiber, alumina fiber, and polyester fiber.

[0008] Optionally, the length of the continuous fiber is greater than or equal to 100 mm.

[0009] Optionally, the short fibers include one or both of glass fibers and carbon fibers; and the length of the short fibers is 0.1-1 mm.

[0010] Optionally, the resin forming the resin matrix includes a first thermosetting resin or a first thermoplastic resin.

[0011] Optionally, the first thermoplastic resin includes one or more of polypropylene resin (PP), polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyethylene resin (PE), and polyamide resin (PA).

[0012] Optionally, in the composite fiber layer, the mass ratio of the continuous fibers, the short fibers and the resin forming the resin matrix is ​​(1.5-3):(1-1.5):1.

[0013] Optionally, the resin forming the base layer includes a second thermosetting resin or a second thermoplastic resin.

[0014] Optionally, the second thermoplastic resin includes one or more of polypropylene resin (PP), polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyethylene resin (PE), and polyamide resin (PA).

[0015] Optionally, the photovoltaic backsheet further comprises a weather-resistant layer, wherein the weather-resistant layer is located on a side of the composite fiber layer away from the base layer; and / or The photovoltaic back sheet further comprises a bonding layer, and the bonding layer is located on a side of the base layer away from the composite fiber layer.

[0016] Optionally, the weather-resistant layer is formed by curing a first fluorine-containing coating; the first fluorine-containing coating comprises a fluorocarbon resin and a first curing agent; and / or The bonding layer is formed by curing a second fluorine-containing coating, wherein the second fluorine-containing coating comprises a fluorocarbon resin and a second curing agent.

[0017] Optionally, the composite fiber layer has a thickness of 30-100 μm; and / or The thickness of the substrate layer is 275-315 μm; and / or The thickness of the weather-resistant layer is 25-105 μm; and / or The thickness of the bonding layer is 5-40 μm.

[0018] In a second aspect, an embodiment of the present application provides a method for preparing a photovoltaic backsheet, comprising: forming a matrix layer on the lower surface of the composite fiber layer; The composite fiber layer includes a resin matrix, and continuous fibers and short fibers dispersed in the resin matrix.

[0019] Optionally, the method for preparing the composite fiber layer comprises: Mixing the short fibers and the resin matrix forming resin to obtain a first mixed material; After the continuous fibers are impregnated and wrapped by the first mixed material, the continuous fibers and the short fibers are dispersed in the resin forming the resin matrix, and fiber-reinforced thermoplastic strips are formed by extrusion; The fiber-reinforced thermoplastic material strips are solidified and pelletized to obtain fiber-reinforced thermoplastic pellets; The fiber-reinforced thermoplastic particles are calendered to form a composite fiber layer.

[0020] Optionally, the method for preparing a photovoltaic backsheet further includes: Coating a weather-resistant layer material on the upper surface of the composite fiber layer to form a weather-resistant layer; The bonding layer material is coated on the lower surface of the base layer to form a bonding layer.

[0021] In a third aspect, an embodiment of the present application provides a photovoltaic module, including the photovoltaic backsheet provided by any one of the above embodiments; Wherein, the photovoltaic back panel is arranged on the backlight side of the solar cell.

[0022] The above technical solution adopted in the embodiment of the present application may have the following advantages: The photovoltaic backsheet of the embodiment of the present application includes: a composite fiber layer and a matrix layer. Among them, the matrix layer is the supporting structure of the photovoltaic backsheet; the composite fiber layer uses continuous fibers as the skeleton and short fibers as the filler. The continuous fibers and short fibers are dispersed in the resin matrix, which can enhance the mechanical strength, impact resistance and wear resistance of the photovoltaic backsheet. The photovoltaic backsheet in the embodiment of the application is not only light in weight, but also has good mechanical properties, mechanical properties, wear resistance, chemical stability and environmental aging resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0024] Figure 1 is a schematic structural diagram of a photovoltaic backsheet according to Example 1 of the present application; Figure 2 is a schematic structural diagram of a composite fiber layer according to Example 2 of the present application; Figure 3 This is a schematic diagram of the structure of the photovoltaic backplane of Comparative Example 1.

