Packaging adhesive film, preparation method thereof and photovoltaic module

Abstract

The invention relates to a packaging adhesive film, a preparation method thereof and a photovoltaic module. The packaging adhesive film comprises an adhesive film body and thermochromic microcapsules dispersed in the adhesive film body, or the packaging adhesive film comprises the adhesive film body and a thermochromic layer arranged on the surface of the adhesive film body, and the material of the thermochromic layer comprises the thermochromic microcapsules; wherein the thermochromic microcapsule comprises an anti-ultraviolet material and a thermochromic material wrapped in the anti-ultraviolet material; the packaging adhesive film is black when the temperature is lower than the preset temperature and is white when the temperature is higher than the preset temperature. The packaging adhesive film is applied to the photovoltaic module and can be heated when the environment temperature is low and cooled when the environment temperature is high, so that the temperature of the photovoltaic module is kept stable, the stability of the performance of the photovoltaic module can be ensured, and the influence of the environment temperature on the generating capacity of the module is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaics, and in particular to an encapsulation film, a preparation method thereof, and a photovoltaic module. BACKGROUND

[0002] In the field of photovoltaics, the performance and reliability of photovoltaic modules, as core components, are crucial to the operation of the entire photovoltaic system. Temperature is one of the important factors affecting the performance of photovoltaic modules, and both excessively high and low temperatures can affect the power generation and reliability of photovoltaic modules. For example, long-term high temperature of photovoltaic modules not only reduces the power generation efficiency of photovoltaic modules, but also accelerates the aging process of the internal materials, thereby affecting the overall performance and service life of photovoltaic modules. In addition, high temperature can also exacerbate the hot spot effect of photovoltaic modules, leading to performance degradation or even damage of photovoltaic modules, and causing internal cell wiring short circuit, resulting in module failure. In addition, in low temperature environment, the energy capture rate of electrons and holes decreases, and the recombination rate of photo-generated carriers decreases, resulting in a significant decrease in the photoelectric conversion efficiency of photovoltaic modules. In addition, in low temperature environment, the open-circuit voltage of photovoltaic modules may increase, which may cause overvoltage protection of the inverter if it exceeds the maximum input voltage of the inverter, thereby affecting normal power generation. SUMMARY

[0003] Therefore, some embodiments of the present application provide an encapsulation film applied in a photovoltaic module, which can heat when the ambient temperature is low and cool when the ambient temperature is high, so as to keep the temperature of the photovoltaic module relatively stable, thereby ensuring the stability of the performance of the photovoltaic module and reducing the influence of the ambient temperature on the power generation of the module.

[0004] In addition, some other embodiments of the present application also provide a preparation method of the encapsulation film and a photovoltaic module comprising the above-mentioned encapsulation film.

[0005] An encapsulation film, comprising a film body and thermochromic microcapsules dispersed in the film body, or the encapsulation film comprising a film body and a thermochromic layer arranged on the surface of the film body, wherein the material of the thermochromic layer comprises thermochromic microcapsules;

[0006] The thermochromic microcapsules comprise an ultraviolet-resistant material and a thermochromic material wrapped inside the ultraviolet-resistant material.

[0007] The encapsulation film appears black when the temperature is lower than a preset temperature, and appears white when the temperature is higher than the preset temperature.

[0008] In some embodiments, the preset temperature is 15℃-35℃.

[0009] Optionally, the preset temperature is 15℃-25℃.

[0010] In some embodiments, the anti-ultraviolet material comprises reduced graphene oxide;

[0011] In some embodiments, the thermochromic material comprises a leuco dye, a developer, and a solvent, the leuco dye comprises crystal violet lactone, the developer comprises bisphenol A, and the solvent comprises one or more of n-tetradecanol, n-hexadecanol, n-octadecanol, and n-docosanol;

[0012] In some embodiments, the mass ratio of the anti-ultraviolet material and the thermochromic material is 2:1 to 1:2;

[0013] In some embodiments, the anti-ultraviolet material and the thermochromic material have electrostatic interaction.

[0014] In some embodiments, in the thermochromic material, the molar ratio of the leuco dye and the developer is 3:1 to 1:3;

[0015] Optionally, the molar ratio of the leuco dye and the developer is 3:1 to 1:1;

[0016] In some embodiments, in the thermochromic material, the molar ratio of the developer and the solvent is 1:(5-20).

[0017] In some embodiments, the thermochromic microcapsules are dispersed in the film body, and the encapsulated film comprises, by mass fraction, 100 parts of an ethylene copolymer matrix and 2-10 parts of thermochromic microcapsules.

[0018] In some embodiments, the encapsulated film further comprises, by mass fraction, 0.15-1 parts of an antioxidant, 0.5-5 parts of a silane coupling agent, 0.05-0.5 parts of a light stabilizer, and 0.5-2 parts of a crosslinking agent.

[0019] In some embodiments, the encapsulated film comprises a film body and a thermochromic layer disposed on the surface of the film body, and the thickness of the thermochromic layer is 0.05-0.2 mm.

