Composition, backplane comprising the composition, method for forming the same, and photovoltaic module

Abstract

The present invention discloses various compositions, a backsheet including the compositions, a forming method thereof, and a photovoltaic module. The backsheet includes a polyester layer; a weather-resistant layer provided on one side of the polyester layer in the thickness direction; and a fluorine-free coating provided on the other side of the polyester layer in the thickness direction. The backsheet according to some embodiments of the present invention has a three-layer structure and includes specially treated PET / weather-resistant PET. Each layer is a fluorine-free polymer material. The process is simple, environmentally friendly and practical, and is beneficial to improving the weather resistance, water resistance and ultraviolet radiation resistance of the photovoltaic module having the backsheet in a complex outdoor environment. After reliability testing, the power attenuation of the module is <1%.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic power generation, and particularly to a resin composition, a polyester composition, an adhesive composition, a coating composition, a backsheet including the compositions, a molding method thereof, and a photovoltaic module. Background Art

[0002] There are various classifications of photovoltaic backsheets, and the two most commonly used ones are: classified by manufacturing process into coating type and composite type; classified by structure into fluorine-containing backsheets and fluorine-free backsheets. The traditional backsheet for photovoltaic modules is a three-layer film structure with double-sided coating. The traditional three-layer fluorine-containing (TPT / KPF) structure backsheet has problems such as difficult recovery of fluorine-containing materials and high prices. From the perspective of sustainable development, it is not recommended for promotion. The double-sided coated backsheet has problems such as intolerance to sand and wind and large water permeability. The existing fluorine-free backsheets are adhesively laminated by multiple layers of PET with adhesives, and the main varieties are PE, DNP, etc. The existing fluorine-free backsheet materials have significant defects in that they are not resistant to damp heat, dry heat, and high ultraviolet radiation, and thus cannot meet the requirement of the 25-year service life of commercial crystalline silicon solar cell photovoltaic modules in environments such as damp heat, dry heat, and ultraviolet, and it is also difficult to be applied to the encapsulation of crystalline silicon solar cell photovoltaic modules. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. For this reason, an object of the present invention is to provide a resin composition, which is used for a photovoltaic backsheet, can meet the hydrolysis resistance requirement of the photovoltaic backsheet material, and is easy to recycle.

[0004] Another object of the present invention is to provide a polyester composition, which is used for a photovoltaic backsheet.

[0005] A third object of the present invention is to provide an adhesive composition, which is used for a photovoltaic backsheet.

[0006] A fourth object of the present invention is to provide a coating composition, which is used for a photovoltaic backsheet.

[0007] A fifth object of the present invention is to provide a backsheet.

[0008] A sixth object of the present invention is to provide a molding method of the backsheet.

[0009] A seventh object of the present invention is to provide a photovoltaic module, which includes the backsheet.

[0010] The resin composition according to an embodiment of the first aspect of the present invention comprises the following components in parts by weight: 10,000 parts of resin, 0.5 - 15 parts of co-crosslinking agent, 0.1 - 5 parts of antioxidant, 0.1 - 5 parts of ultraviolet light absorber, 0.1 - 5 parts of light stabilizer, and 0.1 - 10 parts of lubricant.

[0011] The resin composition according to an embodiment of the first aspect of the present invention has strong water resistance, is easy to recycle, has certain supporting properties when used for photovoltaic backsheets, and is convenient for bonding with weather-resistant layers and internal coatings, being economical and environmentally friendly.

[0012] According to some embodiments of the present invention, the resin is a crosslinkable resin.

[0013] According to some embodiments of the present invention, the resin is one or a mixture of polyethylene, ethylene-vinyl acetate, and POE.

[0014] According to some embodiments of the present invention, the co-crosslinking agent is an organic compound having free radical polymerization properties and containing multiple double bonds.

[0015] According to some embodiments of the present invention, the co-crosslinking agent is one or a mixture of triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethylene glycol diacrylate, and ethylene glycol dimethacrylate; preferably triallyl isocyanurate.

[0016] According to some embodiments of the present invention, the antioxidant is a compound of B225 and DLTP, and the weight ratio of the compounding of B225 and DLTP is 2:1 - 5:1.

[0017] According to some embodiments of the present invention, the ultraviolet light absorber is 2-hydroxy-4-n-octyloxybenzophenone.

[0018] According to some embodiments of the present invention, the light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate.

[0019] According to some embodiments of the present invention, the lubricant is a silicone masterbatch.

[0020] The polyester composition according to an embodiment of the second aspect of the present invention comprises the following components in parts by weight: 10,000 parts of polyester compound, 0.1 - 5 parts of hydrolysis-resistant agent, and 0.1 - 10 parts of the antioxidant.

[0021] According to some embodiments of the present invention, the hydrolysis-resistant agent is carbodiimide.

[0022] According to some embodiments of the present invention, the antioxidant is a high-temperature antioxidant resistant to 150 °C; preferably an aniline antioxidant; more preferably 4,4'-bis(α,α-dimethylbenzyl) diphenylamine.

[0023] The adhesive composition according to the embodiment of the third aspect of the present invention comprises the following components in parts by weight: 10000 parts of an adhesive and 1 to 20 parts of a curing agent.

[0024] According to some embodiments of the present invention, the adhesive is a polyurethane type; preferably a waterborne polyurethane.

[0025] According to some embodiments of the present invention, the curing agent is a yellowing-resistant curing agent; preferably a high light and weather resistance aliphatic polyisocyanate; more preferably HB175MP / X and / or N75 of BASF.

[0026] The coating composition according to the embodiment of the fourth aspect of the present invention comprises the following components in parts by weight: 100 parts of a polyacrylate polymer and 0.1 to 10 parts of a curing agent.

[0027] According to some embodiments of the present invention, the polyacrylate polymer is a compound containing acrylate groups and double bonds.

[0028] According to some embodiments of the present invention, the number average molecular weight of the polyacrylate polymer is Mn, wherein Mn satisfies: 500 ≤ Mn ≤ 2000.

[0029] According to some embodiments of the present invention, the polyacrylate polymer is an acrylate polymer containing polar groups.

[0030] According to some embodiments of the present invention, the polar groups are one or more of amino, sulfhydryl, phosphino, hydroxyl, carboxyl, epoxy groups.

[0031] The backplane according to the embodiment of the fifth aspect of the present invention comprises:

[0032] A polyester layer;

[0033] A weather-resistant layer, the weather-resistant layer is provided on one side in the thickness direction of the polyester layer, and the pre-crosslinking degree of the weather-resistant layer is 50% to 90%, preferably, the pre-crosslinking degree of the weather-resistant layer is 70% to 80%;

[0034] A fluorine-free coating, the fluorine-free coating is provided on the other side in the thickness direction of the polyester layer.

[0035] According to some embodiments of the present invention, the polyester layer comprises the polyester composition.

[0036] According to some embodiments of the present invention, the weather-resistant layer comprises the resin composition.

[0037] According to some embodiments of the present invention, the fluorine-free coating comprises the coating composition described above.

[0038] According to some embodiments of the present invention, the backsheet further comprises:

[0039] An adhesive layer provided between the weather-resistant layer and the polyester layer;

[0040] The adhesive layer comprises the adhesive composition described above.

