A transparent front plate, a preparation method thereof, and a photovoltaic module

Abstract

The present invention discloses a transparent front plate, a preparation method thereof, and a photovoltaic module. The method includes the following steps: S1. Placing the dried PMMA, methyl vinyl silicone rubber, modified glass fiber, halogen-free flame retardant, crosslinking promoter, antioxidant, and anti-ultraviolet auxiliary agent in a mixer, mixing evenly, and then performing single-screw extrusion granulation to obtain a special PMMA halogen-free flame retardant material; S2. Placing the special PMMA halogen-free flame retardant material obtained in S1 in an extrusion casting machine for casting and forming to obtain a halogen-free flame retardant photovoltaic substrate; S3. Placing the halogen-free flame retardant photovoltaic substrate obtained in S2 under an electron accelerator for irradiation crosslinking to obtain a halogen-free flame retardant transparent front plate. Compared with the traditional technology, the present invention does not use halogen-containing flame retardants, and the smoke and toxicity generated during the combustion process are very small, which can reduce environmental pollution and harm to the human body; in addition, the preparation process of the present invention is simple, the cost is low, it can be mass-produced on a large scale, and it can be widely applied to the field of building-integrated photovoltaics.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic modules, and particularly relates to a transparent front plate, a preparation method thereof, and a photovoltaic module. Background Art

[0002] Polymethyl methacrylate (PMMA) is widely used due to its good optical and mechanical properties and is usually used as a substitute for glass. However, PMMA is flammable, and flame retardant modification is required for its application in the field of building integrated photovoltaics. Currently, most commercial flame retardant PMMAs are halogen flame retardant systems, which will generate halogenated hydrocarbon gases during the combustion process, causing harm to the environment and human body. Therefore, the development of halogen-free flame retardant PMMA is urgent. However, there are very few halogen-free flame retardants suitable for PMMA, and the addition of most halogen-free flame retardants will inevitably affect the optical transparency of PMMA. Therefore, the development of highly transparent halogen-free flame retardant PMMA is imperative.

[0003] Ceramicizable silicone rubber is a new type of fireproof material. During the combustion process, it will form a dense and hard ceramic crust, which can prevent the further spread of the flame and achieve the effect of flame retardant and fire prevention. It is widely used in the field of wire and cable. However, its application in the field of photovoltaic backplane is still in its infancy. Summary of the Invention

[0004] Object of the Invention: Aiming at the problems and deficiencies in the prior art, a preparation method of a transparent front plate is provided according to the present invention.

[0005] Due to its excellent physical and chemical properties, good processability and low cost, methyl vinyl silicone rubber has become a common matrix for ceramicizable silicone rubber. Moreover, methyl vinyl silicone rubber is a transparent silicone rubber, and its introduction into the PMMA matrix will not damage the optical properties. The addition of glass fiber will promote the formation of its ceramic crust. Cooperating with a transparent phosphorus-based flame retardant can achieve a good flame retardant effect. Therefore, it is imperative to add an appropriate amount of methyl vinyl silicone rubber to the glass fiber-reinforced PMMA system and select a suitable transparent phosphorus-based flame retardant for the preparation of a halogen-free flame retardant transparent front plate.

[0006] The method of the present application includes the following steps:

[0007] S1. Place the dried PMMA, methyl vinyl silicone rubber, modified glass fiber, halogen-free flame retardant, crosslinking promoter, antioxidant and ultraviolet resistance aid in a mixer and mix evenly, then extrude and pelletize with a single-screw extruder to obtain a special halogen-free flame retardant material for PMMA;

[0008] S2. Place the special halogen-free flame retardant material for PMMA obtained in S1 in an extrusion casting machine for casting and forming to obtain a halogen-free flame retardant photovoltaic substrate;

[0009] S3. Place the halogen-free flame-retardant photovoltaic substrate obtained in S2 under an electron accelerator for radiation crosslinking to obtain a halogen-free flame-retardant transparent front plate.

