Encapsulation film and photovoltaic module

Abstract

The application provides a packaging adhesive film and a photovoltaic module. The packaging adhesive film comprises a UV curing buffer layer and a thermal curing adhesive layer which are stacked in sequence, wherein the material of the UV curing buffer layer comprises a modified POE resin and a UV assistant crosslinking agent, the modified POE resin is grafted with a photoinitiator molecular fragment containing and / or a functional group, wherein "*" represents the connection position thereof in the photoinitiator molecular fragment. The pre-crosslinking degree gradually decreases in the UV curing buffer layer along the direction close to the thermal curing adhesive layer, thereby preventing the problem that the packaging adhesive film penetrates into the gap between the solder strip and the cell piece to form a false weld due to excessive flowability, avoiding the problem that the overall pre-crosslinking degree of the UV curing buffer layer is too large to cause hidden cracks on the cell piece during the laminating process, and preventing the problems of yellowing caused by the migration of the initiator and the precipitation of the assistant, and solving the problems of easy formation of false weld and occurrence of hidden cracks on the cell piece during the packaging of the HJT cell.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, and more specifically, to an encapsulating film and a photovoltaic module. Background Technology

[0002] HJT cells, short for crystalline silicon heterojunction solar cells, have the following advantages: 1. High open-circuit voltage and high photoelectric conversion efficiency; 2. Low temperature coefficient, stable output power, and weak power decay; 3. Symmetrical structure, enabling thin-film fabrication and bifacial power generation; 4. Simple manufacturing process. However, they also have certain limitations: 1. Thin-film solar cells are prone to breakage during photovoltaic module lamination; 2. The presence of an ITO layer on the surface leads to poor adhesion to the encapsulating film; 3. HJT cells lack a main grid structure, requiring low-temperature solder ribbons to be pre-applied to the cells using adhesive. Using conventional encapsulating film can cause overflow into the gap between the solder ribbon and the cell due to its high fluidity, resulting in poor soldering and reduced cell power generation efficiency; 4. HJT cells are sensitive to moisture, and conventional encapsulating film may lead to cell corrosion after aging, causing module failure.

[0003] Currently, HJT battery packaging mainly uses the following methods:

[0004] 1) Ensure the adhesion between the adhesive film and HJT by using EVA for encapsulation. However, the high water vapor permeability of EVA encapsulation affects the reliability during aging.

[0005] 2) Encapsulation is achieved through a multi-layer structure (substrate layer, reinforcing layer, adhesive layer, first / second adhesive layer), which is complex and too costly.

[0006] 3) Adding special functional additives such as wetting agents / light conversion agents can affect the encapsulation adhesion and light transmittance of the film;

[0007] 4) Electron beam irradiation is used to give the film a certain degree of pre-crosslinking, but this process is complicated and the film after electron beam irradiation has problems such as reduced encapsulation adhesion and easy breakage of the battery cell during lamination. Summary of the Invention

[0008] The main objective of this invention is to provide an encapsulating film and a photovoltaic module to solve the problems of poor soldering and microcracks in traditional HJT battery encapsulation in the prior art.

[0009] To achieve the above objectives, according to one aspect of the present invention, an encapsulating film is provided, comprising a UV-curable buffer layer and a thermosetting adhesive layer stacked sequentially, wherein the UV-curable buffer layer is made of a modified POE resin and a UV crosslinking agent, and the modified POE resin is grafted with a material comprising... Photoinitiator molecule fragments with functional groups, where "*" indicates the connection position of the functional group in the photoinitiator molecule fragment.

[0010] Further, the pre-crosslinking degree of the above-mentioned UV-curable buffer layer is 5-45%. Preferably, the UV-curable buffer layer includes at least two buffer layers, and in the thickness direction of the UV-curable buffer layer, the pre-crosslinking degree of each buffer layer in the UV-curable buffer layer decreases in a gradient towards the direction close to the thermosetting adhesive layer. Preferably, the buffer layer farther away from the thermosetting adhesive layer is defined as the first buffer layer, and the buffer layer closer to the thermosetting adhesive layer is defined as the second buffer layer. The pre-crosslinking degree of the first buffer layer is 25-45%, and the pre-crosslinking degree of the second buffer layer is 5-25%. Further, it is preferred that the difference in pre-crosslinking degree between the first buffer layer and the second buffer layer is 10-20%.

[0011] Further, by weight, the raw materials for the modified POE resin include: 100 parts by weight of POE resin; 0.02 to 0.15 parts by weight of graft initiator; 0.1 to 0.5 parts by weight of photoinitiator; and 0.02 to 0.05 parts by weight of first antioxidant; preferably, the photoinitiator contains at least one terminal carbon-carbon double bond and at least one functional group, and the relative molecular mass of the photoinitiator is 150 to 350; further preferably, the photoinitiator is selected from...

