Halogen-free flame-retardant photovoltaic backsheet and preparation method thereof, and photovoltaic module

Abstract

The present invention relates to a halogen-free flame-retardant photovoltaic backboard and a preparation method thereof, and a photovoltaic module. The backboard includes a halogen-free flame-retardant glass fiber reinforced ethylene-vinyl alcohol copolymer (EVOH) layer located in an inner layer and a halogen-free flame-retardant polypropylene layer located outside the EVOH layer. The present invention introduces a halogen-free flame retardant aluminum diethylphosphinate into a weather-resistant layer polypropylene and an inner layer glass fiber reinforced ethylene-vinyl alcohol copolymer matrix, which produces an expanded carbon layer during combustion, achieving the effects of heat insulation, oxygen isolation, and preventing further diffusion of surface flames. The combination with aluminum hydroxide can effectively improve the flame retardant properties of plastic sheets. The present invention abandons the traditional glue bonding method and adopts double-layer co-extrusion to prepare photovoltaic substrates. The halogen-free flame-retardant photovoltaic backboard prepared by the present invention does not use halogen flame retardants. When the material is burned, it produces less smoke and toxicity, which can reduce pollution to the environment and harm to the human body, and can be widely used in photovoltaic building integration and other fields.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic modules, and in particular relates to a halogen-free flame-retardant photovoltaic back panel and a preparation method thereof, and a photovoltaic module. Background Art

[0002] Photovoltaic building integration is a new concept of solar power generation, which is to install photovoltaic modules on the surface of buildings to provide electricity. As a photovoltaic product used in the construction field, the flame retardant and fireproof performance of photovoltaic modules should reach C grade. The flame retardant function of traditional photovoltaic backsheets is mostly achieved by setting a flame retardant fluorine film on its outer surface. However, fluorine-containing backsheets will produce toxic and harmful halogenated hydrocarbons during combustion, causing serious pollution to the environment and adverse effects on human health. Therefore, it is imperative to develop halogen-free flame retardant photovoltaic backsheets.

[0003] Aluminum diethylphosphinate is a halogen-free, green and environmentally friendly flame retardant based on diethylphosphinate. It produces an expanded carbon layer during the combustion process, which achieves the effect of heat insulation, oxygen isolation, and preventing the further spread of surface flames. It can effectively improve the flame retardant properties of plastic sheets when combined with aluminum hydroxide. As an efficient, green and environmentally friendly halogen-free flame retardant, aluminum diethylphosphinate is widely used in the flame retardancy of thermoplastics, fibers and textiles, such as wires and cables, but it is still in the development stage in the field of photovoltaic backplanes. Electron beam irradiation is a simple and clean post-processing technology. Electron beam irradiation can modify the material by cross-linking or degrading the responsive substances. Cross-linking modification of photovoltaic backplanes by electron beam irradiation can further improve the weather resistance of photovoltaic backplanes. However, the application of electron beam irradiation post-processing technology in photovoltaic backplanes is relatively rare. Therefore, it is imperative to introduce the efficient halogen-free flame retardant aluminum diethylphosphinate in the field of photovoltaic backplanes and use electron beam irradiation post-processing technology to cross-link and modify it to prepare halogen-free flame-retardant photovoltaic backplanes. Summary of the invention

[0004] Purpose of the invention: In view of the problems and shortcomings in the prior art, the present invention provides a method for preparing a halogen-free flame-retardant photovoltaic backsheet, comprising the following steps:

[0005] S1, placing the dried polypropylene resin and polypropylene graft, 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 extrusion to obtain polypropylene halogen-free flame retardant special material;

[0006] S2, placing the dried EVOH, cross-linking accelerator, modified glass fiber, halogen-free flame retardant, antioxidant and anti-ultraviolet additive in an internal mixer, mixing them evenly, and then extruding and granulating them into EVOH halogen-free flame retardant special material by single screw extrusion;

[0007] S3, placing the polypropylene halogen-free flame-retardant special material obtained in S1 and the EVOH halogen-free flame-retardant special material obtained in S2 in a double-layer co-extrusion casting machine for casting to obtain a halogen-free flame-retardant photovoltaic substrate;

[0008] S4. The halogen-free flame-retardant photovoltaic substrate obtained in S3 is placed under an electron accelerator for irradiation cross-linking to obtain a halogen-free flame-retardant photovoltaic backplane.

[0009] Furthermore, the polypropylene grafted material in S1 includes any one of the following: polypropylene grafted maleic anhydride, polypropylene grafted glycidyl methacrylate, and the addition ratio is 5-10wt% of the polypropylene resin.