[0010] Further, the mass ratio range of PMMA: methyl vinyl silicone rubber: modified glass fiber in S1 is as follows: 30-40: 1-5: 10-20.

[0011] Further, the halogen-free flame retardant in S1 includes any one or a combination of more than one of the following: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, resorcinol bis(diphenyl phosphate), hexaphenoxycyclotriphosphazene, resorcinol bis[bis(2,6-dimethylphenyl) phosphate], and the addition ratio is 15-20 wt% of PMMA.

[0012] Further, it is characterized in that the crosslinking promoter includes any one or a combination of more than one of the following: trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and the addition ratio of the crosslinking promoter is 0.2 wt% - 10 wt% of PMMA.

[0013] Further, the antioxidant includes any one or a combination of more than one of the following: the antioxidant includes any one of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite, dilauryl thiodipropionate, N,N'-bis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl] hydrazine, n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and the addition ratio is 0.1 wt% - 3 wt% of PMMA.

[0014] Further, the UV-resistant auxiliary includes any one or an arbitrary combination of more than one of the following: bisphenol A disalicylate, cyanuric chloride polymer, p-tert-octylphenyl salicylate, bis(2,2,6,6-tetramethylpiperidinyl) sebacate, 2-(2'-hydroxy-5'-methylphenyl) benzotriazole, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and the addition ratio is 0.1 wt% - 2 wt% of PMMA.

[0015] Further, the temperature of the internal mixer in S1 is 185-195 °C, the mixing time is 20-25 min, and the temperature of single-screw extrusion granulation is 190-210 °C;

[0016] The temperature of the extrusion casting machine in S3 is 231-250 °C.

[0017] Further, the modified glass fiber in S2 is glass fiber treated with a silane coupling agent, and the silane coupling agent includes any one or a mixture of several of the following: γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloxypropyl.

[0018] Further, the dose of electron beam irradiation in S4 is 100-150 kGy, and the irradiation atmosphere includes: nitrogen, vacuum, air atmosphere.

[0019] On the other hand, the present invention provides a transparent front plate. Further, the transparent front plate is prepared by using the above preparation method.

[0020] On the other hand, the present invention provides a photovoltaic module, which is characterized by comprising a halogen-free flame-retardant transparent front plate, a first POE layer, a solar cell, a second POE layer, and a halogen-free flame-retardant photovoltaic back plate prepared by using the preparation method according to any one of claims 1-7.

[0021] Beneficial effects:

[0022] In the present invention, vinyl methyl silicone rubber which can be ceramized is introduced into the PMMA matrix. During the high-temperature burning process, it can form a hard ceramic-like shell to prevent the further spread of the flame. Moreover, the introduction of glass fiber can promote the formation of the ceramic hard shell of vinyl methyl silicone rubber, and when combined with a colorless and transparent phosphorus-based flame retardant, it can achieve a good flame retardant effect. Compared with the traditional technology, the present invention does not use halogen flame retardants, and the smoke and toxicity generated during the combustion process are very small, which can reduce environmental pollution and harm to the human body; in addition, the preparation process of the present invention is simple, the cost is low, it can be mass-produced on a large scale, and it can be widely applied to the field of building-integrated photovoltaics. Description of the drawings

[0023] Figure 1 It is a schematic diagram of a preparation method of a transparent photovoltaic front plate in an embodiment provided by the present invention. Detailed implementation manners

[0024] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to embodiments.

[0025] As Figure 1 shown, the method of this embodiment includes the following steps:

[0026] S1. Place the dried PMMA, vinyl methyl silicone rubber, modified glass fiber, halogen-free flame retardant, crosslinking promoter, antioxidant and ultraviolet-resistant auxiliary agent in a mixer and mix them evenly, and then granulate them by single-screw extrusion to obtain a special PMMA halogen-free flame-retardant material;

[0027] S2. Place the PMMA halogen-free flame retardant special material obtained in S1 into an extrusion casting machine for casting and forming to obtain a halogen-free flame retardant photovoltaic substrate;

[0028] S3. Place the halogen-free flame retardant photovoltaic substrate obtained in S2 under an electron accelerator for radiation crosslinking to obtain a halogen-free flame retardant transparent front plate.

