Polymer film for solar cell backboard, preparation method and photovoltaic backboard

Abstract

The invention relates to the technical field of solar back panels, and particularly provides a polymer film for a solar cell back panel, a preparation method and a photovoltaic back panel. The film comprises the following components: polymer resin and fiber, wherein the diameter of the fiber is 0.5-10 [mu] m, and the length of the fiber is 100-800 [mu] m. The fibers in the polymer film can be easily and uniformly dispersed in the polymer resin. The optimized polymer film material shows more excellent mechanical strength and toughness when being applied to a solar cell back plate. The improvement not only improves the durability of the product, but also possibly provides better guarantee for long-term stable operation of the solar cell.

Description

Technical Field

[0001] The invention relates to the technical field of solar back panels, and specifically provides a polymer film for a solar cell back panel, a preparation method and a photovoltaic back panel. Background Art

[0002] As a packaging material for photovoltaic modules, photovoltaic backplane materials mainly protect modules from environmental erosion in actual applications, including blocking air, water vapor and ultraviolet rays, providing electrical insulation, providing mechanical support, and ensuring bonding strength with packaging materials. Traditional backplane materials are composited with multiple layers of polymer films. Common materials include polyvinyl fluoride (PVF), polyvinylidene chloride (PVDF) and polyethylene terephthalate (PET). Although they have certain impact resistance, they are prone to mechanical performance degradation in long-term use, and the internal components of the modules are not adequately protected. If glass is used as a packaging material, there is a problem of impact resistance, which greatly limits the choice of installation site. At the same time, the high cost of using high-performance materials such as PVF and PVDF backplanes limits their wide application.

[0003] Therefore, it is necessary to improve the backplane material to further enhance the mechanical properties of the photovoltaic backplane. Summary of the invention

[0004] In order to overcome the above defects, the present invention proposes a polymer film for solar cell backplane, a preparation method and a photovoltaic backplane, which optimize the mechanical properties of the backplane.

[0005] In a first aspect, the present invention provides a polymer film for a solar cell back sheet, comprising the following components:

[0006] A polymer resin and fibers with a diameter of 0.5-10 μm and a length of 100-800 μm.

[0007] Furthermore, each component is calculated by the following weight parts:

[0008] Polymer resin: 60-80 parts; and

[0009] Fiber: 10-25 servings.

[0010] Furthermore, the film also includes a modification aid; the weight portion of the modification aid is 2.2-20.6 parts; the modification aid includes one or more of an antioxidant, a compatibilizer, a light stabilizer, a hydrolysis resistance agent and a toughening agent.

[0011] Furthermore, the polymer resin is PET resin; the fiber is treated with a surfactant, and the surfactant includes: anionic surfactant or silane coupling agent.

[0012] Furthermore, in parts by weight, one or more of the modification aids include:

[0013] Antioxidant: 0.1-1.5 parts;

[0014] Compatibilizer: 0.1-3 parts;

[0015] Light stabilizer: 0.1-2 parts;

[0016] Anti-hydrolysis agent: 0.1-3 parts; and

[0017] Toughening agent: 1-15 parts.

[0018] Further, one or more of the following features are included:

[0019] The antioxidant includes one or more of hindered phenols and phosphates.

[0020] The compatibilizer includes one or more of maleic anhydride grafted polyolefin, titanates, and isocyanates.

[0021] The light stabilizer includes one or more of oxalic acid amides, triazines, benzophenones and benzotriazoles.

[0022] The anti-hydrolysis agent includes one or more of epoxy compounds, organic phosphorus compounds and carbodiimides;

[0023] The toughening agent includes one or more of an elastomer and a polymer obtained by copolymerization of ethylene and propylene.

[0024] Furthermore, the fibers include one or more of polymer fibers, glass fibers and carbon fibers.

[0025] Furthermore, the surfactant is sodium dodecylbenzene sulfonate.

[0026] In a second aspect, the present invention provides a method for preparing a polymer film for a solar cell backsheet according to the first aspect, comprising:

[0027] The at least partially deflated fibers are mixed with a polymer resin to form a polymer film.

[0028] Furthermore, after forming the polymer film, the method further comprises:

[0029] The polymer film solidifies and cools.

[0030] In a third aspect, the present invention provides a photovoltaic backsheet, comprising:

[0031] The polymer film for solar cell backsheet according to the first aspect or the polymer film for solar cell backsheet prepared by the method of the second aspect; and

[0032] A weather-resistant layer connected to the upper surface and / or lower surface of the polymer film for the solar cell backsheet.