[0020] A method for preparing an encapsulated film, comprising the following steps:

[0021] Mixing the raw materials for preparing the film body and the thermochromic microcapsules, and heating and extruding to form a film to prepare an encapsulated film; or forming a thermochromic layer on the surface of the film body to prepare an encapsulated film, and the material of the thermochromic layer comprises thermochromic microcapsules;

[0022] In some embodiments, the thermochromic microcapsules comprise an anti-ultraviolet material and a thermochromic material wrapped inside the anti-ultraviolet material;

[0023] The encapsulating adhesive film presents black color below the preset temperature and presents white color above the preset temperature.

[0024] In some of the embodiments, the temperature in the step of heating and extruding the film is 60-120℃.

[0025] Alternatively, the step of forming the thermochromic layer on the surface of the adhesive film body comprises: coating a solution in which the thermochromic microcapsules are dispersed on the surface of the adhesive film body and drying to form the thermochromic layer.

[0026] A photovoltaic module comprises: a panel, a first encapsulating adhesive film, a cell, a second encapsulating adhesive film and a backboard which are sequentially stacked, and at least one of the first encapsulating adhesive film and the second encapsulating adhesive film is prepared as described above or by the preparation method described above.

[0027] The encapsulating adhesive film comprises an adhesive film body and thermochromic microcapsules, the thermochromic microcapsules comprise an ultraviolet-resistant material and a thermochromic material wrapped inside the ultraviolet-resistant material, the encapsulating adhesive film presents black color below the preset temperature, can realize high absorption of solar radiation to effectively absorb heat and realize heating of the photovoltaic module; the encapsulating adhesive film presents white color above the preset temperature, can reflect most of the solar radiation, reduce the temperature and realize cooling of the photovoltaic module. Therefore, the encapsulating adhesive film is applied in the photovoltaic module, can heat when the ambient temperature is low and cool when the ambient temperature is high, keeps the temperature of the photovoltaic module stable, guarantees the performance stability of the photovoltaic module, reduces the influence of outdoor temperature on the power generation of the module and further improves the overall power generation of the photovoltaic system. In addition, the thermochromic material is wrapped by the ultraviolet-resistant material, strengthens the ultraviolet resistance of the material, improves the reliability of the material, enables the encapsulating adhesive film to have the intelligent temperature changing function while guaranteeing the reliability of the encapsulating adhesive film. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0029] Figure 1 A graph of monthly average power generation and monthly temperature for a certain photovoltaic power station;

[0030] Figure 2 A schematic diagram of the reversible thermochromic process of the thermochromic material in the encapsulating adhesive film of some embodiments of the present application;

[0031] Figure 3 A schematic diagram of the encapsulating adhesive film of some embodiments of the present application at different temperatures;

[0032] Figure 4 The reflectivity measurement results of traditional black EVA adhesive film and white EVA adhesive film of a certain manufacturer are shown in the following figures;

[0033] Figure 5 A structural schematic diagram of a photovoltaic module according to some embodiments of the present application is shown in the following figure;

[0034] Figure 6 The daily power generation efficiency detection curve of a photovoltaic module encapsulated with the encapsulating adhesive film of Example 1 and Comparative Example 1 is shown in the following figure. DETAILED DESCRIPTION

[0035] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the specific embodiments. In the specific embodiments, the preferred embodiments of the present application are given. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein is only for the purpose of describing the specific embodiments and is not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0037] Unless otherwise stated or contradictory, the terms or phrases used in the present application have the following meanings:

[0038] In the present application, "first", "second" are only used for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features.

[0039] In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0040] In the present application, "one or more" refers to any one, any two or any two or more of the listed items. Among them, "several" refers to any two or more.

[0041] In the present application, the percentage concentration involved, unless otherwise specified, refers to the final concentration. The final concentration refers to the proportion of the added component in the system after adding the component.

[0042] In the present application, "further", "even further", "in particular", "for example", "for instance", "as an example", "by way of example" and the like are used to describe different embodiments of the application and are not used to limit the scope of the application. In the present application, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0043] In the present application, "optionally", "optional" and "may" mean that it can or can not exist, that is, it means to select any one from the two parallel schemes of "yes" or "no". If there are multiple "optionally" in a technical solution, and there is no contradiction or mutual restriction relationship, each "optionally" is independent. In the present application, "optionally contains", "optionally includes" and the like mean "contains or does not contain". "Optional component X" means that component X exists or does not exist, or means that it contains or does not contain component X.

[0044] When a numerical range is disclosed in the present application, the above range is considered to be continuous, and includes the minimum value and the maximum value of the range, and each value between the minimum value and the maximum value. Further, when the range refers to an integer, each integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed in the present application should be understood to include any and all sub-ranges.

[0045] In the present application, the technical features described in an open manner include a closed technical solution consisting of listed features, and also include an open technical solution including listed features.

[0046] In the present application, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but can optionally include steps or units not listed, or can optionally include other steps or components inherent to the process, method, product or device.