[0025] Description of reference numerals: 1. Weather-resistant layer; 2. Composite fiber layer; 3. Matrix layer; 4. Adhesive layer; 5. Continuous fiber; 6. Short fiber; 7. Resin matrix. DETAILED DESCRIPTION

[0026] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. Wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0027] like Figure 1 and Figure 2 As shown, the embodiment of the present application provides a photovoltaic back sheet, comprising: a composite fiber layer 2 and a base layer 3 stacked in sequence; The composite fiber layer 2 includes a resin matrix 7 , and continuous fibers 5 and short fibers 6 dispersed in the resin matrix 7 .

[0028] In the embodiment of the present application, the photovoltaic backsheet includes: a composite fiber layer and a matrix layer. The matrix layer is the supporting structure of the photovoltaic backsheet; Figure 2 As shown, the composite fiber layer 2 has continuous fibers 5 as a skeleton and short fibers 6 as fillers. The continuous fibers 5 and short fibers 6 are dispersed in a resin matrix 7, which can enhance the mechanical strength, impact resistance and wear resistance of the photovoltaic backsheet. The photovoltaic backsheet in the application embodiment is not only light in weight, but also has good mechanical properties, mechanical properties, wear resistance, chemical stability and environmental aging resistance.

[0029] In some embodiments, the continuous fibers include one or more of glass fibers, carbon fibers, aramid fibers, alumina fibers, and polyester fibers. In some embodiments, the length of the continuous fibers is greater than or equal to 100 mm. These continuous fibers are high-performance fibers that not only have good mechanical properties and corrosion resistance, but also have low density and light weight, and can be used to prepare high-strength and lightweight photovoltaic backsheets.

[0030] In some embodiments, the short fibers include one or both of glass fibers and carbon fibers; the length of the short fibers is 0.1-1 mm. Both glass fibers and carbon fibers have good wear resistance and chemical corrosion resistance. The short fibers with a length of 0.1-1 mm can effectively combine with the resin matrix to form a uniform composite material without significantly increasing the weight of the composite material.

[0031] In some embodiments, the resin forming the resin matrix includes a first thermosetting resin or a first thermoplastic resin.

[0032] In some embodiments, the first thermoplastic resin includes one or more of polypropylene resin (PP), polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyethylene resin (PE), and polyamide resin (PA). These thermoplastic resins are all lightweight materials and have good mechanical properties, chemical resistance, electrical insulation and other properties, which can ensure the stability and durability of the photovoltaic backplane.

[0033] In some embodiments, the first thermosetting resin includes one or more of fluorocarbon resin, acrylic resin, phenolic resin, and urea-formaldehyde resin.

[0034] In some embodiments, in the composite fiber layer, the mass ratio of the continuous fiber, the short fiber and the resin forming the resin matrix is ​​(1.5-3): (1-1.5): 1. By precisely controlling the mass ratio of the three components of the continuous fiber, the short fiber and the resin matrix, the mechanical properties and weather resistance of the composite fiber layer can be optimized. When the mass ratio of the three components is (1.5-3): (1-1.5): 1, the mechanical properties and weather resistance of the photovoltaic backsheet can be optimized. Specifically, the mass ratio of the continuous fiber, the short fiber and the resin forming the resin matrix can be 1.5: 1.5: 1, 2: 1.5: 1, 2.5: 1.5: 1, 3: 1.5: 1, 1.5: 1: 1, 2: 1: 1, 2.5: 1: 1, 3: 1: 1.

[0035] In some embodiments, the forming resin of the base layer includes a second thermosetting resin or a second thermoplastic resin.