[0012] The POE resin is preferably selected from any one or more of the following: 1,1,3,3-tetramethylbutyl peroxypentanoate, pentyl peroxypentanoate, tert-butyl peroxypentanoate, di(3,3,5-trimethylhexanoyl)peroxide, dilauryl peroxide, didecyl peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxide)hexane, 1,1,3,3-tetramethylbutyl peroxide-2-ethylhexanoate, di(4-methylbenzoyl peroxide), and pentyl peroxide-2-ethylhexanoate; the first antioxidant is preferably selected from any one or more of antioxidant 330, antioxidant 168, antioxidant 1010, and antioxidant RD.

[0013] Further, by weight, the UV-curable buffer layer comprises: 100 parts by weight of modified POE resin; 0.5 to 2 parts by weight of UV crosslinking agent; and 0.02 to 0.05 parts by weight of second antioxidant; preferably, the UV crosslinking agent is selected from any one or more of trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, and 1,6-hexanediol diacrylate; preferably, the second antioxidant is selected from any one or more of antioxidant 330, antioxidant 168, antioxidant 1010, and antioxidant RD.

[0014] Furthermore, by weight, the UV-curable buffer layer further includes 0.2 to 0.6 parts by weight of a first tackifier, preferably the first tackifier includes ether bonds and hydroxyl groups, and preferably the first tackifier is selected from any one or more of bisphenol A epoxy resin, polyethylene glycol, and polypropylene glycol.

[0015] Furthermore, at 20–30°C and under DMA compression mode, the storage modulus of the UV-cured buffer layer is 3–10 MPa, and preferably the storage modulus of the thermosetting adhesive layer is <2 MPa.

[0016] Furthermore, the thickness of the UV-curable buffer layer is 0.05 to 0.35 mm, and preferably the thickness of the thermosetting adhesive layer is 0.35 to 0.65 mm.

[0017] Further, by weight, the above-mentioned thermosetting adhesive layer comprises: 100 parts by weight of a matrix resin; 0.5 to 2 parts by weight of a free radical thermal initiator; 0.5 to 2 parts by weight of a thermally crosslinking agent; 0.4 to 2 parts by weight of a second tackifier; and 0.02 to 0.1 parts by weight of a third antioxidant; preferably, the free radical thermal initiator is selected from tert-butyl peroxycarbonate isopropyl ester, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butyl peroxycarbonate-2-ethylhexyl ester, 2,5 -Dimethyl-2,5-di(tert-butylperoxy)hexane, 1,1-bis(tert-pentylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-pentylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, 2,2-bis(tert-butylperoxy)butane, 2-ethylhexyl carbonate peroxide, and tert-pentyl carbonate peroxide; preferably, the heat-assisted crosslinking agent is an ester compound containing multiple unsaturated groups, and preferably the ester compound is selected from tris(2-hydroxyethyl)isocyanurate triacrylate, trimethylolpropane triacrylate, and pentaerythritol. Triacrylate, trimethylolpropane triacrylate ethoxylate, trimethylolpropane triacrylate ethoxylate, glycerol triacrylate ethoxylate, glycerol triacrylate ethoxylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetraacrylate ethoxylate, trimethylolpropane tetraacrylate, bis(trimethylolpropane tetraacrylate), bis(trimethylolpropane tetramethacrylate), pentaerythritol tetraacrylate ethoxylate, tricyclodecanediethanol diacrylate, neopentyl glycol diacrylate ethoxylate, bisphenol A diacrylate ethoxylate, triallyl isocyanurate The second tackifier is selected from any one or more of esters; preferably, the second tackifier is selected from any one or more of γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane; preferably, the third antioxidant is selected from any one or more of antioxidant 330, antioxidant 168, antioxidant 1010, and antioxidant RD; preferably, the matrix resin is selected from any one or more of EVA, PVA, PMMA, and POE.

[0018] According to another aspect of the present invention, a photovoltaic module is provided, comprising a front transparent encapsulation layer, a first encapsulation film layer, an HJT cell array, a second encapsulation film layer, and a back encapsulation layer, wherein the first encapsulation film layer is the aforementioned encapsulation film, and the UV curing buffer layer of the encapsulation film is disposed in direct contact with the HJT cell array.

[0019] Furthermore, the peel strength between the first encapsulating film layer and the HJT cell array is >35N / cm, and the peel strength between the first encapsulating film layer and the front transparent encapsulation layer is >100N / cm.

