Insulating coating adhesive, insulating coating adhesive layer and preparation method thereof, photovoltaic module

Abstract

The application provides an insulating coating adhesive, an insulating coating adhesive layer, a preparation method of the insulating coating adhesive, and a photovoltaic module. The insulating coating adhesive comprises an alicyclic epoxy resin, a fatty epoxy resin and a curing agent. The number average molecular weight of the fatty epoxy resin is 1100-5400. The weight ratio of the alicyclic epoxy resin to the fatty epoxy resin is (0.5-3):1. The synergistic effect of the alicyclic epoxy resin, the fatty epoxy resin and the curing agent can make the obtained insulating coating adhesive layer have good heat resistance and yellowing resistance, and also have good curing performance and bonding performance. When the insulating coating adhesive layer is used in the photovoltaic module, the aging and performance degradation of the insulating coating adhesive layer in the long-term use process can be effectively solved, and the light conversion efficiency and service life of the photovoltaic module can be further improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic adhesive technology, and more specifically, to an insulating coating adhesive, an insulating coating adhesive layer and its preparation method, and a photovoltaic module. Background Technology

[0002] With the rapid increase in global demand for clean energy, the photovoltaic industry, as an important component of sustainable energy, has experienced rapid development in recent years. Continuous technological advancements have pushed the boundaries of battery efficiency, with the advent of BC (back contact) cells marking a significant milestone in photovoltaic technology. BC cells significantly improve photoelectric conversion efficiency through optimized cell structure, but also place more stringent requirements on the insulating materials used for cell encapsulation and protection.

[0003] In traditional photovoltaic modules, insulating coatings play a crucial role in protecting solar cells from environmental damage and ensuring electrical insulation and mechanical strength. However, with the advent of BC cells, insulating coatings must not only possess excellent light transmittance to maximize solar energy absorption and conversion, but also remain stable under high temperatures and intense ultraviolet radiation to prevent yellowing from severely impacting the light absorption capacity of the solar cells and thus reducing light conversion efficiency.

[0004] Most commercially available insulating adhesives are based on resin systems containing benzene rings. While the benzene ring structure provides good heat resistance, it is also a chromophore that easily induces yellowing. To improve the yellowing resistance of insulating adhesives, the industry typically adds yellowing-resistant monomers or chemical additives such as UV absorbers and stabilizers to the resin. However, the effectiveness of these additives gradually weakens or even completely fails over time. When these additives fail, the yellowing of the insulating adhesive gradually intensifies, affecting the appearance and light transmission performance of photovoltaic modules, ultimately leading to a sharp decrease in the power generation efficiency of BC cells. Insulating adhesive systems without benzene ring structures, due to issues such as reactivity and heat resistance, are difficult to use in photovoltaic modules for rapid curing.

[0005] In view of the above problems, it is particularly important to find an insulating adhesive coating that can maintain excellent heat resistance, effectively inhibit yellowing, and have rapid curing ability and good adhesion to improve the light conversion efficiency and service life of photovoltaic cells. Summary of the Invention

[0006] The main objective of this invention is to provide an insulating coating adhesive, an insulating coating adhesive layer, a method for preparing the same, and a photovoltaic module, to address the problem that existing insulating coating adhesives used in the photovoltaic field struggle to maintain excellent heat resistance, effectively inhibit yellowing, and simultaneously possess rapid curing ability and good adhesion. The aim is to provide an insulating coating adhesive that combines good heat resistance and yellowing resistance with good curing and bonding properties, thereby solving the aging and performance degradation problems of insulating adhesives under long-term use and providing technical support for improving the light conversion efficiency and lifespan of photovoltaic modules.

[0007] To achieve the above objectives, a first aspect of the present invention provides an insulating coating adhesive comprising: an alicyclic epoxy resin, an aliphatic epoxy resin, and a curing agent; wherein the number average molecular weight of the aliphatic epoxy resin is 1100-5400; and the weight ratio of the alicyclic epoxy resin to the aliphatic epoxy resin is (0.5-3):1.

[0008] Further, by weight, the insulating coating adhesive comprises: 100-200 parts of alicyclic epoxy resin, 100-200 parts of fatty epoxy resin, 15-30 parts of curing agent, 1-5 parts of additives, 200-400 parts of filler, 1-10 parts of accelerator, and 20-70 parts of organic solvent; preferably, by weight, the insulating coating adhesive comprises: 150-200 parts of alicyclic epoxy resin, 100-150 parts of fatty epoxy resin, 15-20 parts of curing agent, 1-5 parts of additives, 200-300 parts of filler, 5-10 parts of accelerator, and 30-50 parts of organic solvent.

[0009] Furthermore, in the insulating coating adhesive, the weight ratio of alicyclic epoxy resin to fatty epoxy resin is (1~2):1; the epoxy equivalent of the fatty epoxy resin is 165~240; and the number average molecular weight of the fatty epoxy resin is 3000~5400.