[0047] In the present application, "embodiment" means that the specific features, structures or characteristics described in conjunction with the embodiment can be included in at least one embodiment of the present application. The phrase appears at various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present application can be combined with other embodiments.

[0048] As described in the background, temperature is one of the important factors affecting the performance of photovoltaic modules, and too high or too low temperature will affect the power generation and reliability of photovoltaic modules. Researchers select appropriate packaging adhesive films to insulate and protect photovoltaic modules, however, the current packaging adhesive films are also susceptible to environmental influences, especially in high temperature environment, decomposition, discoloration and other phenomena occur, there are obvious limitations, and cannot effectively balance the needs of heat insulation and heat dissipation.

[0049] Based on this, the first aspect of the present application provides an intelligent temperature-variable packaging adhesive film capable of realizing low-temperature heating and high-temperature cooling autonomously according to the working temperature of a photovoltaic module, comprising: a packaging adhesive film comprising an adhesive film body and thermochromic microcapsules dispersed inside the adhesive film body, or a packaging adhesive film comprising an adhesive film body and a thermochromic layer arranged on the surface of the adhesive film body, the material of the thermochromic layer comprising thermochromic microcapsules;

[0050] The thermochromic microcapsules comprise an ultraviolet-resistant material and a thermochromic material wrapped inside the ultraviolet-resistant material.

[0051] The packaging adhesive film appears black below a preset temperature and appears white above the preset temperature.

[0052] The packaging adhesive film comprises an adhesive film body and thermochromic microcapsules, the thermochromic microcapsules comprise an ultraviolet-resistant material and a thermochromic material wrapped inside the ultraviolet-resistant material, the packaging adhesive film appears black below a preset temperature and appears white above the preset temperature, which can realize high absorption of solar radiation to effectively absorb heat and realize heating of the photovoltaic module, and the packaging adhesive film appears white above the preset temperature, which can reflect most of the solar radiation to reduce the temperature and realize cooling of the photovoltaic module. Therefore, the packaging adhesive film is applied to the photovoltaic module, which can heat when the environmental temperature is low and cool when the environmental temperature is high, so that the temperature of the photovoltaic module remains relatively stable, thereby ensuring the performance stability of the photovoltaic module, reducing the influence of outdoor temperature on the power generation of the module, and further improving the overall power generation of the photovoltaic system. In addition, the thermochromic material is wrapped with an ultraviolet-resistant material to strengthen the ultraviolet resistance of the material and improve its reliability, so that the packaging adhesive film has the intelligent temperature-variable function while ensuring its reliability.

[0053] Intelligent adaptive thermal management is a recently emerging cutting-edge temperature-regulating technology that has been applied to textile manufacturing, demonstrating excellent thermal and optical modulation performance. However, this technology has not yet been applied in the photovoltaic field. Therefore, some embodiments of this application, based on intelligent adaptive thermal management technology, develop a novel intelligent temperature-regulating encapsulating film. When applied to photovoltaic modules, this film can autonomously heat when the ambient temperature is low and cool when the ambient temperature is high, thereby ensuring the stability of photovoltaic module performance, reducing the impact of outdoor temperature on module power generation, and ultimately improving the overall photovoltaic system power generation. Furthermore, the encapsulating film and photovoltaic modules described in some embodiments of this application can provide a practical reference for the stable operation and development of photovoltaic energy, further promoting the widespread application of photovoltaic energy.

[0054] In some embodiments, the preset temperature is 15°C to 35°C. Optionally, the preset temperature is 15°C to 25°C.

[0055] Studies have shown that the ideal operating temperature for photovoltaic (PV) modules is around 25°C. For every 1°C increase in temperature, the output power decreases by approximately 0.35%, and the power generation of a PV power plant also decreases by about 0.35%. Annual power generation data for a certain PV power plant is shown below. Figure 1 As shown, from Figure 1 As can be seen, the annual temperature varies between 5℃ and 35℃. In spring and autumn, when the temperature is between 15℃ and 25℃, the overall power generation of the modules is higher. Summer temperatures are higher, resulting in lower power generation than spring and autumn, while winter temperatures are lower, below 15℃, leading to lower power generation than summer. Therefore, in some embodiments of the encapsulation film of this application, the preset temperature is 15℃ to 35℃, preferably 15℃ to 25℃. When applied to photovoltaic modules, this helps maintain the modules at an ideal temperature of around 25℃, thereby ensuring stable power generation.

[0056] In some embodiments, the UV-resistant material includes reduced graphene oxide (rGO).

[0057] In some embodiments, the mass ratio of the UV-resistant material to the thermochromic material is 2:1 to 1:2. For example, the mass ratio of the UV-resistant material to the thermochromic material may be, but is not limited to, 2:1, 1.5:1, 1:1, 1:1.5, 1:2, or any range of two of these values.

[0058] In some embodiments, there is an electrostatic interaction between the UV-resistant material and the thermochromic material.

[0059] In some embodiments, the thermochromic material comprises a leuco dye, a developer, and a solvent, the leuco dye comprises crystal violet lactone (CVL), the developer comprises bisphenol A (BPA), and the solvent comprises one or more of n-tetradecanol (1-tetradecanol), n-hexadecanol, n-octadecanol, and n-docosanol.