[0020] Applying the technical solution of this invention, the encapsulating film of this invention adopts a two-layer structure of a special UV-curable buffer layer and a thermosetting adhesive layer, wherein the material of the UV-curable buffer layer contains... and / or Photoinitiator molecular fragments with functional groups are grafted onto POE resin to create a buffer layer with different pre-crosslinking degrees along the thickness direction of the UV-curable buffer layer. The pre-crosslinking degree gradually decreases along the direction close to the thermosetting adhesive layer in the UV-curable buffer layer. This prevents the encapsulating film from flowing too quickly and penetrating into the gap between the solder ribbon and the cell, thus avoiding the problem of poor soldering. It also avoids the problem of excessive pre-crosslinking of the UV-curable buffer layer causing microcracks in the cell during lamination. At the same time, it can prevent initiator migration, which can lead to yellowing and additive precipitation. When applied to HJT battery encapsulation, it can solve the problems of poor soldering and microcracks in the cell that are easy to form in HJT battery encapsulation. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0022] As analyzed in the background section, traditional HJT battery encapsulation in the prior art is prone to problems such as poor soldering and microcracks in the battery cells. To solve this problem, the present invention provides an encapsulation film and a photovoltaic module.

[0023] In a typical embodiment of this application, an encapsulating film is provided, comprising a UV-curable buffer layer and a thermosetting adhesive layer stacked sequentially. The UV-curable buffer layer is made of a modified POE resin and a UV crosslinking agent, and the modified POE resin is grafted with a material containing… and / or Photoinitiator of functional groups

[0024] The photoinitiator molecule fragment, where "*" indicates its connection position within the photoinitiator molecule fragment.

[0025] The encapsulating film of this invention employs a special two-layer structure consisting of a UV-curable buffer layer and a thermosetting adhesive layer. The UV-curable buffer layer is made of a material containing… and / or Photoinitiator molecular fragments with functional groups are grafted onto POE resin to create a buffer layer with different pre-crosslinking degrees along the thickness direction of the UV-curable buffer layer. The pre-crosslinking degree gradually decreases along the direction close to the thermosetting adhesive layer in the UV-curable buffer layer. This prevents the encapsulating film from flowing too quickly and penetrating into the gap between the solder ribbon and the cell, thus avoiding the problem of poor soldering. It also avoids the problem of excessive pre-crosslinking of the UV-curable buffer layer causing microcracks in the cell during lamination. At the same time, it can prevent initiator migration, which can lead to yellowing and additive precipitation. When applied to HJT battery encapsulation, it can solve the problems of poor soldering and microcracks in the cell that are easy to form in HJT battery encapsulation.

[0026] In one embodiment of this application, the pre-crosslinking degree of the UV-curable buffer layer is 5-45%. Preferably, the UV-curable buffer layer includes at least two buffer layers, and in the thickness direction of the UV-curable buffer layer, the pre-crosslinking degree of each buffer layer decreases gradually along the direction closer to the thermosetting adhesive layer. Preferably, the buffer layer farther from the thermosetting adhesive layer is defined as the first buffer layer, and the buffer layer closer to the thermosetting adhesive layer is defined as the second buffer layer. The pre-crosslinking degree of the first buffer layer is 25-45%, and the pre-crosslinking degree of the second buffer layer is 5-25%. Further, it is preferred that the difference in pre-crosslinking degree between the first buffer layer and the second buffer layer is 10-20%.

[0027] The magnitude and difference of the pre-crosslinking degree of each buffer layer in the UV-cured buffer layer help to form a transition layer with excellent buffering performance in the thickness direction of the UV-cured buffer layer, thereby better protecting the solar cell.

[0028] In one embodiment of this application, the raw materials for the modified POE resin, by weight, include: 100 parts by weight of POE resin; 0.02 to 0.15 parts by weight of graft initiator; 0.1 to 0.5 parts by weight of photoinitiator; and 0.02 to 0.05 parts by weight of first antioxidant; preferably, the photoinitiator contains at least one terminal carbon-carbon double bond and at least one functional group, and the relative molecular mass of the photoinitiator is 150 to 350; further preferably, the photoinitiator is selected from... The POE resin is preferably selected from any one or more of the following: 1,1,3,3-tetramethylbutyl peroxypentanoate, pentyl peroxypentanoate, tert-butyl peroxypentanoate, di(3,3,5-trimethylhexanoyl)peroxide, dilauryl peroxide, didecyl peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxide)hexane, 1,1,3,3-tetramethylbutyl peroxide-2-ethylhexanoate, di(4-methylbenzoyl peroxide), and pentyl peroxide-2-ethylhexanoate; the first antioxidant is preferably selected from any one or more of antioxidant 330, antioxidant 168, antioxidant 1010, and antioxidant RD.

