Photocuring adhesive for photovoltaic module and manufacturing method of photovoltaic module

Abstract

The embodiment of the invention relates to the technical field of photovoltaics, and provides a photocuring adhesive for a photovoltaic module and a manufacturing method of the photovoltaic module, and the photocuring adhesive for the photovoltaic module comprises the following components in parts by mass: 45-60 parts of oligomer, 40-45 parts of monomer and 1-3 parts of initiator; wherein the molar ratio of the monomer to the initiator is (1: 0.005)-(1: 0.075); the molar ratio of the monomer to the oligomer is (1: 0.25)-(1: 1). The photocuring adhesive for the photovoltaic module and the manufacturing method of the photovoltaic module provided by the embodiment of the invention are at least beneficial to improving the tensile force between a welding strip and a battery piece.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of photovoltaic technology, and in particular to a photocurable adhesive for a photovoltaic module and a method for manufacturing a photovoltaic module. Background Art

[0002] At present, the connection between cells in photovoltaic modules is mainly achieved through high-temperature welding with welding ribbons. With the iteration of photovoltaic technology, the size and specifications of cells in photovoltaic modules will become larger and thinner in the future. Therefore, in order to prevent hidden cracks in cells, high-temperature welding technology is no longer applicable. In addition, as the size of the welding ribbon becomes thinner and thinner, the tensile force after welding no longer meets the requirements.

[0003] The current busbar-free cell design can achieve a significant reduction in silver paste consumption, but there is still a risk of insufficient solder ribbon tension. Summary of the invention

[0004] The embodiments of the present application provide a photocurable adhesive for a photovoltaic module and a method for manufacturing a photovoltaic module, which at least helps to increase the tension between the soldering ribbon and the battery cell.

[0005] According to some embodiments of the present application, on the one hand, the embodiments of the present application provide a photocuring adhesive for photovoltaic modules, which comprises the following components in parts by mass: 45 to 60 parts of oligomers, 40 to 45 parts of monomers, and 1 to 3 parts of initiators; wherein the molar ratio of monomers to initiators is 1:0.005 to 1:0.075; and the molar ratio of monomers to oligomers is 1:0.25 to 1:1.

[0006] In some embodiments, the oligomer is selected from one or more of epoxy acrylate, polyurethane acrylate, polyester acrylate, or polyether acrylate.

[0007] In some embodiments, the monomer is selected from one or more of acrylate, styrene, ethyl acrylate, or butyl acrylate.

[0008] In some embodiments, the initiator is selected from one or more of photoinitiator 754, photoinitiator 907, photoinitiator 184, photoinitiator 369, photoinitiator 1173, photoinitiator 819, photoinitiator BP, photoinitiator TPO, photoinitiator PBZ or photoinitiator MBF.

[0009] In some embodiments, the solvent is selected from one or more of methyl chloride, acetone, and ethylene dichloride.

[0010] In some embodiments, the molar ratio of monomer to initiator is 1:0.025; the molar ratio of monomer to oligomer is 1:0.65.

[0011] In some embodiments, the following components are also included in parts by weight: 0 to 3 parts of gas silicone, 0.2 to 0.3 parts of leveling agent, 0.01 to 0.15 parts of inhibitor, 0.4 to 0.5 parts of surfactant, and 0 to 3 parts of plasticizer.

[0012] In some embodiments, the glass transition temperature of the photocurable adhesive after curing is 45° C. to 120° C.

[0013] According to some embodiments of the present application, on the other hand, the embodiments of the present application further provide a method for manufacturing a photovoltaic module, comprising: weighing each component in the photocurable adhesive as in the above embodiments; evenly mixing the oligomer, initiator, solvent and a part of the monomer by mass, and then adding the remaining part of the monomer by mass to the above mixture and mixing evenly to obtain the photocurable adhesive to be used; pre-welding the soldering tape to the position corresponding to the grid line on the battery cell; coating the photocurable adhesive to be used between the two sides of the soldering tape and the surface of the battery cell; using an ultraviolet lamp to perform radiation curing on the photocurable adhesive to be used; and performing a lamination process on the cured battery cell.

[0014] In some embodiments, in the step of uniformly mixing the oligomer, the initiator, the solvent and a portion of the monomer by mass, the portion of the monomer by mass accounts for 60% to 100% of the total mass of the monomer.