[0010] Furthermore, the insulating coating adhesive also includes silicone-modified epoxy resin; preferably, the silicone-modified epoxy resin in the insulating coating adhesive is 100-200 parts by weight, more preferably 150-200 parts by weight; preferably, the silicone-modified epoxy resin is selected from one or more of glycidyl etheroxypropylcyclotetrasiloxane, methylpropene trioxocyclosiloxane, 3-glycidyl etherpropyl heptamethylcyclotetrasiloxane and 3-epoxypropoxy-1,1,3,3-tetramethyldisiloxane.

[0011] Furthermore, the molecular structure of the alicyclic epoxy resin includes at least two epoxy groups, and each epoxy group is directly connected to a polycyclic alicyclic ring, wherein the polycyclic alicyclic ring has 4 to 8 carbon atoms; preferably, the polycyclic alicyclic ring has 5 to 7 carbon atoms, more preferably, the polycyclic alicyclic ring is a six-membered ring; more preferably, the alicyclic epoxy resin is selected from one or more of 3,4-epoxycyclohexanecarboxylic acid (3',4'-epoxycyclohexyl)methyl, di(3,4-epoxycyclohexylmethyl)adipate, 2,2-di(3,3'-epoxycyclohexyl)propane and 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexanecarboxylic acid) ester.

[0012] Furthermore, the molecular structure of the aliphatic epoxy resin includes at least two epoxy groups, and each epoxy group is directly linked to a straight-chain or branched alkyl group, which optionally contains heteroatoms; preferably, the aliphatic epoxy resin is selected from one or more of epoxidized polybutadiene, polypropylene glycol diglycidyl ether, polyethylene glycol monoglycidyl ether, and ethylene glycol diglycidyl ether.

[0013] Further, the curing agent is selected from one or more of dicyandiamide, melamine, ethylenediamine, and methylhexahydrophthalic anhydride; and / or, the additive is selected from one or more of ultraviolet absorbers, leveling agents, and defoamers; and / or, the filler is selected from one or more of barium sulfate, calcium carbonate, and silica; and / or, the accelerator is selected from one or more of dimethylimidazole, 2,4,6-tris(dimethylaminomethyl)phenol, and N-(2-hydroxyphenyl)-N',N'-dimethylurea; and / or, the organic solvent is selected from one or more of diethylene glycol butyl ether, dipropylene glycol methyl ether, and divalent esters; preferably, the leveling agent is an organosilicon leveling agent; and / or, the defoamer is a polyolefin defoamer; and / or, the ultraviolet absorber is 4-hydroxybenzophenone.

[0014] A second aspect of the present invention provides an insulating coating adhesive layer, which is obtained by sequentially coating and curing the aforementioned insulating coating adhesive.

[0015] A third aspect of the present invention provides a method for preparing an insulating coating adhesive layer, the method comprising the following steps: dissolving an aliphatic epoxy resin in an organic solvent to form a liquid aliphatic resin slurry; mixing the liquid aliphatic resin slurry with an alicyclic epoxy resin and a curing agent to obtain a mixed slurry; and coating and curing the mixed slurry to obtain an insulating coating adhesive layer.

[0016] Furthermore, the mixed slurry also includes silicone-modified epoxy resin, additives, fillers, accelerators, and organic solvents; and / or, the coating method is screen printing; and / or, the solid content of the liquid fatty resin slurry is 30~70%; and / or, the thickness of the insulating coating layer is 30~40µm; and / or, the curing method is thermosetting; more preferably, the thermosetting curing temperature is 100~150℃, and the curing time is 20min~60min.

[0017] A fourth aspect of the present invention provides a photovoltaic module including an adhesive layer, the adhesive layer being the aforementioned insulating coating adhesive layer.

[0018] This invention provides an insulating coating adhesive, comprising alicyclic epoxy resin, aliphatic epoxy resin, and a curing agent. The three work synergistically to give the resulting insulating coating adhesive layer good heat resistance and yellowing resistance, as well as good curing and bonding properties. When used in photovoltaic modules, it can effectively solve the problems of aging and performance degradation of the insulating adhesive layer during long-term use, which is beneficial to further improving the light conversion efficiency and service life of photovoltaic modules. Detailed Implementation

[0019] 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.

[0020] As mentioned in the background section, most commercially available insulating adhesive coatings are based on resin systems containing benzene rings. While the benzene ring structure provides good heat resistance, it is also a chromophore that easily induces yellowing. To improve the yellowing resistance of insulating adhesives, the industry typically adds yellowing-resistant monomers or chemical additives such as UV absorbers and stabilizers to the coatings. Although this method can solve the problem to some extent, as the effectiveness of the additives in the insulating adhesive weakens or even completely fails, the yellowing of the coating gradually intensifies, affecting the appearance and light transmission performance of photovoltaic modules, ultimately leading to a sharp decrease in the power generation efficiency of BC cells. Insulating adhesive systems without benzene ring structures are difficult to use for rapid curing in photovoltaic modules due to issues such as reactivity. Therefore, finding an insulating adhesive coating that can maintain excellent heat resistance, effectively inhibit yellowing, and possess rapid curing capability and good adhesion has become crucial for further improving the light conversion efficiency and lifespan of photovoltaic cells.

