A special composite adhesive film for main-gridless photovoltaic modules, its preparation method and application

Abstract

The present invention relates to the field of photovoltaic encapsulation films, and discloses a special composite film for main-grid-free photovoltaic modules, a preparation method thereof, and an application thereof. The composite film sequentially comprises a film layer, an isolation layer, and an adhesive layer that is adhered to the bus bars and the battery cells in the photovoltaic module from top to bottom; the periphery of the film layer is adhered to the periphery of the adhesive layer, and the isolation layer is wrapped around the four sides; the raw materials of the isolation layer include a photosensitive resin prepolymer and a photoinitiator; the raw materials of the adhesive layer include a matrix resin and an amphiphilic polymer; the melt flow rate of the isolation layer after photocuring is less than that of the adhesive layer. The present invention can avoid the composite film from infiltrating between the bus bars and the sub-grids during lamination, while having a high bonding strength between the composite film and the battery cells, and the composite film can be prepared by a three-layer coextrusion molding method, which is relatively simple and efficient in use.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic encapsulation films, and in particular to a special composite film for main-grid-free photovoltaic modules, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous development of photovoltaic power generation technology, cost reduction and efficiency improvement have gradually become the main theme of the industry. In order to improve the charge collection ability of crystalline silicon photovoltaic cells, metal silver paste is used to make grid lines. It is estimated that metal silver ranks second in the cost proportion of photovoltaic modules. Therefore, reducing silver consumption will greatly reduce the module cost. The main-grid-free technology is one of the most effective means to reduce silver consumption at present. Especially for HJT cells with a large amount of silver paste used, it can effectively reduce the silver paste consumption by 30% - 45%. In addition, the main-grid-free technology uses thinner sub-grids, which can minimize the shading area on the surface of crystalline silicon cells and improve the cell conversion efficiency.

[0003] For main-grid-free modules, since the main grid is omitted, an ohmic contact needs to be directly formed between the solder tape and the sub-grid. The traditional string welding technology cannot meet this requirement, and the new welding technology will increase costs and weaken the profit gain brought by reducing silver consumption. As a protective layer directly covering the cell and the solder tape, the encapsulation film can be used to closely fit the solder tape and the sub-grid to achieve good ohmic contact. At present, the commonly used photovoltaic films on the market cannot meet the encapsulation requirements of main-grid-free battery modules. During the lamination process, the molten flow of the film will penetrate between the solder tape and the sub-grid in the cell to form an insulating layer, resulting in the phenomenon of loose connection of the module.

[0004] Patent CN117153916A discloses an isolation film for photovoltaic modules, a composite film for photovoltaic modules, and a photovoltaic module, which adopt the cooperation of a film layer, a support layer, and an adhesive layer. The support layer is pre-crosslinked to limit the flow rate of the adhesive layer during the lamination process. At the same time, the thickness of the adhesive layer is designed to be less than the height of the solder tape, so that the solder tape is not easily embedded in the adhesive layer during the lamination process, thus effectively avoiding the loose connection caused by the film penetrating between the solder tape and the sub-grid during the lamination process. However, in the above patent, the pre-crosslinked support layer cannot be co-extruded with the film layer and the adhesive layer, and needs to be laid layer by layer during preparation, resulting in a long production process and complex technology; moreover, in this patent, the bonding strength between the adhesive layer and the cell is low, which will lead to poor long-term reliability of the photovoltaic module.

[0005] The invention patent CN117025108A discloses a packaging adhesive film for a main-grid-free HJT battery module, its preparation method, and a photovoltaic module. The packaging adhesive film is made by a two-layer co-extrusion method. To avoid the adhesive film seeping into the space between the solder strip and the sub-grid during the lamination process and forming a virtual connection, one layer is subjected to radiation pre-crosslinking treatment, which is called the support layer. When making a photovoltaic module, the support layer is adhered to the battery cell. Although this method can solve the problem of virtual connection, the pre-crosslinking treatment will seriously reduce the bonding strength between the adhesive film and the battery cell, especially for HJT batteries with a TCO layer on the surface, thereby reducing the long-term reliability of the module. Summary of the Invention

[0006] To solve the above technical problems, that is, the existing packaging adhesive film for a main-grid-free photovoltaic module performs pre-crosslinking on the support layer adhered to the battery cell to avoid the adhesive film seeping into the space between the solder strip and the sub-grid and forming a virtual connection. This method has the problem of low bonding strength between the adhesive film and the battery cell. The present invention provides a special composite adhesive film for a main-grid-free photovoltaic module, its preparation method, and application. The present invention can avoid the composite adhesive film seeping into the space between the solder strip and the sub-grid during lamination, while enabling the composite adhesive film to have a high bonding strength with the battery cell. Moreover, the composite adhesive film can be prepared by a three-layer co-extrusion molding method, which is relatively simple and efficient in use.

[0007] The specific technical solution of the present invention is as follows:

[0008] In the first aspect, the present invention provides a special composite adhesive film for a main-grid-free photovoltaic module, which sequentially includes an adhesive film layer, an isolation layer, and a bonding layer that is adhered to the solder strip and the battery cell in the photovoltaic module from top to bottom; the periphery of the adhesive film layer is adhered to the periphery of the bonding layer, wrapping the isolation layer on all four sides; the raw materials of the isolation layer include a photosensitive resin prepolymer and a photoinitiator; the raw materials of the bonding layer include a matrix resin and an amphiphilic polymer; the melt flow rate of the isolation layer after photocuring is less than that of the bonding layer.

[0009] In the present invention, the isolation layer uses a photosensitive resin prepolymer and a photoinitiator as raw materials. Before photocuring, the raw materials of the isolation layer have good fluidity, so they can be formed by three-layer co-extrusion with the adhesive film layer and the bonding layer; after the three-layer co-extrusion molding is completed and photocuring is carried out, the isolation layer can have low fluidity (i.e., less than the melt flow rate of the bonding layer). The composite adhesive film formed in this way, when used in a photovoltaic module, during the lamination process of the photovoltaic module, the isolation layer that is adhered to the bonding layer and has small fluidity can limit the flow of the bonding layer, thereby preventing the bonding layer from seeping into the space between the solder strip and the sub-grid in the battery cell and causing a virtual connection phenomenon in the module. Through the above method, it is possible to avoid the composite adhesive film seeping into the space between the solder strip and the sub-grid, while enabling the composite adhesive film to be prepared by a three-layer co-extrusion molding method. When in use, there is no need to lay the bonding layer, the isolation layer, and the adhesive film layer layer by layer, which can make the production process of the photovoltaic module shorter and the production process simpler.