[0029] Furthermore, it is preferable to prepare the modified POE resin by melt grafting the raw materials of the modified POE resin, and the melt grafting temperature is preferably 130-150°C.

[0030] Under the action of melting and grafting initiators, the terminal carbon-carbon double bonds of the photoinitiator undergo a grafting reaction with POE resin, while simultaneously... Photoinitiator molecular fragments are grafted onto POE resin to obtain modified POE resin. The grafting initiator helps improve the efficiency and effectiveness of the grafting reaction, while the antioxidant helps reduce side reactions during the grafting process, thereby improving the purity and performance of the resulting modified POE resin.

[0031] In one embodiment of this application, the UV-curable buffer layer comprises, by weight, 100 parts of modified POE resin; 0.5 to 2 parts of UV crosslinking agent; and 0.02 to 0.05 parts of a second antioxidant; preferably, the UV crosslinking agent is selected from any one or more of trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, and 1,6-hexanediol diacrylate; preferably, the second antioxidant is selected from any one or more of antioxidant 330, antioxidant 168, antioxidant 1010, and antioxidant RD.

[0032] The types and contents of each component in the UV-curable buffer layer mentioned above help to exert the synergistic effect between the components, resulting in a UV-curable buffer layer with a certain degree of pre-crosslinking.

[0033] In one embodiment of this application, the UV-curable buffer layer further includes 0.2 to 0.6 parts by weight of a first tackifier, preferably comprising ether bonds and hydroxyl groups, and preferably selected from any one or more of bisphenol A epoxy resin, polyethylene glycol, and polypropylene glycol.

[0034] Using a first tackifier containing abundant ether bonds and hydroxyl structures helps improve the wettability of the encapsulating film to the solar cell. At the same time, the ether bonds and hydroxyl groups readily form hydrogen bond structures with the ITO on the surface of the solar cell, thereby helping to improve the adhesion of the encapsulating film to the solar cell.

[0035] In one embodiment of this application, at 20-30°C and under DMA compression mode, the energy storage modulus of the UV-curable buffer layer is 3-10 MPa, and preferably the energy storage modulus of the thermosetting adhesive layer is <2 MPa.

[0036] The UV-cured buffer layer and thermosetting adhesive layer with the above energy storage modulus further highlight the gradual transition from the UV-cured buffer layer to the thermosetting adhesive layer, which improves both the buffering effect of the UV-cured buffer layer on the solar cell and the supporting strength of the thermosetting adhesive layer. Furthermore, DMA (Dynamic Mechanical Analysis) is a dynamic thermomechanical analyzer, and compression mode is one of its testing modes.

[0037] In one embodiment of this application, the thickness of the UV-curable buffer layer is 0.05 to 0.35 mm, and preferably the thickness of the thermosetting adhesive layer is 0.35 to 0.65 mm.

[0038] During the use of the above encapsulating films, the UV-cured buffer layer is in direct contact with the solar cell, and the thermosetting adhesive layer is in direct contact with the glass. The preferred thickness of the UV-cured buffer layer helps to achieve excellent buffering effect on the solar cell. The preferred thickness of the thermosetting adhesive layer helps to ensure the bonding strength between the thermosetting adhesive layer and the glass, thereby forming an effective encapsulation and obtaining an encapsulated component with high durability and low water vapor permeability.

[0039] In one embodiment of this application, the thermosetting adhesive layer comprises, by weight parts: 100 parts by weight of a matrix resin; 0.5 to 2 parts by weight of a free radical thermal initiator; 0.5 to 2 parts by weight of a thermally crosslinking agent; 0.4 to 2 parts by weight of a second tackifier; and 0.02 to 0.1 parts by weight of a third antioxidant; preferably, the free radical thermal initiator is selected from tert-butyl peroxycarbonate isopropyl ester, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, and tert-butyl peroxycarbonate-2-ethylhexane. The crosslinking agent is any one or more of the following: ester, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,1-bis(tert-pentylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-pentylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, 2,2-bis(tert-butylperoxy)butane, tert-amyl peroxide, and tert-amyl peroxide carbonate; preferably, the heat-assisted crosslinking agent is an ester compound containing multiple unsaturated groups, and preferably the ester compound is selected from tris(2-hydroxyethyl)isocyanurate triacrylate, trimethylolpropane triacrylate, and quaternary ammonium carbonate. Pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, propionyl trimethylolpropane triacrylate, ethoxylated glycerol triacrylate, propionyl glycerol triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate, bis(trimethylolpropane tetraacrylate), bis(trimethylolpropane tetramethacrylate), propionyl pentaerythritol tetraacrylate, tricyclodecanediethanol diacrylate, propionyl neopentyl glycol diacrylate, ethoxylated bisphenol A diacrylate, triallyl isoacrylate The second tackifier is selected from any one or more of cyanurate esters; preferably, the second tackifier is selected from any one or more of γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane; preferably, the third antioxidant is selected from any one or more of antioxidant 330, antioxidant 168, antioxidant 1010, and antioxidant RD; preferably, the matrix resin is selected from any one or more of EVA, PVA, PMMA, and POE.