[0015] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0016] The photocurable adhesive for photovoltaic modules provided in the embodiment of the present application includes oligomers, monomers and initiators. Under the irradiation of ultraviolet light in a specific band, the initiator can induce a free radical reaction between the oligomers and the active monomers, thereby curing the fluid photocurable adhesive. The cured photocurable adhesive has a certain tensile strength. The use of the photocurable adhesive to fix the solder strip and the battery cell can be beneficial to improve the tension between the solder strip and the battery cell. Among them, the molar ratio of the monomer to the initiator affects the crosslinking degree of the photocurable adhesive. When the molar ratio of the monomer to the initiator is low, the amount of the initiator is insufficient to initiate the polymerization of the monomer, which easily leads to a low crosslinking degree of the cured photocurable adhesive, a low self-adhesive force, and a small tension between the solder strip and the battery cell; when the molar ratio of the monomer to the initiator is too high, the initiation rate is fast, resulting in rapid polymerization of the monomer, and the inability to form a high molecular weight structure. The cured photocurable adhesive has a low crosslinking degree and a low self-adhesive force, and can provide a small tension between the solder strip and the battery cell. Therefore, the molar ratio of monomer to initiator needs to be within an appropriate range so that the specific reaction rate is moderate, and the cured photocurable adhesive is prevented from being too hard or too soft, which is beneficial for the cured photocurable adhesive to increase the tension between the solder strip and the battery cell. In addition, the molar ratio of monomer to oligomer affects the content of the oligomer coated by the polymer structure formed by polymerization. When the molar ratio of monomer to oligomer is low, the content of the oligomer coated by the polymer structure formed by monomer polymerization is too small, resulting in low self-adhesion of the cured photocurable adhesive, which can provide less tension between the solder strip and the battery cell; when the molar ratio of monomer to oligomer is large, the content of short-chain polymers in the system is high, and the content of the oligomer wrapped by the polymer structure formed by monomer polymerization is too large, resulting in low self-adhesion of the cured photocurable adhesive, which can provide less tension between the solder strip and the battery cell. Therefore, the molar ratio of monomer to oligomer needs to be within an appropriate range so that the content of the oligomer coated by the polymer structure formed by monomer polymerization is moderate, which is beneficial for the cured photocurable adhesive to increase the tension between the solder strip and the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 The tensile force variation diagram corresponding to the samples with different monomer to initiator molar ratios provided in the examples of the present application;

[0019] Figure 2 The tensile force variation diagram corresponding to the samples with different monomer to oligomer molar ratios provided in the examples of the present application;

[0020] Figure 3 This is a graph showing the tensile force variation corresponding to samples with different glass transition temperatures provided in the examples of the present application. DETAILED DESCRIPTION

[0021] As can be seen from the background technology, the busbar-free cell design can achieve a significant reduction in silver paste consumption, but there is still a risk of insufficient solder ribbon tension.

[0022] In the busbar-free technology of photovoltaic modules, low-melting-point metals are usually used as solder to make welding strips, which are first fixed to the surface of the cell by glue; then in the lamination process of the photovoltaic module, the temperature and pressure of the laminator are used to help the low-melting-point welding strips and the grid structure to be combined together. As a result, the grid structures on adjacent cells can be directly electrically connected through the welding strips to form a busbar-free structure, reducing the laying of busbars and reducing the manufacturing cost of the cell; in addition, the busbar-free design can shorten the carrier transport path and reduce the series resistance, thereby increasing the front light-receiving area and improving the module power.

[0023] Photovoltaic modules must meet multiple reliability tests, such as hot and cold cycle tests, high temperature and high humidity tests, static load tests, etc., before they can meet the requirements of qualified products. For busbarless photovoltaic modules, since the metallization between the soldering ribbon and the soldering point of the battery cell is weak, the tensile force that can be sustained between the soldering ribbon and the battery cell is small, and it is difficult to pass the above tests. On this basis, it is necessary to add an additional medium between the soldering ribbon and the battery cell to increase the tensile force. On the basis of meeting the industrial process, light-curing adhesive becomes the preferred medium.

[0024] However, the photocuring adhesives currently used in photovoltaic modules generally have problems such as weak interface bonding with battery cells or solder strips, and low tensile strength after reliability, which in turn leads to the phenomenon of undesirable desoldering between the solder strips and battery cells in photovoltaic modules.

[0025] The embodiments of the present application provide a photocurable adhesive for a photovoltaic module and a method for manufacturing a photovoltaic module, which at least helps to increase the tension between the soldering ribbon and the battery cell.

[0026] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0027] In the description of the embodiments of the present application, when a certain component “includes” another component, unless otherwise stated, other components are not excluded and other components may be further included.

[0028] Those skilled in the art will appreciate that, in the various embodiments of the present application, many technical details are provided in order to enable readers to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can also be implemented.