[0033] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0034] In the technical solution for implementing the present invention, the present invention provides a polymer film for photovoltaic backplane membrane and a preparation method thereof. By reinforcing the polymer film material with nano short fibers of a specific size, the mechanical strength and aging resistance of the material can be improved, and the production cost can be reduced. Specifically, the present invention uniformly embeds fibers with a diameter range of 0.5 to 10 microns and a length of 100 to 800 microns into a substrate of a polyethylene terephthalate (PET) resin, especially a unique mesh structure, thereby obtaining a high-performance polymer film. When this polymer film is applied to the field of photovoltaic backplanes, thanks to the special mesh structure constructed by the fibers, it can not only effectively improve the stability of the entire photovoltaic system, but also significantly enhance its toughness while ensuring that the backplane material has excellent strength, thereby achieving a double improvement in the strength and toughness of the backplane material, providing a solid guarantee for the long-term stable operation of photovoltaic modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In addition, similar numbers in the figures are used to represent similar components, among which:

[0036] Figure 1 is a schematic flow chart of the main steps of a preparation method according to one embodiment of the present invention;

[0037] Figure 2 is a schematic diagram of the distribution of fibers in a polymer film according to one embodiment of the present invention;

[0038] Figure 3 is a schematic diagram of a photovoltaic backsheet including a layer of polymer film according to one embodiment of the present invention;

[0039] Figure 4 is a schematic diagram of a photovoltaic backsheet including two layers of polymer films according to an embodiment of the present invention.

[0040] Reference numerals list :

[0041] 1: polymer film; 2: weather-resistant layer; 3: adhesive layer. DETAILED DESCRIPTION

[0042] Some embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0043] The present invention discloses a polymer film for a solar cell back sheet, comprising the following components:

[0044] The polymer resin is used as the base material, and fibers with diameters between 0.5 and 10 microns and lengths between 100 and 800 microns are specially added.

[0045] In the present invention, polymer resin is used as the main matrix material, and nanometer-scale short fibers of specific sizes are ingeniously integrated. The uniform dispersion of these nanometer-scale short fibers inside the polymer resin has a significant modification effect on the polymer resin. This modification effect is specifically manifested in the mechanical properties of the material, so that the tensile strength in the lateral direction and the tensile strength in the longitudinal direction of the modified material are effectively improved. The modified polymer film involved in the present invention, when applied to the solar cell back panel, can effectively enhance the mechanical strength of the back panel, thereby providing a strong guarantee for the stability and durability of the solar cell.

[0046] The polymer resin may be selected from polyvinyl fluoride (PVF) resin, polyvinylidene chloride (PVDF) resin or polyethylene terephthalate (PET) resin.

[0047] The proportions of the components are described below. In one embodiment, the components are calculated by the following weight parts:

[0048] Polymer resin: 60-80 parts; and

[0049] Fiber: 10-25 servings.

[0050] The present invention adopts polymer resin as the main matrix material, and introduces a specific proportion of nano short fibers into the matrix material. By adjusting the amount of the nano short fibers added, the mechanical properties of the material can be effectively optimized.

[0051] The optimized material has shown more excellent mechanical strength and toughness when used in solar cell backplanes. This improvement not only improves the durability of the product, but also provides better protection for the long-term stable operation of solar cells.

[0052] In order to further enhance the effective dispersion of the fibers in the polymer resin and ensure the uniformity of the entire system, in one embodiment, the polymer film is also added with a modifying agent, which is added to promote the interaction between the fibers and the polymer resin, thereby achieving the purpose of improving the dispersion effect and enhancing the uniformity of the overall system.

[0053] In one embodiment, the weight portion of the modification aid is 2.2-20.6 parts.

[0054] In one embodiment, the polymer resin is PET resin. PET is also known as polyethylene terephthalate (PET) in Chinese and polyethylene terephthalate in Chinese. Its chemical formula is (C 10 H 8 O 4 ) n PET resin can reduce the manufacturing cost of polymer films.

[0055] In one embodiment, the fiber is treated with a surfactant, and the surfactant includes: anionic surfactant or silane coupling agent.

[0056] In one embodiment, the anionic surfactant includes sodium dodecylbenzene sulfonate.

[0057] In one embodiment, the modification aid includes one or more of an antioxidant, a compatibilizer, a light stabilizer, a hydrolysis resistance agent, and a toughening agent.

[0058] Antioxidants, also known as antioxidants, can slow down the degradation, inactivation or deformation of materials caused by oxidation.

[0059] Compatibilizers help improve the compatibility between different materials and ensure the homogeneity of the mixture.

[0060] Light stabilizers protect materials from damaging light sources such as ultraviolet rays.

[0061] Hydrolysis resistant agents, also known as anti-hydrolysis agents, can improve the ability of materials to resist hydrolysis, thereby extending their service life and effectiveness.

[0062] Toughening agent can increase the toughness of the material, making it less likely to break when impacted.

[0063] These modification aids can be used alone or in combination of two or more as required to achieve the best modification effect.

[0064] When the above components are added at the same time, better effects can be obtained.