[0029] Further, the mass ratio range of PMMA: methyl vinyl silicone rubber: modified glass fiber in S1 is as follows: 30-40: 1-5: 10-20.

[0030] Preferably, 30-40 parts of polymethyl methacrylate (PMMA), 10-20 parts of glass fiber, 15-20 parts of halogen-free flame retardant, 1-5 parts of methyl vinyl silicone rubber, 5-10 parts of crosslinking promoter, and 1-5 parts of antioxidant and ultraviolet resistant auxiliary.

[0031] Further, the halogen-free flame retardant in S1 includes any one or a combination of the following: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, resorcinol bis(diphenyl phosphate), hexaphenoxycyclotriphosphazene, resorcinol bis[di(2,6-dimethylphenyl) phosphate], and the addition ratio is 15-20 wt% of PMMA.

[0032] Further, the crosslinking promoter includes any one or a combination of the following: trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and the addition ratio of the crosslinking promoter is 0.2 wt% - 10 wt% of PMMA;

[0033] Further, the antioxidant includes any one or a combination of the following: the antioxidant includes any one of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite, dilauryl thiodipropionate, N,N'-bis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl] hydrazine, n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and the addition ratio is 0.1 wt% - 3 wt% of PMMA.

[0034] Further, the ultraviolet resistant auxiliary includes any one or a combination of the following: bis(4-hydroxyphenyl) methane disalicylate, cyanuric chloride polymer, p-tert-octylphenyl salicylate, bis(2,2,6,6-tetramethylpiperidyl) sebacate, 2-(2'-hydroxy-5'-methylphenyl) benzotriazole, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and the addition ratio is 0.1 wt% - 2 wt% of PMMA.

[0035] Further, in S1, the temperature of the internal mixer is 185 - 195°C, the mixing time is 20 - 25 min, and the temperature of single-screw extrusion granulation is 190 - 210°C;

[0036] In S3, the temperature of the extrusion casting machine is 231 - 250°C.

[0037] Further, the modified glass fiber in S2 is glass fiber treated with a silane coupling agent, and the silane coupling agent includes any one or a mixture of the following: γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloxypropyl.

[0038] Further, in S4, the dose of electron beam irradiation is 100 - 150 kGy, and the irradiation atmosphere includes: nitrogen, vacuum, air atmosphere.

[0039] On the other hand, the present invention provides a transparent front plate. Further, the transparent front plate is prepared by using the above preparation method.

[0040] On the other hand, the present invention provides a photovoltaic module, which is characterized by comprising a halogen-free flame-retardant transparent front plate, a first POE layer, a solar cell, a second POE layer, and a halogen-free flame-retardant photovoltaic backplane prepared by using the preparation method according to any one of claims 1 - 7.

[0041] It should be noted that the production method of the halogen-free flame-retardant photovoltaic backplane can be the same as that of the front plate.

[0042] Beneficial effects:

[0043] In the present invention, by introducing ceramicizable silicone rubber methyl vinyl silicone rubber into the PMMA matrix, a hard ceramic-like hard shell can be formed during the high-temperature burning process to prevent the further spread of the flame. Moreover, the introduction of glass fiber can promote the formation of the ceramicized hard shell of methyl vinyl silicone rubber, and when combined with a colorless and transparent phosphorus-based flame retardant, it can achieve a good flame retardant effect. Compared with the traditional technology, the present invention does not use halogen flame retardants, and the smoke and toxicity generated during combustion are very small, which can reduce environmental pollution and harm to the human body; in addition, the preparation process of the present invention is simple, the cost is low, it can be mass-produced on a large scale, and it can be widely applied to the field of building-integrated photovoltaics.