[0010] On this basis, the present invention adopts the design of "the periphery of the adhesive film layer fits with the periphery of the bonding layer, and the isolation layer is wrapped around the four sides", which can prevent the isolation layer with high fluidity from flowing out of the composite adhesive film before photocuring, so as to ensure that the isolation layer can better play its role of "restricting the flow of the bonding layer" during lamination.

[0011] Moreover, in the present invention, the problem of the adhesive film penetrating between the solder ribbon and the secondary grid during the lamination process is solved by setting the isolation layer (rather than by increasing the crosslinking degree of the bonding layer), so that the negative impact on the bonding strength between the composite adhesive film and the battery chip caused by the increase in the crosslinking degree of the bonding layer can be avoided. In addition, an amphiphilic polymer is added to the bonding layer, and the incompatibility between the hydrophilic segment and the lipophilic segment of the amphiphilic polymer will cause microphase separation to occur, making the amphiphilic polymer exhibit self-assembly characteristics in the bulk and surface interface structures. Therefore, good contact can be formed at the interfaces between the bonding layer and the solder ribbon, and between the bonding layer and the battery chip, thereby improving the bonding property between the bonding layer and the battery chip and the solder ribbon, ensuring that the solder ribbon is firmly fixed on the battery chip, enabling the solder ribbon to be firmly combined with the secondary grid to form an effective ohmic contact, and making the photovoltaic module have good long-term reliability and still have a high bonding strength after aging.

[0012] Preferably, the weight-average molecular weight of the amphiphilic polymer is 1 to 3 kDa.

[0013] By increasing the molecular weight of the amphiphilic polymer, the bonding strength between the composite adhesive film and the solder ribbon and the battery chip can be improved; however, when the molecular weight of the amphiphilic polymer is too high, the bonding layer is not easy to spread on the surface of the battery chip, which will instead have an adverse effect on the bonding strength between the composite adhesive film and the solder ribbon and the battery chip.

[0014] Preferably, the amphiphilic polymer is a graft copolymer or a block copolymer composed of a hydrophilic segment and a hydrophobic segment; the hydrophilic segment includes one or more of polyethylene glycol, polyethylene ether, polyvinyl alcohol, polyethyleneimine, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, and polystyrene sulfonate; the hydrophobic segment includes one or more of polypropylene oxide, polystyrene, polysiloxane, polyolefin, polymethyl methacrylate, polyacrylate methyl, and polyacrylate butyl.

[0015] Preferably, the amphiphilic polymer is a graft copolymer composed of a polyethylene glycol main chain and a polypropylene oxide side chain.

[0016] Preferably, the thicknesses of the isolation layer and the bonding layer are 50 to 100 μm and 50 to 150 μm respectively; the thickness of the bonding layer is less than the thickness of the solder ribbon.

[0017] The isolation layer has a relatively high hardness after photocuring and contains a large number of unsaturated functional groups. By controlling the thickness of the isolation layer within 50 - 100 μm, it is possible to avoid damage to the battery chips during the lamination process and prevent the occurrence of hidden cracks in the photovoltaic module, thereby reducing the photoelectric conversion efficiency.

[0018] The thickness of the above-mentioned solder tape refers to: when the photovoltaic module is placed flat, the vertical distance between the highest point of the solder tape above the battery chip and the battery chip.

[0019] Preferably, the melt flow rate of the isolation layer after photocuring is 1.0 - 5.0 g / 10 min at 120 °C and a load of 2.16 kg; the melt flow rate of the adhesive layer is 3.0 - 10.0 g / 10 min at 120 °C and a load of 2.16 kg; at 120 °C and a load of 2.16 kg, the melt flow rate of the isolation layer after photocuring is 1.0 - 9.0 g / 10 min less than that of the adhesive layer.

[0020] Preferably, the isolation layer comprises the following raw materials in parts by weight: 100 parts of a photosensitive resin prepolymer, 1 - 1.5 parts of a photoinitiator, and 0 - 2 parts of an isolation layer additive; the isolation layer additive includes a reactive diluent.

[0021] Preferably, the photosensitive resin prepolymer includes one or more of acrylated epoxy resin, unsaturated polyester, polyurethane, polythiol photocuring resin, and polyene photocuring resin.

[0022] Preferably, the photoinitiator includes one or more of benzoin - type photoinitiators, acetophenone - type photoinitiators, and triarylsulfonium salt photoinitiators.

[0023] Preferably, the reactive diluent includes a free - radical type reactive diluent and / or a cationic type reactive diluent.

[0024] Preferably, the adhesive layer comprises the following raw materials in parts by weight: 100 parts of a matrix resin, 1 - 2 parts of an amphiphilic polymer, and 0.1 - 3 parts of an adhesive layer additive; the adhesive layer additive includes one or more of a cross - linker, a co - cross - linker, a silane coupling agent, a tackifying resin, an antioxidant, a light stabilizer, and a processing aid.

[0025] Preferably, the matrix resin includes one or more of ethylene - vinyl acetate copolymer (EVA), polyolefin elastomer (POE), thermoplastic polyolefin (TPO), polyvinyl butyral (PVB), and silica gel.

[0026] Preferably, the film layer is a polyolefin elastomer (POE) film, an ethylene - vinyl acetate copolymer (EVA) film, or a polyvinyl butyral (PVB) film.

[0027] The encapsulation film layer can use conventional encapsulation films, such as POE films, EVA films, and PVB films.

[0028] In a second aspect, the present invention provides a method for preparing the composite film, comprising the following steps: preparing a film layer mixture and a bonding layer mixture, and preparing a separation layer mixture in the dark; performing three-layer coextrusion molding in the dark, and then curing the separation layer by ultraviolet irradiation to obtain the composite film.

[0029] In a third aspect, the present invention provides an application of the composite film in a main-gridless photovoltaic module. The main-gridless photovoltaic module includes a backsheet, a first encapsulation film, a welding tape, a cell, a welding tape, a second encapsulation film, and glass stacked in sequence from top to bottom; the first encapsulation film and / or the second encapsulation film is the composite film.

[0030] Preferably, in the main-gridless photovoltaic module, the separation layer completely covers the cell.

[0031] By making the separation layer completely cover the cell (i.e., making the size of the separation layer larger than that of the cell), it can be ensured that during lamination, the bonding layer within the range of the cell has low fluidity under the action of the separation layer, thereby effectively preventing the bonding layer from infiltrating between the welding tape and the sub-grid.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] (1) The present invention uses a separation layer with low fluidity to restrict the flow of the bonding layer during lamination. In this way, without increasing the crosslinking degree of the bonding layer in contact with the cell, it is possible to avoid the composite film infiltrating between the welding tape and the sub-grid during lamination and causing virtual connection, thus avoiding adverse effects on the bonding strength between the composite film and the cell.

