An encapsulation adhesive film, a preparation method and application thereof

Abstract

The application provides a packaging adhesive film and a preparation method and application thereof. The preparation raw material of the packaging adhesive film comprises the following components in parts by weight: 100 parts of POE resin, 0.5-2.5 parts of an initiator, 0.5-3 parts of a co-crosslinking agent, 0.1-3 parts of a silane coupling agent and 0.1-5 parts of dopamine modified acrylate. The packaging adhesive film provided by the application has good adhesion to a heterojunction cell and good adhesion to glass, has good aging resistance, and meets the use requirements of the heterojunction cell.

Description

Technical Field

[0001] This invention belongs to the field of heterojunction battery technology, specifically relating to an encapsulating film, its preparation method, and its application. Background Technology

[0002] Photovoltaic power generation is an important renewable energy source, and its scale is continuously increasing. Currently, PERC cells are the mainstream in the photovoltaic industry. In 2021, PERC cells accounted for 91.2% of the market share, with an average efficiency of 23.1%. Mass production conversion efficiency has gradually approached its theoretical upper limit, leaving little room for further improvement. n-type monocrystalline cell technology (Topcon and heterojunction) has an average conversion efficiency 1-3% higher than PERC p-type monocrystalline cells, making it the next-generation battery technology attracting market attention.

[0003] Heterojunction solar cells offer advantages such as higher conversion efficiency, simpler manufacturing processes, lower light-induced degradation, lower low-temperature coefficient, higher stability, and higher bifaciality. However, they also suffer from higher costs and poor adhesion between the surface ITO layer and the encapsulating film. Therefore, encapsulating films for heterojunction solar cells have become a key research focus.

[0004] CN111621235A discloses a polyolefin encapsulating film for heterojunction solar cells. The raw materials of the polyolefin encapsulating film for heterojunction solar cells, by weight, include: 100 parts of polyolefin copolymer, 0.1-1.5 parts of coupling agent, 0.1-1 parts of UV absorber, 0.01-1 parts of antioxidant, 0.1-2 parts of crosslinking agent, 0.01-4 parts of anti-aging agent, and 0.05-1 parts of viscosity reducer, in any one or more combinations thereof. This technical solution utilizes the synergistic effect of antioxidants and anti-aging agents to give the film good aging resistance, effectively ensuring the service life of heterojunction solar cell modules. However, the adhesion between the encapsulating film and the heterojunction solar cell is relatively poor.

[0005] CN114456731A discloses a high-viscosity, load-bearing integrated heterojunction encapsulating film and its preparation method. The heterojunction encapsulating film comprises, from top to bottom, a reinforcing layer, an adhesive layer, a first substrate layer, a second substrate layer, and a third substrate layer. The thickness of the reinforcing layer is 50-200 μm, the thickness of the adhesive layer is 50-80 μm, the thickness of the first substrate layer is 150-250 μm, the thickness of the second substrate layer is 200-300 μm, and the thickness of the third substrate layer is 150-250 μm. The method for preparing the heterojunction encapsulating film is as follows: EVA matrix resin, antioxidant, coupling agent, and adhesion-enhancing agent are stirred to obtain a first matrix layer mixture; POE matrix resin, EVA matrix resin, antioxidant, and coupling agent are stirred to obtain a second matrix layer mixture; POE matrix resin, antioxidant, crosslinking agent, and coupling agent are stirred to obtain a third matrix layer mixture; the above mixtures are simultaneously extruded through the die of a multi-layer co-extrusion extruder. When the three matrix layers are pressed together by the rubber roller and steel roller, a high-viscosity, load-bearing, integrated heterojunction encapsulating film is formed. Although the encapsulating film provided by this technical solution has good adhesion to the glass side of the heterojunction battery, its structure is relatively complex, resulting in poor adhesion to the heterojunction battery cell.