[0041] According to some embodiments of the present invention, the weather-resistant layer is pre-crosslinked, and the pre-crosslinking treatment comprises the following steps: after the resin composition is melt-cast into a film by a screw extruder, it is formed through a crosslinking reaction.

[0042] According to some embodiments of the present invention, the method of the crosslinking reaction includes any one of electron beam crosslinking, ultraviolet light crosslinking, and silane crosslinking; preferably electron beam crosslinking.

[0043] According to some embodiments of the present invention, the non-fluorine coating is obtained through coating, drying, and curing by an on-line coating process.

[0044] According to some embodiments of the present invention, the thickness of the adhesive layer is d 4 , where the d 4 satisfies: 5 μm ≤ d 4 ≤ 20 μm.

[0045] According to some embodiments of the present invention, the thickness of the polyester layer is d 1 , where the d 1 satisfies: 100 μm ≤ d 1 ≤ 500 μm.

[0046] According to some embodiments of the present invention, the thickness of the weather-resistant layer is d 2 , where the d 2 satisfies: 10 μm ≤ d 2 ≤ 50 μm.

[0047] According to some embodiments of the present invention, the thickness of the fluorine-free coating is d 3 , where the d 3 satisfies: 1 μm ≤ d 3 ≤ 50 μm.

[0048] For the forming method of the backsheet according to the embodiments of the sixth aspect of the present invention, the polyester layer and the weather-resistant layer are bonded, and the polyester layer and the fluorine-free coating are bonded.

[0049] According to some embodiments of the present invention, the bonding method between the weather-resistant layer and the polyester layer is achieved by double-layer co-extrusion using a cast film extrusion unit to obtain a double-layer co-extruded film. Among them, the materials of the weather-resistant layer and the polyester layer are in a molten state, and the two melts are tightly bonded into a film at the die head, and then the exposed side of the outer layer of the double-layer co-extruded film is crosslinked and cured.

[0050] According to some embodiments of the present invention, in the double-layer co-extrusion, the process parameters of the two extruders of the casting unit are different. The main machine temperature for extruding the weather-resistant layer is 140 - 200 °C, and the main machine temperature for extruding the polyester layer is 220 - 270 °C.

[0051] According to some embodiments of the present invention, the bonding method between the weather-resistant layer and the polyester layer is to cast the weather-resistant layer into a film, crosslink it, and then cure and bond it with the polyester layer through an adhesive layer.

[0052] According to some embodiments of the present invention, the weather-resistant layer and the polyester layer are bonded through the adhesive layer, including the following steps:

[0053] 1) Add the curing agent in the specified weight parts to the polyurethane and mix evenly;

[0054] 2) Coat the evenly mixed adhesive on the surface of the weather-resistant layer;

[0055] 3) Through traction, tightly press it against one side of the polyester layer;

[0056] 4) Cure and heat-set the pressed product.

[0057] The photovoltaic module according to the embodiment of the seventh aspect of the present invention includes: the backsheet described above.

[0058] The additional aspects and advantages of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0060] Figure 1 It is a schematic structural diagram of the backsheet of a specific embodiment of the present invention.

[0061] Reference Signs:

[0062] 100: Backsheet;

[0063] 1: Polyester layer;

[0064] 2: Weather-resistant layer;

[0065] 3: Fluorine-free coating;

[0066] 4: Adhesive layer. Specific embodiments

[0067] The embodiments of the present invention will be described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention will be described in detail below.

[0068] Reference will be made below to Figure 1 Describe a resin composition, a polyester composition, an adhesive composition according to an embodiment of the present invention, and a backsheet 100 and a photovoltaic module including the compositions. Among them, the resin composition, the polyester composition, and the adhesive composition of the present invention are all applicable to photovoltaic backsheets.

[0069] The resin composition according to the embodiment of the first aspect of the present invention includes the following components in parts by weight: 10,000 parts of resin, 0.5 - 15 parts of co-crosslinking agent, 0.1 - 5 parts of antioxidant, 0.1 - 5 parts of ultraviolet light absorber, 0.1 - 5 parts of light stabilizer, and 0.1 - 10 parts of lubricant.

[0070] The resin composition according to the embodiment of the first aspect of the present invention has strong water resistance, is easy to recycle, has certain supporting performance when used in a photovoltaic backsheet, and is convenient for bonding with a weather-resistant layer and an internal coating, which is economical and environmentally friendly.

[0071] According to some embodiments of the present invention, the resin is a crosslinkable resin. Preferably, the resin is one or more of polyethylene, ethylene-vinyl acetate, and POE. The crosslinkable resin is the base material of the resin composition. By crosslinking or pre-crosslinking treatment of the crosslinkable resin, the weather resistance of the resin combination is enhanced, and further, the weather resistance of the backsheet including the resin composition is enhanced.

[0072] According to some embodiments of the present invention, the co-crosslinking agent is an organic compound having free radical polymerization properties and containing multiple double bonds. Thus, it can promote the crosslinking polymerization between the components of the resin composition.

[0073] According to the preferred embodiment of the present invention, the co-crosslinking agent is one or more mixtures of triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethylene glycol diacrylate, and ethylene glycol dimethacrylate; more preferably triallyl isocyanurate.

[0074] According to some embodiments of the present invention, the antioxidant is a compound of B225 and DLTP, and the weight ratio of B225 to DLTP in the compound is 2:1 to 5:1. The antioxidant DLTP, English name Dilauryl thiodipropionate, also known as bis(lauryl) thiodipropionate, has the molecular formula C30H58O4S and a molecular weight of 514.8441. The antioxidant B225 is a binary classic compound antioxidant. Composition: IRGANOX1010, 50%; IRGAFOS168, 50%; The antioxidant is a compound of B225 and DLTP. Through the synergistic effect of dilauryl thiodipropionate, i.e., DLTP, and the sterically hindered phenolic antioxidant B225, the stability and oxidation resistance of the resin material of the present application can be significantly improved. The setting of the specific ratio in the compound antioxidant is because B225 plays the main antioxidant role and occupies a better proportion, while DLTP plays an auxiliary antioxidant role and accounts for a smaller weight ratio.

[0075] According to some other preferred embodiments of the present invention, the ultraviolet light absorber is 2-hydroxy-4-n-octyloxybenzophenone, the light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, and the lubricant is a silicone masterbatch.

[0076] The resin material of the specific embodiment of the present invention formed by the above components is subjected to an ultraviolet light aging test of 200 kwh / m 2 (UV200), and the yellowing index is measured. An aging test of 500 h (DH500) is carried out at a constant temperature of 85 °C and a constant humidity of 85% RH, and its mechanical properties are tested. After UV200, the yellowing index Δb ≤ 2, and after DH500, the tensile strength ≥ 15.3 MPa.

[0077] The polyester composition according to the embodiment of the second aspect of the present invention includes the following components in parts by weight: 10000 parts of a polyester compound, 0.1 to 5 parts of a hydrolysis-resistant agent, and 0.1 to 10 parts of an antioxidant. The polyester composition of the present invention is a hydrolysis-resistant polyester composition.

[0078] Among them, the polyester compound is PET.

[0079] According to some embodiments of the present invention, the hydrolysis-resistant agent is carbodiimide.