[0036] In some embodiments, the second thermoplastic resin includes one or more of polypropylene resin (PP), polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyethylene resin (PE), and polyamide resin (PA). Compared with conventional glass substrate layers, these resin materials not only have lower density but also have good mechanical properties. As the substrate layer, the photovoltaic backsheet can have sufficient mechanical strength and support.

[0037] In some embodiments, the second thermosetting resin includes one or more of fluorocarbon resin, acrylic resin, phenolic resin, and urea-formaldehyde resin.

[0038] In some embodiments, Figure 1 As shown, the photovoltaic backsheet further includes a weather-resistant layer 1, which is located on a side of the composite fiber layer 2 away from the base layer 3. The weather-resistant layer can reduce the impact of ultraviolet rays and the external environment on the photovoltaic backsheet.

[0039] In some embodiments, the weather-resistant layer is formed by curing a first fluorine-containing coating; the first fluorine-containing coating includes a fluorocarbon resin and a first curing agent.

[0040] In some embodiments, Figure 1 As shown, the photovoltaic backsheet further comprises a bonding layer 4, which is located on the side of the base layer 3 away from the composite fiber layer 2. The bonding layer is used for subsequent bonding and assembly of the photovoltaic backsheet with other layer structures in the photovoltaic module.

[0041] In some embodiments, the bonding layer is formed by curing a second fluorine-containing coating, wherein the second fluorine-containing coating includes a fluorocarbon resin and a second curing agent.

[0042] It should be noted that fluorine-containing coatings (including fluorocarbon resins and curing agents, and sometimes other substances) have excellent weather resistance and chemical resistance. Fluorocarbon resins and curing agents undergo a curing reaction to form a weather-resistant layer or bonding layer with macromolecular substances. The combination of fluorocarbon resins and curing agents enhances the durability and protective properties of the coating. Therefore, the weather-resistant layer and / or bonding layer formed by curing fluorine-containing coatings can effectively resist the erosion of photovoltaic backsheets by ultraviolet rays, moisture and other environmental factors, and extend the service life of photovoltaic backsheets.

[0043] In an optional embodiment, the first curing agent may include one or more of a peroxide curing agent, an isocyanate curing agent, and an organic acid curing agent.

[0044] In an optional embodiment, the second curing agent may include one or more of a peroxide curing agent, an isocyanate curing agent, and an organic acid curing agent.

[0045] In an optional embodiment, in the first fluorine-containing coating, the mass ratio of the fluorocarbon resin to the first curing agent is (40-70): (2-8). In the first fluorine-containing coating, the proportion of the fluorocarbon resin is relatively high, that is, the fluorine content is relatively high, which can give full play to the weather resistance, protect the photovoltaic back panel, and effectively prevent the aging of the back panel caused by ultraviolet rays, water oxygen and other factors. In the first fluorine-containing coating, the mass ratio of the fluorocarbon resin to the first curing agent can also be (60-70): (2-5).

[0046] In an optional embodiment, in the second fluorine-containing coating, the mass ratio of the fluorocarbon resin to the second curing agent is (10-30): (0.3-4). In the second fluorine-containing coating, the proportion of the fluorocarbon resin is relatively low, that is, the main function of the bonding layer is to fully bond the photovoltaic backsheet and other layer structures in the assembly to ensure that the photovoltaic backsheet does not delaminate, and the weather resistance requirement is lower than that of the weather-resistant layer, so the fluorine content can be reduced. In the second fluorine-containing coating, the mass ratio of the fluorocarbon resin to the second curing agent can also be (10-20): (0.3-2).

[0047] In an optional embodiment, the first fluorine-containing coating and / or the second fluorine-containing coating also include other types of thermosetting resins (thermosetting resins other than fluorocarbon resins, such as acrylic resins and polyester resins). Fluorocarbon resins and other types of thermosetting resins are compounded to form a composite resin, which can stabilize the molecular structure, thereby improving the mechanical properties and mechanical properties of the photovoltaic backplane. When the first fluorine-containing coating contains acrylic resin, the mass ratio of fluorocarbon resin, acrylic resin, and first curing agent is (60-70): (20-30): (2-5). When the second fluorine-containing coating contains polyester resin, the mass ratio of fluorocarbon resin, polyester resin, and second curing agent is (10-20): (70-80): (0.3-2).