[0006] Conventional crystalline silicon solar cells have a silicon nitride surface structure, which allows for excellent adhesion to the encapsulating film. However, the ITO (indium tin oxide) layer on the surface of heterojunction solar cells exhibits adhesion defects with the tackifier within the encapsulating film, making good adhesion difficult. This leads to decreased reliability of heterojunction solar modules and poses risks after long-term use. While existing encapsulating films exhibit good adhesion to glass, their adhesion to heterojunction solar cells is poor.

[0007] Therefore, how to provide an encapsulating film that has good adhesion to both heterojunction solar cells and glass has become an urgent technical problem to be solved. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide an encapsulating film, its preparation method, and its application. In this invention, by designing the raw materials for preparing the encapsulating film and further utilizing the combined use of dopamine-modified acrylate and silane coupling agents, the resulting encapsulating film exhibits good adhesion to both heterojunction solar cells and glass, while also possessing good anti-aging properties, thus meeting the requirements for use in heterojunction solar cells.

[0009] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides an encapsulating film, wherein the raw materials for preparing the encapsulating film comprise the following components in parts by weight: The composition includes 100 parts of POE resin, 0.5-2.5 parts of initiator, 0.5-3 parts of co-crosslinking agent, 0.1-3 parts of silane coupling agent, and 0.1-5 parts of dopamine-modified acrylate.

[0010] In this invention, by designing the raw materials for preparing the encapsulating film, and further by using dopamine-modified acrylate, the adhesion between the encapsulating film and the heterojunction solar cell can be improved; by using silane coupling agent, the adhesion between the encapsulating film and the glass can be improved, thereby preparing an encapsulating film with excellent performance that meets the requirements for use in heterojunction solar cells.

[0011] In this invention, the initiator can be 0.5 parts, 0.7 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, or 2.5 parts, etc.

[0012] In this invention, the crosslinking agent can be 0.5 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.3 parts, 2.5 parts, 2.7 parts, or 3 parts, etc.

[0013] The silane coupling agent can be 0.1 parts, 0.5 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.3 parts, 2.5 parts, 2.7 parts, or 3 parts, etc.

[0014] The dopamine-modified acrylate can be in quantities of 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, or 5 parts, etc.

[0015] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0016] As a preferred embodiment of the present invention, the initiator is selected from any one or a combination of at least two of the following: tert-butyl peroxycarbonate, 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-bis(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-pentyl peroxycarbonate, and tert-pentyl peroxycarbonate.

[0017] Preferably, the crosslinking agent is selected from any one or a combination of at least two of the following: triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, propionyl glycerol triacrylate, ethoxylated triglycerol triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate, bis(trimethylolpropane tetraacrylate), and bis(trimethylolpropane tetramethacrylate).

[0018] As a preferred embodiment of the present invention, the silane coupling agent is selected from γ-aminopropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltrimethoxysilane, and... N Any one or a combination of at least two of the following: -(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0019] As a preferred embodiment of the present invention, the raw materials for preparing the dopamine-modified acrylate include dopamine, pentaerythritol triacrylate, and a condensing agent.

[0020] Preferably, the molar ratio of dopamine to pentaerythritol triacrylate is 1:1.

[0021] Preferably, the condensing agent is selected from any one or a combination of at least two of 1,3-dicyclohexylcarbodiimide (DCC), condensing agent HBTU, condensing agent TBTU, and condensing agent HOBT.

[0022] Preferably, the molar ratio of dopamine to condensing agent is 1:(1~1.5), for example, it can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5, etc.

[0023] As a preferred embodiment of the present invention, the dopamine-modified acrylic acid is prepared by the following method, the method comprising: Dopamine, pentaerythritol triacrylate, and a condensing agent are added to a solvent and reacted to obtain the dopamine-modified acrylic acid.

[0024] The solution is then precipitated in hexane or chloroform, washed several times with hexane or chloroform, and finally dried under vacuum overnight and refrigerated.

[0025] Preferably, the reaction is carried out in a nitrogen atmosphere.

[0026] Preferably, the reaction temperature is 60~80℃, for example, it can be 60℃, 62℃, 64℃, 66℃, 68℃, 70℃, 72℃, 74℃, 76℃, 78℃ or 80℃, etc.