[0080] According to some embodiments of the present invention, the antioxidant is a high-temperature antioxidant resistant to 150 °C; preferably an aniline antioxidant; more preferably 4,4'-bis(α,α-dimethylbenzyl) diphenylamine.

[0081] The polyester compositions according to the specific embodiments of the present invention are respectively prepared into polyester materials by conventional methods, and the hydrolysis resistance of the polyester materials is tested. The temperature is set at 85 °C and the humidity is 100% RH for 96 h, and its mechanical properties are tested. The tensile strength is greater than 11.6 MPa.

[0082] The adhesive composition according to the third aspect embodiment of the present invention comprises components in the following parts by weight: 10,000 parts of an adhesive and 1 to 20 parts of a curing agent.

[0083] According to some embodiments of the present invention, the adhesive is a polyurethane type; preferably, it is a waterborne polyurethane.

[0084] According to some embodiments of the present invention, the curing agent is a yellowing-resistant curing agent; preferably, it is a high light and weather resistance aliphatic polyisocyanate; more preferably, it is HB175MP / X and / or N75 of BASF.

[0085] The adhesive compositions according to the specific embodiments of the present invention are respectively prepared into adhesive materials by conventional methods, and the adhesive properties of the adhesive materials are tested. The peel strength of the polyester layer and the resin layer adhered with the adhesive materials of the specific embodiments of the present invention is greater than 96.2 N / cm, and the test standard refers to GB-T2790-1995 Adhesives - 180° Peel Strength Test Method.

[0086] The coating composition according to the fourth aspect embodiment of the present invention comprises components in the following parts by weight: 100 parts of a polyacrylate polymer and 0.1 to 10 parts of a curing agent. Among them, the curing agent is any one of the conventional commercially available curing agents. For example, it can be p-hydroxybenzenesulfonic acid, titanium tetraisopropoxide, etc., but not limited thereto.

[0087] According to some embodiments of the present invention, the polyacrylate polymer is a compound containing acrylate groups and double bonds. Preferably, the polyacrylate polymer is one or more of methyl acrylate and polyacrylate phosphate.

[0088] According to some embodiments of the present invention, the number average molecular weight of the polyacrylate polymer is Mn, where Mn satisfies: 500 ≤ Mn ≤ 2000.

[0089] According to some embodiments of the present invention, the polyacrylate polymer is an acrylate containing polar groups.

[0090] According to some embodiments of the present invention, the polar groups are one or more of amino, sulfhydryl, phosphino, hydroxyl, and carboxyl.

[0091] The coating compositions according to the specific embodiments of the present invention are respectively prepared into coatings by conventional methods, and the adhesion properties of the coatings are tested. The peel strength of the polyester layer (including the coating layer) and the adhesive film layer is greater than 167.4 N / cm, and the test standard refers to GB-T2790-1995 Adhesives - 180° Peel Strength Test Method.

[0092] The backsheet 100 according to the embodiment of the fifth aspect of the present invention includes a polyester layer 1, a weather-resistant layer 2, and a fluorine-free coating 3. The weather-resistant layer 2 is provided on one side of the polyester layer 1 in the thickness direction, and the fluorine-free coating 3 is provided on the other side of the polyester layer 1 in the thickness direction.

[0093] Among them, the pre-crosslinking degree of the weather-resistant layer 2 is 50% - 90%. If the pre-crosslinking degree is less than 50%, the pre-crosslinking degree of the weather-resistant layer 2 is too low, and the high-temperature resistance of the weather-resistant layer 2 may be reduced, and water vapor is likely to penetrate the weather-resistant layer 2 into the interior of the backsheet 100, and the moisture and heat resistance of the backsheet 100 is poor. If the pre-crosslinking degree is greater than 90%, the pre-crosslinking degree of the weather-resistant layer 2 is too high, and the adhesive film formed by the weather-resistant layer 2 may be too hard, and the adhesion between the weather-resistant layer 2 and the polyester layer 1 may decrease. In this way, it is not conducive to the winding of the weather-resistant layer 2, and the weather-resistant layer 2 is prone to cracking. At the same time, when the pre-crosslinking degree is greater than 90%, the irradiation time of the weather-resistant layer 2 may be longer, which may lead to material degradation. At the same time, the irradiation process will also be longer, increasing the production cost of the backsheet 100. Among them, the pre-crosslinking degree can be tested by the test method of national standard GB|T18474-2001. Thus, by setting the pre-crosslinking degree of the weather-resistant layer 2 to 50% - 90%, the obtained pre-crosslinking degree of the weather-resistant layer 2 is appropriate, and the weather-resistant layer 2 has good high-temperature and moisture and heat resistance and strong bonding ability. Optionally, the pre-crosslinking degree of the weather-resistant layer 2 is 70% - 80%. Thus, the weather-resistant layer 2 has good weather resistance and a large adhesion between the weather-resistant layer 2 and the polyester layer 1. While improving the weather resistance of the backsheet 100, it is convenient for the preparation and molding of the backsheet 100.

[0094] The backsheet 100 according to the embodiment of the present invention is a three-layer structure, including specially treated PET / weather-resistant PET, which has strong weather resistance and can meet the requirements of the long service life of commercial crystalline silicon solar cell photovoltaic modules under environmental conditions of high ultraviolet intensity, high temperature, high humidity, and high sand and dust. For example, it can meet the requirements of the 25-year service life of solar cell photovoltaic modules.

[0095] According to some embodiments of the present invention, the polyester layer 1 includes a polyester composition. Since the polyester composition has excellent hydrolysis resistance and mechanical properties, thus, it is beneficial to improve the hydrolysis resistance and mechanical properties of the backsheet 100.

[0096] According to some embodiments of the present invention, the weather-resistant layer 2 includes a resin composition. Since the resin composition has excellent weather resistance, thus, it is beneficial to improve the weather resistance of the backsheet 100.

[0097] According to some embodiments of the present invention, the fluorine-free coating 3 includes a coating composition. Since the coating composition has strong bonding properties, thus, when the backsheet 100 is laminated to form a photovoltaic module, it is beneficial to improve the reliability of the photovoltaic module.

[0098] According to some preferred embodiments of the present invention, the backsheet 100 further comprises:

[0099] An adhesive layer 4, which is disposed between the weather-resistant layer 2 and the polyester layer 1;

[0100] The adhesive layer 4 comprises an adhesive composition.

[0101] According to some embodiments of the present invention, the backsheet 100 further comprises an adhesive layer 4, and the adhesive layer 4 is disposed between the weather-resistant layer 2 and the polyester layer 1. The weather-resistant layer 2 and the polyester layer 1 are tightly bonded through the adhesive layer 4, so that the structure of the backsheet 100 is more dense.

[0102] According to some other embodiments of the present invention, the weather-resistant layer 2 is subjected to a pre-crosslinking treatment, and the pre-crosslinking treatment comprises the following steps: After the resin composition is melt-cast into a film by a screw extruder, it is formed through a crosslinking reaction.

[0103] According to some preferred embodiments of the present invention, the crosslinking reaction method includes any one of electron beam crosslinking, ultraviolet light crosslinking and silane crosslinking; preferably electron beam crosslinking.

[0104] The weather-resistant layer 2 according to the specific embodiment of the present invention is a fluorine-free weather-resistant layer, and is subjected to a pre-crosslinking treatment by electron beam, which can ensure the high weather resistance and high temperature resistance of the weather-resistant layer, and can greatly improve the weather resistance of the outer layer of the backsheet, achieving excellent comprehensive weather resistance.