[0034] (2) The composite film of the present invention adopts a three-layer composite structure of a film layer, a separation layer, and a bonding layer, and uses a photosensitive resin prepolymer and a photoinitiator as raw materials in the separation layer. It can avoid the composite film infiltrating between the welding tape and the sub-grid during lamination and causing virtual connection, while enabling the composite film to adopt a preparation method of three-layer coextrusion molding, without the need for layer-by-layer laying during use, so that the production process of the photovoltaic module is shorter and the production process is simpler.

[0035] (3) By adding an amphiphilic polymer to the bonding layer, the present invention can improve the bonding strength between the composite film and the cell, making the photovoltaic module have better long-term reliability; on this basis, by controlling the molecular weight of the amphiphilic polymer, the bonding strength between the composite film and the cell can be further improved.

[0036] (4) By controlling the thickness of the isolation layer, the present invention can avoid the occurrence of hidden cracks in the photovoltaic module, enabling the photovoltaic module to have a high photoelectric conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic cross-sectional structure diagram of a photovoltaic module in the present invention.

[0038] The reference numerals are: composite adhesive film 1, adhesive film layer 11, isolation layer 12, bonding layer 13, solder ribbon 2, and cell 3. SPECIFIC EMBODIMENTS

[0039] The present invention will be further described below in conjunction with embodiments.

[0040] A special composite adhesive film for a main-grid-free photovoltaic module includes, from top to bottom, an adhesive film layer, an isolation layer, and a bonding layer that adheres to the solder ribbon and the cell in the photovoltaic module; the periphery of the adhesive film layer adheres to the periphery of the bonding layer, wrapping the isolation layer on all sides; the raw materials of the isolation layer include a photosensitive resin prepolymer and a photoinitiator; the raw materials of the bonding layer include a matrix resin and an amphiphilic polymer; the melt flow rate of the isolation layer after photocuring is less than that of the bonding layer.

[0041] In some specific embodiments, the thicknesses of the isolation layer and the bonding layer are 50 - 100 μm and 50 - 150 μm respectively; the thickness of the bonding layer is less than that of the solder ribbon.

[0042] In some specific embodiments, the melt flow rate of the isolation layer after photocuring is 1.0 - 5.0 g / 10 min at 120 °C and a load of 2.16 kg; the melt flow rate of the bonding layer is 3.0 - 10.0 g / 10 min at 120 °C and a load of 2.16 kg; at 120 °C and a load of 2.16 kg, the melt flow rate of the isolation layer after photocuring is 1.0 - 9.0 g / 10 min less than that of the bonding layer.

[0043] In some specific embodiments, the adhesive film layer can use a conventional encapsulation adhesive film, including but not limited to a polyolefin elastomer (POE) adhesive film, an ethylene-vinyl acetate copolymer (EVA) adhesive film, or a polyvinyl butyral (PVB) adhesive film.

[0044] In some specific embodiments, the isolation layer includes the following raw materials in parts by weight: 100 parts of photosensitive resin prepolymer, 1 - 1.5 parts of photoinitiator, and 0 - 2 parts of isolation layer additive. The isolation layer additive includes but is not limited to a reactive diluent; the reactive diluent includes but is not limited to a free radical type reactive diluent and / or a cationic type reactive diluent.

[0045] In some specific embodiments, the photosensitive resin prepolymer includes one or more of acrylated epoxy resin, unsaturated polyester, polyurethane, polythiol photocuring resin, and polyene photocuring resin; the photoinitiator includes one or more of benzoin-based photoinitiators, acetophenone-based photoinitiators, and triaryl sulfonium salt photoinitiators.

[0046] In some specific embodiments, the adhesive layer comprises raw materials in the following weight parts: 100 parts of matrix resin, 1 - 2 parts of amphiphilic polymer, and 0.1 - 3 parts of adhesive layer additive. The adhesive layer additive includes, but is not limited to, one or more of crosslinking agents, co-crosslinking agents, silane coupling agents, tackifying resins, antioxidants, light stabilizers, and processing aids.

[0047] In some specific embodiments, the matrix resin can be a conventional encapsulation film resin, including, but not limited to, one or more of ethylene - vinyl acetate copolymer (EVA), polyolefin elastomer (POE), thermoplastic polyolefin (TPO), polyvinyl butyral (PVB), and silica gel.

[0048] In some specific embodiments, the amphiphilic polymer is a graft copolymer or block copolymer composed of a hydrophilic segment and a hydrophobic segment, with a weight - average molecular weight of 1 - 3 kDa; the hydrophilic segment includes one or more of polyethylene glycol, polyethylene ether, polyvinyl alcohol, polyethyleneimine, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, and polystyrene sulfonate; the hydrophobic segment includes one or more of polypropylene oxide, polystyrene, polysiloxane, polyolefin, polymethyl methacrylate, polyacrylate methyl ester, and polyacrylate butyl ester.

[0049] A method for preparing the composite film includes the following steps: preparing a film layer mixture and an adhesive layer mixture, and preparing a separator layer mixture in the dark; performing three - layer co - extrusion molding in the dark, and then curing the separator layer by ultraviolet irradiation to obtain the composite film.

[0050] The application of the composite film in a main - grid - less photovoltaic module, the main - grid - less photovoltaic module includes a backsheet, a first encapsulation film, solder tapes, solar cells, solder tapes, a second encapsulation film, and glass stacked in sequence from top to bottom; the first encapsulation film and / or the second encapsulation film is the composite film.

[0051] In some specific embodiments, in the main - grid - less photovoltaic module, the separator layer completely covers the solar cells.

[0052] The present invention will be described below through specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be conceived by those skilled in the art are included in the present invention, and the scope of protection of the present invention is defined by the appended claims and any equivalents thereof.

[0053] Embodiment 1

[0054] The structure of the photovoltaic module in this embodiment is as Figure 1 shown, specifically as follows: It is composed of a backsheet, composite adhesive film 1, solder ribbon 2, solar cell 3, solder ribbon 2, composite adhesive film 1, and glass stacked in sequence from top to bottom ( Figure 1 the backsheet and glass are not shown in

[0055] The preparation method of the composite adhesive film used in this embodiment is as follows:

[0056] S1: Prepare the mixture for the adhesive film layer:

[0057] Weigh the following raw materials according to parts by weight: 100 parts of EVA resin, 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, the mixture for the adhesive film layer is obtained and placed in a storage bin for standby.