[0010] Furthermore, the halogen-free flame retardants in S1 and S2 include: diethyl aluminum phosphinate and aluminum hydroxide; wherein the addition ratio of diethyl aluminum phosphinate in S1 and S2 is 10-20wt% of the polypropylene and ethylene-vinyl alcohol copolymer resin, respectively, and the addition ratio of aluminum hydroxide in S1 and S2 is 10-20wt% of the polypropylene and ethylene-vinyl alcohol copolymer resin, respectively.

[0011] Further, the cross-linking accelerator comprises: trimethylolpropane trimethacrylate, and the addition ratio of the cross-linking accelerator in S1 and S2 is 2wt% to 10wt% of the polypropylene resin and EVOH respectively;

[0012] The antioxidant includes any one of the following: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate or tris(2,4-di-tert-butylphenyl) phosphite, and the antioxidant addition ratio in S1 and S2 is 0.1wt% to 0.5wt% of the polypropylene resin and EVOH respectively;

[0013] The anti-ultraviolet additive is any one or more of any combination: 2-hydroxy-4-octyloxybenzophenone, (2,2,6,6-tetramethylpiperidinyl) sebacate, and the anti-ultraviolet additives in S1 and S2 are added in an amount of 0.1wt% to 0.3wt% of the polypropylene resin and EVOH, respectively.

[0014] Furthermore, the temperature of the internal mixer in S1 is 180°C, the internal mixing time is 30 min, and the temperature of the single screw extrusion granulation is 180-200°C;

[0015] The mixing temperature in S2 is 200°C, the mixing time is 30 min, and the temperature of single screw extrusion granulation is 220-230°C;

[0016] The temperature of the double-layer co-extrusion casting extruder in S3 is 210-230°C.

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

[0018] Furthermore, the inner layer of the halogen-free flame-retardant photovoltaic backsheet is ethylene-vinyl alcohol copolymer with a thickness of 290um to 310um, and the outer layer of the halogen-free flame-retardant photovoltaic backsheet is modified polypropylene with a thickness of 190 to 210um.

[0019] Furthermore, the dose of the electron beam irradiation in S4 is 100-150 kGy, and the irradiation atmosphere includes: nitrogen, vacuum or air atmosphere.

[0020] On the other hand, the present invention provides a halogen-free flame-retardant photovoltaic backsheet. Furthermore, the halogen-free flame-retardant photovoltaic backsheet is prepared using the above-mentioned preparation method.

[0021] On the other hand, the present invention provides a photovoltaic module, characterized in that the photovoltaic module includes a transparent front panel, a first POE layer, a solar cell, a second POE layer, and a halogen-free flame-retardant photovoltaic back panel prepared by the above preparation method in sequence along the light incident direction.

[0022] Beneficial effects:

[0023] The present invention introduces a halogen-free flame retardant aluminum diethylphosphinate into the weather-resistant layer polypropylene and the inner layer glass fiber reinforced ethylene-vinyl alcohol copolymer matrix. The aluminum diethylphosphinate produces an expanded carbon layer during the combustion process, achieving the effects of heat insulation, oxygen isolation, and preventing the further spread of surface flames. It can effectively improve the flame retardant properties of plastic sheets when used in combination with aluminum hydroxide. In order to improve the weather resistance of photovoltaic backboards, the present invention abandons the traditional glue bonding method, adopts double-layer co-extrusion to prepare photovoltaic substrates, and adopts electron beam irradiation cross-linking to further improve its weather resistance. Because the halogen-free flame retardant photovoltaic backboard prepared by the present invention does not use halogen flame retardants, the material produces less smoke and toxicity when burned, which can reduce pollution to the environment and harm to the human body, and can be widely used in photovoltaic building integration and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a method for preparing a halogen-free flame-retardant photovoltaic backsheet in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments.

[0026] The present invention provides a method for preparing a halogen-free flame-retardant photovoltaic backsheet, comprising the following steps:

[0027] S1, placing the dried polypropylene resin and polypropylene graft, 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 extrusion to obtain polypropylene halogen-free flame retardant special material;

[0028] S2, placing the dried EVOH, cross-linking accelerator, modified glass fiber, halogen-free flame retardant, antioxidant and anti-ultraviolet additive in an internal mixer, mixing them evenly, and then extruding and granulating them into EVOH halogen-free flame retardant special material by single screw extrusion;

[0029] S3, placing the polypropylene halogen-free flame-retardant special material obtained in S1 and the EVOH halogen-free flame-retardant special material obtained in S2 in a double-layer co-extrusion casting machine for casting to obtain a halogen-free flame-retardant photovoltaic substrate;

[0030] S4. The halogen-free flame-retardant photovoltaic substrate obtained in S3 is placed under an electron accelerator for irradiation cross-linking to obtain a halogen-free flame-retardant photovoltaic backplane.