[0040] The preferred types and contents of each component in the thermosetting adhesive layer help to exert the synergistic effect between the components, so that the thermosetting adhesive layer forms excellent sealing adhesion between the thermosetting adhesive layer and the glass during lamination, thus ensuring the encapsulation reliability of the HJT battery module.

[0041] In addition, the UV-curable buffer layer material and the thermosetting adhesive layer material are extruded through a two-layer co-extrusion extruder at a temperature of 70–90°C. The extrudate is then cast and irradiated with UV light online, preferably on the UV-curable buffer layer side, with a light intensity of 2000 mW / cm². 2 ~4000mW / cm 2 The HJT battery cell encapsulation film is obtained by irradiating the cell for 5 to 10 seconds at 30 to 40°C under a high-pressure mercury lamp or LED light source with a wavelength of 200 nm to 40 nm, followed by cooling, edge trimming, and winding.

[0042] In another typical embodiment of this application, a photovoltaic module is provided, including a front transparent encapsulation layer, a first encapsulation film layer, an HJT cell array, a second encapsulation film layer, and a back encapsulation layer. The first encapsulation film layer is the aforementioned encapsulation film, and the UV curing buffer layer of the encapsulation film is directly in contact with the HJT cell array.

[0043] Photovoltaic modules containing the above-mentioned encapsulating films can solve the problems of poor soldering and microcracks in HJT cell encapsulation. At the same time, they can prevent initiator migration leading to yellowing and additive precipitation, resulting in high encapsulation reliability, improved product yield, and high photoelectric conversion efficiency of photovoltaic modules.

[0044] In one embodiment of this application, the peel strength between the first encapsulating film layer and the HJT battery cell array is >35N / cm, and the peel strength between the first encapsulating film layer and the front transparent encapsulation layer is >100N / cm.

[0045] The first encapsulating film layer has excellent adhesion to both the HJT cell array and the front transparent encapsulation layer, resulting in excellent sealing between the thermosetting adhesive layer and the front transparent encapsulation layer, thus improving the weather resistance and reliability of the photovoltaic module.

[0046] The beneficial effects of this application will be explained below with reference to specific embodiments and comparative examples.

[0047] Example 1

[0048] By weight, 0.1 parts of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxide)hexane and 0.1 parts of... Modified POE resin was obtained by melt grafting granulation of 100 parts by weight of POE (melt index of 30 g / 10 min) and 0.05 parts by weight of antioxidant 330 at 130°C using a co-rotating twin-screw granulator.

[0049] 100 parts by weight of modified POE resin, 0.5 parts by weight of trimethylolpropane trimethacrylate, 0.2 parts by weight of bisphenol A epoxy resin E51, and 0.05 parts by weight of antioxidant 330 are mixed evenly to obtain a UV-curable buffer layer material.

[0050] 100 parts by weight of EVA, 0.5 parts by weight of tert-butylperoxycarbonate-2-ethylhexyl ester, 0.6 parts by weight of triallyl isocyanurate, 0.4 parts by weight of γ-aminopropyltriethoxysilane, and 0.1 parts by weight of antioxidant 330 were mixed evenly to obtain a thermosetting adhesive layer material. The UV-curing buffer layer material and the thermosetting adhesive layer material were extruded through a two-layer co-extrusion extruder at a temperature of 70-90℃. The extrudate was cast and then irradiated with online UV light (irradiation surface is the UV-curing buffer layer side, light intensity 2000mW / cm²). 2 The process involves irradiating the film under a high-pressure mercury lamp or LED light source with a wavelength of 200nm at 40℃ for 10s, followed by cooling, trimming, and winding to obtain an HJT cell encapsulation film with a UV-curable buffer layer thickness of 0.1mm and a thermosetting adhesive layer thickness of 0.4mm.