[0058] S2: Prepare the mixture for the isolation layer:

[0059] Weigh the following raw materials according to parts by weight: 100 parts of acrylated epoxy resin, 1.2 parts of 1-p-tolyl-2-diethylamino-1-propanone, 0.7 part of cationic active diluent (epoxy active diluent, purchased from Jiangmen Xinhui Xirixu Electronic Materials Co., Ltd.). Mix the above raw materials at high speed under light-shielded conditions. After the auxiliaries are completely absorbed, the mixture for the isolation layer is obtained and placed in a light-shielded storage bin for standby.

[0060] S3: Prepare the mixture for the bonding layer:

[0061] Weigh the following raw materials by parts by weight: 98 parts of EVA resin, 1 part of amphiphilic polymer (a graft copolymer composed of a polyethylene glycol main chain and a polypropylene oxide side chain, with a weight-average molecular weight of 2 kDa), 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, a bonding layer mixture is obtained and placed in a storage bin for standby.

[0062] S4: Molding and curing:

[0063] Add the film layer mixture, the isolation layer mixture, and the bonding layer mixture into a three-layer co-extrusion storage bin respectively. Carry out three-layer co-extrusion molding under light-shielded conditions, and then uniformly irradiate with an ultraviolet lamp to completely cure the isolation layer, and then wind up to obtain a composite film. In the composite film prepared in this example, the thickness of the film layer is 300 μm, the thickness of the isolation layer is 50 μm, and the thickness of the bonding layer is 100 μm; the melt flow rate of the isolation layer after photo-curing is 2.0 g / 10 min at 120 °C and a load of 2.16 kg, and the melt flow rate of the bonding layer is 5.0 g / 10 min at 120 °C and a load of 2.16 kg.

[0064] Example 2

[0065] The structure of the photovoltaic module in this example is the same as that in Example 1.

[0066] The preparation method of the composite film used in this example is as follows:

[0067] S1: Prepare the film layer mixture:

[0068] Weigh the following raw materials by parts by weight: 100 parts of EVA resin, 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, a film layer mixture is obtained and placed in a storage bin for standby.

[0069] S2: Prepare the isolation layer mixture:

[0070] Weigh the following raw materials by weight parts: 100 parts of acrylated epoxy resin, 1 part of 1-p-tolyl-2-diethylamino-1-propanone, 0.1 part of cationic active diluent (epoxy active diluent, purchased from Jiangmen Xinhui Xinrixu Electronic Materials Co., Ltd.). Under light-shielded conditions, mix the above raw materials at high speed. After the additives are completely absorbed, an isolation layer mixture is obtained and stored in a light-shielded storage bin for later use.

[0071] S3: Prepare the adhesive layer mixture:

[0072] Weigh the following raw materials by weight parts: 98 parts of EVA resin, 1.5 parts of amphiphilic polymer (a graft copolymer composed of a polyethylene glycol main chain and a polypropylene oxide side chain, with a molecular weight of 3 kDa), 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloyloxypropyltrimethoxysilane, 0.2 part of antioxidant 1076, 0.2 part of light stabilizer UV770. Mix the above raw materials at high speed. After the additives are completely absorbed, an adhesive layer mixture is obtained and stored in a storage bin for later use.

[0073] S4: Molding and curing:

[0074] Add the adhesive film layer mixture, the isolation layer mixture, and the adhesive layer mixture into a three-layer co-extrusion storage bin respectively. Under light-shielded conditions, perform three-layer co-extrusion molding, and then uniformly irradiate with an ultraviolet lamp to completely cure the isolation layer, and then wind up to obtain a composite adhesive film. In the composite adhesive film prepared in this example, the thickness of the adhesive film layer is 300 μm, the thickness of the isolation layer is 50 μm, and the thickness of the adhesive layer is 50 μm; the melt flow rate of the isolation layer after photocuring at 120 °C and a load of 2.16 kg is 1.8 g / 10 min, and the melt flow rate of the adhesive layer at 120 °C and a load of 2.16 kg is 5.6 g / 10 min.

[0075] Example 3

[0076] The photovoltaic module structure in this example is the same as that in Example 1.

[0077] The preparation method of the composite adhesive film used in this example is as follows:

[0078] S1: Prepare the adhesive film layer mixture:

[0079] Weigh the following raw materials by weight parts: 100 parts of EVA resin, 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, a mixed material for the adhesive film layer is obtained and stored in a storage bin for standby.

[0080] S2: Prepare the mixed material for the isolation layer:

[0081] Weigh the following raw materials by weight parts: 100 parts of acrylated epoxy resin, 1.5 parts of 1-p-tolyl-2-diethylamino-1-propanone, and 2 parts of cationic active diluent (epoxy active diluent, purchased from Xinxurui Electronic Materials Co., Ltd., Xinhui District, Jiangmen City). Mix the above raw materials at high speed under light-shielded conditions. After the auxiliaries are completely absorbed, a mixed material for the isolation layer is obtained and stored in a light-shielded storage bin for standby.

[0082] S3: Prepare the mixed material for the bonding layer:

[0083] Weigh the following raw materials by weight parts: 98 parts of EVA resin, 2 parts of amphiphilic polymer (a graft copolymer composed of a polyethylene glycol main chain and a polypropylene oxide side chain, with a molecular weight of 1 kDa), 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, a mixed material for the bonding layer is obtained and stored in a storage bin for standby.

[0084] S4: Molding and curing:

[0085] Add the mixed material for the adhesive film layer, the mixed material for the isolation layer, and the mixed material for the bonding layer into a three-layer co-extrusion storage bin respectively. Carry out three-layer co-extrusion molding under light-shielded conditions, and then uniformly irradiate with an ultraviolet lamp to completely cure the isolation layer. Subsequently, wind up to obtain a composite adhesive film. In the composite adhesive film prepared in this example, the thickness of the adhesive film layer is 300 μm, the thickness of the isolation layer is 50 μm, and the thickness of the bonding layer is 150 μm; the melt flow rate of the isolation layer after photo-curing is 1.0 g / 10 min at 120 °C and a load of 2.16 kg, and the melt flow rate of the bonding layer is 5.0 g / 10 min at 120 °C and a load of 2.16 kg.

[0086] Example 4

[0087] The photovoltaic module structure in this example is the same as that in Example 1.

[0088] The difference between the method for preparing the composite adhesive film used in this embodiment and that in Embodiment 1 is only that: the thickness of the isolation layer is increased. The steps for preparing the composite adhesive film in this embodiment are as follows:

[0089] S1: Prepare the mixture for the adhesive film layer:

[0090] Weigh the following raw materials by weight parts: 100 parts of EVA resin, 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, the mixture for the adhesive film layer is obtained and stored in a storage bin for standby.