[0021] To address the aforementioned problems, this invention provides an insulating coating adhesive comprising: alicyclic epoxy resin, aliphatic epoxy resin, and a curing agent; wherein the number average molecular weight of the aliphatic epoxy resin is 1100-5400; and the weight ratio of the alicyclic epoxy resin to the aliphatic epoxy resin is (0.5-3):1. Through the synergistic effect of these three components, the resulting insulating coating adhesive layer exhibits both good heat resistance and yellowing resistance, as well as good curing and adhesion properties. When used in photovoltaic modules, it effectively solves the aging and performance degradation problems of the insulating adhesive layer during long-term use, thus contributing to further improving the light conversion efficiency and service life of photovoltaic modules.

[0022] Specifically, the alicyclic epoxy resin in the insulating coating adhesive, due to the presence of alicyclic structures in its molecular structure, can resist high-temperature and ultraviolet radiation in the insulating coating adhesive, thus improving the heat resistance, UV resistance, and anti-yellowing properties of the insulating coating layer. Furthermore, the introduction of ring structures in the alicyclic epoxy resin also helps to further improve the electrical insulation performance and dielectric strength of the coating layer, enhancing the long-term operational safety of photovoltaic modules. The chain structure of the alicyclic epoxy resin in the insulating coating adhesive imparts good flexibility to the insulating coating layer, allowing it to adapt to the thermal expansion and contraction of the substrate and reducing cracks caused by thermal stress. This alicyclic epoxy resin has a number-average molecular weight of 1100-5400, exhibiting a high molecular weight and low epoxy equivalent, with abundant reaction sites, enabling rapid molecular weight increase and cross-linking structure formation. Therefore, this resin can effectively improve the curing speed of the insulating coating layer, meeting the process requirements for rapid curing in the fabrication of photovoltaic BC cells. Meanwhile, the resulting insulating coating adhesive has both good heat resistance and hardness, which can effectively prevent the insulation layer from being punctured in the high-temperature solder resist process, thereby avoiding short circuits in the battery cells.

[0023] To further improve the performance of the insulating coating adhesive, the weight ratio of alicyclic epoxy resin to fatty epoxy resin in the insulating coating adhesive of this invention is controlled at (0.5~3):1. The alicyclic epoxy resin, due to its alicyclic structure, is beneficial for improving the heat resistance, UV resistance, and yellowing resistance of the insulating coating adhesive. The fatty epoxy resin not only improves the heat resistance and stability of the insulating coating adhesive layer but also increases the overall curing speed of the insulating adhesive, meeting the requirements of rapid curing processes. The synergistic effect of the two further enhances the adhesion between the insulating coating adhesive layer and the substrate, as well as the heat resistance, yellowing resistance, and mechanical properties of the insulating coating adhesive layer. If too much fatty epoxy resin is added, it causes the insulating adhesive layer to change from a glassy state to a highly elastic state, affecting the hardness of the insulating coating adhesive layer and further affecting the insulation performance of the insulating adhesive, leading to short circuits in the battery cells and reduced yield. Controlling the content of both within the above-mentioned range allows the above effects to be better realized, which is beneficial for further improving the overall performance of the insulating coating adhesive layer.

[0024] Furthermore, the curing agent promotes the cross-linking and curing of the epoxy resin, forming a three-dimensional cross-linked network structure in the insulating coating layer, which in turn helps to further improve the chemical resistance and mechanical strength of the insulating coating layer. In summary, the synergistic effect of various components provided in this application, including alicyclic epoxy resin, fatty epoxy resin, curing agent, additives, and fillers, significantly improves the yellowing resistance, heat resistance, reactivity, curing speed, service life, and adhesion of the insulating coating, providing key material technology support for the further optimization of photovoltaic module performance.

[0025] The aforementioned insulating coating adhesive system can be further enhanced by including curing agents, additives, fillers, accelerators, and organic solvents. Fillers can enhance the coating's hardness, abrasion resistance, and thermal stability, and also improve its thermal conductivity, aiding in heat dissipation from the insulating coating adhesive layer. Accelerators can help lower the curing temperature or increase the curing speed during the curing process. Additives, through their inherent physicochemical properties, improve the coating's processing performance and final performance; for example, antioxidants and UV absorbers prevent coating aging and yellowing by absorbing free radicals and ultraviolet light. Leveling agents and defoamers help form a uniform, smooth surface by reducing surface tension. Organic solvents ensure the thorough dispersion of the aforementioned components.