[0051] Example 2

[0052] The difference from Example 1 is that, by weight, 0.02 parts of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxide)hexane and 0.3 parts of... Modified POE resin was obtained by melt grafting granulation of 100 parts by weight of POE and 0.03 parts by weight of antioxidant 330 at 130°C using a co-rotating twin-screw granulator.

[0053] Example 3

[0054] The difference from Example 1 is that, by weight, 0.15 parts of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxide)hexane and 0.5 parts of... Modified POE resin was obtained by melt grafting granulation of 100 parts by weight of POE and 0.02 parts by weight of antioxidant 330 at 130°C using a co-rotating twin-screw granulator.

[0055] Example 4

[0056] The difference from Example 1 is that, by weight, 0.01 parts of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxide)hexane and 0.08 parts of... Modified POE resin was obtained by melt grafting granulation of 100 parts by weight of POE and 0.05 parts by weight of antioxidant 330 at 130°C using a co-rotating twin-screw granulator.

[0057] Example 5

[0058] The difference from Example 1 is that the photoinitiator is

[0059] Example 6

[0060] The difference from Example 1 is that the photoinitiator is

[0061] Example 7

[0062] The difference from Example 1 is that the photoinitiator is

[0063] Example 8

[0064] The difference from Example 1 is that the photoinitiator is

[0065] Example 9

[0066] The difference from Example 1 is that the grafting initiator is bis(3,3,5-trimethylhexanoyl)peroxide and the antioxidant is antioxidant 168.

[0067] Example 10

[0068] The difference from Example 1 is that the melt index of the POE resin is 10 g / 10 min.

[0069] Example 11

[0070] The difference from Example 1 is that 100 parts by weight of modified POE resin, 1 part by weight of trimethylolpropane trimethacrylate, 0.4 parts by weight of bisphenol A epoxy resin E51, and 0.02 parts by weight of antioxidant 330 are mixed evenly to obtain a UV-curable buffer layer material.

[0071] Example 12

[0072] The difference from Example 1 is that 100 parts by weight of modified POE resin, 2 parts by weight of trimethylolpropane trimethacrylate, 0.6 parts by weight of bisphenol A epoxy resin E51, and 0.05 parts by weight of antioxidant 330 are mixed evenly to obtain a UV-curable buffer layer material.

[0073] Example 13

[0074] The difference from Example 1 is that 100 parts by weight of modified POE resin, 0.4 parts by weight of trimethylolpropane trimethacrylate, 0.1 parts by weight of bisphenol A epoxy resin E51, and 0.06 parts by weight of antioxidant 330 are mixed evenly to obtain UV-curable buffer layer material.

[0075] Example 14

[0076] The difference from Example 1 is that the UV co-crosslinking agent is 1,6-hexanediol diacrylate.

[0077] Example 15

[0078] The difference from Example 1 is that 100 parts by weight of EVA, 1 part by weight of tert-butyl peroxycarbonate-2-ethylhexyl ester, 1 part by weight of triallyl isocyanurate, 1 part by weight of γ-aminopropyltriethoxysilane, and 0.05 parts by weight of antioxidant 330 are mixed evenly to obtain a thermosetting adhesive layer material.

[0079] Example 16

[0080] The difference from Example 1 is that 100 parts by weight of EVA, 2 parts by weight of tert-butyl peroxycarbonate-2-ethylhexyl ester, 2 parts by weight of triallyl isocyanurate, 2 parts by weight of γ-aminopropyltriethoxysilane, and 0.02 parts by weight of antioxidant 330 are mixed evenly to obtain a thermosetting adhesive layer material.

[0081] Example 17

[0082] The difference from Example 1 is that 100 parts by weight of EVA, 0.4 parts by weight of tert-butyl peroxycarbonate-2-ethylhexyl ester, 0.4 parts by weight of triallyl isocyanurate, 0.3 parts by weight of γ-aminopropyltriethoxysilane, and 0.1 parts by weight of antioxidant 330 are mixed evenly to obtain a thermosetting adhesive layer material.

[0083] Example 18

[0084] The difference from Example 1 is that the free radical thermal initiator is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane and the co-crosslinking agent is trimethylolpropane tetraacrylate.

[0085] Example 19

[0086] The difference from Example 1 is that the UV curing buffer layer of the HJT cell encapsulation film has a thickness of 0.05 mm and the thermosetting adhesive layer has a thickness of 0.35 mm.

[0087] Example 20

[0088] The difference from Example 1 is that the UV curing buffer layer of the HJT cell encapsulation film has a thickness of 0.35 mm and the thermosetting adhesive layer has a thickness of 0.65 mm.