[0091] S2: Prepare the mixture for the isolation layer:

[0092] Weigh the following raw materials by weight parts: 100 parts of acrylated epoxy resin, 1.2 parts of 1-p-tolyl-2-diethylamino-1-propanone, 0.7 part of cationic active diluent (epoxy active diluent, purchased from Jiangmen Xinhui Xinrixu Electronic Materials Co., Ltd.). Mix the above raw materials at high speed under light-proof conditions. After the auxiliaries are completely absorbed, the mixture for the isolation layer is obtained and stored in a light-proof storage bin for standby.

[0093] S3: Prepare the mixture for the bonding layer:

[0094] Weigh the following raw materials by weight parts: 98 parts of EVA resin, 1 part of amphiphilic polymer (a graft copolymer composed of a polyethylene glycol main chain and a polypropylene oxide side chain, with a weight-average molecular weight of 2 kDa), 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, the mixture for the bonding layer is obtained and stored in a storage bin for standby.

[0095] S4: Molding and curing:

[0096] The adhesive film layer mixture, the isolation layer mixture, and the bonding layer mixture are respectively added into a three-layer co-extrusion storage bin, and three-layer co-extrusion molding is carried out under light-shielded conditions. Then, uniform irradiation is performed using an ultraviolet lamp to completely cure the isolation layer, and then winding is carried out to obtain a composite adhesive film. In the composite adhesive film prepared in this example, the thickness of the adhesive film layer is 300 μm, the thickness of the isolation layer is 80 μm, and the thickness of the bonding layer is 100 μm; the melt flow rate of the isolation layer after photocuring at 120 °C and a load of 2.16 kg is 2.0 g / 10 min, and the melt flow rate of the bonding layer at 120 °C and a load of 2.16 kg is 5.0 g / 10 min.

[0097] Example 5

[0098] The photovoltaic module structure in this example is the same as that in Example 1.

[0099] The difference between the method for preparing the composite adhesive film used in this example and that in Example 1 is only that: the thickness of the isolation layer is increased. The steps for preparing the composite adhesive film in this example are as follows:

[0100] S1: Prepare the adhesive film layer mixture:

[0101] Weigh the following raw materials according to parts by weight: 100 parts of EVA resin, 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, the adhesive film layer mixture is obtained and placed in a storage bin for standby.

[0102] S2: Prepare the isolation layer mixture:

[0103] Weigh the following raw materials according to parts by weight: 100 parts of acrylated epoxy resin, 1.2 parts of 1-p-tolyl-2-diethylamino-1-propanone, and 0.7 part of cationic active diluent (epoxy active diluent, purchased from Xinxurui Electronic Materials Co., Ltd., Xinhui District, Jiangmen City). Mix the above raw materials at high speed under light-shielded conditions. After the auxiliaries are completely absorbed, the isolation layer mixture is obtained and placed in a light-shielded storage bin for standby.

[0104] S3: Prepare the bonding layer mixture:

[0105] Weigh the following raw materials by weight parts: 98 parts of EVA resin, 1 part of amphiphilic polymer (a graft copolymer composed of a polyethylene glycol main chain and a polypropylene oxide side chain, with a weight average molecular weight of 2 kDa), 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, a bonding layer mixture is obtained and stored in a storage bin for standby.

[0106] S4: Molding and curing:

[0107] Add the film layer mixture, the isolation layer mixture, and the bonding layer mixture into a three-layer co-extrusion storage bin respectively. Carry out three-layer co-extrusion molding under light-shielded conditions, and then uniformly irradiate with an ultraviolet lamp to completely cure the isolation layer. Subsequently, wind up to obtain a composite film. In the composite film prepared in this example, the thickness of the film layer is 300 μm, the thickness of the isolation layer is 100 μm, and the thickness of the bonding layer is 100 μm; the melt flow rate of the isolation layer after photocuring is 2.0 g / 10 min at 120 °C and a load of 2.16 kg, and the melt flow rate of the bonding layer is 5.0 g / 10 min at 120 °C and a load of 2.16 kg.

[0108] Example 6

[0109] The photovoltaic module structure in this example is the same as that in Example 1.

[0110] The difference between the method for preparing the composite film used in this example and that in Example 1 is only that: the type of photosensitive resin prepolymer in the isolation layer is changed. The steps for preparing the composite film in this example are as follows:

[0111] S1: Prepare the film layer mixture:

[0112] Weigh the following raw materials by weight parts: 100 parts of EVA resin, 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, a film layer mixture is obtained and stored in a storage bin for standby.

[0113] S2: Prepare the isolation layer mixture:

[0114] Weigh the following raw materials by weight parts: 100 parts of unsaturated polyester resin, 1.2 parts of 1-p-tolyl-2-diethylamino-1-propanone, and 0.7 parts of cationic active diluent (epoxy active diluent, purchased from Jiangmen Xinhui Xinrixu Electronic Materials Co., Ltd.). Mix the above raw materials at high speed under light-shielded conditions. After the auxiliaries are completely absorbed, an isolation layer mixture is obtained and stored in a light-shielded storage bin for standby.

[0115] S3: Prepare the adhesive layer mixture:

[0116] Weigh the following raw materials by weight parts: 98 parts of EVA resin, 1 part of amphiphilic polymer (a graft copolymer composed of a polyethylene glycol main chain and a polypropylene oxide side chain, with a weight average molecular weight of 2 kDa), 0.7 parts of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 parts of triallyl isocyanurate, 0.3 parts of trimethylolpropane triacrylate, 0.4 parts of γ-methacryloyloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, an adhesive layer mixture is obtained and stored in a storage bin for standby.

[0117] S4: Molding and curing:

[0118] Add the film layer mixture, isolation layer mixture, and adhesive layer mixture into a three-layer co-extrusion storage bin respectively. Perform three-layer co-extrusion molding under light-shielded conditions, and then uniformly irradiate with an ultraviolet lamp to completely cure the isolation layer, and then wind up to obtain a composite film. In the composite film prepared in this example, the thickness of the film layer is 300 μm, the thickness of the isolation layer is 50 μm, and the thickness of the adhesive layer is 100 μm; the melt flow rate of the isolation layer after photo-curing is 4.0 g / 10 min at 120 °C and a load of 2.16 kg, and the melt flow rate of the adhesive layer is 5.0 g / 10 min at 120 °C and a load of 2.16 kg.

[0119] Example 7

[0120] The photovoltaic module structure in this example is the same as that in Example 1.

[0121] The difference between the method for preparing the composite film used in this example and that in Example 1 is only that: the type of amphiphilic polymer in the adhesive layer is changed. The steps for preparing the composite film in this example are specifically as follows:

[0122] S1: Prepare the film layer mixture:

[0123] Weigh the following raw materials by weight parts: 100 parts of EVA resin, 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, a mixture for the adhesive film layer is obtained and stored in a storage bin for standby.