[0048] In some embodiments, the thickness of the composite fiber layer is 30-100 μm. If the thickness of the composite fiber layer is small, it cannot fully play the supporting role, which will lead to insufficient strength of the photovoltaic backsheet and even delamination; if the thickness of the composite fiber layer is large, the strength does not change much with the increase of thickness, but the cost will increase. When the thickness of the composite fiber layer is controlled to be 30-100 μm, not only the photovoltaic backsheet has higher strength, but also the cost can be reasonably controlled. Specifically, the thickness of the composite fiber layer can be 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm.

[0049] In some embodiments, the thickness of the substrate layer is 275-315 μm. When the thickness of the substrate layer is 275-315 μm, the photovoltaic backsheet has sufficient structural stability while maintaining the lightness of the photovoltaic backsheet. Specifically, the thickness of the substrate layer can be 275 μm, 80 μm, 285 μm, 290 μm, 295 μm, 300 μm, 305 μm, 310 μm, 315 μm.

[0050] In some embodiments, the thickness of the weather-resistant layer is 25-105 μm. In other embodiments, the thickness of the bonding layer is 5-40 μm. The thicknesses of the weather-resistant layer and the bonding layer are 25-105 μm and 5-40 μm, respectively. A too thin weather-resistant layer may result in insufficient UV resistance and water vapor resistance, reducing the durability of the backsheet; a too thin bonding layer may result in poor interlayer adhesion, peeling or damage; a too thick weather-resistant layer or bonding layer may increase the weight and cost of the photovoltaic backsheet. Specifically, the thickness of the weather-resistant layer may be 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 105 μm. Specifically, the thickness of the bonding layer may be 5 μm, 10 μm, 20 μm, 30 μm, 40 μm.

[0051] The present application provides a method for preparing a photovoltaic backsheet, comprising: S100: providing a composite fiber layer, wherein the composite fiber layer comprises a resin matrix, and continuous fibers and short fibers dispersed in the resin matrix; S200: forming a matrix layer on the lower surface of the composite fiber layer.

[0052] In some embodiments, the method for preparing a photovoltaic backsheet further includes: S300: coating a weather-resistant layer material on the upper surface of the composite fiber layer to form a weather-resistant layer; S400: coating the bonding layer material on the lower surface of the base layer to form a bonding layer.

[0053] In some embodiments, in step S100, the method for preparing the composite fiber layer includes: S110: mixing the short fibers and the resin forming the resin matrix and adding the mixture into a single screw extruder to obtain a first mixed material, and extruding the mixed material into an extruder head mold; S120: under the traction of the traction device, the continuous fiber is fed into the extruder head mold, so that the continuous fiber is impregnated and wrapped by the first mixed material, and then extruded to form a fiber-reinforced thermoplastic material strip; S130: cooling, solidifying, and pelletizing the fiber-reinforced thermoplastic strips to obtain fiber-reinforced thermoplastic pellets; S140: Use the matching single-screw extruder and calendering die to calender the fiber-reinforced thermoplastic particles to form a composite fiber layer.

[0054] In an optional embodiment, in step S110, during the process of calendering the fiber-reinforced thermoplastic particles to form a composite fiber layer, the temperature distribution from the feed port of the single-screw extruder to the calendering die is 160°C, 170°C, 185°C, 200°C; the screw speed is 60r / min-80r / min (for example, 60r / min, 70r / min, 80r / min); the speed of the calendering roller is 15r / min-35r / min (for example, 15r / min, 20r / min, 25r / min, 30r / min, 35r / min). The temperature from the feed port of the single-screw extruder to the calendering die gradually increases. This setting helps the uniform melting and flow of the material, and also helps to reduce the degradation of the material. The speed of the calendering roller is different, and calendered films with different orientation degrees can be prepared.