[0065] In one embodiment, one or more of the above-mentioned modifying aids are added in the following weight portions, and the addition amount is:

[0066] In parts by weight,

[0067] Antioxidant: 0.1-1.5 parts;

[0068] Compatibilizer: 0.1-3 parts;

[0069] Light stabilizer: 0.1-2 parts;

[0070] Anti-hydrolysis agent: 0.1-3 parts; and

[0071] Toughening agent: 1-15 parts.

[0072] The specific material selection of each auxiliary agent is described below. In one embodiment, it includes one or more of the following characteristics:

[0073] The antioxidant includes one or more of hindered phenols and phosphates.

[0074] The compatibilizer includes one or more of maleic anhydride grafted polyolefin, titanates, and isocyanates.

[0075] The light stabilizer includes one or more of oxalic acid amides, triazines, benzophenones (UV-531) and benzotriazoles.

[0076] The anti-hydrolysis agent includes one or more of epoxy compounds, organic phosphorus compounds and carbodiimides;

[0077] The toughening agent includes one or more of an elastomer and an ethylene-propylene copolymer, ie, a polymer obtained by copolymerizing ethylene and propylene.

[0078] For example, the elastomer may be thermoplastic polyurethane elastomer, also known as thermoplastic polyurethane rubber, abbreviated as TPU.

[0079] The elastomer may also be a styrene-based thermoplastic elastomer, which is a block copolymer formed by emulsion copolymerization of styrene and butadiene, such as SBS, which is a styrene-butadiene-styrene triblock copolymer, and SEBS, which is a styrene-ethylene / butylene-styrene triblock copolymer.

[0080] In one embodiment, the surfactant is sodium dodecylbenzene sulfonate.

[0081] In one embodiment, the fibers include one or more of polymer fibers, glass fibers, and carbon fibers.

[0082] In one embodiment, the fiber includes one or more of polyethylene terephthalate fiber, polyethylene naphthalate (PEN) short fiber, chopped glass fiber, and carbon fiber.

[0083] The present invention also discloses a method for preparing the polymer film for the solar cell backplane. Figure 1 ,include:

[0084] S1, mixing at least partially broken-up fibers with a polymer resin;

[0085] S2, a polymer film is formed after mixing.

[0086] The diameter of the short fibers used in the present invention ranges from 0.5 microns to 10 microns, and the length thereof ranges from 100 microns to 800 microns. In the present invention, the short fibers are used to reinforce polymer resins, so that the composite material exhibits more excellent physical properties. Specifically, the tensile strength of the polymer resin, especially the PET material, reinforced by the short fibers is significantly improved, and the impact strength is also enhanced. Such improvements have significantly improved the mechanical properties of the backplane, so when the backplane is subjected to different forms of external influences such as external pressure and wind loads, the shape stability of the backplane is enhanced and is not easily deformed. In addition, the short fiber reinforced polymer resin also exhibits higher thermal stability, which means that during the operation of the component, even in the face of higher temperature fluctuations, the material can maintain its stable performance, effectively reducing the risks caused by thermal expansion.

[0087] The specific process of the preparation method includes:

[0088] S11, breaking up the fibers to a degree that the fibers are at least partially broken up to ensure that the fibers are no longer tightly entangled with each other.

[0089] The fiber of the present invention adopts the existing spinning technology, and through the action of the electric field, the solution is sprayed into a continuous fibrous material with a diameter ranging from 0.5 microns to 10 microns, and then these fibers are broken up by high-speed stirring and other methods, so that the length of the broken fibers reaches the range of 100 microns to 800 microns. In this way, a fiber web of micron-level to nanometer-level can be obtained. These fiber webs are composed of countless such fibers, which are arranged in a disordered three-dimensional form.

[0090] The specific operation of breaking up is to promote the dispersion of fibers through the action of mechanical force under the action of stirring, so as to achieve the purpose of dispersing the fibers.

[0091] S12, mixing at least part of the dispersed fibers with a polymer resin.

[0092] S2, after mixing, forms a polymer film.

[0093] In step S2, the fiber is mixed with the polymer resin and melt-blended under appropriate temperature conditions to ensure that the two materials can be fully melt-blended. Subsequently, the mixture is processed into a polymer film for photovoltaic backsheets with a certain thickness through an extrusion process.

[0094] In order to ensure the smooth progress of the mixing process, an appropriate blending temperature is selected according to the melting temperature characteristics of the fiber and the polymer thin resin. This can effectively avoid partial melting of the fiber due to excessive temperature during the mixing process, thereby ensuring the quality and performance of the final product.

[0095] The fibers in step S11 of the present invention are short fibers, which are relatively easy to be evenly dispersed in the polymer resin. The schematic diagram after dispersion is shown in FIG. Figure 2 This dispersion allows the short fibers to be evenly mixed with the matrix material, i.e., polymer resin, during processing by using traditional processing techniques such as injection molding, extrusion, etc. This ensures the consistency of the final material properties, thereby improving the overall quality of the product.

[0096] In one embodiment, the polymer resin is PET resin.