[0044] In order to make the purpose, technical solution and advantages of the present invention clearer, the following examples are used to further illustrate the present invention in detail.

[0045] Example 1:

[0046] A transparent front plate is prepared as follows:

[0047] (1) Mix the dried polymethyl methacrylate resin (PMMA), methyl vinyl silicone rubber, glass fiber modified with γ-(2,3-epoxypropoxy) propyltrimethoxysilane coupling agent, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), trimethylolpropane trimethacrylate, pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) in a mixer until evenly mixed, and then granulate by single-screw extrusion to obtain a special halogen-free flame-retardant material for PMMA; the mass ratio of polymethyl methacrylate: methyl vinyl silicone rubber: modified glass fiber is 40:5:20, and trimethylolpropane trimethacrylate is 10 wt% of the PMMA resin; the addition ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is 20 wt% of the PMMA resin; pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-hydroxy-4-methoxybenzophenone and bis(2,2,6,6-tetramethylpiperidinol) sebacate are 0.2 wt%, 0.2 wt% and 0.3 wt% of polymethyl methacrylate (PMMA) respectively. The temperature of the mixer is 190 °C, the mixing time is 25 min, and the temperature of the single-screw extrusion granulation is 190 - 210 °C.

[0048] (2) Place the special halogen-free flame-retardant material for PMMA obtained in step (1) in an extrusion casting machine for casting and molding to obtain a halogen-free flame-retardant photovoltaic substrate. The temperature of the extrusion casting machine is 231 - 250 °C;

[0049] (3) Place the halogen-free flame-retardant photovoltaic substrate obtained in step (3) under an electron accelerator for irradiation. The irradiation dose is 150 kGy, and the irradiation atmosphere is nitrogen.

[0050] Example 2:

[0051] A transparent front plate is prepared as follows:

[0052] (1) After drying polymethyl methacrylate resin (PMMA), methyl vinyl silicone rubber, glass fiber modified with γ-aminopropyltriethoxysilane coupling agent, resorcinol bis(diphenyl phosphate) (RDP), trimethylolpropane triacrylate, pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) are placed in a mixer and mixed evenly, and then granulated by single-screw extrusion to obtain a special halogen-free flame-retardant material for PMMA; the mass ratio of polymethyl methacrylate: methyl vinyl silicone rubber: modified glass fiber is 35:5:15, and trimethylolpropane triacrylate is 5 wt% of the PMMA resin; the addition ratio of resorcinol bis(diphenyl phosphate) (RDP) is 20 wt% of the PMMA resin; tris(2,4-di-tert-butylphenyl) phosphite, 2-hydroxy-4-octyloxybenzophenone and bis(2,2,6,6-tetramethylpiperidinol) sebacate are 0.1 wt%, 0.1 wt% and 0.3 wt% of polymethyl methacrylate (PMMA) respectively, the mixing temperature is 185 °C, the mixing time is 30 min, and the temperature for single-screw extrusion granulation is 190-210 °C.

[0053] (2) The special halogen-free flame-retardant material for PMMA obtained in step (1) is placed in an extrusion casting machine for casting molding to obtain a halogen-free flame-retardant photovoltaic substrate, and the temperature of the extrusion casting machine is 231-250 °C;

[0054] (3) The halogen-free flame-retardant photovoltaic substrate obtained in step (3) is irradiated under an electron accelerator, the irradiation dose is 100 kGy, and the irradiation atmosphere is air.