[0105] One existing solution for a fluorine-free backsheet is to bond and compound multiple layers of PET through an adhesive, and there is also the use of EVA material as the weather-resistant layer. However, when these materials are affected by high ultraviolet intensity, high temperature, high humidity, and high sand and dust in the outside world, problems such as cracking, yellowing, delamination, and corrosion will occur.

[0106] The solution of the present invention is to use a crosslinkable material as the weather-resistant layer. When the material is not crosslinked, its melting point is relatively low, and the long-term use temperature is generally below 100°C. The molecular chains of the material can move, and water vapor is easily infiltrated between the molecular chains, resulting in a reduction in the efficiency of the photovoltaic module. After the material of the present invention is subjected to a pre-crosslinking treatment, the molecular chain structure of the material changes from disordered to a dense network structure, which is not easily infiltrated by water vapor, and cracking is not likely to occur during long-term use. The temperature resistance grade of the weather-resistant layer 2 is increased from 90°C to 125°C - 150°C. When subjected to high ultraviolet intensity, high temperature and high humidity, and high sand and dust in the outside world, the occurrence probability of yellowing, delamination, corrosion, and cracking is greatly reduced, ensuring the long-term use of the photovoltaic module. In addition, the electron beam crosslinking process is simple, and the product quality controllability is strong.

[0107] According to some embodiments of the present invention, the non-fluoride coating 3 is obtained through an on-line coating process by coating, drying and curing.

[0108] The backsheet 100 according to some embodiments of the present invention has a PPC structure, and each layer is a fluorine-free polymer material. The process is simple, environmentally friendly and practical, greatly reducing environmental pollution. At the same time, the cost is much lower than that of fluorine materials, and the raw materials are abundant, which is conducive to reducing the cost of photovoltaic modules. In addition, the use of this backsheet 100 in components is beneficial to improving the performance of components with this backsheet in complex outdoor environments, such as weather resistance, water resistance, ultraviolet resistance. After reliability testing, the power attenuation of the components is <1%.

[0109] According to some embodiments of the present invention, the thickness of the adhesive layer 4 is d 4 , where d 4 satisfies: 5μm ≤ d 4 ≤ 20μm. In this way, it can not only meet the bonding needs, but also not add too much weight and thickness to the backsheet 100.

[0110] According to some embodiments of the present invention, the thickness of the polyester layer 1 is d 1 , where d 1 satisfies: 100μm ≤ d 1 ≤ 500μm. In this way, it can not only support the backsheet 100, but also not add too much weight and thickness to the backsheet 100.

[0111] According to some embodiments of the present invention, the thickness of the weather-resistant layer 2 is d 2 , where d 2 satisfies: 10μm ≤ d 2 ≤ 50μm. In this way, it can not only effectively shield ultraviolet rays, high temperature and high humidity, but also not add too much weight and thickness to the backsheet 100.

[0112] According to some embodiments of the present invention, the thickness of the fluorine-free coating 3 is d 3 , where d 3 satisfies: 1μm ≤ d 3 ≤ 50μm. In this way, it can not only meet the effective protection of the backsheet 100, but also not add too much weight and thickness to the backsheet 100.

[0113] According to the forming method of the backsheet according to the sixth aspect embodiment of the present invention, the polyester layer 1 and the weather-resistant layer 2 are bonded, and the polyester layer 1 and the fluorine-free coating 3 are bonded.

[0114] According to some embodiments of the present invention, the bonding method between the weather-resistant layer 2 and the polyester layer 1 is double-layer co-extrusion through a cast film extrusion unit to obtain a double-layer co-extruded film. Among them, the materials of the weather-resistant layer 2 and the polyester layer 1 are in a molten state, and the two melts are tightly bonded into a film at the die head, and then the exposed side of the outer layer of the double-layer co-extruded film is crosslinked and cured.

[0115] According to some specific embodiments of the present invention, the process parameters of the two extruders in the double-layer co-extrusion casting unit are different. The main machine temperature for extruding the material of the weather-resistant layer 2 is 140-200 °C, and the main machine temperature for extruding the material of the polyester layer 1 is 220-270 °C.

[0116] According to some embodiments of the present invention, the bonding method between the weather-resistant layer 2 and the polyester layer 1 is to cast the weather-resistant layer 2 into a film, and after cross-linking, it is then cured and bonded with the polyester layer 1 through the adhesive layer 4.

[0117] According to some embodiments of the present invention, the weather-resistant layer 2 and the polyester layer 1 are bonded through the adhesive layer 4, including the following steps:

[0118] 1) Add the curing agent in the weight parts of the components of the adhesive layer 4 to the polyurethane type and mix evenly;

[0119] 2) Uniformly coat the uniformly mixed adhesive on the surface of the weather-resistant layer 2;

[0120] 3) Tightly press it against one side of the polyester layer 1 through traction;

[0121] 4) Cure and heat-set the pressed product.

[0122] The photovoltaic module according to the embodiment of the seventh aspect of the present invention includes: a backsheet 100.

[0123] The additional aspects and advantages of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention.

[0124] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments, but the present invention is not limited to the described embodiments.

[0125] Example 1

[0126] A resin composition includes the following components in weight parts: 10000 parts of resin, 0.5 part of co-crosslinking agent, 0.1 part of antioxidant, 0.1 part of ultraviolet light absorber, 0.1 part of light stabilizer, and 0.1 part of lubricant;

[0127] Among them, the resin is polyethylene; the co-crosslinking agent is triallyl cyanurate; the antioxidant is a compound of B225 and DLTP in a weight ratio of 2:1; the ultraviolet light absorber is 2-hydroxy-4-n-octyloxybenzophenone; the light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate; the lubricant is a silicone masterbatch.

[0128] Example 2

[0129] A resin composition comprising the following components in parts by weight: 10,000 parts of resin, 15 parts of co-crosslinking agent, 5 parts of antioxidant, 5 parts of ultraviolet light absorber, 5 parts of light stabilizer, and 10 parts of lubricant;

[0130] Among them, the resin is ethylene-vinyl acetate; the co-crosslinking agent is trimethylolpropane triacrylate; the antioxidant is a compound of B225 and DLTP in a weight ratio of 5:1; the ultraviolet light absorber is 2-hydroxy-4-n-octyloxybenzophenone; the light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate; the lubricant is a silicone masterbatch.

[0131] Example 3

[0132] A resin composition comprising the following components in parts by weight: 10,000 parts of resin, 7.5 parts of co-crosslinking agent, 2.5 parts of antioxidant, 2.6 parts of ultraviolet light absorber, 2.5 parts of light stabilizer, and 5 parts of lubricant.

[0133] Among them, the resin is polypropylene; the co-crosslinking agent is triallyl isocyanurate; the antioxidant is a compound of B225 and DLTP in a weight ratio of 3:1; the ultraviolet light absorber is 2-hydroxy-4-n-octyloxybenzophenone; the light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate; the lubricant is a silicone masterbatch.

[0134] Example 4

[0135] A resin composition comprising the following components in parts by weight: 10,000 parts of resin, 8 parts of co-crosslinking agent, 3 parts of antioxidant, 1 part of ultraviolet light absorber, 2 parts of light stabilizer, and 4 parts of lubricant.