[0027] Preferably, the reaction time is 8 to 12 hours, for example, 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours or 12 hours.

[0028] Preferably, the solvent is selected from any one or a combination of at least two of dichloromethane (DCM), tetrahydrofuran, acetonitrile, or dimethylamide.

[0029] Preferably, the reaction further includes a post-processing step.

[0030] Preferably, the post-processing method includes precipitation, washing, and vacuum drying.

[0031] The solution is then precipitated in hexane or chloroform, washed several times with hexane or chloroform, and finally dried under vacuum overnight and refrigerated.

[0032] It should also be noted that in this invention, dopamine-modified acrylic acid is obtained by reacting the amino group in dopamine with the hydroxyl group in pentaerythritol triacrylate, followed by a carbon-carbon double bond polymerization reaction. The reaction process between the amino group in dopamine and the hydroxyl group in pentaerythritol triacrylate is as follows: In this invention, the dopamine-modified acrylic acid is prepared by the following method, the method comprising: Dopamine, pentaerythritol triacrylate, and a condensing agent were added to a solvent, nitrogen gas was introduced, and the mixture was stirred at 60-80°C for 8-12 hours. The reaction solution was then precipitated in hexane or chloroform and washed several times with hexane or chloroform. Finally, the mixture was dried under vacuum overnight and refrigerated to obtain the dopamine-modified acrylate.

[0033] As a preferred technical solution of the present invention, the raw materials for preparing the encapsulating film further include 0.05 to 1.5 parts of light stabilizer, for example, 0.05 parts, 0.1 parts, 0.2 parts, 0.4 parts, 0.5 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.2 parts, or 1.5 parts, etc.

[0034] Preferably, the light stabilizer is selected from any one or a combination of at least two of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, and polysuccinate (4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol).

[0035] Preferably, the raw materials for preparing the encapsulating film also include 0.05 to 1.5 parts of ultraviolet light absorber, for example, 0.05 parts, 0.1 parts, 0.2 parts, 0.4 parts, 0.5 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.2 parts, or 1.5 parts.

[0036] Preferably, the ultraviolet absorber is selected from any one or a combination of at least two of 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-5-tert-octyl)phenylbenzotriazole, 2-(2-hydroxy-3,5-dicumylphenyl)benzotriazole, and 2-hydroxy-4-n-octyloxybenzophenone.

[0037] As a preferred embodiment of the present invention, the thickness of the encapsulating film is 0.45~0.8 μm, for example, it can be 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm or 0.8 μm, etc.

[0038] In a second aspect, the present invention provides a method for preparing an encapsulating film as described in the first aspect, the method comprising the following steps: The raw materials for preparing the encapsulating film are mixed and then cast and extruded to obtain the encapsulating film.

[0039] As a preferred embodiment of the present invention, the mixing time is 4 to 8 hours, for example, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours.

[0040] Preferably, the mixing method is to use a high-speed mixer; Preferably, the high-speed mixer has a rotation speed of 750~1500 rpm, for example, 750 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm or 1500 rpm.

[0041] Preferably, the casting extrusion method is as follows: the mixture obtained by mixing the raw materials for preparing the encapsulating film is placed in the single-screw extruder of the casting machine, melted and conveyed at 80~100℃ (for example, it can be 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, 92℃, 94℃, 96℃, 98℃ or 100℃, etc.), and flows to the casting die head for casting extrusion; wherein, the temperature of the casting die head is 100~120℃ (for example, it can be 100℃, 102℃, 104℃, 106℃, 108℃, 110℃, 112℃, 114℃, 116℃, 118℃ or 120℃, etc.).

[0042] Preferably, the extrusion process further includes a post-processing step.

[0043] Preferably, the post-processing method includes stretching, cooling and shaping, trimming and winding.