[0031] Furthermore, the halogen-free flame retardants in S1 and S2 include: diethyl aluminum phosphinate and aluminum hydroxide; wherein the addition ratio of diethyl aluminum phosphinate in S1 and S2 is 10-20wt% of the polypropylene and ethylene-vinyl alcohol copolymer resin, respectively, and the addition ratio of aluminum hydroxide in S1 and S2 is 10-20wt% of the polypropylene and ethylene-vinyl alcohol copolymer resin, respectively.

[0032] Further, the cross-linking accelerator comprises: trimethylolpropane trimethacrylate, and the addition ratio of the cross-linking accelerator in S1 and S2 is 2wt% to 10wt% of the polypropylene resin and EVOH respectively;

[0033] The antioxidant includes any one of the following: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate or tris(2,4-di-tert-butylphenyl) phosphite, and the antioxidant addition ratio in S1 and S2 is 0.1wt% to 0.5wt% of the polypropylene resin and EVOH respectively;

[0034] The anti-ultraviolet additive is any one or more of any combination: 2-hydroxy-4-octyloxybenzophenone, (2,2,6,6-tetramethylpiperidinyl) sebacate, and the anti-ultraviolet additives in S1 and S2 are added in an amount of 0.1wt% to 0.3wt% of the polypropylene resin and EVOH, respectively.

[0035] Furthermore, the temperature of the internal mixer in S1 is 180°C, the internal mixing time is 30 min, and the temperature of the single screw extrusion granulation is 180-200°C;

[0036] The mixing temperature in S2 is 200°C, the mixing time is 30 min, and the temperature of single screw extrusion granulation is 220-230°C;

[0037] The temperature of the double-layer co-extrusion casting extruder in S3 is 210-230°C.

[0038] Furthermore, the modified glass fiber in S2 is a glass fiber treated with a silane coupling agent, and the silane coupling agent is any one or a mixture of the following: γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and γ-methacryloxypropyl.

[0039] Furthermore, the inner layer of the halogen-free flame-retardant photovoltaic backsheet is ethylene-vinyl alcohol copolymer with a thickness of 290um to 310um, and the outer layer of the halogen-free flame-retardant photovoltaic backsheet is modified polypropylene with a thickness of 190 to 210um.

[0040] Furthermore, the dose of the electron beam irradiation in S4 is 100-150 kGy, and the irradiation atmosphere includes: nitrogen, vacuum or air atmosphere.

[0041] On the other hand, the present invention provides a halogen-free flame-retardant photovoltaic backsheet. Furthermore, the halogen-free flame-retardant photovoltaic backsheet is prepared using the above-mentioned preparation method.

[0042] On the other hand, the present invention provides a photovoltaic module, characterized in that the photovoltaic module includes a transparent front panel, a first POE layer, a solar cell, a second POE layer, and a halogen-free flame-retardant photovoltaic back panel prepared by the above preparation method in sequence along the light incident direction.

[0043] Beneficial effects:

[0044] The present invention introduces a halogen-free flame retardant aluminum diethylphosphinate into the weather-resistant layer polypropylene and the inner layer glass fiber reinforced ethylene-vinyl alcohol copolymer matrix. The aluminum diethylphosphinate produces an expanded carbon layer during the combustion process, achieving the effects of heat insulation, oxygen isolation, and preventing the further spread of surface flames. It can effectively improve the flame retardant properties of plastic sheets when used in combination with aluminum hydroxide. In order to improve the weather resistance of photovoltaic backboards, the present invention abandons the traditional glue bonding method, adopts double-layer co-extrusion to prepare photovoltaic substrates, and adopts electron beam irradiation cross-linking to further improve its weather resistance. Because the halogen-free flame retardant photovoltaic backboard prepared by the present invention does not use halogen flame retardants, the material produces less smoke and toxicity when burned, which can reduce pollution to the environment and harm to the human body, and can be widely used in photovoltaic building integration and other fields.

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments.