[0029] According to some embodiments of the present application, on the one hand, the embodiments of the present application provide a photocurable adhesive for photovoltaic modules, which comprises the following components by weight: 45 to 60 parts of oligomers, 40 to 45 parts of monomers, and 1 to 3 parts of initiators. The molar ratio of the monomer to the initiator is 1:0.005 to 1:0.075, for example, it can be 1:0.005, 1:0.008, 1:0.01, 1:0.025, 1:0.03, 1:0.05 or 1:0.075; the molar ratio of the monomer to the oligomer is 1:0.25 to 1:1, for example, it can be 1:0.25, 1:0.5, 1:0.65, 1:0.8 or 1:1.

[0030] The photocurable adhesive for photovoltaic modules provided in the embodiment of the present application includes oligomers, monomers and initiators. Under the irradiation of ultraviolet light in a specific band, the initiator can induce a free radical reaction between the oligomers and the active monomers, thereby curing the fluid photocurable adhesive. The cured photocurable adhesive has a certain tensile strength. The use of the photocurable adhesive to fix the solder strip and the battery cell can be beneficial to improve the tension between the solder strip and the battery cell. Among them, the molar ratio of the monomer to the initiator affects the crosslinking degree of the photocurable adhesive. When the molar ratio of the monomer to the initiator is low, the amount of the initiator is insufficient to initiate the polymerization of the monomer, which easily leads to a low crosslinking degree of the cured photocurable adhesive, a low self-adhesive force, and a small tension between the solder strip and the battery cell; when the molar ratio of the monomer to the initiator is too high, the initiation rate is fast, resulting in rapid polymerization of the monomer, and the inability to form a high molecular weight structure. The cured photocurable adhesive has a low crosslinking degree and a low self-adhesive force, and can provide a small tension between the solder strip and the battery cell. Therefore, the molar ratio of monomer to initiator needs to be within an appropriate range so that the specific reaction rate is moderate, and the cured photocurable adhesive is prevented from being too hard or too soft, which is beneficial for the cured photocurable adhesive to increase the tension between the solder strip and the battery cell. In addition, the molar ratio of monomer to oligomer affects the content of the oligomer coated by the polymer structure formed by polymerization. When the molar ratio of monomer to oligomer is low, the content of the oligomer coated by the polymer structure formed by monomer polymerization is too small, resulting in low self-adhesion of the cured photocurable adhesive, which can provide less tension between the solder strip and the battery cell; when the molar ratio of monomer to oligomer is large, the content of short-chain polymers in the system is high, and the content of the oligomer wrapped by the polymer structure formed by monomer polymerization is too large, resulting in low self-adhesion of the cured photocurable adhesive, which can provide less tension between the solder strip and the battery cell. Therefore, the molar ratio of monomer to oligomer needs to be within an appropriate range so that the content of the oligomer coated by the polymer structure formed by monomer polymerization is moderate, which is beneficial for the cured photocurable adhesive to increase the tension between the solder strip and the battery cell.

[0031] In some embodiments, the oligomer is selected from one or more of epoxy acrylate, polyurethane acrylate, polyester acrylate, or polyether acrylate.

[0032] In some embodiments, the monomer is selected from one or more of acrylate, styrene, ethyl acrylate or butyl acrylate. The monomer can act as a diluent and can adjust the viscosity of the glue and the hardness of the light-curing glue.

[0033] In some embodiments, the initiator is selected from one or more of photoinitiator 754, photoinitiator 907, photoinitiator 184, photoinitiator 369, photoinitiator 1173, photoinitiator 819, photoinitiator BP, photoinitiator TPO, photoinitiator PBZ or photoinitiator MBF.

[0034] In some embodiments, the solvent of the photocurable adhesive for photovoltaic modules is selected from one or more of methyl chloride, acetone, and ethylene dichloride.

[0035] In some embodiments, the molar ratio of monomer to initiator is 1:0.025; the molar ratio of monomer to oligomer is 1:0.65.

[0036] In some embodiments, the photocurable adhesive for photovoltaic modules further comprises one or more of a gas silicone, a leveling agent, an inhibitor, a surfactant or a plasticizer.

[0037] Among them, the mass proportions of gas silicone, leveling agent, inhibitor, surfactant or plasticizer are as follows: gas silicone 0-3 parts, leveling agent 0.2-0.3 parts, inhibitor 0.01-0.15 parts, surfactant 0.4-0.5 parts, plasticizer mass proportion is 0-3 parts.