[0136] Among them, the resin is POE; the co-crosslinking agent is triallyl isocyanurate; the antioxidant is a compound of B225 and DLTP in a weight ratio of 4:1; the ultraviolet light absorber is 2-hydroxy-4-n-octyloxybenzophenone; the light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate; the lubricant is a silicone masterbatch.

[0137] The resin compositions of Examples 1 to 4 were respectively prepared into resin materials according to conventional methods, and the resin materials were subjected to ultraviolet light aging tests and constant temperature and humidity aging tests.

[0138] The resins of Examples 1 to 4 were subjected to an ultraviolet light aging test of 200 kwh / m 2 (UV200), and the yellowing index was measured. An aging test of 500 h (DH500) was carried out at a constant temperature of 85 °C and a constant humidity of 85% RH, and its mechanical properties were measured.

[0139] Among them, the outermost layer of the conventional fluorine-free backplane is not irradiated, the yellowing index △b after UV200 is >5, and the tensile strength after DH500 is <5 MPa.

[0140] Table 1. Test results of the resin material properties of Examples 1 to 4

[0141]

[0142] Example 5

[0143] A polyester composition comprising the following components in parts by weight: 10,000 parts of a polyester compound, 0.1 part of a hydrolysis-resistant agent, and 0.1 part of an antioxidant; wherein, the polyester compound is PET, the hydrolysis-resistant agent is carbodiimide, and the antioxidant is 4,4'-bis(α,α-dimethylbenzyl) diphenylamine.

[0144] Example 6

[0145] A polyester composition comprising the following components in parts by weight: 10,000 parts of a polyester compound, 0.1 part of a hydrolysis-resistant agent, and 0.1 part of an antioxidant; wherein, the polyester compound is PET, the hydrolysis-resistant agent is carbodiimide; the antioxidant is 4,4'-bis(α,α-dimethylbenzyl) diphenylamine.

[0146] Example 7

[0147] A polyester composition comprising the following components in parts by weight: 10,000 parts of a polyester compound, 2.5 parts of a hydrolysis-resistant agent, and 5 parts of an antioxidant; wherein, the polyester compound is PET, the hydrolysis-resistant agent carbon is carbodiimide; the antioxidant is 4,4'-bis(α,α-dimethylbenzyl) diphenylamine.

[0148] Example 8

[0149] A polyester composition comprising the following components in parts by weight: 10,000 parts of a polyester compound, 4 parts of a hydrolysis-resistant agent, and 6 parts of an antioxidant; wherein, the polyester compound is PET, the hydrolysis-resistant agent is carbodiimide; the antioxidant is 4,4'-bis(α,α-dimethylbenzyl) diphenylamine.

[0150] The polyester compositions of Examples 5 to 8 were respectively prepared into polyester materials according to the conventional method, and the hydrolysis resistance performance of the polyester materials was tested. The constant temperature was set at 85 °C and the constant humidity was 100% RH for 96 h, and their mechanical properties were tested.

[0151] Among them, the outermost layer of the conventional fluorine-free backplane is not irradiated, and the tensile strength after 96 h of hydrolysis resistance test is <5 MPa.

[0152] Table 2. Test results of the polyester material properties of Examples 5 to 8

[0153]

[0154] Example 9

[0155] An adhesive composition comprising the following components in parts by weight: 10,000 parts of an adhesive and 1 part of a curing agent; wherein, the adhesive is polyurethane adhesive du294b and the curing agent is HB175MP / X of BASF.

[0156] Example 10

[0157] An adhesive composition comprising the following components in parts by weight: 10,000 parts of an adhesive and 20 parts of a curing agent; wherein, the adhesive is polyurethane adhesive du294b and the curing agent is N75.

[0158] Example 11

[0159] An adhesive composition comprising the following components in parts by weight: 10,000 parts of an adhesive and 10 parts of a curing agent; wherein, the adhesive is polyurethane adhesive du294b; the curing agent is HB175MP / X of BASF.

[0160] Example 12

[0161] An adhesive composition comprising the following components in parts by weight: 10,000 parts of an adhesive and 15 parts of a curing agent; wherein, the adhesive is polyurethane adhesive du294b; the curing agent is N75.

[0162] The adhesive compositions of Examples 9 to 12 were respectively prepared into adhesive materials according to conventional methods, and the adhesive properties of the adhesive materials were tested. The peel strength between the polyester layer and the resin layer was tested, and the test standard referred to GB-T2790-1995 Test Method for 180° Peel Strength of Adhesives.

[0163] Among them, the outermost layer of the conventional fluorine-free backsheet was not irradiated, and the peel strength between the outer layer and the intermediate layer was < 40 N / cm.

[0164] Table 3. Test Results of the Performance of the Adhesive Materials of Examples 9 to 12

[0165]

[0166] Example 13

[0167] A coating composition comprising the following components in parts by weight: 100 parts of a polyacrylate polymer and 0.1 part of a curing agent; wherein, the polyacrylate polymer is polymethyl acrylate, and the polar group contained therein is an amino group; the number-average molecular weight of the polymer is Mn, wherein, Mn satisfies: 500 ≤ Mn ≤ 2000, and the curing agent is p-hydroxybenzenesulfonic acid.

[0168] Example 14

[0169] A coating composition comprising the following components in parts by weight: 100 parts of a polyacrylate polymer and 10 parts of a curing agent; wherein, the polyacrylate polymer is a polyacrylic acid phosphate, and the polar group contained therein is a sulfhydryl group; the number average molecular weight of the polymer is Mn, wherein, Mn satisfies: 500 ≤ Mn ≤ 2000, and the curing agent is p-hydroxybenzenesulfonic acid.

[0170] Example 15

[0171] A coating composition comprising the following components in parts by weight: 100 parts of a polyacrylate polymer and 6 parts of a curing agent; wherein, the polyacrylate polymer is a mixture of poly(methyl acrylate) and polyacrylic acid phosphate in equal weights, and the polar group contained therein is a hydroxyl group; the number average molecular weight of the polyacrylate polymer is Mn, wherein, Mn satisfies: 500 ≤ Mn ≤ 2000, and the curing agent is tetra(isopropoxy)titanium.

[0172] Example 16

[0173] A coating composition comprising the following components in parts by weight: 100 parts of a polyacrylate polymer and 3 parts of a curing agent; wherein, the polyacrylate polymer is a polyacrylic acid phosphate, and the polar groups contained therein are a hydroxyl group and a carboxyl group; the number average molecular weight of the polyacrylate polymer is Mn, wherein, Mn satisfies: 500 ≤ Mn ≤ 2000, and the curing agent is tetra(isopropoxy)titanium.

[0174] The coating compositions of Examples 13 to 16 were respectively prepared into coatings according to a conventional method, and the adhesion performance of the coatings was tested. The peel strength between the polyester layer (including the coating layer) and the adhesive film layer was tested, and the test standard referred to GB-T 2790-1995 Adhesives - 180° Peel Strength Test Method.

[0175] Among them, the peel strength between the innermost layer of the conventional fluorine-free backsheet and the adhesive film layer < 130 N / cm.