[0089] Comparative Example 1

[0090] The difference from Example 1 is that the modified POE resin is directly replaced with POE resin.

[0091] At 20–30°C and under DMA compression mode, the storage modulus (denoted as A) of the UV-cured buffer layer and the storage modulus (denoted as B) of the thermosetting adhesive layer in Examples 1 to 20 and Comparative Example 1 were tested. The pre-crosslinking degree of the upper surface of the UV-cured buffer layer (denoted as C), the pre-crosslinking degree of the lower surface of the UV-cured buffer layer (denoted as D), and the difference between the pre-crosslinking degree of the upper surface of the UV-cured buffer layer and the pre-crosslinking degree of the lower surface of the UV-cured buffer layer (denoted as E) were also tested. The test results are listed in Table 1.

[0092] Table 1

[0093]

[0094]

[0095] The HJT cell encapsulation films obtained in Examples 1 to 20 and Comparative Example 1 were used as the first encapsulation film layer. The front transparent encapsulation layer, the first encapsulation film layer, the HJT cell array, the second encapsulation film layer and the back encapsulation layer were stacked in sequence to obtain a photovoltaic module. The test piece was obtained by laminating it in a laminator at 150°C for 15 minutes.

[0096] 1. Peel strength F and G: The test method is as described in GB / T 2790. The peel strength (denoted as F) between the first encapsulating film layer and the HJT cell array and the peel strength (denoted as G) between the first encapsulating film layer and the front transparent encapsulating layer are measured on a tensile tester at a tensile speed of 100 mm / min.

[0097] 2. Photoelectric conversion efficiency: The test method is specified in GB / T34160-2017.

[0098] 3. Check for poor soldering and microcracks in the battery cells: the test method is described in IEC TS 60904-13-2018.

[0099] The test results are listed in Table 2.

[0100] Table 2

[0101]

[0102]

[0103] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0104] The encapsulating film of this invention employs a special two-layer structure consisting of a UV-curable buffer layer and a thermosetting adhesive layer. The UV-curable buffer layer is made of a material containing… and / or Photoinitiator molecular fragments with functional groups are grafted onto POE resin to create a buffer layer with different pre-crosslinking degrees along the thickness direction of the UV-curable buffer layer. The pre-crosslinking degree gradually decreases along the direction close to the thermosetting adhesive layer in the UV-curable buffer layer. This prevents the encapsulating film from flowing too quickly and penetrating into the gap between the solder ribbon and the cell, thus avoiding the problem of poor soldering. It also avoids the problem of excessive pre-crosslinking of the UV-curable buffer layer causing microcracks in the cell during lamination. At the same time, it can prevent initiator migration, which can lead to yellowing and additive precipitation. When applied to HJT battery encapsulation, it can solve the problems of poor soldering and microcracks in the cell that are easy to form in HJT battery encapsulation.

[0105] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An encapsulation film, characterized by, The encapsulation adhesive film comprises a UV curing buffer layer and a thermal curing adhesive layer stacked in sequence, wherein the material of the UV curing buffer layer comprises a modified POE resin and a UV auxiliary crosslinking agent, the modified POE resin is grafted with a UV initiator molecule fragment containing and / or a functional group, wherein "*" represents its connection position in the UV initiator molecule fragment; The UV-cured cushion layer has a pre-crosslinking degree of 5-45%, and the pre-crosslinking degree of the UV-cured cushion layer decreases along a direction close to the heat-cured adhesive layer in a thickness direction of the UV-cured cushion layer.

2. The encapsulation film according to claim 1, wherein, The raw materials of the modified POE resin include, in parts by weight: 100 parts by weight of a POE resin; 0.02-0.15 parts by weight of a grafting initiator; 0.1-0.5 parts by weight of a photoinitiator; and 0.02-0.05 parts by weight of a first antioxidant.

3. The encapsulation film according to claim 2, wherein, The photoinitiator contains at least one terminal carbon-carbon double bond and at least one functional group, and the relative molecular mass of the photoinitiator is 150-350.

4. The encapsulation film according to claim 3, wherein, The photoinitiator is selected from any one or more of , , , , .

5. The encapsulation film of claim 2, wherein The POE resin has a melt index of 10-30 g / 10 min.

6. The encapsulation film of claim 2, wherein, The grafting initiator is selected from any one or more of 1,1,3,3-tetramethylbutyl peroxy pivalate, t-amyl peroxy pivalate, t-butyl peroxy pivalate, di(3,3,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, didecanoyl peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoyl peroxide) hexane, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, di(4-methylbenzoyl) peroxide, t-amyl peroxy-2-ethylhexanoate.