[0026] In a preferred embodiment, the insulating coating adhesive, by weight, comprises: 100-200 parts of alicyclic epoxy resin, 100-200 parts of aliphatic epoxy resin, 15-30 parts of curing agent, 1-5 parts of additives, 200-400 parts of filler, 1-10 parts of accelerator, and 20-70 parts of organic solvent. As analyzed above, in the insulating coating adhesive, the alicyclic epoxy resin provides the basis for heat resistance and yellowing resistance; the aliphatic epoxy resin enhances flexibility and improves the reactivity of the raw materials; the curing agent promotes the cross-linking and curing of the resin; the additives improve the processing performance and durability of the coating; the filler increases physical properties and reduces coating costs; and the accelerator accelerates the curing process. By controlling the proportions of each component in the insulating coating adhesive within the above range, the effects of each component can be better utilized. Through the synergistic effect among these components, the insulating coating adhesive layer can have better light transmittance, heat resistance, yellowing resistance, and mechanical properties, while also meeting the requirement for rapid curing. Preferably, the insulating coating adhesive, by weight, comprises: 150-200 parts of alicyclic epoxy resin, 100-150 parts of fatty epoxy resin, 15-20 parts of curing agent, 1-5 parts of additives, 200-300 parts of filler, 5-10 parts of accelerator, and 30-50 parts of organic solvent. Controlling the proportions of each component in the insulating coating adhesive within the above-mentioned preferred range yields better results and a more superior insulating coating adhesive layer.

[0027] To further improve the performance of the insulating coating adhesive, in a preferred embodiment, the weight ratio of alicyclic epoxy resin to fatty epoxy resin in the insulating coating adhesive is (1~2):1. As analyzed above, the alicyclic epoxy resin in the insulating coating adhesive, due to its alicyclic structure, is beneficial for improving the heat resistance, UV resistance, and anti-yellowing properties of the insulating coating adhesive, and can further improve the electrical insulation properties and dielectric strength of the coating adhesive, thus improving the durability of photovoltaic modules. The fatty epoxy resin not only improves the heat resistance and stability of the insulating coating adhesive layer, but also enhances the activity of the alicyclic epoxy resin, improving the curing speed of the insulating coating adhesive. Under the synergistic effect of the two, the adhesion between the insulating coating adhesive layer and the substrate, as well as the heat resistance, anti-yellowing properties, and mechanical properties of the insulating coating adhesive layer, can be further enhanced. Controlling the content of both within the above-mentioned range allows the above effects to be better exerted, which is beneficial for further improving the overall performance of the insulating coating adhesive layer. Meanwhile, the epoxy equivalent of the preferred aliphatic epoxy resin is 165~240. The epoxy equivalent of the preferred aliphatic epoxy resin is within the above range. On the one hand, it can optimize the flexibility of the coating and alleviate the structural damage to the insulating coating layer caused by high temperature. On the other hand, it can further improve the bonding performance of the formed insulating coating layer, which is conducive to further improving the resistance of the coating layer to environmental stress and maintaining the integrity of the coating.

[0028] In a preferred embodiment, the insulating coating adhesive further includes a silicone-modified epoxy resin. Using silicone-modified epoxy resin as the insulating coating adhesive can further improve its heat resistance and aging resistance, thus enhancing the durability of the insulating coating layer. Firstly, the silane-modified resin contains Si-O-Si bonds, which are more stable than ordinary CC or CH bonds, resisting photo-oxidative decomposition under high-temperature environments and preventing damage to the internal structure of the insulating coating layer. Secondly, the introduction of silane groups into the insulating coating adhesive creates a hydrophobic protective layer within the resulting insulating coating layer structure, slowing the penetration of moisture and oxygen into the internal structure of the insulating coating layer. This reduces the rate of chemical reactions within the coating, making the insulating coating layer less prone to aging and degradation even under high-temperature and high-humidity environments. Under these multiple effects, the addition of silicone-modified epoxy resin effectively enhances not only the heat resistance and aging resistance of the insulating coating adhesive, but also further improves the mechanical strength, wear resistance, and weather resistance of the coating.

[0029] Preferably, the silicone-modified epoxy resin in the insulating coating adhesive is 100-200 parts; preferably, the epoxy equivalent of the silicone-modified epoxy resin is 220-300. Controlling the addition ratio of the silicone-modified epoxy resin and its epoxy equivalent and number-average molecular weight within the above-mentioned ranges in the insulating coating adhesive can further enhance the aforementioned effects of the silicone-modified epoxy resin, resulting in better overall performance of the insulating coating adhesive layer. Preferably, the silicone-modified epoxy resin is selected from one or more of glycidyl etheroxypropylcyclotetrasiloxane, epoxy polysiloxane, methylpropene trioxocyclosiloxane, 3-glycidyl etherpropyl heptamethylcyclotetrasiloxane, and 3-epoxypropoxy-1,1,3,3-tetramethyldisiloxane. Using the above-mentioned silicone-modified epoxy resin as the insulating coating adhesive can improve the performance of the insulating coating adhesive layer. More preferably, the amount of silicone-modified epoxy resin in the insulating coating adhesive is 150-200 parts; controlling the amount of silicone-modified epoxy resin added within the above range will result in better effects.