[0046] Embodiment 1:

[0047] A halogen-free flame-retardant photovoltaic backsheet is prepared by the following steps:

[0048] (1) Drying polypropylene (PP), polypropylene grafted maleic anhydride resin, aluminum diethylphosphinate, aluminum hydroxide, trimethylolpropane trimethacrylate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are placed in an internal mixer and mixed evenly, and then single-screw extrusion granulation is performed to obtain PP halogen-free flame retardant special material; wherein the amount of polypropylene grafted maleic anhydride added is 10wt% of the polypropylene resin; trimethylolpropane trimethacrylate is polypropylene; The addition ratio of aluminum diethylphosphinate and aluminum hydroxide is 20wt% and 15wt% of the polypropylene resin respectively; pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are 0.2wt%, 0.2wt% and 0.3wt% of the total mass of polypropylene and polypropylene grafted maleic anhydride resin respectively, the banburying temperature is 180°C, the banburying time is 30min, and the temperature of single-screw extrusion granulation is 180-200°C.

[0049] (2) Dry ethylene-vinyl alcohol copolymer particles (EVOH), trimethylolpropane trimethacrylate, glass fiber modified by γ-aminopropyl triethoxysilane coupling agent, aluminum diethylphosphinate, aluminum hydroxide, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are placed in an internal mixer and mixed uniformly, and single-screw extrusion granulation is performed to obtain EVOH halogen-free flame retardant special material; wherein the ratio of modified glass fiber to ethylene-vinyl alcohol copolymer is 30:70; trimethylolpropane trimethacrylate is 1:10; and the ratio of modified glass fiber to ethylene-vinyl alcohol copolymer is 30:70; and the ratio of modified glass fiber to ethylene-vinyl alcohol copolymer is 1:10. The addition ratios of alkyltrimethylpropylene, aluminum diethylphosphinate and aluminum hydroxide are 8wt%, 15wt% and 20wt% of the ethylene-vinyl alcohol copolymer particles, respectively; the addition ratios of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl)sebacate are 0.2wt%, 0.2wt% and 0.3wt% of the ethylene-vinyl alcohol copolymer, respectively; the banburying temperature is 200°C, the banburying time is 30min, and the temperature of single-screw extrusion granulation is 220-230°C;

[0050] (3) placing the PP halogen-free flame-retardant special material obtained in step (1) and the EVOH halogen-free flame-retardant special material obtained in step (2) in a double-layer co-extrusion casting machine for casting to obtain a halogen-free flame-retardant photovoltaic substrate, wherein the temperature of the double-layer co-extrusion casting extruder is 210-230° C.;

[0051] (4) placing the halogen-free flame-retardant photovoltaic substrate obtained in step (3) under an electron accelerator for irradiation, with an irradiation dose of 100 kGy and an irradiation atmosphere of air.

[0052] Embodiment 2:

[0053] A halogen-free flame-retardant photovoltaic backsheet is prepared by the following steps:

[0054] (1) Drying polypropylene (PP), polypropylene grafted maleic anhydride resin, aluminum diethylphosphinate, aluminum hydroxide, trimethylolpropane trimethacrylate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are placed in an internal mixer and mixed evenly, and then single-screw extrusion granulation is performed to obtain PP halogen-free flame retardant special material; wherein the amount of polypropylene grafted maleic anhydride added is 5wt% of the polypropylene resin; the amount of trimethylolpropane trimethacrylate added is 5wt% of the polypropylene resin; The addition ratios of aluminum diethylphosphinate and aluminum hydroxide are 20wt% and 20wt% of the polypropylene resin respectively; pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl)sebacate are 0.5wt%, 0.5wt% and 0.2wt% of the total mass of polypropylene and polypropylene grafted maleic anhydride resin respectively; the banburying temperature is 180°C, the banburying time is 30min, and the temperature of single-screw extrusion granulation is 180-200°C.

[0055] (2) Dry ethylene-vinyl alcohol copolymer particles (EVOH), trimethylolpropane trimethacrylate, glass fiber modified by γ-(2,3-epoxypropoxy)propyltrimethoxysilane coupling agent, aluminum diethylphosphinate, aluminum hydroxide, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are placed in an internal mixer and mixed evenly, and single-screw extrusion granulation is performed to obtain EVOH halogen-free flame retardant special material; wherein the ratio of modified glass fiber to ethylene-vinyl alcohol copolymer is 20:80; The addition ratios of hydroxymethylpropane trimethylpropylene, aluminum diethylphosphinate and aluminum hydroxide are 10wt%, 20wt% and 15wt% of the ethylene-vinyl alcohol copolymer particles, respectively; the addition ratios of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are 0.5wt%, 0.5wt% and 0.2wt% of the ethylene-vinyl alcohol copolymer, respectively; the banburying temperature is 200°C, the banburying time is 30min, and the temperature of single-screw extrusion granulation is 220-230°C;