[0044] Preferably, the method for preparing the encapsulating film specifically includes the following steps: The raw materials for preparing the encapsulating film were placed in a high-speed mixer and mixed for 30 to 60 minutes at a speed of 1200 to 3000 rpm to obtain a mixture. The mixture is placed in the single-screw extruder of the casting machine, melted and conveyed at 80~100℃, and then flowed to the casting die head for casting extrusion, stretching, cooling and shaping, trimming and winding to obtain the encapsulating film; wherein the temperature of the casting die head is 100~150℃.

[0045] Thirdly, the present invention provides an application of the encapsulating film as described in the first aspect in heterojunction batteries.

[0046] Compared with the prior art, the present invention has the following beneficial effects: In this invention, by designing the raw materials for preparing the encapsulating film, and further using the combined application of dopamine-modified acrylate and silane coupling agent, while controlling the content of dopamine-modified acrylate within a specific range, the resulting encapsulating film exhibits good adhesion to both heterojunction solar cells and glass, as well as good anti-aging properties. Its peel strength with the heterojunction solar cell before PCT is 116~133 N / cm, and after PCT is 100~108 N / cm. Its peel strength with glass before PCT is 85~97 N / cm, and after PCT is 76~84 N / cm, meeting the requirements for heterojunction solar cells. Detailed Implementation

[0047] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0048] The sources of some components in the following examples and comparative examples are as follows: POE resin: composed of ENGAGE™ PV 8660 and ENGAGE™ PV 8669 in a 1:1 mass ratio, both of which were purchased from Dow Chemical Company.

[0049] Example 1 This embodiment provides an encapsulating film and its preparation method. The raw materials for preparing the encapsulating film include the following components in parts by weight: 100 parts of POE resin, 1 part of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2 parts of trimethylolpropane triacrylate, 1 part of γ-methacryloyloxypropyltrimethoxysilane, 2 parts of dopamine-modified acrylate, 1 part of bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, and 1 part of 2-(2-hydroxy-5-tertoctyl)phenylbenzotriazole; The dopamine-modified acrylate was prepared by the following method: Dopamine, pentaerythritol triacrylate and 1,3-dicyclohexylcarbodiimide were added to dichloromethane (20 mL), nitrogen gas was introduced, and the mixture was stirred at 70 °C for 10 h. The reaction solution was then precipitated in hexane and washed several times with hexane. Finally, it was dried under vacuum overnight and refrigerated to obtain the dopamine-modified acrylate. The molar ratio of dopamine, pentaerythritol triacrylate and 1,3-dicyclohexylcarbodiimide is 1:1:1.2.

[0050] The preparation method of the above-mentioned encapsulating film is as follows: The raw materials for preparing the encapsulating film were placed in a high-speed mixer and mixed for 6 hours at a speed of 1000 rpm to obtain a mixture. The mixture is placed in the single-screw extruder of the casting machine, melted and conveyed at 90°C, and then flowed to the casting die head for casting extrusion, stretching, cooling and shaping, trimming and winding to obtain an encapsulation film with a thickness of 0.6 μm; wherein the temperature of the casting die head is 110°C.

[0051] Example 2 This embodiment provides an encapsulating film and its preparation method. The raw materials for preparing the encapsulating film include the following components in parts by weight: 100 parts of POE resin, 0.5 parts of tert-butyl peroxycarbonate, 0.5 parts of triallyl isocyanurate, 0.5 parts of γ-aminopropyltriethoxysilane, 0.5 parts of dopamine-modified acrylate, 0.05 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and 0.05 parts of 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole; The dopamine-modified acrylate was prepared by the following method: Dopamine, pentaerythritol triacrylate and condensing agent HBTU were added to tetrahydrofuran (30 mL), nitrogen gas was introduced, and the mixture was stirred at 60 °C for 12 h. The reaction solution was then precipitated in hexane or chloroform and washed several times with hexane or chloroform. Finally, the mixture was dried under vacuum overnight and refrigerated to obtain the dopamine-modified acrylate. The molar ratio of dopamine, pentaerythritol triacrylate, and condensing agent HBTU is 1:1:1.