[0038] After the fumed silica is evenly dispersed in the photocuring adhesive system, a large number of particles form hydrogen bonds through the surface silanol (Si-OH), which can form a silica aggregate network, restricting the fluidity of the system and increasing the viscosity, thereby playing a thickening role. Under the action of shear force, the hydrogen bonds and the silica network are destroyed, resulting in a decrease in the viscosity of the system, thixotropy, and ease of construction; once the external force is eliminated, the hydrogen bonds and the silica network are re-formed. In this way, the photocuring adhesive can be effectively prevented from sagging during construction and use.

[0039] The leveling agent in the photocuring adhesive system can improve the adhesion of the photocuring adhesive on the surface of the object, reduce the convexity or concaveity generated during the coating process of the photocuring adhesive, and make the photocuring adhesive more flat and uniform during bonding. For example, the leveling agent can be polydimethylsiloxane or polymethylphenylsiloxane.

[0040] In the photocurable adhesive system, the polymerization inhibitor can prevent the vinyl monomer from polymerizing during the refining, synthesis, storage and transportation. For example, the polymerization inhibitor can be ferric chloride, cuprous chloride, copper sulfate, titanium trichloride, sodium sulfate or ammonium thiocyanate.

[0041] Surfactants can significantly reduce the surface tension of the solution in the photocurable adhesive system, effectively change the physical and chemical properties of the interface, and improve the uniformity and stability of the dispersion of each component in the photocurable adhesive. For example, the surfactant can be fatty acid soap, sodium dodecyl sulfate, sodium lauryl polyoxyethylene ether sulfate, sodium cetyl polyoxyethylene ether phosphate, soybean lecithin, octadecyl trimethyl ammonium chloride, distearyl dimethyl sodium chloride or cocamidopropyl betaine, etc.

[0042] Plasticizers in the photocuring adhesive system can increase the plasticity of the photocuring adhesive, improve the elasticity of the photocuring adhesive, improve the cold resistance, and increase the fluidity of the components of the photocuring adhesive, which is conducive to wetting, diffusion and adsorption, thereby improving the performance and bonding strength of the photocuring adhesive. For example, the plasticizer can be phthalates, epoxy esters or phosphates.

[0043] In some embodiments, the glass transition temperature of the cured photocurable adhesive is 45°C to 120°C, for example, 45°C, 50°C, 64°C, 70°C, 83°C, 95°C, 100°C, 114°C or 120°C. The lower the degree of crosslinking of the cured photocurable adhesive, the lower the glass transition temperature; the higher the degree of crosslinking of the cured photocurable adhesive, the higher the glass transition temperature. However, if the degree of crosslinking of the cured photocurable adhesive is too high, it is easy to cause the cured photocurable adhesive to become brittle, which in turn causes the tensile force provided by the cured photocurable adhesive to the battery cell and the soldering strip to decrease. Therefore, the glass transition temperature of the cured photocurable adhesive needs to be within an appropriate range.

[0044] According to some embodiments of the present application, on the other hand, the embodiments of the present application further provide a method for manufacturing a photovoltaic module, comprising: weighing each component in the photocurable adhesive as in the above embodiments; evenly mixing the oligomer, initiator, solvent and a part of the monomer by mass, and then adding the remaining part of the monomer by mass to the above mixture and mixing evenly to obtain the photocurable adhesive to be used; pre-welding the soldering tape to the position corresponding to the grid line on the battery cell; coating the photocurable adhesive to be used between the two sides of the soldering tape and the surface of the battery cell; using an ultraviolet lamp to perform radiation curing on the photocurable adhesive to be used; and performing a lamination process on the cured battery cell.

[0045] In the manufacturing method of the photovoltaic module provided in the embodiment of the present application, the components provided by the photocuring adhesive in the above embodiment are used, and the oligomer, initiator, solvent and part of the monomer by mass are first mixed evenly, and then the remaining part of the monomer by mass is added to the above mixture and mixed evenly to obtain the photocuring adhesive to be used. In this way, it is helpful to control the overall viscosity of the photocuring adhesive and avoid the viscosity of the photocuring adhesive to be used being too large or too small to be unfavorable for coating. Further, the soldering strip is first pre-welded to the position corresponding to the grid line on the battery cell, and then the photocuring adhesive to be used is coated between the two sides of the soldering strip and the surface of the battery cell and cured with an ultraviolet lamp. In this way, under the condition of low temperature and time of the pre-welding process, damage to the battery cell can be avoided, and at the same time, partial welding tension can be provided between the battery cell and the soldering strip; at the same time, the soldering strip and the battery cell are fixed by the cured photocuring adhesive, and the partial tension between the soldering strip and the battery cell can also be increased. Later in the lamination process, the pre-welded parts between the soldering ribbon and the grid line and the unwelded parts are alloyed using the temperature of the lamination process, which further improves the welding stability between the cell and the soldering ribbon, further increases the tension between the soldering ribbon and the cell, and improves the overall stability of the photovoltaic module.