[0056] (3) placing the PP halogen-free flame-retardant special material obtained in step (1) and the EVOH halogen-free flame-retardant special material obtained in step (2) in a double-layer co-extrusion casting machine for casting to obtain a halogen-free flame-retardant photovoltaic substrate, wherein the temperature of the double-layer co-extrusion casting extruder is 210-230° C.;

[0057] (4) The halogen-free flame-retardant photovoltaic substrate obtained in step (3) is placed under an electron accelerator for irradiation, the irradiation dose is 150 kGy, and the irradiation atmosphere is nitrogen.

[0058] Embodiment 3:

[0059] A halogen-free flame-retardant photovoltaic backsheet is prepared by the following steps:

[0060] (1) Drying polypropylene (PP), polypropylene grafted glycidyl methacrylate resin, aluminum diethylphosphinate, aluminum hydroxide, trimethylolpropane trimethacrylate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are placed in an internal mixer and mixed evenly, and then single-screw extrusion granulation is performed to obtain PP halogen-free flame retardant special material; wherein the addition amount of polypropylene grafted maleic anhydride is 10wt% of the polypropylene resin; the trimethylolpropane trimethacrylate is The invention discloses a method for preparing a polypropylene resin comprising: a polypropylene resin comprising: a polypropylene resin and a polypropylene grafted maleic anhydride resin; ...

[0061] (2) Dry ethylene-vinyl alcohol copolymer particles (EVOH), trimethylolpropane trimethacrylate, glass fiber modified by γ-methacryloxypropyl coupling agent, aluminum diethylphosphinate, aluminum hydroxide, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are placed in an internal mixer and mixed evenly, and single-screw extrusion granulation is performed to obtain EVOH halogen-free flame retardant special material; wherein the ratio of modified glass fiber to ethylene-vinyl alcohol copolymer is 30:70; trimethylolpropane trimethacrylate is 1:10; and the ratio of modified glass fiber to ethylene-vinyl alcohol copolymer is 30:70; aluminum hydroxide is 1:10; pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is 1:10. The addition ratios of alkyltrimethylpropylene, aluminum diethylphosphinate and aluminum hydroxide are 2wt%, 15wt% and 20wt% of the ethylene-vinyl alcohol copolymer particles, respectively; the addition ratios of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl)sebacate are 0.1wt%, 0.1wt% and 0.3wt% of the ethylene-vinyl alcohol copolymer, respectively; the banburying temperature is 200°C, the banburying time is 30min, and the temperature of single-screw extrusion granulation is 220-230°C;

[0062] (3) placing the PP halogen-free flame-retardant special material obtained in step (1) and the EVOH halogen-free flame-retardant special material obtained in step (2) in a double-layer co-extrusion casting machine for casting to obtain a halogen-free flame-retardant photovoltaic substrate, wherein the temperature of the double-layer co-extrusion casting extruder is 210-230° C.;

[0063] (4) placing the halogen-free flame-retardant photovoltaic substrate obtained in step (3) under an electron accelerator for irradiation, with an irradiation dose of 100 kGy and an irradiation atmosphere of vacuum.

[0064] Embodiment 4:

[0065] A halogen-free flame-retardant photovoltaic backsheet is prepared by the following steps:

[0066] (1) Drying polypropylene (PP), polypropylene grafted maleic anhydride resin, aluminum diethylphosphinate, aluminum hydroxide, trimethylolpropane trimethacrylate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are placed in an internal mixer and mixed evenly, and then single-screw extrusion granulation is performed to obtain PP halogen-free flame retardant special material; wherein the amount of polypropylene grafted maleic anhydride added is 10wt% of the polypropylene resin; trimethylolpropane trimethacrylate is polypropylene; The addition ratio of aluminum diethylphosphinate and aluminum hydroxide is 20wt% and 15wt% of the polypropylene resin respectively; pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are 0.2wt%, 0.2wt% and 0.3wt% of the total mass of polypropylene and polypropylene grafted maleic anhydride resin respectively, the mixing temperature is 180°C, the mixing time is 30min, and the temperature of single-screw extrusion granulation is 180-200°C.