[0030] In this invention, the alicyclic epoxy resin comprises at least two epoxy groups in its molecular structure, and each epoxy group is directly linked to a polycyclic alicyclic ring, wherein the polycyclic alicyclic ring has 4 to 8 carbon atoms; preferably, the polycyclic alicyclic ring has 5 to 7 carbon atoms, and more preferably, the polycyclic alicyclic ring is a six-membered ring. Controlling the number and type of ester rings in the alicyclic epoxy resin within the above-mentioned range can improve the transparency and stability of the insulating coating adhesive, making it less prone to yellowing over a longer service life, and further enhancing the mechanical strength and heat resistance of the insulating coating adhesive. Preferably, the alicyclic epoxy resin is selected from one or more of 3,4-epoxycyclohexanecarboxylic acid (3',4'-epoxycyclohexyl)methyl, di(3,4-epoxycyclohexylmethyl)adipate, 2,2-di(3,3'-epoxycyclohexyl)propane, and 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexanecarboxylic acid) ester. The specific alicyclic epoxy resins described above are more effective in improving the performance of the insulating coating adhesive.

[0031] In this invention, the aliphatic epoxy resin comprises at least two epoxy groups in its molecular structure, and each epoxy group is directly linked to a straight-chain or branched alkyl group, which optionally contains heteroatoms. Specifically, the aliphatic epoxy resin is selected from one or more of epoxidized polybutadiene, polypropylene glycol diglycidyl ether, polyethylene glycol monoglycidyl ether, and ethylene glycol diglycidyl ether. In a preferred embodiment, the aliphatic epoxy resin is epoxidized polybutadiene with a number-average molecular weight of 1100-5400. This aliphatic epoxy resin has a high molecular weight and a high epoxy value, which is beneficial for improving the reactivity of alicyclic epoxy resins and improving the heat resistance and stability of insulating coating layers. The above-mentioned effects are even better with aliphatic epoxy resins having the above-mentioned number-average molecular weight. For example, but not limitingly, the epoxidized polybutadiene is one or more of EPOLEAD PB3600, EPOLEAD PB4700, JP-100, and JP-200. Using the aforementioned specific aliphatic epoxy resin as an insulating coating adhesive can further improve the overall performance of the insulating coating adhesive.

[0032] In a preferred embodiment, the curing agent is selected from one or more of dicyandiamide, melamine, ethylenediamine, and methylhexahydrophthalic anhydride; preferably, the additive is selected from one or more of ultraviolet absorbers, leveling agents, and defoamers; and / or, the filler is selected from one or more of barium sulfate, calcium carbonate, and silica; and / or, the accelerator is selected from one or more of dimethylimidazole, 2,4,6-tris(dimethylaminomethyl)phenol, and N-(2-hydroxyphenyl)-N',N'-dimethylurea. Using the specific curing agents, additives, stabilizers, defoamers, dispersants, and accelerators described above can improve the performance of the prepared insulating coating layer.

[0033] In practical applications, the organic solvent is selected from at least one of diethylene glycol butyl ether, dipropylene glycol methyl ether, and divalent esters. Using the above solvents and controlling the weight content of the organic solvent within the aforementioned range allows for more uniform dispersion of the various components in the insulating coating adhesive. The leveling agent can be a silicone leveling agent; and / or, the defoamer can be a polyolefin defoamer; and / or, the ultraviolet absorber can be 4-hydroxybenzophenone.

[0034] According to a second aspect of the present invention, an insulating coating adhesive layer is also provided, which is obtained by sequentially coating and curing the aforementioned insulating coating adhesive.

[0035] According to a third aspect of the present invention, a method for preparing the above-mentioned insulating coating adhesive layer is also provided. The method includes the following steps: dissolving an aliphatic epoxy resin in an organic solvent to form a liquid aliphatic resin slurry; mixing the liquid aliphatic resin slurry with an alicyclic epoxy resin and a curing agent to obtain a mixed slurry; and coating and curing the mixed slurry to obtain an insulating coating adhesive layer. In the above preparation method, the aliphatic epoxy resin is first dissolved in an organic solvent to uniformly disperse it, and then an alicyclic epoxy resin and a curing agent are added to it to obtain a mixed slurry; the mixed slurry is then coated and cured to obtain an insulating coating adhesive layer.

[0036] In a preferred embodiment, the mixed slurry further includes a silicone-modified epoxy resin, additives, fillers, accelerators, and organic solvents.