[0060] In some of the embodiments, the thermochromic material is prepared by mixing, heating, and stirring the leuco dye, the developer, and the solvent.

[0061] In some of the embodiments, the leuco dye is crystal violet lactone, the developer is bisphenol A, and the solvent is 1-tetradecanol.

[0062] In some of the embodiments, the thermochromic microcapsule comprises reduced graphene oxide and a thermochromic material (TM) encapsulated inside the reduced graphene oxide. The TM is prepared by mixing, heating, and stirring crystal violet lactone (CVL), bisphenol A (BPA), and 1-tetradecanol in water, modifying the positive charge, and encapsulating the TM using rGO.

[0063] In some of the embodiments, the thermochromic microcapsule is prepared by mixing, heating, and stirring CVL, BPA, and 1-tetradecanol to obtain a thermochromic powder, modifying the thermochromic powder using an organic salt to obtain a positively charged thermochromic material, mixing and stirring the positively charged thermochromic material with negatively charged reduced graphene oxide in water, and centrifuging and drying to obtain the thermochromic microcapsule.

[0064] In one example, the thermochromic microcapsule is prepared by adding CVL, BPA, and 1-tetradecanol to a flask, heating at 70°C in a water bath while stirring at 600 rpm / min for 1 hour, centrifuging and drying to obtain a thermochromic powder. Then, mixing a positively charged AAPH (C8H 18 N6·2HCl) and the thermochromic powder in a 50% ethanol aqueous solution at a mass ratio of 1:10, heating in a water bath at 75°C for 5 hours, filtering to obtain a positively charged thermochromic material (TM). Mixing the positively charged TM and negatively charged rGO in deionized water at a high speed for 10 minutes, and centrifuging and drying to obtain the thermochromic microcapsule.

[0065] In some embodiments, the molar ratio of the leuco dye to the developer is 3:1 to 1:3. Alternatively, the molar ratio of the leuco dye to the developer is 3:1 to 1:1.

[0066] In some embodiments, in the thermochromic material, the molar ratio of the color developer and the solvent is 1: (5-20). For example, the molar ratio of the color developer and the solvent can be, but is not limited to, 1:5, 1:6, 1:8, 1:10, 1:12, 1:15, 1:18, 1:20, or a range formed by any two of these values.

[0067] The transition temperature of the thermochromic microcapsule is controlled by adjusting the feeding ratio of CVL and BPA, and the specific parameters are shown in the following table. Among them, the molar ratio of BPA: 1-tetradecanol is kept at 1:20.

[0068] Table 1 Raw material ratio and transition temperature comparison table

[0069]

[0070] Therefore, by selecting the molar ratio of the indole lactone and the bisphenol A to be 3:1-1:3, it is beneficial to make the encapsulation film transition at 15℃-35℃. Further, the molar ratio of the crystal violet indole lactone and the bisphenol A is 3:1-1:1, so that the preset temperature of the encapsulation film is 15℃-25℃.

[0071] The essence of the intelligent temperature change of the thermochromic microcapsule is the mutual conversion of thermal energy and chemical energy. The reversible structure of TM molecule is used to respond differently to high temperature and low temperature. For details, please refer to Figure 2 When the temperature is low, CVL and BPA form a complex, the conjugated structure increases, resulting in absorption of visible light, and black color. At high temperature, the complex structure of CVL and BPA is destroyed, the conjugation is reduced, the reflection of light is increased, and it becomes white.

[0072] In some embodiments, taking 25℃ as the preset temperature, the reflectivity of the encapsulation film in the 380nm-1100nm waveband is 40%-50%, 80%-90%, and 95%-99% respectively when the temperature is lower than the preset temperature (for example, 15℃), the preset temperature, and higher than the preset temperature (for example, 35℃).

[0073] In some embodiments, the thermochromic microcapsule is dispersed in the film body, and the encapsulation film includes, by mass fraction, 100 parts of an ethylene copolymer matrix and 2-10 parts of the thermochromic microcapsule.

[0074] Among them, the ethylene copolymer matrix includes any one or several of ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-octene copolymer, and ethylene-pentene copolymer.

[0075] In one example, the mass fraction of the thermochromic microcapsules can be, but is not limited to, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, or a range between any two of these values. If the amount of the thermochromic microcapsules is too large, for example, greater than 10 parts, the adhesion of the encapsulating film will be affected. If the amount of the thermochromic microcapsules is too small, for example, less than 2 parts, the intelligent temperature change effect will not be obvious.

[0076] In some embodiments, the encapsulating film further comprises one or more of an antioxidant, a silane coupling agent, a light stabilizer, and a crosslinking agent. Specifically, the encapsulating film comprises, by mass fraction, 100 parts of the ethylene copolymer matrix, 2-10 parts of the thermochromic microcapsules, 0.15-1 part of the antioxidant, 0.5-5 parts of the silane coupling agent, 0.05-0.5 part of the light stabilizer, and 0.5-2 parts of the crosslinking agent.