[0055] Example 3:

[0056] A transparent front plate is prepared as follows:

[0057] (1) After drying polymethyl methacrylate resin (PMMA), methyl vinyl silicone rubber, glass fiber modified with γ-(2,3-epoxypropoxy) propyltrimethoxysilane coupling agent, hexaphenoxycyclotriphosphazene (HPCTP), trimethylolpropane trimethacrylate, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl), they are mixed evenly in a mixer and then granulated by single-screw extrusion to obtain a special PMMA halogen-free flame retardant material; wherein the mass ratio of polymethyl methacrylate: methyl vinyl silicone rubber: modified glass fiber is 40:5:20, and trimethylolpropane trimethacrylate is 8 wt% of the PMMA resin; the addition ratio of hexaphenoxycyclotriphosphazene (HPCTP) is 20 wt% of the PMMA resin; octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2-hydroxy-4-octyloxybenzophenone and bisphenol A disalicylate are 1.5 wt%, 1.5 wt% and 2 wt% of polymethyl methacrylate (PMMA) respectively, the temperature of mixing is 190 °C, the mixing time is 25 min, and the temperature of single-screw extrusion granulation is 190-210 °C.

[0058] (2) The special PMMA halogen-free flame retardant material obtained in step (1) is cast and formed in an extrusion casting machine to obtain a halogen-free flame retardant photovoltaic substrate, and the temperature of the extrusion casting machine is 231-250 °C;

[0059] (3) The halogen-free flame retardant photovoltaic substrate obtained in step (3) is irradiated under an electron accelerator, the irradiation dose is 150 kGy, and the irradiation atmosphere is nitrogen.

[0060] Example 4:

[0061] A transparent front plate is prepared as follows:

[0062] (1) The dried polymethyl methacrylate resin (PMMA), methyl vinyl silicone rubber, glass fibers modified with γ-methacryloxypropylsilane coupling agent, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), trimethylolpropane trimethacrylate, pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-hydroxy-4-octyloxybenzophenone, and 2-(2'-hydroxy-5'-methylphenyl)benzotriazole sebacate are placed in a mixer and mixed evenly, and then granulated by single-screw extrusion to obtain a special PMMA halogen-free flame retardant material; the mass ratio of polymethyl methacrylate: methyl vinyl silicone rubber: modified glass fibers is 40:5:20, and trimethylolpropane trimethacrylate is 10 wt% of the PMMA resin; the addition ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is 20 wt% of the PMMA resin; pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-hydroxy-4-octyloxybenzophenone, and 2-(2'-hydroxy-5'-methylphenyl)benzotriazole sebacate are 2 wt%, 2 wt%, and 3 wt% of polymethyl methacrylate (PMMA) respectively. The temperature of mixing is 190 °C, the mixing time is 20 min, and the temperature of single-screw extrusion granulation is 190 - 210 °C.

[0063] (2) The special PMMA halogen-free flame retardant material obtained in step (1) is placed in an extrusion casting machine for casting molding to obtain a halogen-free flame retardant photovoltaic substrate, and the temperature of the extrusion casting machine is 231 - 250 °C;

[0064] (3) The halogen-free flame retardant photovoltaic substrate obtained in step (3) is irradiated under an electron accelerator, the irradiation dose is 125 kGy, and the irradiation atmosphere is nitrogen.

[0065] Example 5:

[0066] A transparent front plate is prepared as follows:

[0067] (1) After drying polymethyl methacrylate resin (PMMA), methyl vinyl silicone rubber, glass fiber modified by γ-(2,3-epoxypropoxy) propyltrimethoxysilane coupling agent, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), hexaphenoxycyclophosphazene (HPCTP), trimethylolpropane trimethacrylate, pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2-hydroxy-4-octyloxybenzophenone and p-tert-octylphenyl salicylate are placed in a mixer and mixed evenly, and then granulated by single-screw extrusion to obtain a special halogen-free flame retardant material for PMMA; the mass ratio of polymethyl methacrylate: methyl vinyl silicone rubber: modified glass fiber is 40:5:20, and trimethylolpropane trimethacrylate is 10 wt% of PMMA resin; the addition ratios of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and hexaphenoxycyclophosphazene (HPCTP) are 10 wt% and 10 wt% of PMMA resin respectively; pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2-hydroxy-4-octyloxybenzophenone and p-tert-octylphenyl salicylate are 2 wt%, 2 wt% and 3 wt% of polymethyl methacrylate (PMMA) respectively, the temperature of mixing is 195 °C, the mixing time is 25 min, and the temperature of single-screw extrusion granulation is 190-210 °C.