[0037] Preferably, the coating method is screen printing; preferably, the solid content of the liquid fatty resin slurry is 30-70%; preferably, the thickness of the insulating coating layer is 30-40µm. Controlling the parameters in the preparation process of the insulating coating adhesive within the above range can further improve the performance of the insulating coating adhesive. Preferably, the curing method is thermal curing; preferably, the curing temperature is 100-150℃ (more preferably 120±10℃), and the curing time is 20min-60min (more preferably 30±5min). Using thermal curing is more efficient, and controlling the curing temperature and curing time within the above range can improve the curing effect and further improve the curing efficiency.

[0038] According to a fourth aspect of the present invention, a photovoltaic module is also provided, including an adhesive layer, which is the aforementioned insulating coating adhesive layer.

[0039] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0040] Example 1

[0041] A method for preparing an insulating coating adhesive layer:

[0042] The insulating coating layer provided in this embodiment, by weight, is made from an insulating coating adhesive, the composition of which is shown in the table below:

[0043]

[0044] The aliphatic epoxy resin in the above insulating coating adhesive is dissolved in the organic solvent diethylene glycol butyl ether to obtain a liquid aliphatic resin slurry with a solid content of 50%. The alicyclic epoxy resin, silicone-modified epoxy resin, curing agent, additives, fillers, and accelerator are mixed with the liquid aliphatic resin slurry in the above proportions to obtain a mixed slurry. The mixed slurry is coated onto the surface of the photovoltaic module by screen printing, with the thickness controlled at 30µm, and heat-cured at 120℃ for 30min to obtain the insulating coating adhesive layer.

[0045] Example 2

[0046] A method for preparing an insulating coating adhesive layer:

[0047] The only difference between this embodiment and Embodiment 1 is that the types of insulating coating adhesive components are different, as shown in the table below.

[0048]

[0049] Example 3

[0050] A method for preparing an insulating coating adhesive layer:

[0051] The only difference between this embodiment and Embodiment 1 is that the types of insulating coating adhesive components are different, as shown in the table below.

[0052]

[0053] Example 4

[0054] A method for preparing an insulating coating adhesive layer:

[0055] The only difference between this embodiment and Example 1 is that the weight parts of 4,4-(1-methylethylindenyl)dicycloethyl diglyceride ester are changed to 120 parts. At this point, the weight ratio of alicyclic epoxy resin to fatty epoxy resin is 0.8:1.

[0056] Example 5

[0057] A method for preparing an insulating coating adhesive layer:

[0058] The only difference between this embodiment and Example 1 is that the weight parts of 4,4-(1-methylethylindenyl)dicycloethyl diglyceride ester are changed to 250 parts, and the weight parts of epoxidized polybutadiene are changed to 100 parts. At this point, the weight ratio of alicyclic epoxy resin to fatty epoxy resin is 2.5:1.

[0059] Example 6

[0060] A method for preparing an insulating coating adhesive layer:

[0061] The only difference between this embodiment and Embodiment 1 is that no silicone-modified epoxy resin was added.

[0062] Example 7

[0063] A method for preparing an insulating coating adhesive layer:

[0064] The difference between this embodiment and Embodiment 1 lies only in the condition parameters after obtaining the mixed slurry, specifically:

[0065] The mixed slurry was screen-printed onto the surface of the photovoltaic module, with the thickness controlled at 20µm. It was then heat-cured at 100℃ for 60 minutes to obtain an insulating coating layer.

[0066] Example 8

[0067] A method for preparing an insulating coating adhesive layer:

[0068] The difference between this embodiment and Embodiment 1 lies only in the condition parameters after obtaining the mixed slurry, specifically:

[0069] The mixed slurry was screen-printed onto the surface of the photovoltaic module, with the thickness controlled at 50µm. It was then heat-cured at 150℃ for 20 minutes to obtain an insulating coating layer.

[0070] Comparative Example 1

[0071] A method for preparing an insulating coating adhesive layer:

[0072] The only difference between this comparative example and Example 1 is that no aliphatic epoxy resin was added to the insulating coating adhesive.

[0073] Comparative Example 2

[0074] A method for preparing an insulating coating adhesive layer:

[0075] The only difference between this comparative example and Example 1 is that no alicyclic epoxy resin was added to the insulating coating adhesive.

[0076] Comparative Example 3

[0077] A method for preparing an insulating coating adhesive layer:

[0078] The only difference between this comparative example and Example 1 is that a benzene ring-type epoxy resin system from the prior art is used. Specifically, the two epoxy resins in Example 1 are replaced with an equal weight of E54 epoxy resin.

[0079] Comparative Example 4

[0080] A method for preparing an insulating coating adhesive layer:

[0081] The only difference between this comparative example and Example 1 is that the aliphatic epoxy resin in Example 1 is replaced with an equal weight of aliphatic epoxy resin ethylene glycol diglycidyl ether with a molecular weight of 174.