[0067] (2) Dry ethylene-vinyl alcohol copolymer particles (EVOH), trimethylolpropane trimethacrylate, glass fiber modified by γ-aminopropyl triethoxysilane coupling agent, aluminum diethylphosphinate, aluminum hydroxide, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are placed in an internal mixer and mixed uniformly, and single-screw extrusion granulation is performed to obtain EVOH halogen-free flame retardant special material; wherein the ratio of modified glass fiber to ethylene-vinyl alcohol copolymer is 20:80; trimethylolpropane trimethacrylate is 20:80; The addition ratios of alkyltrimethylpropylene, aluminum diethylphosphinate and aluminum hydroxide are 6wt%, 15wt% and 15wt% of the ethylene-vinyl alcohol copolymer particles, respectively; the addition ratios of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl)sebacate are 0.2wt%, 0.2wt% and 0.3wt% of the ethylene-vinyl alcohol copolymer, respectively; the banburying temperature is 200°C, the banburying time is 30min, and the temperature of single-screw extrusion granulation is 220-230°C;

[0068] (3) placing the PP halogen-free flame-retardant special material obtained in step (1) and the EVOH halogen-free flame-retardant special material obtained in step (2) in a double-layer co-extrusion casting machine for casting to obtain a halogen-free flame-retardant photovoltaic substrate, wherein the temperature of the double-layer co-extrusion casting extruder is 210-230° C.;

[0069] (4) The halogen-free flame-retardant photovoltaic substrate obtained in step (3) is placed under an electron accelerator for irradiation, the irradiation dose is 125 kGy, and the irradiation atmosphere is air.

[0070] Embodiment 5:

[0071] A halogen-free flame-retardant photovoltaic backsheet is prepared by the following steps:

[0072] (1) Drying polypropylene (PP), polypropylene grafted glycidyl methacrylate resin, aluminum diethylphosphinate, aluminum hydroxide, trimethylolpropane trimethacrylate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are placed in an internal mixer and mixed evenly, and then single-screw extrusion granulation is performed to obtain PP halogen-free flame retardant special material; wherein the addition amount of polypropylene grafted glycidyl methacrylate is 10wt% of the polypropylene resin; trimethylolpropane trimethacrylate is 10wt% of the polypropylene resin; and The ester is 8wt% of the polypropylene resin; the addition ratio of aluminum diethylphosphinate and aluminum hydroxide is 20wt% and 15wt% of the polypropylene resin respectively; pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are 0.4wt%, 0.4wt% and 0.2wt% of the total mass of polypropylene and polypropylene grafted maleic anhydride resin respectively, the mixing temperature is 180°C, the mixing time is 30min, and the temperature of single-screw extrusion granulation is 180-200°C.

[0073] (2) Dry ethylene-vinyl alcohol copolymer particles (EVOH), trimethylolpropane trimethacrylate, glass fiber modified by γ-(2,3-epoxypropoxy)propyltrimethoxysilane coupling agent, aluminum diethylphosphinate, aluminum hydroxide, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are placed in an internal mixer and mixed evenly, and then single-screw extrusion granulation is performed to obtain EVOH halogen-free flame retardant special material; wherein the ratio of modified glass fiber to ethylene-vinyl alcohol copolymer is 20:80; The addition ratios of trimethylolpropane trimethylpropylene, aluminum diethylphosphinate and aluminum hydroxide are 8wt%, 15wt% and 20wt% of the ethylene-vinyl alcohol copolymer particles, respectively; the addition ratios of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are 0.4wt%, 0.4wt% and 0.2wt% of the ethylene-vinyl alcohol copolymer, respectively; the banburying temperature is 200°C, the banburying time is 30min, and the temperature of single-screw extrusion granulation is 220-230°C;

[0074] (3) placing the PP halogen-free flame-retardant special material obtained in step (1) and the EVOH halogen-free flame-retardant special material obtained in step (2) in a double-layer co-extrusion casting machine for casting to obtain a halogen-free flame-retardant photovoltaic substrate, wherein the temperature of the double-layer co-extrusion casting extruder is 210-230° C.;

[0075] (4) The halogen-free flame-retardant photovoltaic substrate obtained in step (3) is placed under an electron accelerator for irradiation, the irradiation dose is 150 kGy, and the irradiation atmosphere is nitrogen.