[0124] S2: Prepare the mixture for the isolation layer:

[0125] Weigh the following raw materials by weight parts: 100 parts of acrylated epoxy resin, 1.2 parts of 1-p-tolyl-2-diethylamino-1-propanone, 0.7 part of cationic active diluent (epoxy active diluent, purchased from Jiangmen Xinhui Xinrixu Electronic Materials Co., Ltd.). Mix the above raw materials at high speed under light-shielded conditions. After the auxiliaries are completely absorbed, a mixture for the isolation layer is obtained and stored in a light-shielded storage bin for standby.

[0126] S3: Prepare the mixture for the bonding layer:

[0127] Weigh the following raw materials by weight parts: 98 parts of EVA resin, 1 part of amphiphilic polymer (a graft copolymer composed of a polyethyleneimine main chain and a polysiloxane side chain, with a weight-average molecular weight of 2 kDa), 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, a mixture for the bonding layer is obtained and stored in a storage bin for standby.

[0128] S4: Molding and curing:

[0129] Add the mixture for the adhesive film layer, the mixture for the isolation layer, and the mixture for the bonding layer into a three-layer co-extrusion storage bin respectively. Carry out three-layer co-extrusion molding under light-shielded conditions, and then uniformly irradiate with an ultraviolet lamp to completely cure the isolation layer. Subsequently, wind up to obtain a composite adhesive film. In the composite adhesive film prepared in this example, the thickness of the adhesive film layer is 300 μm, the thickness of the isolation layer is 50 μm, and the thickness of the bonding layer is 100 μm; the melt flow rate of the isolation layer after photo-curing is 2.0 g / 10 min at 120 °C and a load of 2.16 kg, and the melt flow rate of the bonding layer is 5.3 g / 10 min at 120 °C and a load of 2.16 kg.

[0130] Comparative Example 1

[0131] The difference between the photovoltaic module structure of this comparative example and that of Example 1 lies only in that: the composite adhesive film 1 is composed of an adhesive film layer 11 and an adhesive layer 13, and the isolation layer 12 is not provided.

[0132] The difference between the preparation method of the composite adhesive film used in this comparative example and that of Example 1 lies only in that: the isolation layer is cancelled. The steps for preparing the composite adhesive film in this comparative example are as follows:

[0133] S1: Prepare the adhesive film layer mixture:

[0134] Weigh the following raw materials according to parts by weight: 100 parts of EVA resin, 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, the adhesive film layer mixture is obtained and placed in a storage bin for standby.

[0135] S2: Prepare the adhesive layer mixture:

[0136] Weigh the following raw materials according to parts by weight: 98 parts of EVA resin, 1 part of amphiphilic polymer (a graft copolymer composed of a polyethylene glycol main chain and a polypropylene oxide side chain, with a weight average molecular weight of 2 kDa), 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, the adhesive layer mixture is obtained and placed in a storage bin for standby.

[0137] S3: Molding and curing:

[0138] Add the adhesive film layer mixture and the adhesive layer mixture into a double-layer co-extrusion storage bin respectively, carry out double-layer co-extrusion molding, and then wind up to obtain a composite adhesive film. In the composite adhesive film prepared in this comparative example, the thickness of the adhesive film layer is 300 μm, and the thickness of the adhesive layer is 100 μm; the melt flow rate of the adhesive layer at 120 °C and a load of 2.16 kg is 5.0 g / 10 min.

[0139] Comparative Example 2

[0140] The photovoltaic module structure of this comparative example is the same as that of Example 1.

[0141] The difference between the preparation method of the composite adhesive film used in this comparative example and that of Example 1 lies only in that: the thickness of the isolation layer is increased. The steps for preparing the composite adhesive film in this comparative example are as follows:

[0142] S1: Prepare the adhesive film layer mixture:

[0143] Weigh the following raw materials by weight parts: 100 parts of EVA resin, 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloyloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, a mixed material for the adhesive film layer is obtained and stored in a storage bin for standby.

[0144] S2: Prepare a mixed material for the isolation layer:

[0145] Weigh the following raw materials by weight parts: 100 parts of acrylated epoxy resin, 1.2 parts of 1-p-tolyl-2-diethylamino-1-propanone, 0.7 part of cationic active diluent (epoxy active diluent, purchased from Xinxurui Electronic Materials Co., Ltd., Xinhui District, Jiangmen City). Mix the above raw materials at high speed under light-shielded conditions. After the auxiliaries are completely absorbed, a mixed material for the isolation layer is obtained and stored in a light-shielded storage bin for standby.

[0146] S3: Prepare a mixed material for the bonding layer:

[0147] Weigh the following raw materials by weight parts: 98 parts of EVA resin, 1 part of amphiphilic polymer (a graft copolymer composed of a polyethylene glycol main chain and a polypropylene oxide side chain, with a weight average molecular weight of 2 kDa), 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloyloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, a mixed material for the bonding layer is obtained and stored in a storage bin for standby.

[0148] S4: Molding and curing:

[0149] Add the mixed material for the adhesive film layer, the mixed material for the isolation layer, and the mixed material for the bonding layer into a three-layer co-extrusion storage bin respectively. Carry out three-layer co-extrusion molding under light-shielded conditions, and then uniformly irradiate with an ultraviolet lamp to completely cure the isolation layer. Then wind up to obtain a composite adhesive film. In the composite adhesive film prepared in this comparative example, the thickness of the adhesive film layer is 300 μm, the thickness of the isolation layer is 150 μm, and the thickness of the bonding layer is 100 μm; the melt flow rate of the isolation layer after light curing is 2.0 g / 10 min at 120 °C and a load of 2.16 kg, and the melt flow rate of the bonding layer is 5.0 g / 10 min at 120 °C and a load of 2.16 kg.

[0150] Comparative Example 3

[0151] The photovoltaic module structure of this comparative example is the same as that of Example 1.

[0152] The difference between the preparation method of the composite adhesive film used in this comparative example and that of Example 1 is only that: no amphiphilic polymer is added to the adhesive layer. The steps for preparing the composite adhesive film in this comparative example are as follows:

[0153] S1: Prepare the mixture for the adhesive film layer:

[0154] Weigh the following raw materials by weight: 100 parts of EVA resin, 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the additives are completely absorbed, the mixture for the adhesive film layer is obtained and stored in a storage bin for standby.