[0082] Comparative Example 5

[0083] A method for preparing an insulating coating adhesive layer:

[0084] The only difference between this comparative example and Example 1 is that the weight parts of 4,4-(1-methylethylindenyl)dicycloethyl diglyceride ester are changed to 60 parts. In this case, the weight ratio of alicyclic epoxy resin to fatty epoxy resin is 0.4:1.

[0085] Comparative Example 6

[0086] A method for preparing an insulating coating adhesive layer:

[0087] The only difference between this comparative example and Example 1 is that the weight parts of 4,4-(1-methylethylindenyl)dicycloethyl diglyceride ester are changed to 525 parts. In this case, the weight ratio of alicyclic epoxy resin to fatty epoxy resin is 3.5:1.

[0088] Test methods

[0089] Heat resistance: The insulating adhesive coatings of the compositions prepared in the above examples and comparative examples were tested using a thermogravimetric analyzer. The coating thickness was 35 micrometers, the insulating adhesive mass was 6-8 mg, and the test was conducted in air atmosphere. The 5% heat loss temperature of the insulating adhesive was measured.

[0090] Yellowing resistance: The compositions prepared in the above examples and comparative examples were coated and cured to prepare a transparent insulating coating with a thickness of 35 micrometers. The coating was then placed in a UVA chamber, and the L, a, and b values ​​of the coating after treatment with an irradiation dose of 60 kW·h were tested. The difference Δb between the b value after the test and the value before the test was calculated.

[0091] Adhesion: The coatings prepared in the above embodiments and comparative examples were applied to the back of the photovoltaic cells with a coating thickness of 35 micrometers. The photovoltaic cells were then arranged in an array to form photovoltaic cell strings. The photovoltaic modules were then fabricated in the manner of front substrate, front encapsulant film, photovoltaic cell strings, back encapsulant film, and back substrate. The initial adhesion was then tested.

[0092] Pencil Hardness Test (Rigidity): The pencil tip applies a load of 7.35N to the paint film surface. Hold the pencil vertically and rub it against sandpaper at a 90° angle until the lead tip is flattened, resulting in a pencil lead with a round cross-section, smooth edges, and no nicks. Repeat this step before each use. Use a pencil cart to test the paint film surface and observe for scratches. Test results of 3H, 4H, or 5H indicate that the surface hardness of the paint film can withstand the scratches of a pencil of the corresponding hardness level (3H, 4H, 5H) without producing scratches; the larger the number before H, the harder the lead and the higher the hardness of the paint film.

[0093] The insulating coating adhesive layers obtained in the above embodiments and comparative examples were subjected to the above tests, and the results are shown in Table 1.

[0094] Table 1

[0095]

[0096] As can be seen from the above description, compared with the comparative examples, especially comparative examples 3 and 4, the above embodiments of the present invention achieve the following technical effects:

[0097] Compared with existing insulating adhesives, this invention provides an insulating adhesive without benzene rings. First, the benzene rings are replaced with six-membered alicyclic rings, which improves the resistance to yellowing, as well as the heat resistance, stability, and aging performance, extending the service life of the insulating adhesive on BC batteries. Second, a high molecular weight alicyclic epoxy resin is introduced to improve the reactivity of the alicyclic epoxy resin, meeting the requirement of rapid curing at 120~180℃. The high molecular weight epoxy resin improves the heat resistance of the insulating adhesive and further enhances the adhesion between the insulating adhesive and the BC battery cells.

[0098] Specifically:

[0099] Comparing Examples 4 and 5, Comparative Examples 1 and 2, and Comparative Examples 5 and 6 with Example 1, it can be seen that the preferred weight ratio of alicyclic epoxy resin to fatty epoxy resin in the insulating coating adhesive allows for better synergistic effects between the two resins, thereby further improving the overall performance of the insulating coating adhesive layer.

[0100] Comparing Example 6 with Example 1, it can be seen that using silicone-modified epoxy resin as an insulating coating adhesive can further improve the heat resistance and aging resistance of the insulating coating adhesive, which is beneficial to further improving the durability of the insulating coating adhesive layer.

[0101] Comparing Examples 7 and 8 with Example 1, it can be seen that by optimizing the screen printing thickness and the curing conditions of the adhesive layer, the various properties of the insulating coating adhesive can be further improved.

[0102] 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 insulating coating adhesive, characterized in that, The insulating coating adhesive includes: alicyclic epoxy resin, fatty epoxy resin, and curing agent; The number-average molecular weight of the aliphatic epoxy resin is 1100~5400. The weight ratio of the alicyclic epoxy resin to the fatty epoxy resin is (0.5~3):

1.