[0055] In an optional embodiment, continuous fibers and short fibers exist simultaneously in the composite fiber layer; wherein the continuous fibers serve as a skeleton structure, forming a grid structure composed of warp and weft; the short fibers are 0.1-1 mm in length and vary in length, and are randomly distributed in the gaps of the skeleton structure.

[0056] In an optional embodiment, in step S200, forming a matrix layer on the lower surface of the composite fiber layer includes: evenly placing the matrix layer material on the lower surface of the composite fiber layer, and then subjecting it to high-temperature hot roller pressing, and cooling to form the matrix layer. Specifically, an extrusion device is used to extrude the matrix layer material so that the matrix layer material with a thickness of 0.27-0.32 mm is placed on the lower surface of the composite fiber layer, wherein the extrusion temperature is 80-300°C.

[0057] In an optional embodiment, in step S300, the weather-resistant layer material is coated on the upper surface of the composite fiber layer, and the weather-resistant layer is formed through a curing process; in step S400, the bonding layer material is coated on the lower surface of the base layer, and the bonding layer is formed through a curing process. The curing processes in step S300 and step S400 can be performed simultaneously, and the weather-resistant layer and the bonding layer are formed simultaneously through one-time curing. Specifically, when forming the weather-resistant layer and the bonding layer, the weather-resistant layer material can be coated on the upper surface of the composite fiber layer, and the bonding layer material can be coated on the lower surface of the base layer, and then the weather-resistant layer material and the bonding layer material are cured simultaneously through a one-time curing process to form the weather-resistant layer and the bonding layer.

[0058] In an optional embodiment, in step S300 and step S400, the curing process includes a pre-curing step and a full curing step. In an optional embodiment, the pre-curing step includes: curing the composite sheet coated with the weather-resistant layer material and the bonding layer material in an environment with a temperature of 120-175°C (for example, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 175°C) for 1-20 minutes (for example, 1 minute, 5 minutes, 10 minutes, 15 minutes, 20 minutes). Specifically, the pre-curing step is performed in a tunnel furnace. In an optional embodiment, the full curing step includes: curing the pre-cured composite sheet in an environment with a temperature of 50-60°C (for example, 50°C, 55°C, 60°C) for 24-30 hours (for example, 24 hours, 26 hours, 28 hours, 30 hours). Specifically, the full curing step is performed in a drying room.

[0059] Through the pre-curing step, the surface materials of the weather-resistant layer and the bonding layer are cross-linked and cured, and the solvents in the weather-resistant layer materials and the bonding layer materials are volatilized; through the complete curing step, the fluorocarbon resin or thermosetting resin and its corresponding curing agent undergo a complete cross-linking and curing reaction.

[0060] An embodiment of the present application provides a photovoltaic module, comprising the photovoltaic backplane provided by any one of the above embodiments; wherein the photovoltaic backplane is arranged on the backlight side of the solar cell.

[0061] The present application provides a method for preparing a photovoltaic module, comprising: In a high-temperature negative pressure environment, packaging glass, adhesive film, solar cells, adhesive film and photovoltaic backplane are laminated and packaged to obtain a photovoltaic module; wherein the packaging glass is located on the light-incident side of the solar cell, the photovoltaic backplane is located on the backlight side of the solar cell, and the photovoltaic backplane is the photovoltaic backplane provided by any of the above embodiments.

[0062] Encapsulation glass is the outermost layer of photovoltaic modules, which is used to protect solar cells from external environmental influences such as moisture, oxygen and mechanical impact. Encapsulation glass needs to have good visible light transmittance.

[0063] Solar cells are the core part of photovoltaic modules. In some embodiments, the solar cells include: PN junction devices containing III-V or II-IV group elements, Cu-In-Ga-Se (CIGS) thin film devices, organic sensitizer devices, organic thin film devices, quantum dot thin film devices, amorphous silicon solar cells, microcrystalline silicon solar cells, and crystalline silicon solar cells. In other embodiments, the solar cells can also be heterojunction (HJT) solar cells.