[0097] Compared with the long fiber reinforced PET back sheet, the short fiber reinforced PET back sheet of the present invention has simpler requirements in terms of processing equipment, which makes it have better processing performance. This feature significantly reduces the cost of the production process. In addition, the PET material itself has excellent recyclability, and it performs well in environmental protection, which is in line with the current development trend of green production.

[0098] In one embodiment, in step S2, after forming the polymer film, the method further comprises:

[0099] S3, the polymer film is solidified and cooled.

[0100] In one embodiment, in step S3, curing the polymer film includes:

[0101] The polymer film is cured at a temperature of 100 to 200° C. for 30 to 60 minutes.

[0102] In one embodiment, the polymer film may be a PET film formed of PET resin, and the cooling may be natural cooling or other common cooling methods such as air cooling and water cooling.

[0103] The cooling time is at least 10s, cooling to 20℃-50℃.

[0104] The PET film obtained after extrusion is cured at a temperature of 100-200°C for 30-60 minutes to make the bond between the fiber and the PET matrix stronger. After curing, the PET film is cooled by a cooling device. Slow cooling helps to reduce the internal stress of the material. Finally, the film is further thinned to the required thickness through a calendering process.

[0105] In one embodiment, the fibers are pre-treated with a surfactant.

[0106] In one embodiment, during the preliminary surface treatment of the fiber, the added amount of the surfactant is 1%-2% of the fiber mass.

[0107] In one embodiment, the method of treating with a surfactant is: mixing the fiber with a solution of a surfactant and stirring the mixture evenly.

[0108] For example, the fiber surface can be modified before mixing. Sodium dodecylbenzene sulfonate can be used to pre-treat the fiber. Sodium dodecylbenzene sulfonate is dissolved in a suitable solvent to form a solution, and the nanofibers are added to the above solution and stirred / ultrasonicated for a period of time (30-90 minutes) to ensure that the fibers are evenly distributed in the solution.

[0109] Sodium dodecylbenzene sulfonate (SDBS) is used as a surfactant. The benzenesulfonate group of sodium dodecylbenzene sulfonate is combined with the surface of nanofibers through mutual adsorption or hydrogen bonding. It can prevent the reunion between fibers by electrostatic repulsion, and form a functional film on the fiber surface to improve the compatibility of fiber and PET. Since the fiber diameter is small and the top surface energy is large, under the action of surface tension and van der Waals force, the fiber tops can contact and overlap together. At the same time, the fiber net in three-dimensional form is randomly distributed inside PET, which can expand and strengthen the three-dimensional skeleton formed by the fiber. Therefore, the fibers repel each other radially, and the tops attract, forming a three-dimensional structure on a large scale. In this way, a three-dimensional skeleton is formed in PET resin. This special structure improves the tensile strength and tensile strength retention rate of the backboard. In addition, the evenly dispersed fibers can also improve the anti-aging performance of the PET backboard and reduce the penetration of ultraviolet rays and oxygen.

[0110] Pre-treating fibers with sodium dodecylbenzene sulfonate can achieve a number of positive effects:

[0111] 1. Sodium dodecylbenzene sulfonate can effectively reduce the surface tension between the fiber and the matrix (PET resin), thereby promoting the uniform dispersion of the fiber in the matrix. This process is easy to operate, just add sodium dodecylbenzene sulfonate to the solution and mix it evenly. The uniform dispersion of the fiber is crucial to improving the anti-aging performance of the PET backsheet, because it can significantly reduce the penetration of ultraviolet rays and oxygen, thereby extending the service life of the material.

[0112] 2. Sodium dodecylbenzene sulfonate can enhance the bonding force between fiber and matrix through van der Waals force and electrostatic action. This enhanced bonding force helps to improve the overall performance of composite materials, making them show better stability and durability in various applications.

[0113] 3. The cost of using sodium dodecylbenzene sulfonate as a pretreatment surfactant is relatively low, which makes the entire treatment process more economically feasible, especially suitable for large-scale industrial applications.

[0114] 4. The toxicity of this surfactant is relatively low, and it has good biodegradability and eco-friendliness. Compared with other chemical coupling agents, sodium dodecylbenzene sulfonate is more in line with environmental protection requirements because it has less impact on the environment during use and is more easily accepted and decomposed by the natural environment, thereby reducing potential harm to the ecosystem.

[0115] In one embodiment, before step S11, the method further includes:

[0116] The fibers are dried in advance to remove moisture.

[0117] The specific process is:

[0118] Using existing spinning technology, the solution is sprayed into a continuous fiber-like material with a diameter ranging from 0.5 microns to 10 microns through the action of an electric field;

[0119] Dry the continuous fibrous material in an oven at 180°C for 2-6 hours to prevent it from being hydrolyzed in subsequent processes;

[0120] The dried fibers are then broken up into the desired size by high-speed stirring or the like, while an appropriate amount of the fiber web may be retained.