[0068] (2) The special halogen-free flame retardant material for PMMA obtained in step (1) is placed in an extrusion casting machine for casting molding to obtain a halogen-free flame retardant photovoltaic substrate, and the temperature of the extrusion casting machine is 231-250 °C;

[0069] (3) The halogen-free flame retardant photovoltaic substrate obtained in step (3) is irradiated under an electron accelerator, the irradiation dose is 150 kGy, and the irradiation atmosphere is nitrogen.

[0070] Example 6:

[0071] A transparent front plate is prepared as follows:

[0072] (1) The dried polymethyl methacrylate resin (PMMA), methyl vinyl silicone rubber, glass fibers modified with γ-(2,3-epoxypropoxy) propyltrimethoxysilane coupling agent, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), resorcinol bis(diphenyl phosphate) (RDP), trimethylolpropane trimethacrylate, pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-hydroxy-4-octyloxybenzophenone, and 2-(2'-hydroxy-5'-methylphenyl)benzotriazole are placed in a mixer and mixed evenly, and then granulated by single-screw extrusion to obtain a special halogen-free flame-retardant material for PMMA; the mass ratio of polymethyl methacrylate: methyl vinyl silicone rubber: modified glass fibers is 40:5:20, and trimethylolpropane trimethacrylate is 10 wt% of the PMMA resin; the addition ratios of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and resorcinol bis(diphenyl phosphate) (RDP) are 15 wt% and 5 wt% of the PMMA resin, respectively; pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-hydroxy-4-octyloxybenzophenone, and 2-(2'-hydroxy-5'-methylphenyl)benzotriazole are 2 wt%, 2 wt%, and 3 wt% of polymethyl methacrylate (PMMA), respectively. The temperature of mixing is 190 °C, the mixing time is 25 min, and the temperature of single-screw extrusion granulation is 190 - 210 °C.

[0073] (2) The special halogen-free flame-retardant material for PMMA obtained in step (1) is placed in an extrusion casting machine for casting molding to obtain a halogen-free flame-retardant photovoltaic substrate. The temperature of the extrusion casting machine is 231 - 250 °C;

[0074] (3) The halogen-free flame-retardant photovoltaic substrate obtained in step (3) is irradiated under an electron accelerator. The irradiation dose is 150 kGy, and the irradiation atmosphere is air.

[0075] Comparative Example 1 is a conventional PVDF / PET / FFC front plate purchased on the market.

[0076] The test standards for the adhesion to EVA and the vertical burning experiment of the examples and comparative examples are as follows:

[0077] Adhesion to EVA: The test method is the peel strength test. Use a knife to cut a 1 cm wide strip through the backplane and EVA, and ensure that it is cut through. Use a tensile testing machine to pull the peeling layer at a speed of 100 mm / min in the 180° direction. Take points when the material is peeled evenly, and take the minimum value. It is determined that the peel strength between EVA and the backplane is 40 N / cm as qualified.

[0078] Vertical burning test: Samples with a thickness of 125 ± 5 mm × 13.0 ± 0.5 mm × 0.5 mm were prepared using a rectangular cutter and tested according to the UL-94:2017 standard using a vertical burning test machine. Record the afterflame time t after the first departure from the flame 1 and the afterflame time t after the second departure from the flame 2 as well as the afterglow burning time t 3 . Each group of samples includes at least 5 samples and is judged according to the UL-94 flame rating criterion. It should be noted that ±5 mm means the error is not greater than 5 mm.