[0052] The preparation method of the above-mentioned encapsulating film is as follows: The raw materials for preparing the encapsulating film were placed in a high-speed mixer and mixed for 8 hours at a speed of 750 rpm to obtain a mixture. The mixture is placed in the single-screw extruder of the casting machine, melted and conveyed at 90°C, and then fed into the casting die head for casting extrusion, stretching, cooling and shaping, trimming and winding to obtain an encapsulation film with a thickness of 0.45 μm; wherein the temperature of the casting die head is 100°C.

[0053] Example 3 This embodiment provides an encapsulating film and its preparation method. The raw materials for preparing the encapsulating film include the following components in parts by weight: 100 parts of POE resin, 2.5 parts of 1,1-bis(tert-butylperoxy)cyclohexane, 3 parts of glycerol triacrylate ethoxylate, 3 parts of vinyltrimethoxysilane, 4 parts of dopamine-modified acrylate, 1.5 parts of poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol) ester, and 1.2 parts of 2-hydroxy-4-n-octyloxybenzophenone; The dopamine-modified acrylate was prepared by the following method: Dopamine, pentaerythritol triacrylate and condensing agent TBTU were added to dimethylamide (25 mL), nitrogen gas was introduced, and the mixture was stirred at 80 °C for 8 h. After the reaction was completed, the reaction solution was precipitated in hexane or chloroform and washed several times with hexane or chloroform. Finally, the solution was dried under vacuum overnight and refrigerated to obtain the dopamine-modified acrylate. The molar ratio of dopamine, pentaerythritol triacrylate and condensing agent TBTU is 1:1:1.5.

[0054] The preparation method of the above-mentioned encapsulating film is as follows: The raw materials for preparing the encapsulating film were placed in a high-speed mixer and mixed for 4 hours at a speed of 1500 rpm to obtain a mixture. The mixture is placed in the single-screw extruder of the casting machine, melted and conveyed at 90°C, and then flowed to the casting die head for casting extrusion, stretching, cooling and shaping, trimming and winding to obtain an encapsulation film with a thickness of 0.8 μm; wherein, the temperature of the casting die head is 120°C.

[0055] Example 4 This embodiment provides an encapsulating film and its preparation method. The raw materials for preparing the encapsulating film include the following components in parts by weight: 100 parts POE resin, 2 parts 2-ethylhexyl carbonate tert-amyl peroxide, 1 part pentaerythritol tetraacrylate N 0.1 parts of β-aminoethyl)-γ-aminopropyltrimethoxysilane, 5 parts of dopamine-modified acrylate, 1.5 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and 1.5 parts of 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole; The dopamine-modified acrylate was prepared by the following method: Dopamine, pentaerythritol triacrylate and condensing agent HOBT were added to tetrahydrofuran (35 mL), nitrogen gas was introduced, and the mixture was stirred at 70 °C for 9 h. The reaction solution was then precipitated in hexane or chloroform and washed several times with hexane or chloroform. Finally, the mixture was dried under vacuum overnight and refrigerated to obtain the dopamine-modified acrylate. The molar ratio of dopamine, pentaerythritol triacrylate and condensing agent HOBT is 1:1:1.3.

[0056] The preparation method of the above-mentioned encapsulating film is as follows: The raw materials for preparing the encapsulating film were placed in a high-speed mixer and mixed for 7 hours at a speed of 1200 rpm to obtain a mixture. The mixture is placed in the single-screw extruder of the casting machine, melted and conveyed at 90°C, and then flowed to the casting die head for casting extrusion, stretching, cooling and shaping, trimming and winding to obtain an encapsulation film with a thickness of 0.6 μm; wherein, the temperature of the casting die head is 100°C.

[0057] Example 5 This embodiment provides an encapsulating film and its preparation method. The only difference from Embodiment 1 is that the weight of dopamine-modified acrylate in the encapsulating film is 0.1 parts, and the other conditions are the same as in Embodiment 1.

[0058] Example 6 This embodiment provides an encapsulating film and its preparation method. The only difference from Embodiment 1 is that the dopamine-modified acrylate in the encapsulating film is 5 parts by weight, and the other conditions are the same as in Embodiment 1.