[0076] Embodiment 6:

[0077] A halogen-free flame-retardant photovoltaic backsheet is prepared by the following steps:

[0078] (1) Drying polypropylene (PP), polypropylene grafted maleic anhydride resin, aluminum diethylphosphinate, aluminum hydroxide, trimethylolpropane trimethacrylate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are placed in an internal mixer and mixed evenly, and then single-screw extrusion granulation is performed to obtain PP halogen-free flame retardant special material; wherein the addition amount of polypropylene grafted maleic anhydride is 6wt% of the polypropylene resin; trimethylolpropane trimethacrylate is the polypropylene resin; The addition ratios of aluminum diethylphosphinate and aluminum hydroxide are 20wt% and 20wt% of the polypropylene resin respectively; pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl)sebacate are 0.2wt%, 0.2wt% and 0.3wt% of the total mass of polypropylene and polypropylene grafted maleic anhydride resin respectively; the mixing temperature is 180°C, the mixing time is 30min, and the temperature of single-screw extrusion granulation is 180-200°C.

[0079] (2) Dry ethylene-vinyl alcohol copolymer particles (EVOH), trimethylolpropane trimethacrylate, glass fiber modified by γ-aminopropyl triethoxysilane coupling agent, aluminum diethylphosphinate, aluminum hydroxide, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are placed in an internal mixer and mixed evenly, and then single-screw extrusion granulation is performed to obtain EVOH halogen-free flame retardant special material; wherein the ratio of modified glass fiber to ethylene-vinyl alcohol copolymer is 30:70; trimethylolpropane trimethacrylate is 30:70; aluminum diethylphosphinate is 30:70; aluminum hydroxide is 30:70; tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is 2-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate ... The addition ratios of trimethylpropylene, aluminum diethylphosphinate and aluminum hydroxide are 0.5wt%, 15wt% and 20wt% of the ethylene-vinyl alcohol copolymer particles, respectively; the addition ratios of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-hydroxy-4-octyloxybenzophenone and (2,2,6,6-tetramethylpiperidinyl) sebacate are 0.2wt%, 0.2wt% and 0.3wt% of the ethylene-vinyl alcohol copolymer, respectively; the banburying temperature is 200°C, the banburying time is 30min, and the temperature of single-screw extrusion granulation is 220-230°C;

[0080] (3) placing the PP halogen-free flame-retardant special material obtained in step (1) and the EVOH halogen-free flame-retardant special material obtained in step (2) in a double-layer co-extrusion casting machine for casting to obtain a halogen-free flame-retardant photovoltaic substrate, wherein the temperature of the double-layer co-extrusion casting extruder is 210-230° C.;

[0081] (4) placing the halogen-free flame-retardant photovoltaic substrate obtained in step (3) under an electron accelerator for irradiation, with an irradiation dose of 150 kGy and an irradiation atmosphere of air.

[0082] The comparative example is a conventional PVDF / PET / PVDF backboard purchased on the market.

[0083] The examples and comparative examples were tested for adhesion to EVA and water vapor transmission rate performance. The test standards are as follows:

[0084] Adhesion with EVA: The test method is peel strength test. Use a knife to cut a 1cm wide strip between the back panel and the EVA, and make sure to cut through it. Use a tensile testing machine to pull the peeling layer in a 180° direction at a speed of 100mm / min. Take points when the material is peeled off at a uniform speed and take the minimum value. The peel strength between the EVA and the back panel is determined to be 40N / cm to be qualified.

[0085] Water vapor transmission rate test: According to GB / T 21529-2008 standard, the test was conducted using W3 / 330 water vapor transmission rate test system. The test area was 108 mm x 108 mm, the test temperature was 40°C, the test humidity was 90%, and three samples were tested for each halogen-free flame-retardant photovoltaic backsheet, and the average value was taken.

[0086] Vertical burning test: Use a rectangular cutter to prepare a sample with a thickness of 125±5mm×13.0±0.5mm×0.5mm, and use a vertical burning test machine to test according to the UL-94:2017 standard. Record the afterflame time t1 after leaving the flame for the first time, the afterflame time t2 after leaving the flame for the second time, and the afterflame time t3. Each group of samples includes at least 5 samples, and the samples are judged according to the UL-94 flame grade judgment standard.

[0087] The water vapor transmission rate test results of the halogen-free flame-retardant photovoltaic backsheet and the EVA adhesion test results are shown in Table 1:

[0088] Table 1

[0089]

[0090] It can be seen from Table 1 that the halogen-free flame-retardant photovoltaic backsheets prepared in the examples all pass the UL-94 standard, have a low water vapor permeability, and have good adhesion to the EVA film.