7. The encapsulation film of claim 2, wherein The first antioxidant is selected from any one or more of antioxidant 330, antioxidant 168, antioxidant 1010, antioxidant RD.

8. The encapsulation film of claim 1, wherein, The UV-cured cushion layer includes, in parts by weight: 100 parts by weight of the modified POE resin; 0.5-2 parts by weight of the UV co-crosslinking agent; and 0.02-0.05 parts by weight of a second antioxidant.

9. The encapsulation film according to claim 8, wherein, The UV co-crosslinking agent is selected from any one or more of trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate.

10. The encapsulation film of claim 8, wherein, The second antioxidant is selected from any one or more of antioxidant 330, antioxidant 168, antioxidant 1010, antioxidant RD.

11. The encapsulation film of claim 1, wherein, The UV-cured cushion layer further includes, in parts by weight, 0.2-0.6 parts by weight of a first tackifier.

12. The encapsulation film according to claim 11, wherein, The first tackifier includes an ether bond and a hydroxyl group.

13. The encapsulation film of claim 11, wherein, The first tackifier is selected from any one or more of bisphenol A epoxy resin, polyethylene glycol, polypropylene glycol.

14. The encapsulation film of claim 1, wherein, The UV-cured cushion layer has a storage modulus of 3-10 MPa under 20-30 °C in DMA compression mode.

15. The encapsulation film of claim 1, wherein, The heat-cured adhesive layer has a storage modulus of <2 MPa.

16. The encapsulation film of claim 1, wherein, The UV-cured cushion layer has a thickness of 0.05-0.35 mm.

17. The encapsulation film of claim 1, wherein, The heat-cured adhesive layer has a thickness of 0.35-0.65 mm.

18. The encapsulation film of claim 1, wherein, The heat-cured adhesive layer includes, in parts by weight: 100 parts by weight of a base resin; 0.5-2 parts by weight of a free radical thermal initiator; 0.5-2 parts by weight of a thermal co-crosslinking agent; 0.4-2 parts by weight of a second tackifier; and 0.02-0.1 parts by weight of a third antioxidant.

19. The encapsulation film of claim 18, wherein, The free radical thermal initiator is selected from any one or more of t-butyl peroxy isopropyl carbonate, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 1-bis(t-butylperoxy)-3,3,5-trimethyl cyclohexane, t-butyl peroxy-2-ethylhexyl carbonate, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,1-bis(t-amylperoxy)-3,3,5-trimethyl cyclohexane, 1,1-bis(t-amylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)butane, t-amyl peroxy-2-ethylhexyl carbonate, t-amyl peroxy carbonate.

20. The encapsulation film of claim 18, wherein, The thermal co-agent is an ester compound containing multiple unsaturated groups.

21. The encapsulation film of claim 20, wherein, The ester compound is selected from any one or more of tris(2-hydroxyethyl)isocyanurate triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, ethoxylated glycerol triacrylate, propoxylated glycerol triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate, ditrimethylolpropane tetraacrylate, ditrimethylolpropane tetramethacrylate, propoxylated pentaerythritol tetraacrylate, tricyclodecane dimethanol diacrylate, propoxylated neopentyl glycol diacrylate, ethoxylated bisphenol A diacrylate, trivinyl isocyanurate.

22. The encapsulation film of claim 18, wherein, The second adhesion promoter is selected from any one or more of gamma-aminopropyl triethoxysilane, gamma-methacryloxypropyl trimethoxysilane, gamma-(2,3-epoxypropoxy)propyl trimethoxysilane, vinyl trimethoxysilane, N-(beta-aminoethyl)-gamma-aminopropyl trimethoxysilane.

23. The encapsulation film of claim 18, wherein, The third antioxidant is selected from any one or more of antioxidant 330, antioxidant 168, antioxidant 1010, antioxidant RD.

24. The encapsulation film of claim 18, wherein, The base resin is selected from any one or more of EVA, PVA, PMMA, POE. 25.A photovoltaic module, comprising a front transparent encapsulation layer, a first encapsulation film layer, an array of HJT cell pieces, a second encapsulation film layer, and a back encapsulation layer, characterized in that, The first encapsulation adhesive film layer is the encapsulation adhesive film of any one of claims 1 to 24, and the UV-cured buffer layer of the encapsulation adhesive film is directly in contact with the array of HJT cell pieces.

26. The photovoltaic module of claim 25, wherein, The peeling strength between the first encapsulation adhesive film layer and the array of HJT cell pieces is greater than 35 N / cm, and the peeling strength between the first encapsulation adhesive film layer and the front transparent encapsulation layer is greater than 100 N / cm.

Images