[0059] Comparative Example 1 This comparative example provides an encapsulating film and its preparation method. The only difference from Example 1 is that the weight of dopamine-modified acrylate in the encapsulating film is 0.05 parts, and the other conditions are the same as in Example 1.

[0060] Comparative Example 2 This comparative example provides an encapsulating film and its preparation method. The only difference from Example 1 is that the dopamine-modified acrylate in the encapsulating film is 7 parts by weight, and the other conditions are the same as in Example 1.

[0061] Comparative Example 3 This comparative example provides an encapsulating film and its preparation method. The only difference from Example 1 is that the dopamine-modified acrylate in the encapsulating film is 3 parts by weight and does not contain silane coupling agent. Other conditions are the same as in Example 1.

[0062] Comparative Example 4 This comparative example provides an encapsulating film and its preparation method. The only difference from Example 1 is that the encapsulating film contains 3 parts by weight of silane coupling agent and does not contain dopamine-modified acrylate. Other conditions are the same as in Example 1.

[0063] Comparative Example 5 This comparative example provides an encapsulating film and its preparation method. The only difference from Example 2 is that the encapsulating film does not contain dopamine-modified acrylate, while the other conditions are the same as in Example 2.

[0064] The performance of the encapsulating films provided in the above embodiments and comparative examples was tested, and the specific test methods are as follows: Peel strength to glass: The glass / encapsulating film (two pieces) / flexible backsheet are stacked in sequence and placed in a vacuum laminator, and laminated at 145℃ for 15 min; then the peel strength is tested according to GB / T 29848-2018 Test method for peel strength of ethylene-vinyl acetate copolymer (EVA) film for photovoltaic module encapsulation.

[0065] Peel strength with heterojunction solar cells: The glass / encapsulating film / heterojunction solar cells / double-sided release film / encapsulating film / flexible backsheet are stacked in sequence and placed in a vacuum laminator, where they are laminated at 145°C for 15 minutes. The double-sided release film is pre-cut with a 1 cm wide and 15 cm long notch to ensure that the 1 cm wide strips of contact between the encapsulating film and the solar cells do not include the grid lines on the solar cell surface. The peel strength is then tested according to GB / T 29848-2018 Test Method for Peel Strength of Ethylene-Vinyl Acetate Copolymer (EVA) Film for Photovoltaic Module Encapsulation.

[0066] The performance test results of the encapsulating films provided in the above embodiments and comparative examples are shown in Table 1 below: Table 1 As shown in Table 1, by designing the raw materials for preparing the encapsulating film in this invention, and further by using dopamine-modified acrylate and silane coupling agent in combination, while controlling the content of dopamine-modified acrylate within a specific range, the resulting encapsulating film exhibits good adhesion to both heterojunction solar cells and glass, and also has good anti-aging properties. Its peel strength with the heterojunction solar cell before PCT is 116~133 N / cm, and its peel strength after PCT is 100~108 N / cm. Its peel strength with the glass before PCT is 85~97 N / cm, and its peel strength after PCT is 76~84 N / cm, meeting the requirements for use with heterojunction solar cells.

[0067] Compared with Example 1, if the content of dopamine-modified acrylate in the encapsulating film is too low (Comparative Example 1) or the content of dopamine-modified acrylate in the encapsulating film is too high (Comparative Example 2), the peel strength of the encapsulating film after PCT to the heterojunction cell is low and the anti-aging performance is poor.

[0068] Compared with Example 1, if the encapsulating film does not contain silane coupling agent (Comparative Example 3) or dopamine modified acrylate (Comparative Example 4), the overall performance of the encapsulating film is poor.

[0069] Compared with Example 2, if the encapsulating film does not contain dopamine-modified acrylate (Comparative Example 5), the performance of the encapsulating film prepared is worse.