[0155] S2: Prepare the mixture for the release layer:

[0156] Weigh the following raw materials by weight: 100 parts of acrylated epoxy resin, 1.2 parts of 1-p-tolyl-2-diethylamino-1-propanone, and 0.7 part of cationic active diluent (epoxy active diluent, purchased from Jiangmen Xinhui Xinxurui Electronic Materials Co., Ltd.). Mix the above raw materials at high speed under light-shielded conditions. After the additives are completely absorbed, the mixture for the release layer is obtained and stored in a light-shielded storage bin for standby.

[0157] S3: Prepare the mixture for the adhesive layer:

[0158] Weigh the following raw materials by weight: 98 parts of EVA resin, 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the additives are completely absorbed, the mixture for the adhesive layer is obtained and stored in a storage bin for standby.

[0159] S4: Molding and curing:

[0160] The adhesive film layer mixture, the isolation layer mixture, and the bonding layer mixture are respectively added into a three-layer co-extrusion storage bin, and three-layer co-extrusion molding is carried out under light-shielded conditions. Then, uniform irradiation is performed using an ultraviolet lamp to completely cure the isolation layer, and then winding is carried out to obtain a composite adhesive film. In the composite adhesive film prepared in this comparative example, the thickness of the adhesive film layer is 300 μm, the thickness of the isolation layer is 50 μm, and the thickness of the bonding layer is 100 μm; the melt flow rate of the isolation layer after photocuring is 2.0 g / 10 min at 120 °C and a load of 2.16 kg, and the melt flow rate of the bonding layer is 6.3 g / 10 min at 120 °C and a load of 2.16 kg.

[0161] Comparative Example 4

[0162] The photovoltaic module structure of this comparative example is the same as that of Example 1.

[0163] The difference between the method for preparing the composite adhesive film used in this comparative example and that of Example 2 is only that: the molecular weight of the amphiphilic polymer used in the bonding layer is increased. The steps for preparing the composite adhesive film in this comparative example are as follows:

[0164] S1: Prepare the adhesive film layer mixture:

[0165] Weigh the following raw materials according to parts by weight: 100 parts of EVA resin, 0.7 parts of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 parts of triallyl isocyanurate, 0.3 parts of trimethylolpropane triacrylate, 0.4 parts of γ-methacryloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the auxiliaries are completely absorbed, the adhesive film layer mixture is obtained and placed in a storage bin for standby.

[0166] S2: Prepare the isolation layer mixture:

[0167] Weigh the following raw materials according to parts by weight: 100 parts of acrylated epoxy resin, 1 part of 1-p-tolyl-2-diethylamino-1-propanone, and 0.1 part of cationic active diluent (epoxy active diluent, purchased from Jiangmen Xinhui Xinxurui Electronic Materials Co., Ltd.). Mix the above raw materials at high speed under light-shielded conditions. After the auxiliaries are completely absorbed, the isolation layer mixture is obtained and placed in a light-shielded storage bin for standby.

[0168] S3: Prepare the bonding layer mixture:

[0169] Weigh the following raw materials by parts by weight: 98 parts of EVA resin, 1.5 parts of amphiphilic polymer (a graft copolymer composed of a polyethylene glycol main chain and a polypropylene oxide side chain, with a molecular weight of 5 kDa), 0.7 parts of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 parts of triallyl isocyanurate, 0.3 parts of trimethylolpropane triacrylate, 0.4 parts of γ-methacryloyloxypropyltrimethoxysilane, 0.2 parts of antioxidant 1076, and 0.2 parts of light stabilizer UV770. Mix the above raw materials at high speed. After the additives are completely absorbed, a bonding layer mixture is obtained and placed in a storage bin for standby.

[0170] S4: Molding and curing:

[0171] Add the film layer mixture, the release layer mixture, and the bonding layer mixture into a three-layer co-extrusion storage bin respectively. Perform three-layer co-extrusion molding under light-shielded conditions, and then uniformly irradiate with an ultraviolet lamp to completely cure the release layer. Then wind it up to obtain a composite film. In the composite film prepared in this comparative example, the thickness of the film layer is 300 μm, the thickness of the release layer is 50 μm, and the thickness of the bonding layer is 50 μm; the melt flow rate of the release layer after photo-curing is 1.8 g / 10 min at 120 °C and a load of 2.16 kg, and the melt flow rate of the bonding layer is 4.9 g / 10 min at 120 °C and a load of 2.16 kg.

[0172] Comparative Example 5

[0173] The photovoltaic module structure in this comparative example is the same as that in Example 1.

[0174] The difference between the method for preparing the composite film used in this comparative example and that in Example 3 is only that: the molecular weight of the amphiphilic polymer used in the bonding layer is reduced. The steps for preparing the composite film in this comparative example are as follows:

[0175] S1: Prepare the film layer mixture:

[0176] Weigh the following raw materials by parts by weight: 100 parts of EVA resin, 0.7 parts of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 parts of triallyl isocyanurate, 0.3 parts of trimethylolpropane triacrylate, 0.4 parts of γ-methacryloyloxypropyltrimethoxysilane, 0.1 parts of antioxidant 1076, and 0.1 parts of light stabilizer UV770. Mix the above raw materials at high speed. After the additives are completely absorbed, a film layer mixture is obtained and placed in a storage bin for standby.

[0177] S2: Prepare the release layer mixture:

[0178] Weigh the following raw materials by weight parts: 100 parts of acrylated epoxy resin, 1.5 parts of 1-p-tolyl-2-diethylamino-1-propanone, and 2 parts of cationic active diluent (epoxy active diluent, purchased from Xinxurui Electronic Materials Co., Ltd., Xinhui District, Jiangmen City). Under light-shielded conditions, mix the above raw materials at high speed. After the additives are completely absorbed, an isolation layer mixture is obtained and stored in a light-shielded storage bin for later use.

[0179] S3: Prepare the adhesive layer mixture:

[0180] Weigh the following raw materials by weight parts: 98 parts of EVA resin, 2 parts of amphiphilic polymer (a graft copolymer composed of a polyethylene glycol main chain and a polypropylene oxide side chain, with a molecular weight of 0.5 kDa), 0.7 part of tert-amyl peroxy (2-ethylhexyl) carbonate, 0.7 part of triallyl isocyanurate, 0.3 part of trimethylolpropane triacrylate, 0.4 part of γ-methacryloyloxypropyltrimethoxysilane, 0.1 part of antioxidant 1076, and 0.1 part of light stabilizer UV770. Mix the above raw materials at high speed. After the additives are completely absorbed, an adhesive layer mixture is obtained and stored in a storage bin for later use.