2. The insulating coating adhesive according to claim 1, characterized in that, By weight, the insulating coating adhesive comprises: 100-200 parts of the alicyclic epoxy resin, 100-200 parts of the fatty epoxy resin, 15-30 parts of the curing agent, 1-5 parts of the additives, 200-400 parts of the filler, 1-10 parts of the accelerator, and 20-70 parts of the organic solvent. Preferably, by weight, the insulating coating adhesive comprises: 150-200 parts of the alicyclic epoxy resin, 100-150 parts of the fatty epoxy resin, 15-20 parts of the curing agent, 1-5 parts of the additives, 200-300 parts of the filler, 5-10 parts of the accelerator, and 30-50 parts of the organic solvent.

3. The insulating coating adhesive according to claim 1 or 2, characterized in that, In the insulating coating adhesive, the weight ratio of the cycloaliphatic epoxy resin to the aliphatic epoxy resin is (1~2):1; The epoxy equivalent of the aliphatic epoxy resin is 165~240; The number average molecular weight of the aliphatic epoxy resin is 3000~5400.

4. The insulating coating adhesive according to any one of claims 1 to 3, characterized in that, The insulating coating adhesive also includes silicone-modified epoxy resin; Preferably, in the insulating coating adhesive, the silicone-modified epoxy resin comprises 100-200 parts by weight, more preferably 150-200 parts by weight; Preferably, the silicon-modified epoxy resin is selected from one or more of glycidyl etheroxypropylcyclotetrasiloxane, methylpropene trioxocyclosiloxane, 3-glycidyl etheroxypropylheptamethylcyclotetrasiloxane and 3-epoxypropoxy-1,1,3,3-tetramethyldisiloxane.

5. The insulating coating adhesive according to any one of claims 1 to 4, characterized in that, The molecular structure of the alicyclic epoxy resin includes at least two epoxy groups, and each epoxy group is directly connected to a polycyclic alicyclic ring, wherein the polycyclic alicyclic ring has 4 to 8 carbon atoms. Preferably, the number of carbon atoms in the multi-membered aliphatic ring is 5 to 7; more preferably, the multi-membered aliphatic ring is a six-membered ring. More preferably, the alicyclic epoxy resin is selected from one or more of 3,4-epoxycyclohexanecarboxylic acid (3',4'-epoxycyclohexyl)methyl, di(3,4-epoxycyclohexylmethyl)adipate, 2,2-di(3,3'-epoxycyclohexyl)propane and 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexanecarboxylic acid) ester.

6. The insulating coating adhesive according to any one of claims 1 to 5, characterized in that, The molecular structure of the aliphatic epoxy resin includes at least two epoxy groups, and each epoxy group is directly linked to a straight-chain or branched alkyl group, wherein the straight-chain or branched alkyl group may optionally contain heteroatoms. Preferably, the aliphatic epoxy resin is selected from one or more of epoxidized polybutadiene, polypropylene glycol diglycidyl ether, polyethylene glycol monoglycidyl ether, and ethylene glycol diglycidyl ether.

7. The insulating coating adhesive according to any one of claims 1 to 6, characterized in that, The curing agent is selected from one or more of dicyandiamide, melamine, ethylenediamine, and methylhexahydrophthalic anhydride; and / or, The additive is selected from one or more of ultraviolet absorbers, leveling agents, and defoamers; and / or, The filler is selected from one or more of barium sulfate, calcium carbonate, and silicon dioxide; and / or, The accelerator is selected from one or more of dimethylimidazole, 2,4,6-tris(dimethylaminomethyl)phenol, and N-(2-hydroxyphenyl)-N',N'-dimethylurea; and / or, The organic solvent is selected from one or more of diethylene glycol butyl ether, dipropylene glycol methyl ether, and divalent esters; Preferably, the leveling agent is a silicone leveling agent; and / or, the defoamer is a polyolefin defoamer; and / or, the ultraviolet absorber is 4-hydroxybenzophenone.

8. An insulating coating adhesive layer, characterized in that, The insulating coating adhesive as described in any one of claims 1 to 7 is obtained by sequentially coating and curing.

9. A method for preparing the insulating coating adhesive layer according to claim 8, characterized in that, The preparation method includes the following steps: Aliphatic epoxy resin is dissolved in an organic solvent to form a liquid aliphatic resin slurry; The liquid aliphatic resin slurry is mixed with alicyclic epoxy resin and a curing agent to obtain a mixed slurry; The mixed slurry is coated and cured to obtain the insulating coating layer.

10. The method for preparing the insulating coating adhesive layer according to claim 9, characterized in that, The mixed slurry also includes silicone-modified epoxy resin, additives, fillers, accelerators, and organic solvents; and / or, The coating method is screen printing; and / or, The solid content of the liquid fatty resin slurry is 30-70%; and / or, The thickness of the insulating coating layer is 30~40µm; and / or, The curing method is thermosetting; More preferably, the curing temperature of the thermosetting process is 100~150℃, and the curing time is 20min~60min.

11. A photovoltaic module, comprising an adhesive layer, characterized in that, The adhesive layer is the insulating coating adhesive layer as described in claim 8.

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