[0070] In summary, by designing the raw materials for preparing the encapsulating film, and further by using dopamine-modified acrylate and silane coupling agent in combination, while controlling the content of dopamine-modified acrylate within a specific range, the resulting encapsulating film exhibits good adhesion to both heterojunction solar cells and glass, as well as good anti-aging properties.

[0071] The applicant declares that the detailed process flow of this invention is illustrated by the above embodiments, but this invention is not limited to the above detailed process flow, that is, it does not mean that this invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. An encapsulating film, characterized in that, The raw materials for preparing the encapsulating film include the following components in parts by weight: 100 parts of POE resin, 0.5-2.5 parts of initiator, 0.5-3 parts of co-crosslinking agent, 0.1-3 parts of silane coupling agent, and 0.1-5 parts of dopamine-modified acrylate; The raw materials for preparing the dopamine-modified acrylate include dopamine, pentaerythritol triacrylate, and a condensing agent. The molar ratio of dopamine to pentaerythritol triacrylate is 1:1; The condensing agent is selected from any one or a combination of at least two of 1,3-dicyclohexylcarbodiimide, condensing agent HBTU, condensing agent TBTU, and condensing agent HOBT. The molar ratio of dopamine to condensing agent is 1:(1~1.5).

2. The encapsulating film according to claim 1, characterized in that, The initiator is selected from any one or a combination of at least two of the following: tert-butyl peroxycarbonate, 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-bis(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-pentyl peroxycarbonate, and tert-pentyl peroxycarbonate.

3. The encapsulating film according to claim 1, characterized in that, The co-crosslinking agent is selected from any one or a combination of at least two of the following: triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, propionyl glycerol triacrylate, ethoxylated triglycerol triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate, bis(trimethylolpropane tetraacrylate), and bis(trimethylolpropane tetramethacrylate).

4. The encapsulating film according to claim 1, characterized in that, The silane coupling agent is selected from γ-aminopropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltrimethoxysilane, and... N Any one or a combination of at least two of the following: -(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

5. The encapsulating film according to claim 1, characterized in that, The dopamine-modified acrylic acid is prepared by the following method, the method comprising: Dopamine, pentaerythritol triacrylate, and a condensing agent are added to a solvent and reacted to obtain the dopamine-modified acrylic acid.

6. The encapsulating film according to claim 5, characterized in that, The reaction was carried out in a nitrogen atmosphere.

7. The encapsulating film according to claim 5, characterized in that, The reaction temperature is 60~80℃.

8. The encapsulating film according to claim 5, characterized in that, The reaction time is 8-12 h.

9. The encapsulating film according to claim 1, characterized in that, The raw materials for preparing the encapsulating film also include 0.05 to 1.5 parts of light stabilizer.

10. The encapsulating film according to claim 9, characterized in that, The light stabilizer is selected from any one or a combination of at least two of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, and poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol) ester.

11. The encapsulating film according to claim 1, characterized in that, The raw materials for preparing the encapsulating film also include 0.05 to 1.5 parts of ultraviolet light absorber.

12. The encapsulating film according to claim 11, characterized in that, The ultraviolet absorber is selected from any one or a combination of at least two of 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-5-tert-octyl)phenylbenzotriazole, 2-(2-hydroxy-3,5-dicumylphenyl)benzotriazole, and 2-hydroxy-4-n-octyloxybenzophenone.

13. The encapsulating film according to claim 1, characterized in that, The thickness of the encapsulating film is 0.45~0.8 μm.

14. A method for preparing an encapsulating film as described in any one of claims 1-13, characterized in that, The preparation method includes the following steps: The raw materials for preparing the encapsulating film are mixed and then cast and extruded to obtain the encapsulating film.

15. The preparation method according to claim 14, characterized in that, The mixing time is 4 to 8 hours.

16. The preparation method according to claim 14, characterized in that, The mixing method is to use a high-speed mixer.

17. The preparation method according to claim 16, characterized in that, The high-speed mixer operates at a speed of 750~1500 rpm.

18. The application of an encapsulating film as described in any one of claims 1-14 in a heterojunction solar cell.

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