[0064] The photovoltaic backplane is the back protective layer of the photovoltaic module. The photovoltaic backplane provided by any of the above embodiments of the present application is used to make the prepared photovoltaic module not only light in weight but also having good mechanical properties, wear resistance, chemical stability and resistance to environmental aging.

[0065] Photovoltaic modules usually include two layers of adhesive film, which are located on the front and back of the solar cell respectively. The adhesive film is used to bond the encapsulation glass and the photovoltaic back panel to the solar cell respectively to fix the solar cell. The composition of the two layers of adhesive film can be the same or different. In some embodiments, the adhesive film can be a random copolymer of ethylene and vinyl acetate (EVA) adhesive film. EVA adhesive film has good visible light transmittance, aging resistance and sealing performance, and can effectively block water vapor and gas.

[0066] Under high temperature and negative pressure, the layers of materials of the photovoltaic module are placed in order and laminated. By heating and applying pressure, the adhesive film melts and flows, evenly filling the gap between the battery and the encapsulation glass or photovoltaic backplane, ensuring the sealing of the module and the uniform distribution of the adhesive film. The temperature during the encapsulation process can be 120-140°C (for example, 120°C, 130°C or 140°C). After lamination, the adhesive film will solidify to form a strong adhesive layer that tightly binds the layers of materials together.

[0067] The following specific embodiments further describe the present application in detail, but should not be construed as limiting the present application. Without departing from the spirit and substance of the present application, modifications or replacements made to the structure of the present application are within the scope of the present application.

[0068] Example 1 like Figure 1 and Figure 2 As shown, the photovoltaic back sheet of Example 1 comprises: a weather-resistant layer 1, a composite fiber layer 2, a base layer 3, and a bonding layer 4 which are stacked; The composite fiber layer 2 includes a resin matrix 7 (thermoplastic resin), and continuous fibers 5 and short fibers 6 dispersed in the resin matrix 7; the continuous fibers are glass fibers, the short fibers are glass fibers (length 0.1-1 mm), the thermoplastic resin is polyamide resin (PA), and the mass ratio C1 of the continuous fibers, the short fibers and the thermoplastic resin is 2.3:1.2:1; The base layer is polyethylene terephthalate resin (PET); The weather-resistant layer is formed by a curing reaction of fluorocarbon resin, acrylic resin and a first curing agent (trimethylhexamethylene diisocyanate), wherein the mass ratio C2 of the fluorocarbon resin, acrylic resin and the first curing agent is 64:26:3; The bonding layer is formed by a curing reaction of a fluorocarbon resin, a polyester resin and a second curing agent (dibenzoyl peroxide), wherein a mass ratio C3 of the fluorocarbon resin, the polyester resin and the second curing agent is 16:74:0.5.

[0069] The method for preparing the photovoltaic backsheet of embodiment 1 comprises: S110a: mixing the short fibers and the thermoplastic resin, adding the mixture to a single screw extruder to obtain a first mixed material, and extruding the mixed material into an extruder head mold; S120a: under the traction of the traction device, the continuous fiber is fed into the extruder head mold, so that the continuous fiber is impregnated and wrapped by the first mixed material, and then extruded to form a fiber-reinforced thermoplastic material strip; S130a: cooling, solidifying, and pelletizing the fiber-reinforced thermoplastic strips to obtain fiber-reinforced thermoplastic pellets; S140a: Using a matching single screw extruder and calendering die, the fiber-reinforced thermoplastic particles are calendered to form a composite fiber layer with a thickness of 50 µm; S200a: using an extrusion device, at an extrusion temperature of 200°C, extruding the base layer material, placing the base layer material with a thickness of 0.2 mm on the lower surface of the composite fiber layer, and then subjecting it to high-temperature hot roller pressing, and after cooling, forming a base layer with a thickness of 275 µm; S300a: Coat the weather-resistant layer material on the upper surface of the composite fiber layer, and coat the bonding layer material on the lower surface of the base layer. Through a pre-curing step and full curing, a weather-resistant layer with a thickness of 37µm is formed on the upper surface of the composite fiber layer, and a bonding layer with a thickness of 15µm is formed on the lower surface of the base layer; wherein the pre-curing temperature T1 is 160°C, and the pre-curing time t1 is 3 minutes; the full curing temperature T2 is 50°C, and the full curing time t2 is 28 hours.