[0077] Specifically, the antioxidant comprises any one or more of butylated hydroxyanisole, octadecyl beta-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(2,-di-tert-butylphenyl) phosphite, and bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite.

[0078] Specifically, the silane coupling agent comprises any one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(tert-butylperoxy)silane, and gamma-mercaptopropyltrimethoxysilane.

[0079] Specifically, the light stabilizer comprises any one or more of 2-hydroxy-4-dodecyloxybenzophenone, a polymer of succinic acid and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinethanol, 3,5-tert-butyl-4-hydroxy-benzoic acid hexadecyl ester, 2-hydroxy-4-methoxybenzophenone, and 2-hydroxy-4-n-octylbenzophenone.

[0080] Specifically, the crosslinking agent comprises any one or more of triallyl cyanurate, isobornyl methacrylate, ethoxylated pentaerythritol tetraacrylate, propoxylated pentaerythritol tetraacrylate, trimethylolpropane trimethacrylate, diethylene glycol dimethacrylate, and acrylated glycerol derivatives.

[0081] It can be understood that the above only gives some specific types of additives, but is not limited thereto, and the types of additives can be adjusted according to actual needs in the art, which will not be described here.

[0082] In some embodiments, the encapsulation adhesive film comprises an adhesive film body and a thermochromic layer formed on a surface of the adhesive film body, and the thickness of the thermochromic layer is 0.05mm-0.2mm. For example, the thickness of the thermochromic layer can be, but is not limited to, 0.05mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, or a range formed by any two of these values. At this time, the adhesive film body comprises, in terms of mass fraction, 100 parts of an ethylene copolymer matrix, 0.15-1 parts of an antioxidant, 0.5-5 parts of a silane coupling agent, 0.05-0.5 parts of a light stabilizer, and 0.5-2 parts of a crosslinking agent. The specific substances are the same as described above and will not be repeated.

[0083] By layering the thermochromic layer on the traditional adhesive film body, the same intelligent temperature changing effect of cooling at high ambient temperature and heating at low ambient temperature can also be achieved. However, from the perspective of uniformity and stability, it is preferred to disperse the thermochromic microcapsules inside the adhesive film body.

[0084] As shown in Figure 3 , the encapsulation adhesive film of some embodiments of the present application appears black at low temperature and white at high temperature. The reflectivity of the conventional black adhesive film and white adhesive film is shown in Figure 4 . The measured data show that the black adhesive film has high absorption of sunlight and the white adhesive film has high reflection of light, so that the encapsulation adhesive film of some embodiments of the present application appears black below the preset temperature, which is beneficial to high absorption of sunlight and temperature increase, and appears white above the preset temperature, which reflects sunlight and reduces temperature, thereby helping to achieve the intelligent temperature changing function of low-temperature heating and high-temperature cooling.

[0085] The second aspect of the present application provides a preparation method of an encapsulation adhesive film, comprising the following steps:

[0086] The preparation raw materials of the adhesive film body and the thermochromic microcapsules are mixed and heated to be extruded into a film to prepare the encapsulation adhesive film, or a thermochromic layer is formed on the surface of the adhesive film body to prepare the encapsulation adhesive film, and the material of the thermochromic layer comprises the thermochromic microcapsules;

[0087] The thermochromic microcapsules comprise an ultraviolet-resistant material and a thermochromic material wrapped inside the ultraviolet-resistant material;

[0088] The encapsulation adhesive film appears black below the preset temperature and white above the preset temperature.

[0089] The thermochromic microcapsules and the preparation raw materials of the adhesive film body are mixed and heated to be extruded to obtain the encapsulation adhesive film with the thermochromic microcapsules dispersed inside, or a thermochromic layer is formed on the surface of the adhesive film body to obtain the encapsulation adhesive film, and the above preparation method is simple in process.

[0090] In some embodiments, the step of mixing the raw materials for preparing the film body and the thermochromic microcapsules and heating and extruding into a film includes mixing for 1-2 hours to ensure uniform dispersion of the raw materials. In one example, the mixing step is performed in a mixer.

[0091] Specifically, the step of heating and extruding into a film is performed in an extruder.

[0092] Specifically, the temperature for heating and extruding into a film is 60-120°C.

[0093] Specifically, after the step of heating and extruding into a film, a cooling step is further included. The cooling step can be air cooling or water cooling.

[0094] In other embodiments, the step of forming the thermochromic layer on the surface of the film body includes coating a solution containing the thermochromic microcapsules on the surface of the film body and drying to form the thermochromic layer.

[0095] Specifically, the solution containing the thermochromic microcapsules includes polyurethane, ethanol and water. The polyurethane has strong adhesion, which helps the thermochromic microcapsules to be stably attached to the surface of the film body. In one example, the volume ratio of ethanol to water is 1:1. The mass ratio of polyurethane to thermochromic microcapsules is (5-8):1.

[0096] Specifically, the coating method can be, but is not limited to, spraying.