[0121] In one embodiment, before step S11, the method further includes:

[0122] The polymer resin is dried in advance to remove moisture, so as to further avoid moisture in the mixed system of fiber and polymer resin.

[0123] In one embodiment, when the polymer film for solar cell backsheet contains a modification aid, the preparation method includes:

[0124] Under stirring, the fibers are at least partially broken up.

[0125] The dispersed fibers are mixed with polymer resin, antioxidant, compatibilizer, light stabilizer, hydrolysis resistance agent and toughening agent according to a preset ratio and stirred evenly.

[0126] The uniformly stirred materials are fed into a twin-screw extruder, melt-blended and extruded at a preset temperature to obtain a polymer film.

[0127] The polymer film is sequentially solidified and cooled.

[0128] In one embodiment, the fiber is mixed with a polymer resin, an antioxidant, a compatibilizer, a light stabilizer, a hydrolysis resistance agent and a toughening agent in a preset ratio, and then added to a high-speed mixer, and mixed at high speed by the mixer. After mixing evenly, the mixed material is then added to a twin-screw extruder.

[0129] In one embodiment, the polymer resin is PET resin, and during the melt blending process, the preset temperature is 230° C.-310° C., and the duration is 1 min-15 min.

[0130] The present invention also discloses a photovoltaic back panel, comprising:

[0131] The polymer film for solar cell backsheet or the polymer film for solar cell backsheet prepared by the method; and

[0132] A weather-resistant layer connected to the upper surface and / or lower surface of the polymer film for the solar cell backsheet.

[0133] In one embodiment, the weather-resistant layer is bonded to the upper surface and / or lower surface of the polymer film respectively.

[0134] The polymer film 1 and the weather-resistant layer 2 are bonded together via an adhesive layer 3 .

[0135] The polymer film of the present invention can effectively improve the mechanical strength of the backplane, and thus the polymer film can be considered as a reinforced polymer film layer or a reinforced substrate layer.

[0136] The polymer film 1 may be a PET film.

[0137] In one embodiment, the upper surface and the lower surface of the polymer film are bonded together by an adhesive layer and a weather-resistant layer. After lamination, the polymer film is tightly combined with other layers to form a complete photovoltaic backsheet.

[0138] Figure 3 The case where the PET polymer film is a layer is shown, and the back plate includes a weather-resistant layer 2, an adhesive layer 3, a PET polymer film 1, an adhesive layer 3 and a weather-resistant layer 2 from the outside to the inside. Figure 4 The case where the PET polymer film is two layers is shown.

[0139] The mechanical properties of the photovoltaic backsheet of the present invention are tested by the following examples and comparative examples.

[0140] Embodiment 1:

[0141] The polymer film for solar cell backsheet of this embodiment includes the following components in parts by weight:

[0142] PET: 72.6 parts;

[0143] Fiber: 20 parts, the diameter of the fiber is 0.5-10μm and the length is 100-800um;

[0144] Antioxidant: 0.2 parts;

[0145] Compatibilizer: 1 part;

[0146] Light stabilizer: 0.5 parts;

[0147] Anti-hydrolysis agent: 0.3 parts;

[0148] Toughener: 5 parts.

[0149] The fiber of the embodiment 1 is chopped glass fiber, the antioxidant is 2,6-di-tert-butyl-p-cresol which is a hindered phenol oxidant, the light stabilizer is UV-531 which is a benzophenone, the hydrolysis resistance agent is tris(2,4-di-tert-butylphenyl) phosphate which is an organic phosphorus compound, the compatibilizer is polyethylene grafted maleic anhydride which is a maleic anhydride grafted polyolefin, and the toughening agent is the elastomer SBS.

[0150] The preparation method comprises the following steps:

[0151] The first step: the solution is sprayed into continuous fibers with a diameter of 0.5-10 μm through the action of an electric field; the obtained fibers are placed in an oven at 180°C and dried for 4 hours; the dried continuous fibers are then rotated at 1500 r / min for 1-2 minutes to at least partially break up the fibers, while retaining a proper amount of fiber webs to obtain fibers with a length of 100-800 um. The first step obtains a micron to nanometer fiber web, whose constituent fibers are arranged in a disordered three-dimensional form.

[0152] Step 2: The fiber is surface modified before mixing. Sodium dodecylbenzene sulfonate is used for pretreatment of the fiber. Sodium dodecylbenzene sulfonate is dissolved in deionized water to form a surface treatment solution. The mass fraction of sodium dodecylbenzene sulfonate in the surface treatment solution is 0.5%-1%. The fiber is then added to the surface treatment solution and stirred for 60 minutes to ensure that the fiber is evenly distributed in the surface treatment solution. The amount of sodium dodecylbenzene sulfonate added is 1.6% of the total mass of the fiber.