[0091] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a halogen-free flame-retardant photovoltaic backsheet, characterized in that: The following steps are involved: S1. The dried polypropylene resin and polypropylene graft, halogen-free flame retardant, cross-linking accelerator, antioxidant and anti-ultraviolet additive are placed in an internal mixer and mixed evenly, and then single-screw extrusion granulation is performed to obtain a polypropylene halogen-free flame retardant special material; the cross-linking accelerator comprises trimethylolpropane trimethacrylate, and the addition ratio of the cross-linking accelerator is 2wt% to 10wt% of the polypropylene resin; the halogen-free flame retardant comprises aluminum diethylphosphinate and aluminum hydroxide, wherein the addition ratio of aluminum diethylphosphinate is 10 to 20wt% of the polypropylene resin, and the addition ratio of aluminum hydroxide is 10 to 20wt% of the polypropylene resin; S2, placing dried EVOH, cross-linking accelerator, modified glass fiber, halogen-free flame retardant, antioxidant and anti-ultraviolet additive in an internal mixer, mixing them evenly, and extruding and granulating them by single screw to obtain EVOH halogen-free flame retardant special material; the cross-linking accelerator includes trimethylolpropane trimethacrylate, and the addition ratio of the cross-linking accelerator is 2wt% to 10wt% of the EVOH resin; the halogen-free flame retardant includes aluminum diethylphosphinate and aluminum hydroxide, wherein the addition ratio of aluminum diethylphosphinate is 10 to 20wt% of EVOH, and the addition ratio of aluminum hydroxide is 10 to 20wt% of EVOH; S3, placing the polypropylene halogen-free flame-retardant special material obtained in S1 and the EVOH halogen-free flame-retardant special material obtained in S2 in a double-layer co-extrusion casting machine for casting to obtain a halogen-free flame-retardant photovoltaic substrate; S4, placing the halogen-free flame-retardant photovoltaic substrate obtained in S3 under an electron accelerator for irradiation cross-linking to obtain a halogen-free flame-retardant photovoltaic backplane; the electron beam irradiation dose in S4 is 100 to 150 kGy, and the irradiation atmosphere includes: nitrogen, vacuum, and air atmosphere; The temperature of the internal mixer in S1 is 180°C, the internal mixing time is 30 min, and the temperature of the single screw extrusion granulation is 180-200°C; The mixing temperature in S2 is 200°C, the mixing time is 30 min, and the temperature of single screw extrusion granulation is 220-230°C; The temperature of the double-layer co-extrusion casting extruder in S3 is 210-230°C.

2. The method for preparing the halogen-free flame-retardant photovoltaic backsheet according to claim 1, characterized in that: The polypropylene grafted material in S1 includes any one of the following: polypropylene grafted maleic anhydride, polypropylene grafted glycidyl methacrylate, and the addition ratio is 5-10wt% of the polypropylene resin.

3. The method for preparing the halogen-free flame-retardant photovoltaic backsheet according to claim 1, characterized in that: The antioxidant includes any one of the following: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tris(2,4-di-tert-butylphenyl) phosphite, and the antioxidant addition ratio in S1 and S2 is 0.1wt% to 0.5wt% of the polypropylene resin and EVOH respectively; The anti-ultraviolet additive is any one or more of any combination: 2-hydroxy-4-octyloxybenzophenone, (2,2,6,6-tetramethylpiperidinyl) sebacate, and the anti-ultraviolet additives in S1 and S2 are added in an amount of 0.1wt% to 0.3wt% of the polypropylene resin and EVOH, respectively.

4. The method for preparing the halogen-free flame-retardant photovoltaic backsheet 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 is any one or a mixture of the following: γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and γ-methacryloxypropyl.

5. A halogen-free flame-retardant photovoltaic backsheet, characterized in that: The halogen-free flame-retardant photovoltaic backsheet is prepared by using the preparation method described in any one of claims 1 to 4.

6. The halogen-free flame-retardant photovoltaic backsheet according to claim 5, characterized in that: The inner layer of the halogen-free flame-retardant photovoltaic backsheet is ethylene-vinyl alcohol copolymer with a thickness of 290um to 310um, and the outer layer of the halogen-free flame-retardant photovoltaic backsheet is modified polypropylene with a thickness of 190 to 210um.

7. A photovoltaic module, characterized in that The photovoltaic module comprises, in order along the light incident direction, a transparent front plate, a first POE layer, a solar cell sheet, a second POE layer, and a halogen-free flame-retardant photovoltaic back plate prepared by the preparation method according to any one of claims 1 to 4.

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