[0070] Embodiment 2-8 The photovoltaic backsheets of Examples 2-8 were prepared by referring to the preparation method of Example 1, with the only difference being that the materials and preparation parameters of each layer of the photovoltaic backsheets in Examples 2-8 were different. The materials and preparation parameters of each layer of the photovoltaic backsheets in Examples 2-8 are shown in Table 1.

[0071] Table 1

[0072] In order to more clearly illustrate the technical effects of the embodiments of the present application, the present application also provides a comparative example 1.

[0073] Comparative Example 1 like Figure 3 As shown, the photovoltaic backsheet of comparative example 1 comprises: a weather-resistant layer 1, a base layer 3 and a bonding layer 4 stacked in sequence, but does not include a composite fiber layer; The materials of the weather-resistant layer, the base layer and the adhesive layer of the photovoltaic backsheet of Comparative Example 1 are the same as those of the weather-resistant layer, the base layer and the adhesive layer of the photovoltaic backsheet of Example 1.

[0074] The preparation method of the photovoltaic backsheet of Comparative Example 1 comprises: S100b: using an extrusion device, extruding the base layer material at an extrusion temperature of 200°C, with an extrusion thickness of 275µm, and forming a base layer after cooling; S200b: A weather-resistant layer material is coated on the upper surface of the base layer, and an adhesive layer material is coated on the lower surface of the base layer. Through a pre-curing step and full curing, a weather-resistant layer with a thickness of 37µm is formed on the upper surface of the base layer, and an adhesive layer with a thickness of 15µm is formed on the lower surface of the base layer; wherein the pre-curing temperature T1 is 160°C, and the pre-curing time t1 is 3 minutes; the full curing temperature T2 is 50°C, and the full curing time t2 is 28 hours.

[0075] The present application refers to the ASTM D-882 standard to test the tensile strength of the photovoltaic backsheets of Examples 1 to 8 and Comparative Example 1 using a universal tensile machine. Five samples are tested for each example, and the measured values ​​are averaged. The test results are shown in Table 2.

[0076] Table 2

[0077] From the data in Table 2, it can be seen that the tensile strength of the photovoltaic modules of Examples 1 to 8 of the present application is significantly greater than the tensile strength of the photovoltaic modules of Comparative Example 1. This is because the photovoltaic backsheets of Examples 1 to 8 of the present application have a composite fiber layer formed by long fibers, short fibers and resin. When subjected to transverse or longitudinal tensile action, the long fiber skeleton in a mesh structure can effectively withstand the tensile load along the fiber direction. At the same time, the long fibers are interwoven with each other, so that the fibers support each other, effectively improving the strength of the backsheet material. In addition, the short fibers and the resin fully impregnate and wrap the long fiber skeleton, which can effectively improve the tensile strength of the photovoltaic backsheet.

[0078] In summary, the photovoltaic backsheet in the embodiment of the present application includes: a composite fiber layer and a matrix layer. Among them, the matrix layer is the supporting structure of the photovoltaic backsheet; the composite fiber layer uses continuous fibers as the skeleton and short fibers as the filler. The continuous fibers and short fibers are dispersed in the resin matrix, which can enhance the mechanical strength, impact resistance and wear resistance of the photovoltaic backsheet. The photovoltaic backsheet in the embodiment of the application is not only light in weight, but also has good mechanical properties, mechanical properties, wear resistance, chemical stability and environmental aging resistance.