[0079] Front panel light transmittance test: The test was carried out with reference to the IEC-62805-2 test standard.

[0080] The test results of the adhesion force between the front panel of the solar cell and EVA, light transmittance, and UL-94 vertical burning test are shown in Table 1:

[0081] Table 1

[0082]

[0083] It can be seen from Table 1 that the front panels of the solar cells prepared in the examples all passed the UL-94 standard, had good adhesion to the EVA film, and had a light transmittance ≥ 85%.

[0084] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a transparent front plate, characterized in that: The following steps are involved: S1, placing the dried PMMA, methyl vinyl silicone rubber, modified glass fiber, halogen-free flame retardant, cross-linking accelerator, antioxidant and anti-ultraviolet additive in an internal mixer, mixing them evenly, and then extruding and granulating them by single screw extruder to obtain PMMA halogen-free flame retardant special material; S2, placing the PMMA halogen-free flame-retardant special material obtained in S1 in an extrusion casting machine for casting to obtain a halogen-free flame-retardant photovoltaic substrate; S3, placing the halogen-free flame-retardant photovoltaic substrate obtained in S2 under an electron accelerator for irradiation cross-linking to obtain a halogen-free flame-retardant transparent front plate; The mass ratio of PMMA: methyl vinyl silicone rubber: modified glass fiber in S1 is as follows: 30-40: 1-5: 10-20; The halogen-free flame retardant in S1 includes any one or more of the following combinations: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, resorcinol bis(diphenyl phosphate), hexaphenoxy cyclophosphazene, resorcinol bis[di(2,6-dimethylphenyl) phosphate], and the addition ratio of the halogen-free flame retardant is 15-20wt% of PMMA.

2. The method for preparing a transparent front plate according to claim 1, characterized in that: The cross-linking accelerator comprises any one or more of the following combinations: trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and the cross-linking accelerator is added in an amount of 0.2wt% to 10wt% of PMMA; The antioxidant comprises any one or more of the following combinations: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(2,4-di-tert-butylphenyl) phosphite, dilauryl thiodipropionate, N,N'-bis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, and n-octadecanol β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. The antioxidant is added in an amount of 0.1wt% to 3wt% of PMMA.

3. The method for preparing a transparent front plate according to claim 1, characterized in that: The anti-ultraviolet auxiliary agent includes any one or more of the following in any combination: bisphenol A disalicylate, p-tert-octylphenyl salicylate, bis-2,2,6,6-tetramethylpiperidinol sebacate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and the addition ratio of the anti-ultraviolet auxiliary agent is 0.1wt% to 2wt% of PMMA.

4. The method for preparing a transparent front plate according to claim 1, characterized in that: The temperature of the internal mixer in S1 is 185-195°C, the internal mixing time is 20-25 min, the temperature of the single screw extrusion granulation is 190-210°C; the temperature of the extrusion casting machine in S3 is 231-250°C.

5. The method for preparing a halogen-free flame-retardant transparent front plate according to claim 1, characterized in that: The modified glass fiber in S2 is a glass fiber treated with a silane coupling agent, and the silane coupling agent includes any one or a mixture of the following: γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropyloxy)propyltrimethoxysilane.

6. The method for preparing a halogen-free flame-retardant transparent front plate according to claim 1, characterized in that: The dose of electron beam irradiation in S4 is 100-150 kGy, and the irradiation atmosphere includes: nitrogen, vacuum, and air atmosphere.

7. A transparent front plate, characterized in that: The transparent front plate is prepared by using the preparation method described in any one of claims 1 to 6.

8. A photovoltaic module, characterized in that: The photovoltaic module comprises, in order along the light incident direction, a transparent front plate prepared by the preparation method according to any one of claims 1 to 6, a first POE layer, a solar cell sheet, a second POE layer, and a halogen-free flame-retardant photovoltaic back plate.

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