[0181] S4: Molding and curing:

[0182] Add the adhesive film layer mixture, the isolation layer mixture, and the adhesive layer mixture into a three-layer co-extrusion storage bin respectively. Under light-shielded conditions, perform three-layer co-extrusion molding, and then use an ultraviolet lamp for uniform irradiation to completely cure the isolation layer. Subsequently, wind it up to obtain a composite adhesive film. In the composite adhesive film prepared in this comparative example, the thickness of the adhesive film layer is 300 μm, the thickness of the isolation layer is 50 μm, and the thickness of the adhesive layer is 150 μm; the melt flow rate of the isolation layer after photo-curing is 1.0 g / 10 min at 120 °C and a load of 2.16 kg, and the melt flow rate of the adhesive layer is 5.4 g / 10 min at 120 °C and a load of 2.16 kg.

[0183] Test example

[0184] Take the composite adhesive films and photovoltaic modules in each example and comparative example for performance testing. The results are shown in Table 1. Among them, the peel strength between the composite adhesive film and the HJT cell is tested according to the test method in GB / T 29848-2018, and the photoelectric conversion efficiency of the photovoltaic module is tested according to the test method in GB / T 34160-2017.

[0185] Table 1 Performance test results of composite adhesive films and photovoltaic modules

[0186]

[0187] It can be seen from Table 1 that:

[0188] (1) There are no shadows in the EL images of the photovoltaic modules of Examples 1 to 7, and the photoelectric conversion efficiency is higher than that of Comparative Example 1. This is because: on the basis of Comparative Example 1, Examples 1 to 7 added an isolation layer, which can limit the flow of the adhesive layer during the lamination process, thereby preventing the adhesive layer from infiltrating between the solder tape and the sub-grid in the cell, resulting in a virtual connection phenomenon in the module, and thus improving the photoelectric conversion efficiency of the photovoltaic module.

[0189] (2) On the basis of Examples 1, 4, and 5, when the thickness of the isolation layer was increased in Comparative Example 2, hidden cracks appeared in the photovoltaic module, and the photoelectric conversion efficiency of the photovoltaic module decreased significantly. This is because: the isolation layer has a relatively high hardness after photocuring and contains a large number of unsaturated functional groups. When its thickness is too large, it will cause damage to the cell during lamination.

[0190] (3) On the basis of Comparative Example 3, Examples 1 and 7 added an amphiphilic polymer to the adhesive layer, and the peel strength of the composite adhesive film from the HJT cell and the photoelectric conversion efficiency of the photovoltaic module were significantly improved. This is because: the incompatibility between the hydrophilic segment and the lipophilic segment in the amphiphilic polymer causes microphase separation to occur, making the amphiphilic polymer exhibit self-assembly characteristics in the bulk and surface interface structures. Therefore, it can form good contact at the interfaces between the adhesive layer and the solder tape, and between the adhesive layer and the cell, thereby improving the adhesion between the adhesive layer and the cell and the solder tape, ensuring that the solder tape is firmly fixed on the cell, and enabling the solder tape to be firmly combined with the sub-grid to form an effective ohmic contact, and thus improving the photoelectric conversion efficiency of the photovoltaic module.

[0191] (4) On the basis of Example 2, when the molecular weight of the amphiphilic polymer was increased in Comparative Example 4, the peel strength of the composite adhesive film from the HJT cell decreased; on the basis of Example 3, when the molecular weight of the amphiphilic polymer was decreased in Comparative Example 5, the peel strength of the composite adhesive film from the HJT cell also decreased. This is because: when the molecular weight of the amphiphilic polymer is too low, its tackifying effect is weak, and the adhesion strength between the adhesive layer and the cell is low; when the molecular weight of the amphiphilic polymer is too high, the adhesive layer is not easy to spread on the cell surface, which will also have an adverse effect on the adhesion strength between the adhesive layer and the cell.

[0192] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. The raw materials and equipment used in the present invention are conventional raw materials and equipment in the art and can be obtained from conventional commercial channels without special instructions; the methods used in the present invention are conventional methods in the art without special instructions.

[0193] The above are only the preferred embodiments of the present invention and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent transformations made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A composite adhesive film for busbar-free photovoltaic modules, characterized in that: From top to bottom, it includes a film layer, an isolation layer and a bonding layer that is bonded to the welding strip and the battery cell in the photovoltaic module; the periphery of the film layer is bonded to the periphery of the bonding layer to wrap the isolation layer inside; the raw materials of the isolation layer include photosensitive resin prepolymer and photoinitiator; the raw materials of the bonding layer include base resin and amphiphilic polymer; the weight average molecular weight of the amphiphilic polymer is 1~3kDa, and it is a graft copolymer composed of a polyethylene glycol main chain and a polypropylene oxide side chain; the melt flow rate of the isolation layer after photocuring is less than the melt flow rate of the bonding layer; the thickness of the isolation layer and the bonding layer are 50~100μm and 50~150μm, respectively.

2. The composite adhesive film according to claim 1, characterized in that: The thickness of the bonding layer is smaller than the thickness of the welding strip.

3. The composite adhesive film according to claim 1, characterized in that: After light curing, the isolation layer has a melt flow rate of 1.0-5.0 g / 10 min at 120° C. and a load of 2.16 kg.

4. The composite adhesive film according to claim 1 or 3, characterized in that: The adhesive layer has a melt flow rate of 3.0-10.0 g / 10 min at 120° C. and a load of 2.16 kg.

5. The composite adhesive film according to claim 1, characterized in that: The isolation layer comprises the following raw materials in parts by weight: 100 parts of photosensitive resin prepolymer, 0.1-1.5 parts of photoinitiator, and 0-2 parts of isolation layer auxiliary agent; the isolation layer auxiliary agent comprises an active diluent.

6. The composite adhesive film according to claim 1, characterized in that: The bonding layer comprises the following raw materials in parts by weight: 100 parts of base resin, 1-2 parts of amphiphilic polymer, and 0.1-3 parts of bonding layer auxiliary agent.

7. The composite adhesive film according to claim 6, characterized in that: The bonding layer auxiliary agent includes one or more of a crosslinking agent, a co-crosslinking agent, a silane coupling agent, a tackifying resin, an antioxidant, a light stabilizer and a processing aid.

8. A method for preparing the composite adhesive film according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: preparing a film layer mixture and a bonding layer mixture, and preparing an isolation layer mixture in a light-proof manner; performing three-layer co-extrusion molding in a light-proof manner, and then curing the isolation layer by ultraviolet irradiation to obtain the composite film.

9. The use of the composite adhesive film according to any one of claims 1 to 7 in a busbar-free photovoltaic module, characterized in that: The busbar-free photovoltaic module comprises a backplane, a first packaging film, a welding strip, a battery cell, a welding strip, a second packaging film and glass stacked in sequence from top to bottom; the first packaging film and / or the second packaging film is the composite film.

Images