[0176] Table 4. Test Results of the Coating Properties of Examples 13 to 16

[0177]

[0178] Example 17

[0179] A backsheet 100 comprising: a polyester layer 1; a weather-resistant layer 2 provided on one side of the polyester layer 1 in the thickness direction; and a fluorine-free coating 3 provided on the other side of the polyester layer 1 in the thickness direction.

[0180] The polyester layer 1 comprises the polyester composition of Example 5; the weather-resistant layer 2 comprises the resin composition of Example 1; and the fluorine-free coating 3 comprises the coating composition of Example 13.

[0181] Among them, the weather-resistant layer 2 is subjected to pre-crosslinking treatment, and the pre-crosslinking treatment includes the following steps: melting and casting the resin composition into a film through a screw extruder and then forming it through a crosslinking reaction; the method of the crosslinking reaction is electron beam crosslinking.

[0182] The thickness of the polyester layer 1 is d 1 , where d 1 = 100 μm; the thickness of the weather-resistant layer 2 is d 2 , where d 2 = 10 μm; the thickness of the fluorine-free coating 3 is d 3 , where d 3 satisfies = 1 μm.

[0183] Example 17-1

[0184] A backplane 100 includes: a polyester layer 1; a weather-resistant layer 2, and the weather-resistant layer 2 is provided on one side in the thickness direction of the polyester layer 1; a fluorine-free coating 3, and the fluorine-free coating 3 is provided on the other side in the thickness direction of the polyester layer 1.

[0185] The polyester layer 1 includes the polyester composition of Example 6; the weather-resistant layer 2 includes the resin composition of Example 1; the fluorine-free coating 3 includes the coating composition of Example 14.

[0186] Among them, the weather-resistant layer 2 is subjected to pre-crosslinking treatment, and the pre-crosslinking treatment includes the following steps: melting and casting the resin composition into a film through a screw extruder and then forming it through a crosslinking reaction, and the pre-crosslinking degree of the weather-resistant layer 2 is 70%; the method of the crosslinking reaction is electron beam crosslinking.

[0187] The thickness of the polyester layer 1 is d 1 , where d 1 = 300 μm; the thickness of the weather-resistant layer 2 is d 2 , where d 2 = 20 μm; the thickness of the fluorine-free coating 3 is d 3 , where d 3 satisfies = 20 μm.

[0188] Example 17-2

[0189] Example 17-2 is basically the same as Example 17-1, and the difference lies in that the pre-crosslinking degree of the weather-resistant layer 2 is 20%.

[0190] Example 17-3

[0191] Example 17-3 is basically the same as Example 17-1, and the difference lies in that the pre-crosslinking degree of the weather-resistant layer 2 is 95%.

[0192] Example 18

[0193] A backplane 100, comprising: a polyester layer 1; a weather-resistant layer 2 provided on one side of the polyester layer 1 in the thickness direction; and a fluorine-free coating 3 provided on the other side of the polyester layer 1 in the thickness direction.

[0194] The polyester layer 1 comprises the polyester composition of Example 6; the weather-resistant layer 2 comprises the resin composition of Example 2; and the fluorine-free coating 3 comprises the coating composition of Example 14.

[0195] Wherein, the thickness of the polyester layer 1 is d 1 , wherein, d 1 = 500 μm; the thickness of the weather-resistant layer 2 is d 2 , wherein, d 2 = 50 μm; the thickness of the fluorine-free coating 3 is d 3 , wherein, d 3 = 50 μm.

[0196] Example 19

[0197] A backplane 100, comprising: a polyester layer 1; a weather-resistant layer 2 provided on one side of the polyester layer 1 in the thickness direction; and a fluorine-free coating 3 provided on the other side of the polyester layer 1 in the thickness direction. The polyester layer 1 comprises the polyester composition of Example 7; the weather-resistant layer 2 comprises the resin composition of Example 3; and the fluorine-free coating 3 comprises the coating composition of Example 15.

[0198] Wherein, the thickness of the polyester layer 1 is d 1 , wherein, d 1 = 300 μm; the thickness of the weather-resistant layer 2 is d 2 , wherein, d 2 = 30 μm; the thickness of the fluorine-free coating 3 is d 3 , wherein, d 3 = 25 μm.

[0199] Example 20

[0200] A backplane 100, comprising: a polyester layer 1; a weather-resistant layer 2 provided on one side of the polyester layer 1 in the thickness direction; and a fluorine-free coating 3 provided on the other side of the polyester layer 1 in the thickness direction. The polyester layer 1 comprises the polyester composition of Example 8; the weather-resistant layer 2 comprises the resin composition of Example 4; and the fluorine-free coating 3 comprises the coating composition of Example 16.

[0201] Wherein, the thickness of the polyester layer 1 is d 1 , wherein, d 1 = 200 μm. The thickness of the weather-resistant layer 2 is d 2 , wherein, d 2 = 20 μm; the thickness of the fluorine-free coating 3 is d 3 , wherein, d3 = 30 μm.

[0202] Example 21

[0203] Example 21 is substantially the same as Example 17, except that the backsheet 100 further includes: an adhesive layer 4, which is provided between the weather-resistant layer 2 and the polyester layer 1. The adhesive layer 4 includes the adhesive composition of Example 9.

[0204] Wherein, the thickness of the adhesive layer 4 is d 4 , wherein, d 4 = 5 μm.

[0205] Example 22

[0206] Example 22 is substantially the same as Example 18, except that the backsheet 100 further includes: an adhesive layer 4, which is provided between the weather-resistant layer 2 and the polyester layer 1. The adhesive layer 4 includes the adhesive composition of Example 10.

[0207] Wherein, the thickness of the adhesive layer 4 is d 4 , wherein, d 4 = 20 μm.

[0208] Example 23

[0209] Example 23 is substantially the same as Example 19, except that the backsheet 100 further includes: an adhesive layer 4, which is provided between the weather-resistant layer 2 and the polyester layer 1. The adhesive layer 4 includes the adhesive composition of Example 11.

[0210] Wherein, the thickness of the adhesive layer 4 is d 4 , wherein, d 4 = 12 μm.

[0211] Example 24

[0212] Example 24 is substantially the same as Example 20, except that the backsheet 100 further includes: an adhesive layer 4, which is provided between the weather-resistant layer 2 and the polyester layer 1. The adhesive layer 4 includes the adhesive composition of Example 12.

[0213] Wherein, the thickness of the adhesive layer 4 is d 4 , wherein, d 4 = 18 μm.

[0214] Example 25

[0215] A forming method of a backplane, in which the bonding between the polyester layer 1 and the weather-resistant layer 2, and between the polyester layer 1 and the fluorine-free coating 3 is achieved by bonding; the bonding method between the weather-resistant layer 2 and the polyester layer 1 is through double-layer co-extrusion by a cast film extrusion unit to obtain a double-layer co-extruded film. Among them, the materials of the weather-resistant layer 2 and the polyester layer 1 are in a molten state, and the two melts are tightly bonded into a film at the die head, and then the exposed side of the outer layer of the double-layer co-extruded film is crosslinked and cured.

[0216] In the double-layer co-extrusion, the process parameters of the two extruders of the cast film unit are different. The main machine temperature for extruding the material of the weather-resistant layer 2 is 140, and the main machine temperature for extruding the material of the polyester layer 1 is 220.