[0153] The third step: drying the PET resin to remove moisture, then adding the dried PET resin, the fiber obtained in the first step (length 100-800um, diameter 0.5-10μm), antioxidant, compatibilizer, light stabilizer, hydrolysis resistance agent, toughening agent into a high-speed mixer according to the components and proportions in Table 1, mixing at high speed using the mixer, and then adding the mixed materials into a twin-screw extruder, melt blending at 280°C for 15 minutes, and obtaining a polymer film for photovoltaic backplane with a thickness of 340μm after extrusion.

[0154] Step 4: The polymer film obtained after extrusion is cured at a temperature of 150°C for 45 minutes to make the bond between the fiber and the PET resin substrate more solid. After curing, the film is cooled by a cooling device, and after a cooling time of 30 seconds, it is cooled to 50°C. Finally, through the calendering process, the film is further thinned to a thickness of 275μm.

[0155] Step 5: The two sides of the polymer film obtained in step 4 are bonded together with an adhesive layer and a weather-resistant layer to form Figure 2 Structure. After lamination, the polymer film is tightly combined with other layers to form a complete photovoltaic backsheet.

[0156] The backplane prepared in five steps of Example 1 was tested. The results showed that the longitudinal tensile strength of the backplane prepared in Example 1 was 106.2 MPa, and the transverse tensile strength was 92.5 MPa; after 5000 hours of ultraviolet exposure, the performance remained above 91%.

[0157] For a rectangular backsheet, the transverse tensile strength is the strength in the length direction, and the longitudinal tensile strength is the strength in the width direction.

[0158] Embodiment 2:

[0159] The polymer film for solar cell backsheet of this embodiment includes the following components in parts by weight:

[0160] PET: 73 parts;

[0161] Fiber: 20 parts, the diameter of the fiber is 0.5-10 μm and the length is 100-800 μm;

[0162] Antioxidant: 0.2 parts;

[0163] Compatibilizer: 1 part;

[0164] Light stabilizer: 0.5 parts;

[0165] Anti-hydrolysis agent: 0.3 parts;

[0166] Toughener: 5 parts.

[0167] The fiber of the embodiment 2 is polyethylene naphthalate PEN fiber, the antioxidant is tri(2,4-di-tert-butylphenyl) phosphate of the phosphate antioxidant, the light stabilizer is UV-531 of the benzophenone type, the hydrolysis resistance agent is monomeric carbodiimide of the carbodiimide type, the compatibilizer is PE-g-ST of the isocyanate type, and the toughening agent is the elastomer SEBS.

[0168] The difference between the preparation method of this embodiment and that of embodiment 1 is only the following 1-3:

[0169] 1. The second step is not included;

[0170] 2. In the third step, melt blending is performed at 230°C for 10 minutes, and a polymer film for photovoltaic backplane having a thickness of 350 μm is obtained after extrusion.

[0171] 3. Step 4: The polymer film obtained after extrusion is cured at 100°C for 60 minutes to make the bond between the fiber and the PET resin substrate more solid. After curing, the film is cooled by a cooling device, and after a cooling time of 30 seconds, it is cooled to 30°C. Finally, through the calendering process, the film is further thinned to a thickness of 280μm.

[0172] The back panel prepared in Example 2 has a transverse tensile strength of 82.1 MPa and a longitudinal tensile strength of 90.2 MPa; after 5000 hours of ultraviolet exposure, the performance remains above 82%.

[0173] Embodiment 3:

[0174] The polymer film for solar cell backsheet of this embodiment includes the following components in parts by weight:

[0175] PET: 77.3 parts;

[0176] Fiber: 15 parts, the diameter of the fiber is 0.5-10 μm and the length is 100-800 μm;

[0177] Antioxidant: 0.3 parts;

[0178] Compatibilizer: 1 part;

[0179] Light stabilizer: 0.5 parts;

[0180] Anti-hydrolysis agent: 0.2 parts;

[0181] Toughener: 5 parts.

[0182] The fiber of the embodiment 3 is polyethylene naphthalate PEN fiber, the antioxidant is Irganox 1010 of the hindered phenol type, the light stabilizer is UV-405 of the triazine type, the hydrolysis resistance agent is tris(2,4-di-tert-butylphenyl) phosphate of the organic phosphorus compound, the compatibilizer is polypropylene grafted maleic anhydride of maleic anhydride grafted polyolefin, and the toughening agent is the elastomer SEBS.

[0183] The difference between the preparation method and Example 1 is the following 1-3:

[0184] 1. In the second step, the addition amount of sodium dodecylbenzene sulfonate is 1% of the total mass of the fiber.

[0185] 2. In the third step, melt blending is carried out at a temperature of 310°C for 1 minute, and a polymer film for photovoltaic backplane having a thickness of 355 μm is obtained after extrusion.

[0186] 3. Step 4: The polymer film obtained after extrusion is cured at 200°C for 30 minutes to make the bond between the fiber and the PET resin substrate more solid. After curing, the film is cooled by a cooling device for 30 seconds to 20°C. Finally, the film is further thinned to a thickness of 285μm through a calendering process.