[0097] In a third aspect, referring to Figure 5 The present application provides a photovoltaic module 100, comprising: a panel 110, a first encapsulating film 120, a cell 130, a second encapsulating film 140 and a back sheet 150 which are sequentially stacked, wherein at least one of the first encapsulating film 120 and the second encapsulating film 140 is prepared as described in the first aspect or by the preparation method of the second aspect.

[0098] In some embodiments, the panel 110 is made of a light-transmitting material, such as glass or the like. The back sheet 150 can be made of glass or a polymer material, without particular limitation.

[0099] In some embodiments, the second encapsulating film 140 is prepared as described in the first aspect or by the preparation method of the second aspect. The first encapsulating film 120 is a transparent film, which achieves high transmittance of sunlight. Specifically, the light transmittance of the first encapsulating film 120 is >90%.

[0100] Specifically, when the second encapsulating film includes a film body and a thermochromic layer disposed on the surface of the film body, in the photovoltaic module, one side of the thermochromic layer faces the back sheet, and one side of the film body faces the cell.

[0101] The photovoltaic module has the encapsulating adhesive film with intelligent temperature change performance, can present black below the preset temperature, is beneficial to high absorption of sunlight, increases temperature, presents white above the preset temperature, reflects sunlight, reduces temperature, and thus can guarantee the performance stability of the photovoltaic module, reduce the influence of outdoor temperature on the power generation of the module, and further improve the overall power generation of the photovoltaic system.

[0102] In order to make the purpose and advantages of the present application more clear, the encapsulating adhesive film and its effects are further described in detail below in combination with specific examples. It should be understood that the specific examples described herein are only used to explain the present application and should not be used to limit the present application. The following examples do not include other components except for unavoidable impurities, unless otherwise specified. In the examples, the drugs and instruments are selected according to the conventional selection in the art, unless otherwise specified. The experimental methods in the examples are implemented according to the conventional conditions, such as the conditions described in the literature, books or the methods recommended by the manufacturers.

[0103] Example 1

[0104] The present embodiment provides an encapsulating adhesive film, which comprises, by mass fraction: 100 parts of ethylene-vinyl acetate copolymer, 8 parts of thermochromic microcapsules, 0.5 parts of antioxidant (specifically, butylated hydroxyanisole), 3 parts of silane coupling agent (specifically, vinyltrimethoxysilane), 0.25 parts of light stabilizer (specifically, 2-hydroxy-4-dodecyloxybenzophenone), and 2 parts of crosslinking agent (specifically, triallyl cyanurate). The thermochromic microcapsules are obtained by the following steps: crystal violet lactone, bisphenol A and 1-tetradecanol with a molar ratio of 1:1:20 are added to a flask and heated in a water bath at 70°C, while stirring at a speed of 600 rpm / min for 1 hour; after centrifugal drying, the reversible thermochromic compound is obtained. Then, positively charged AAPH (C8H 18 N6·2HCl) and the thermochromic compound are mixed in an ethanol aqueous solution with a concentration of 50% at a mass ratio of 1:10, heated in a water bath at 75°C for 5 hours, and then filtered to obtain positively charged thermochromic powder (TM). Then, TM and rGO are mixed at a mass ratio of 1:1 and stirred rapidly in deionized water, and finally centrifugally dried to obtain thermochromic microcapsules.

[0105] The preparation steps of the encapsulating adhesive film of the present embodiment are as follows:

[0106] The raw materials are mixed and added to a mixer, fully stirred and mixed for 2 hours, and then the mixed materials are put into an extruder to melt by heating and extruding, and then extruded into a film through a die; the extrusion temperature is 100°C; the finally extruded adhesive film is cooled and solidified by a cooling device to obtain an encapsulating adhesive film with a thickness of 0.45 mm.

[0107] Example 2

[0108] The present example provides a packaging adhesive film, which is similar to the packaging adhesive film of Example 1, except that the amount of the thermochromic microcapsules is different, in the present example, the mass fraction of the thermochromic microcapsules is 5 parts.

[0109] Example 3

[0110] The present example provides a packaging adhesive film, which is similar to the packaging adhesive film of Example 1, except that the amount of the thermochromic microcapsules is different, in the present example, the mass fraction of the thermochromic microcapsules is 2 parts.

[0111] Example 4

[0112] The present example provides a packaging adhesive film, which is similar to the packaging adhesive film of Example 1, except that in the thermochromic microcapsules, the molar ratio of crystal violet lactone to bisphenol A is 2:1.

[0113] Example 5

[0114] The present example provides a packaging adhesive film, which includes an adhesive film body and a thermochromic layer arranged on the adhesive film body. The adhesive film body includes, in terms of mass fraction: 100 parts of ethylene-vinyl acetate copolymer, 0.5 parts of antioxidant (specifically, butylated hydroxyanisole), 3 parts of silane coupling agent (specifically, vinyltrimethoxysilane), 0.25 parts of light stabilizer (specifically, 2-hydroxy-4-dodecyloxybenzophenone), and 2 parts of crosslinking agent (specifically, triallyl cyanurate), with a thickness of 0.45 mm. The material of the thermochromic layer is thermochromic microcapsules, with a thickness of 0.1 mm.