[0217] Example 26

[0218] A forming method of a backplane, in which the bonding between the polyester layer 1 and the weather-resistant layer 2, and between the polyester layer 1 and the fluorine-free coating 3 is achieved by bonding;

[0219] The bonding method between the weather-resistant layer 2 and the polyester layer 1 is through double-layer co-extrusion by a cast film extrusion unit to obtain a double-layer co-extruded film. Among them, the materials of the weather-resistant layer 2 and the polyester layer 1 are in a molten state, and the two melts are tightly bonded into a film at the die head, and then the exposed side of the outer layer of the double-layer co-extruded film is crosslinked and cured.

[0220] In the double-layer co-extrusion, the process parameters of the two extruders of the cast film unit are different. The main machine temperature for extruding the material of the weather-resistant layer 2 is 200 °C, and the main machine temperature for extruding the material of the polyester layer 1 is 270 °C.

[0221] Example 27

[0222] A forming method of a backplane, in which the bonding between the polyester layer 1 and the weather-resistant layer 2, and between the polyester layer 1 and the fluorine-free coating 3 is achieved by bonding;

[0223] The bonding method between the weather-resistant layer 2 and the polyester layer 1 is through double-layer co-extrusion by a cast film extrusion unit to obtain a double-layer co-extruded film. Among them, the materials of the weather-resistant layer 2 and the polyester layer 1 are in a molten state, and the two melts are tightly bonded into a film at the die head, and then the exposed side of the outer layer of the double-layer co-extruded film is crosslinked and cured.

[0224] In the double-layer co-extrusion, the process parameters of the two extruders of the cast film unit are different. The main machine temperature for extruding the material of the weather-resistant layer 2 is 170 °C, and the main machine temperature for extruding the material of the polyester layer 1 is 250 °C.

[0225] Example 28

[0226] A forming method of a backplane, in which the bonding between the polyester layer 1 and the weather-resistant layer 2, and between the polyester layer 1 and the fluorine-free coating 3 is achieved by bonding;

[0227] The bonding method between the weather-resistant layer 2 and the polyester layer 1 is to cast the weather-resistant layer 2 into a film, and after electron beam cross-linking, it is then cured and bonded to the polyester layer 1 through the adhesive layer 4.

[0228] The weather-resistant layer 2 and the polyester layer 1 are bonded through the adhesive layer 4, including the following steps:

[0229] 1) Add the corresponding weight portion of the curing agent to the adhesive composition of the adhesive layer 4 in the polyurethane type and mix evenly;

[0230] 2) Uniformly coat the evenly mixed adhesive on the surface of the weather-resistant layer 2;

[0231] 3) Tightly press it against one side of the polyester layer 1 through traction;

[0232] 4) Feed the pressed product into an oven for curing and heat setting.

[0233] Example 29

[0234] A forming method of a backplane, in which the bonding between the polyester layer 1 and the weather-resistant layer 2 and between the polyester layer 1 and the fluorine-free coating 3 is by bonding and forming;

[0235] The bonding method between the weather-resistant layer 2 and the polyester layer 1 is to cast the weather-resistant layer 2 into a film, and after ultraviolet light cross-linking, it is then cured and bonded to the polyester layer 1 through the adhesive layer 4.

[0236] The weather-resistant layer 2 and the polyester layer 1 are bonded through the adhesive layer 4, including the following steps:

[0237] 1) Add the corresponding weight portion of the curing agent to the adhesive composition of the adhesive layer 4 in the polyurethane type and mix evenly;

[0238] 2) Uniformly coat the evenly mixed adhesive on the surface of the weather-resistant layer 2;

[0239] 3) Tightly press it against one side of the polyester layer 1 through traction;

[0240] 4) Cure and heat set the pressed product.

[0241] Example 30

[0242] A forming method of a backplane, in which the bonding between the polyester layer 1 and the weather-resistant layer 2 and between the polyester layer 1 and the fluorine-free coating 3 is by bonding and forming;

[0243] The bonding method between the weather-resistant layer 2 and the polyester layer 1 is to cast the weather-resistant layer 2 into a film, and after silane cross-linking, it is then cured and bonded to the polyester layer 1 through the adhesive layer 4.

[0244] The weather-resistant layer 2 and the polyester layer 1 are bonded through the adhesive layer 4, including the following steps:

[0245] 1) Add the corresponding parts by weight of the curing agent in the adhesive composition of the adhesive layer 4 to the polyurethane and mix evenly;

[0246] 2) Evenly coat the evenly mixed adhesive on the surface of the weather-resistant layer 2;

[0247] 3) Tightly press it against one side of the polyester layer 1 through traction;

[0248] 4) Cure and heat-set the pressed product.

[0249] Comparative Example 1

[0250] Conventional fluorine backsheet

[0251] Comparative Example 2

[0252] Conventional fluorine-free EVA backsheet

[0253] Comparative Example 3

[0254] Conventional fluorine-free PPC structure backsheet

[0255] Comparative Example 4

[0256] Comparative Example 4 is basically the same as Example 17, the difference is that the weather-resistant layer 2 is not pre-crosslinked.

[0257] Comparative Example 5

[0258] Comparative Example 5 is basically the same as Example 18, the difference is that in the coating composition of Example 14, the number-average molecular weight of the polyacrylate polymer is Mn, where Mn = 200.

[0259] Performance test and test method:

[0260] The backsheets of Examples 17-24 and the backsheets and adhesive films obtained in Comparative Examples 1-5 were laminated and cured to make photovoltaic modules for reliability tests.

[0261] The test method refers to the international standard IEC 61215. The content of the reliability test includes the power loss of the module after 200 kwh under ultraviolet light (UV200), the power loss of the module after the wet-freeze test of the module (HF10), the power loss of the module after 2000 h of the damp-heat test of the module (DH2000), and the power loss of the module after the thermal cycle test of the module (TC200). The test results are shown in Table 5 below.

[0262] Table 5. Power attenuation test results of reliability tests:

[0263]

[0264] As can be seen from Table 5, by optimizing the composition materials of each layer and the unique production and preparation process, the backsheets provided in Specific Embodiments 17-24 of the present invention have excellent weather resistance, and after reliability testing, the power attenuation of the components is <1%. Specifically, the results of various reliability tests of the backsheets provided in Embodiments 17-24 show that they are all below 1%. Among them, the attenuation in the DH2000 test is below 0.91%, the attenuation in the UV200 test is below 0.87%, the attenuation in the TC200 test is below 0.99%, and the attenuation in the HF10 test is below 0.94%. Moreover, as a preferred embodiment of the present application, the attenuation in the DH2000 test of Embodiment 21 is 0.32%, the attenuation in the UV200 test of Embodiment 24 is 0.26%, the attenuation in the TC200 test of Embodiment 22 is 0.34%, and the attenuation in the HF10 test of Embodiment 17 is 0.35%. It can be seen that the differences in the components in the material composition can significantly affect the performance of the backsheet.