[0187] The backboard prepared in Example 3 has a transverse tensile strength of 89.3 MPa and a longitudinal tensile strength of 103.1 MPa; after 5000 hours of ultraviolet exposure, the performance remains above 88%.

[0188] Embodiment 4:

[0189] The polymer film for solar cell backsheet of this embodiment includes the following components in parts by weight:

[0190] PET resin: 77.4 parts;

[0191] Fiber: 20 parts, the diameter of the fiber is 0.5-10μm and the length is 100-800um;

[0192] Antioxidant: 0.2 parts;

[0193] Compatibilizer: 1 part;

[0194] Light stabilizer: 0.5 parts;

[0195] Anti-hydrolysis agent: 0.5 parts;

[0196] The fiber of the embodiment 4 is carbon fiber, the antioxidant is tris(2,4-di-tert-butylphenyl) phosphate of the phosphate ester class, the light stabilizer is 2-(2′-hydroxy 3′,5′-di-tert-butylphenyl) benzotriazole (UV-320) of the benzotriazole class, the anti-hydrolysis agent is tris(2,4-di-tert-butylphenyl) phosphate of the organic phosphorus compound, and the compatibilizer is the titanate coupling agent TMC-130 of the titanate class.

[0197] The difference between the preparation method and Example 1 is only the following 1-3:

[0198] 4. In the second step, the amount of sodium dodecylbenzene sulfonate added is 2% of the total mass of the fiber.

[0199] 5. In the third step, melt blending is performed at 290°C for 10 minutes, and a polymer film for photovoltaic backplane having a thickness of 315 μm is obtained after extrusion.

[0200] 6. Step 4: The polymer film obtained after extrusion is cured at a temperature of 200°C for 40 minutes to make the bond between the fiber and the PET resin substrate more solid. After curing, the film is cooled by a cooling device, and after a cooling time of 10 seconds, it is cooled to 40°C. Finally, the film is further thinned to a thickness of 245μm through a calendering process.

[0201] The backboard prepared in Example 4 has a transverse tensile strength of 82.4 MPa and a longitudinal tensile strength of 95.2 MPa; after 5000 hours of ultraviolet exposure, the performance remains above 76%.

[0202] Example 5

[0203] The difference between this embodiment and embodiment 1 is that in embodiment 5, the polymer film for solar cell backsheet includes the following components in parts by weight:

[0204] PET resin: 60 parts;

[0205] Fiber: 25 parts, the diameter of the fiber is 0.5-10 μm and the length is 100-800 μm;

[0206] Antioxidant: 0.1 part;

[0207] Compatibilizer: 3 parts;

[0208] Light stabilizer: 2 parts;

[0209] Anti-hydrolysis agent: 0.1 part;

[0210] Toughener: 1 part.

[0211] Example 6

[0212] The difference between this embodiment and embodiment 1 is that in embodiment 6, the polymer film for solar cell backsheet includes the following components in parts by weight:

[0213] PET resin: 80 parts;

[0214] Fiber: 10 parts, the diameter of the fiber is 0.5-10μm and the length is 100-800um;

[0215] Antioxidant: 1.5 parts;

[0216] Compatibilizer: 0.1 part;

[0217] Light stabilizer: 1 part;

[0218] Hydrolysis resistance agent: 3 parts;

[0219] Toughener: 15 parts.

[0220] Comparative Example 1:

[0221] Back sheet without fiber modification

[0222] The polymer film for solar cell back sheet of this comparative example comprises the following components in parts by weight:

[0223] PET resin: 97.9 parts;

[0224] Antioxidant: 0.5 parts;

[0225] Compatibilizer: 1 part;

[0226] Light stabilizer: 0.5 parts;

[0227] Anti-hydrolysis agent: 0.1 part;

[0228] The components of the comparative example are selected to be the same as the corresponding components of Example 1.

[0229] The difference between the preparation method and Example 1 is only the following 1-3:

[0230] 1. Excluding the first and second steps;

[0231] 2. In the third step, the dried PET resin, antioxidant, compatibilizer, light stabilizer and hydrolysis resistance agent are added into a high-speed mixer according to the components and proportions in Table 1, and the mixer is used for high-speed mixing.

[0232] The back sheet prepared in Comparative Example 1 has a longitudinal tensile strength of 63 MPa and a transverse tensile strength of 48 MPa; after 5000 hours of ultraviolet exposure, the performance remains above 75%.

[0233] Comparative Example 2

[0234] The polymer film for solar cell back sheet of this comparative example comprises the following components in parts by weight:

[0235] PET resin: 71.5 parts;

[0236] Fiber: 20 parts;

[0237] Antioxidant: 0.3 parts;

[0238] Compatibilizer: 2 parts;

[0239] Light stabilizer: 0.5 parts;

[0240] Anti-hydrolysis agent: 0.3 parts;

[0241] Toughener: 5 parts.

[0242] The components of the comparative example are selected to be the same as the corresponding components of Example 1.