[0115] The preparation steps of the packaging adhesive film of the present example are as follows:

[0116] (1) Mix the raw materials in the adhesive film body and add them to a mixing machine, stir and mix thoroughly for 2 hours, then put the mixed material into an extruder, melt by heating and extruding through a die to form a film; the extrusion temperature is 100°C; the finally extruded adhesive film is cooled and solidified by a cooling device to obtain an adhesive film body with a thickness of 0.45 mm.

[0117] Crystal violet lactone, bisphenol A and 1-tetradecanol with a molar ratio of 1:1:20 are added to a flask and heated in a 70°C water bath while stirring at a speed of 600 rpm / min for 1 hour; after centrifugal drying, the reversible thermochromic compound is obtained. Then, positively charged AAPH (C8H 18N6·2HCl) and the thermochromic compound were mixed in an ethanol aqueous solution with a concentration of 50% at a mass ratio of 1:10, heated in a water bath at 75°C for 5 hours, and then filtered to obtain a positively charged thermochromic powder (TM). TM and rGO were mixed at a mass ratio of 1:1 and then mixed rapidly in deionized water, and finally centrifugal drying was performed to obtain thermochromic microcapsules. The thermochromic microcapsules were dissolved in an ethanol aqueous solution of polyurethane, the volume ratio of ethanol to water was 1:1, and the mass ratio of polyurethane to thermochromic microcapsules was 6:1, and then sprayed onto the surface of the film body to obtain a thermochromic layer with a thickness of 0.1 mm, thereby obtaining the encapsulating film of the example.

[0118] Comparative Example 1

[0119] Comparative Example 1 provides an encapsulating film, which is similar to the encapsulating film of Example 1, and the difference is that no thermochromic microcapsules are added.

[0120] The encapsulating films of the above examples and comparative examples were used for the encapsulation of TOPCon photovoltaic modules, wherein the encapsulating films of the examples and comparative examples were used for back encapsulation, and other encapsulating materials were kept consistent, and two photovoltaic modules were prepared for each encapsulating film. The obtained photovoltaic modules were divided into two groups, and were subjected to 50°C heat baking and -20°C freezing treatment, respectively, and the temperatures of the photovoltaic modules before and after the treatment were tested. The test results are shown in Tables 2 and 3 as follows:

[0121] Table 2 Temperature of photovoltaic module before and after heat baking

[0122]

[0123] Table 3 Temperature of photovoltaic module before and after freezing treatment

[0124]

[0125] As can be seen from the above tables, by adding a certain amount of thermochromic microcapsules to the conventional encapsulating film, Example 1 can achieve a cooling effect of about 17.5°C at high temperature and a heating effect of about 14.3°C at low temperature, and has a good heat management capability compared with Comparative Example 1. Similarly, the other examples also have a good heat management capability compared with Comparative Example 1.

[0126] In addition, the power generation efficiency of the two photovoltaic modules of Example 1 and Comparative Example 1 was monitored, and the results are shown in Table 4 as follows. Figure 6 The power generation efficiency of the photovoltaic module encapsulated with the encapsulating film of Example 1 is more stable and has smaller fluctuations than that of the photovoltaic module encapsulated with the encapsulating film of Comparative Example 1, and can maintain a high power generation efficiency throughout the day.

[0127] Meanwhile, reliability tests were also conducted on the two photovoltaic modules of Comparative Example 1 and Comparative Example 1, and the results are shown in Table 4 below. TC200 represents the Thermal Cycle Test, which involves subjecting the photovoltaic module to 200 cycles between -40°C and 85°C to simulate the temperature changes experienced by the photovoltaic module in actual use, thereby evaluating its structural and material stability. DH1000 represents a 1000-hour test of the photovoltaic module at 85°C and 85% humidity. UV30 represents the ultraviolet irradiation test, where "30" indicates a cumulative ultraviolet irradiation dose of 30 kWh / m², used to evaluate the module's resistance to degradation under long-term ultraviolet irradiation. HF20 represents the Humidity Freeze test, where "20" indicates 20 cycles, used to evaluate the structural stability of the module in alternating hot and cold and humid environments. The test conditions are as follows: High temperature and high humidity stage: 85℃, 85% relative humidity, for about 10 hours; Low temperature stage: -40℃, for about 14 hours; Cycle period: each complete cycle is about 24 hours, and a total of 20 cycles are performed.

[0128] Table 4 Power attenuation results after reliability test

[0129]

[0130] As can be seen from the table above, the photovoltaic modules prepared using the encapsulating film of Example 1 and those prepared using traditional encapsulating films show little difference in power attenuation after reliability testing, both exhibiting high reliability. Furthermore, the above description only uses Example 1 as an example to illustrate the good reliability of the encapsulating film in this example; other examples have comparable reliability to Example 1, and will not be elaborated upon here.