[0265] At the same time, it can be seen from the data in the table that the performance of the backsheets provided in Specific Embodiments 17-24 of the present invention is significantly better than that of the backsheets provided in Comparative Examples 1-5. The specific analysis is as follows: First, by comparing the embodiments with Comparative Examples 1-3, it can be seen that the parameters of the weather resistance performance of the backsheets provided in the embodiments of the present application are better than those of the conventional fluorine backsheet of Comparative Example 1, the conventional fluorine-free EVA backsheet of Comparative Example 2, and the conventional fluorine-free PPC structure backsheet of Comparative Example 3. Secondly, by comparing Comparative Example 4 with Embodiment 17, since the pre-crosslinking treatment is not carried out, it directly affects the performance of the weather-resistant layer, thereby increasing the attenuation amplitude of the performance of each test in the reliability test. Thirdly, by comparing Comparative Example 4 with Embodiment 18, changing the number-average molecular weight of the polyacrylate polymer in the coating composition directly affects the performance of the fluorine-free coating, thereby increasing the attenuation amplitude of the performance of each test in the reliability test.

[0266] Furthermore, by comparing the performance test data of the backsheets of Embodiment 17-1, Embodiment 17-2, and Embodiment 17-3, it can be seen that the pre-crosslinking degree of the weather-resistant layer 2 affects the performance of the backsheet.

[0267] In the description of this specification, the descriptions with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example.

[0268] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and purposes of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A backplane, characterized in that, it comprises: a polyester layer; a weather-resistant layer, the weather-resistant layer is provided on one side in the thickness direction of the polyester layer, the weather-resistant layer is pre-crosslinked, and the pre-crosslinking degree of the weather-resistant layer is 50% - 90%. The weather-resistant layer comprises a resin composition, and the resin composition comprises the following components in parts by weight: 10000 parts of resin, 0.5 - 15 parts of co-crosslinking agent, 0.1 - 5 parts of antioxidant, 0.1 - 5 parts of ultraviolet light absorber, 0.1 - 5 parts of light stabilizer, and 0.1 - 10 parts of lubricant. The resin is one or more mixtures of polyethylene, ethylene-vinyl acetate, and POE. The co-crosslinking agent is an organic compound with free radical polymerization properties and containing multiple double bonds; an adhesive layer, the adhesive layer is provided between the weather-resistant layer and the polyester layer; a fluorine-free coating, the fluorine-free coating is provided on the other side in the thickness direction of the polyester layer, and the fluorine-free coating comprises a coating composition, which comprises the following components in parts by weight: 100 parts of polyacrylate polymer and 0.1 - 10 parts of curing agent. The number average molecular weight of the polyacrylate polymer is Mn, and wherein, Mn satisfies: 500 ≤ Mn ≤ 2000; wherein, the pre-crosslinking treatment comprises the following steps: melting and casting the resin composition into a film through a screw extruder and then forming it through a crosslinking reaction.

2. The backplane according to claim 1, characterized in that, the pre-crosslinking degree of the weather-resistant layer is 70% - 80%.

3. The backplane according to claim 1, characterized in that, the co-crosslinking agent is one or more mixtures of triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethylene glycol diacrylate, and ethylene glycol dimethacrylate.

4. The backplane according to claim 3, characterized in that, the co-crosslinking agent is triallyl isocyanurate.

5. The backplane according to claim 1, characterized in that, the antioxidant is a compound of B225 and DLTP, and the weight ratio of the compound of B225 and DLTP is 2:1 - 5:

1.

6. The backplane according to claim 1, characterized in that, the ultraviolet light absorber is 2-hydroxy-4-n-octyloxybenzophenone.

7. The backplane according to claim 1, characterized in that, the light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate.

8. The backplane according to claim 1, characterized in that, the lubricant is a silicone masterbatch.

9. The backplane according to claim 1, characterized in that, the polyester layer comprises a polyester composition, and the polyester composition comprises the following components in parts by weight: 10000 parts of polyester compound, 0.1 - 5 parts of hydrolysis-resistant agent, and 0.1 - 10 parts of antioxidant.

10. The backplane according to claim 9, characterized in that, the hydrolysis-resistant agent is carbodiimide.

11. The backplane according to claim 9, characterized in that, the antioxidant is a high-temperature antioxidant resistant to 150°C.

12. The backplane according to claim 11, It is characterized in that the antioxidant is an aniline antioxidant.

13. The backsheet according to claim 12, it is characterized in that The aniline antioxidant is 4,4 ＇ -bis(α,α-dimethylbenzyl) diphenylamine.

14. The backsheet according to claim 1, it is characterized in that the adhesive layer comprises an adhesive composition, and the adhesive composition comprises the following components in parts by weight: 10,000 parts of an adhesive and 1 to 20 parts of a curing agent.

15. The backsheet according to claim 14, it is characterized in that the adhesive is a polyurethane adhesive.

16. The backsheet according to claim 15, it is characterized in that the adhesive is a waterborne polyurethane.

17. The backsheet according to claim 14, it is characterized in that the curing agent is a yellowing-resistant curing agent.

18. The backsheet according to claim 17, it is characterized in that the curing agent is a high light and weather resistance aliphatic polyisocyanate.

19. The backsheet according to claim 1, it is characterized in that the polyacrylate polymer is a compound containing acrylate groups and double bonds.

20. The backsheet according to claim 1, it is characterized in that the polyacrylate polymer is an acrylate polymer containing polar groups.

21. The backsheet according to claim 20, it is characterized in that the polar group is one or more of amino group, sulfhydryl group, phosphino group, hydroxyl group, carboxyl group, epoxy group.

22. The backsheet according to claim 1, it is characterized in that the fluorine-free coating is obtained by coating, drying and curing through an on-line coating process.

23. The backsheet according to claim 1, it is characterized in that the pre-crosslinking method includes any one of electron beam crosslinking, ultraviolet crosslinking and silane crosslinking.

24. The backsheet according to claim 23, it is characterized in that the pre-crosslinking method is electron beam crosslinking.

25. The backsheet according to claim 1, it is characterized in that The thickness of the adhesive layer is d 4 , where the d 4 satisfies: 5μm ≤ d 4 ≤ 20μm.

26. The backsheet according to claim 1, it is characterized in that The thickness of the polyester layer is d 1 , wherein the d 1 satisfies: 100 μm ≤ d 1 ≤ 500 μm.

27. The backsheet according to claim 1, it is characterized in that The thickness of the weather-resistant layer is d ２ , where the d ２ satisfies: 10 μm ≤ d 2 ≤ 50 μm.

28. The backsheet according to claim 1, it is characterized in that The thickness of the fluorine-free coating is d ３ , where the d ３ satisfies: 1 μm ≤ d 3 ≤ 50 μm.

29. A forming method of the backsheet according to any one of claims 15-18, it is characterized in that the polyester layer and the weather-resistant layer are bonded, and the polyester layer and the fluorine-free coating are bonded.

30. The forming method according to claim 29, it is characterized in that the bonding method between the weather-resistant layer and the polyester layer is to cast the weather-resistant layer into a film, after crosslinking, and then cure and bond with the polyester layer through an adhesive layer.

31. The forming method according to claim 30, it is characterized in that the bonding of the weather-resistant layer and the polyester layer through the adhesive layer comprises the following steps: 1) adding the curing agent in the above-mentioned parts by weight to the polyurethane adhesive and mixing evenly; 2) evenly coating the evenly mixed adhesive on the surface of the weather-resistant layer; 3) tightly pressing through traction with one side of the polyester layer; 4) curing and heat setting the pressed product.

32. A photovoltaic module, it is characterized in that comprising: the backsheet according to any one of claims 1-28.

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