[0243] The only difference between Comparative Example 2 and Example 1 is that the fiber has a diameter of 0.5-10 μm and a length of 20-100 μm.

[0244] The back sheet prepared in Comparative Example 2 has a longitudinal tensile strength of 90.4 MPa and a transverse tensile strength of 65.3 MPa; after 5000 hours of ultraviolet exposure, the performance remains above 80%.

[0245] Table 1 Composition ratio and test results of Examples 1-4 and Comparative Examples 1-2

[0246]

[0247]

[0248] Most current technical solutions use continuous fiber reinforced PET film to improve the mechanical strength of the backplane. However, continuous fibers are heavy and difficult to disperse evenly in the matrix, and fiber agglomeration is prone to occur. After processing and forming, this will lead to uneven distribution of material properties, thereby affecting the overall mechanical properties of the backplane. Stress concentration is prone to occur in certain areas, leading to local damage. At the same time, long fiber reinforced PET materials often significantly improve the rigidity of the material, but have relatively poor flexibility, which is limited in some photovoltaic backplane application environments.

[0249] The present invention provides a polymer film for photovoltaic backplane membrane and a preparation method thereof, which can improve the mechanical strength and aging resistance of the material and reduce the production cost by reinforcing a polymer resin such as PET material with nano short fibers of a specific size. Specifically, the present invention uses existing spinning technology to prepare long fibers with a diameter range of 0.5 to 10 microns, and then breaks up the fibers by stirring to form fibers with a length of 100 to 800 microns.

[0250] These fibers are evenly embedded in the polyethylene terephthalate (PET) resin matrix to form a unique mesh structure, thereby producing a high-performance PET film. When this PET film is used in the field of photovoltaic backplanes, thanks to the special mesh structure constructed by the fibers, it can not only effectively improve the stability of the entire photovoltaic system, but also significantly enhance its toughness while ensuring that the backplane material has excellent strength, thereby achieving a double improvement in the strength and toughness of the backplane material, providing a solid guarantee for the long-term stable operation of photovoltaic modules.

[0251] It should be pointed out that although the various steps in the above embodiments are described in a specific order, those skilled in the art can understand that in order to achieve the effects of the present invention, different steps do not have to be performed in such an order. They can be performed simultaneously (in parallel) or in other orders. These changes are within the scope of protection of the present invention.

[0252] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A polymer film for a solar cell back sheet, characterized in that: Includes the following components: A polymer resin and fibers with a diameter of 0.5-10 μm and a length of 100-800 μm.

2. The film according to claim 1, characterized in that Each component is calculated by the following weight parts: Polymer resin: 60-80 parts; and Fiber: 10-25 servings.

3. The film according to claim 2, characterized in that The film also includes a modification aid; the weight portion of the modification aid is 2.2-20.6 parts; the modification aid includes one or more of an antioxidant, a compatibilizer, a light stabilizer, a hydrolysis resistance agent and a toughening agent.

4. The film according to any one of claims 1 to 3, characterized in that: The polymer resin is PET resin and / or The fiber is treated with a surfactant and / or a silane coupling agent, wherein the surfactant includes an anionic surfactant; the anionic surfactant includes sodium dodecylbenzene sulfonate.

5. The film according to claim 4, characterized in that By weight, the modification aid includes: Antioxidant: 0.1-1.5 parts; Compatibilizer: 0.1-3 parts; Light stabilizer: 0.1-2 parts; Anti-hydrolysis agent: 0.1-3 parts; and Toughening agent: 1-15 parts.

6. The film according to claim 5, characterized in that Include one or more of the following characteristics: The antioxidant includes one or more of hindered phenols and phosphates; The compatibilizer includes one or more of maleic anhydride grafted polyolefin, titanate, and isocyanate; The light stabilizer includes one or more of oxalic acid amides, triazines, benzophenones and benzotriazoles; The anti-hydrolysis agent includes one or more of epoxy compounds, organic phosphorus compounds and carbodiimides; The toughening agent includes one or more of an elastomer and a polymer obtained by copolymerization of ethylene and propylene.

7. The film according to claim 1, characterized in that The fibers include one or more of polymer fibers, glass fibers and carbon fibers; preferably, the polymer fibers include polyethylene terephthalate fibers and / or polyethylene naphthalate fibers.

8. The method for preparing a polymer film for a solar cell back sheet according to any one of claims 1 to 7, characterized in that: include: The at least partially deflated fibers are mixed with a polymer resin to form a polymer film.

9. The method according to claim 8, characterized in that After forming the polymer film, the method further comprises: The polymer film solidifies and cools.

10. A photovoltaic back sheet, characterized in that: include: The polymer film for solar cell backsheet according to any one of claims 1 to 7 or the polymer film for solar cell backsheet prepared by the method according to any one of claims 8 to 9; and A weather-resistant layer connected to the upper surface and / or lower surface of the polymer film for the solar cell backsheet.

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