[0131] The above results demonstrate that the encapsulating films of some embodiments of this application, when applied in photovoltaic modules, can autonomously regulate their own temperature, thereby reducing the impact of temperature on the module's power generation, maintaining stable and high power generation under different ambient temperatures, and ensuring good reliability. Furthermore, based on... Figure 1 Based on the annual power generation data of a photovoltaic power station in China, and assuming that the power generation of a photovoltaic power station decreases by approximately 0.35% for every 1°C increase in temperature, it is calculated that if the encapsulating film of some embodiments of this application is used in photovoltaic modules, the annual power generation of this photovoltaic power station can be increased by approximately 1.1 GWh. In longer-term applications such as 10 or 20 years, photovoltaic modules can further enhance power generation, demonstrating significant application value and promising prospects.

[0132] Any technical features in the above-described embodiments can be combined, and for the sake of brevity, not all possible combinations of the technical features are described, however, any combination of the technical features should be considered as within the scope of the present disclosure.

[0133] The above-described embodiments only express several implementation manners of the present application, facilitate specific and detailed understanding of the technical solutions of the present application, but should not be understood as a limitation on the patent protection scope of the present application. It should be pointed out that, for ordinary skilled persons in the art, a number of modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. It should be understood that, on the basis of the technical solutions provided by the present application, technical solutions obtained by logical analysis, reasoning or limited experiments by those skilled in the art all belong to the protection scope of the appended claims of the present application. Therefore, the patent protection scope of the present application should be subject to the contents of the appended claims, and the description and drawings can be used to explain the contents of the claims.

Claims

1. An encapsulating film, characterized in that, The encapsulating film includes a film body and thermochromic microcapsules dispersed in the film body; or, the encapsulating film includes a film body and a thermochromic layer disposed on the surface of the film body, wherein the thermochromic layer is made of thermochromic microcapsules. The thermochromic microcapsule includes an anti-ultraviolet material and a thermochromic material encapsulated inside the anti-ultraviolet material; The encapsulating film is black when the temperature is below a preset temperature and white when the temperature is above a preset temperature.

2. The encapsulating film according to claim 1, characterized in that, The preset temperature is 15℃~35℃; Optionally, the preset temperature is 15℃~25℃.

3. The encapsulating film according to claim 2, characterized in that, The UV-resistant material includes reduced graphene oxide; And / or, the thermochromic material includes a leucocyanide, a color developer, and a solvent, wherein the leucocyanide includes crystal violet lactone, the color developer includes bisphenol A, and the solvent includes one or more of n-tetradecyl alcohol, n-hexadecyl alcohol, n-octadecyl alcohol, and n-dodecyl alcohol. And / or, the mass ratio of the UV-resistant material to the thermochromic material is 2:1 to 1:2; And / or, there is an electrostatic interaction between the UV-resistant material and the thermochromic material.

4. The encapsulating film according to claim 3, characterized in that, In the thermochromic material, the molar ratio of the leucoant to the chromogenic agent is 3:1 to 1:3; Optionally, the molar ratio of the leucoant to the color developer is 3:1 to 1:1; And / or, in the thermochromic material, the molar ratio of the color developer to the solvent is 1:(5~20).

5. The encapsulating film according to any one of claims 1 to 4, characterized in that, The thermochromic microcapsules are dispersed in the encapsulation film body. By mass, the encapsulation film comprises: 100 parts of ethylene copolymer matrix and 2 to 10 parts of thermochromic microcapsules.

6. The encapsulating film according to claim 5, characterized in that, The encapsulating film, by weight, further comprises: 0.15 to 1 part antioxidant, 0.5 to 5 parts silane coupling agent, 0.05 to 0.5 parts light stabilizer, and 0.5 to 2 parts crosslinking agent.

7. The encapsulating film according to any one of claims 1 to 4, characterized in that, The encapsulating film includes a film body and a thermochromic layer disposed on the surface of the film body, wherein the thickness of the thermochromic layer is 0.05 mm to 0.2 mm.

8. A method for preparing an encapsulating film, characterized in that, Includes the following steps: The encapsulation film is prepared by mixing the raw materials for the film body with thermochromic microcapsules, heating and extruding them into a film; or, the encapsulation film is prepared by forming a thermochromic layer on the surface of the film body, wherein the material of the thermochromic layer includes thermochromic microcapsules. The thermochromic microcapsule includes an anti-ultraviolet material and a thermochromic material encapsulated inside the anti-ultraviolet material; The encapsulating film is black when the temperature is below a preset temperature and white when the temperature is above a preset temperature.

9. The method for preparing the encapsulating film according to claim 8, characterized in that, In the step of heating and extruding to form a film, the temperature is 60℃~120℃; Alternatively, the step of forming a thermochromic layer on the surface of the film body includes: coating a solution containing the thermochromic microcapsules onto the surface of the film body and drying it to form the thermochromic layer.

10. A photovoltaic module, characterized in that, include: A panel, a first encapsulating film, a battery cell, a second encapsulating film, and a backsheet are stacked in sequence, wherein at least one of the first encapsulating film and the second encapsulating film is prepared as described in any one of claims 1 to 7 or by the preparation method described in any one of claims 8 to 9.

Images