[0079] It should be noted that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0080] It should be noted that the terms "first", "second", "front", "back", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0081] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0082] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0083] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A photovoltaic backsheet, characterized in that: include: A composite fiber layer and a matrix layer are stacked in sequence; The composite fiber layer includes a resin matrix, and continuous fibers and short fibers dispersed in the resin matrix.

2. The photovoltaic backsheet according to claim 1, characterized in that: The continuous fibers include one or more of glass fibers, carbon fibers, aramid fibers, alumina fibers, and polyester fibers; and / or The length of the continuous fibers is greater than or equal to 100 mm.

3. The photovoltaic backsheet according to claim 1, characterized in that: The short fibers include one or both of glass fibers and carbon fibers; and the length of the short fibers is 0.1-1 mm.

4. The photovoltaic backsheet according to claim 1, characterized in that: The resin forming the resin matrix includes a first thermosetting resin or a first thermoplastic resin.

5. The photovoltaic backsheet according to claim 4, characterized in that: The first thermoplastic resin includes one or more of polypropylene resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene resin, and polyamide resin.

6. The photovoltaic backsheet according to claim 1, characterized in that: In the composite fiber layer, the mass ratio of the continuous fibers, the short fibers and the resin forming the resin matrix is ​​(1.5-3):(1-1.5):

1.

7. The photovoltaic backsheet according to claim 1, characterized in that: The base layer forming resin includes a second thermosetting resin or a second thermoplastic resin.

8. The photovoltaic backsheet according to claim 7, characterized in that: The second thermoplastic resin includes one or more of polypropylene resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene resin, and polyamide resin.

9. The photovoltaic backsheet according to claim 1, characterized in that: The photovoltaic backsheet further comprises a weather-resistant layer, wherein the weather-resistant layer is located on a side of the composite fiber layer away from the base layer; and / or The photovoltaic back sheet further comprises a bonding layer, and the bonding layer is located on a side of the base layer away from the composite fiber layer.

10. The photovoltaic backsheet according to claim 9, characterized in that: The weather-resistant layer is formed by curing a first fluorine-containing coating; the first fluorine-containing coating comprises a fluorocarbon resin and a first curing agent; and / or The bonding layer is formed by curing a second fluorine-containing coating, wherein the second fluorine-containing coating comprises a fluorocarbon resin and a second curing agent.

11. The photovoltaic backsheet according to claim 9, characterized in that: The thickness of the composite fiber layer is 30-100 μm; and / or The thickness of the substrate layer is 275-315 μm; and / or The thickness of the weather-resistant layer is 25-105 μm; and / or The thickness of the bonding layer is 5-40 μm.

12. A method for preparing a photovoltaic backsheet, characterized in that: include: forming a matrix layer on the lower surface of the composite fiber layer; The composite fiber layer includes a resin matrix, and continuous fibers and short fibers dispersed in the resin matrix.

13. The method for preparing a photovoltaic back sheet according to claim 12, characterized in that: The method for preparing the composite fiber layer comprises: Mixing the short fibers and the resin matrix forming resin to obtain a first mixed material; After the continuous fibers are impregnated and wrapped by the first mixed material, the continuous fibers and the short fibers are dispersed in the resin forming the resin matrix, and fiber-reinforced thermoplastic strips are formed by extrusion; The fiber-reinforced thermoplastic material strips are solidified and pelletized to obtain fiber-reinforced thermoplastic pellets; The fiber-reinforced thermoplastic particles are calendered to form a composite fiber layer.

14. The method for preparing a photovoltaic back sheet according to claim 12, characterized in that: Also includes: Coating a weather-resistant layer material on the upper surface of the composite fiber layer to form a weather-resistant layer; The bonding layer material is coated on the lower surface of the base layer to form a bonding layer.

15. A photovoltaic module, characterized in that: A photovoltaic backsheet comprising any one of claims 1 to 11; Wherein, the photovoltaic back panel is arranged on the backlight side of the solar cell.

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