[0046] In some embodiments, in the step of uniformly mixing the oligomer, initiator, solvent and some mass fraction of monomer, the proportion of some mass fraction of monomer to the total mass of monomer is 60% to 100%, for example, it can be 60%, 65%, 70%, 74%, 80%, 86%, 90%, 93%, 100%, and the proportion of some mass fraction of monomer to the total mass of monomer can be adjusted according to the viscosity after mixing. It is understandable that when the step of uniformly mixing the oligomer, initiator, solvent and some mass fraction of monomer, the proportion of some mass fraction of monomer to the total mass of monomer is 100%, which means that the oligomer, initiator, solvent and monomer are directly blended.

[0047] In some embodiments, the preparation process of the photocurable adhesive is carried out in a yellow light environment. Since the wavelength of yellow light is far away from the wavelength of ultraviolet light, the yellow light environment can block ultraviolet light to avoid accidental exposure of the photocurable adhesive.

[0048] In some embodiments, the pre-soldering temperature is 200°C to 300°C, such as 200°C, 230°C, 250°C, 280°C or 300°C; the time is 1s to 5s, such as 1s, 2s, 3s, 4s or 5s.

[0049] In some embodiments, the time for radiation curing the photocurable adhesive using an ultraviolet lamp is 2s to 5s, for example, 2s, 3s, 4s or 5s.

[0050] In some embodiments, the wavelength of the ultraviolet lamp is 365nm to 400nm, such as 365nm, 370nm, 386nm, 394nm or 400nm, etc.; the power of the ultraviolet lamp is 750mW / cm 2 ~2000mW / cm 2 , for example, 750 mW / cm 2 、864mW / cm 2 、888mW / cm 2 , 1000mW / cm 2 、1130mW / cm 2 、1400mW / cm 2 、1580mW / cm 2 、1840mW / cm 2 or 2000mW / cm 2If the wavelength of the UV lamp does not match the formulation of the photocuring adhesive to be used, it may lead to incomplete curing, affecting the bonding strength and durability. Therefore, the wavelength of the UV lamp can be adjusted within an appropriate range according to the formulation of the photocuring adhesive. If the power of the UV lamp is too high, it is easy to generate too much heat and cure the surface layer quickly, but it does not speed up the curing speed of the deep layer, which is easy to cause excessive polymerization shrinkage. Therefore, the power of the UV lamp needs to be adjusted within an appropriate range.

[0051] In some embodiments, during the preparation of the photocurable adhesive, a viscosity test is performed on the photocurable adhesive using a viscometer, for example, a Brookfield viscometer may be used for the test.

[0052] In some embodiments, the viscosity of the photocurable adhesive to be used is 1000 mPa·s to 5000 mPa·s, for example, 1000 mPa·s, 1350 mPa·s, 2000 mPa·s, 2480 mPa·s, 3000 mPa·s, 3690 mPa·s, 4000 mPa·s, 4170 mPa·s or 5000 mPa·s.

[0053] The following are specific embodiments of the present application:

[0054] Example 1

[0055] 1. Weigh the components of the photocurable adhesive according to the following mass parts: 40 parts of ethyl acrylate monomer, weigh the corresponding mass of polyurethane ethyl acrylate oligomer according to the molar ratio of monomer to oligomer of 1:0.25, weigh the corresponding mass of photoinitiator BP according to the molar ratio of monomer to initiator of 1:0.005, and 3 parts of dichloroethylene solvent.

[0056] 2. The oligomer, initiator, solvent and 60% by weight of 40 parts of ethyl acrylate monomer are mixed evenly, and then 40% by weight of 40 parts of ethyl acrylate monomer is added to the above mixture and mixed evenly to obtain a ready-to-use photocurable adhesive.

[0057] 3. Pre-solder the solder strip to the corresponding grid line position on the battery cell.

[0058] 4. Apply the light-curing adhesive between the two sides of the solder strip and the surface of the battery cell.

[0059] 5. Use ultraviolet light to radiate and cure the photocurable adhesive for 2 seconds, and then perform a lamination process on the cured battery cells.

[0060] Example 2

[0061] The preparation method of Example 2 is the same as that of Example 1, except that in Example 2, the molar ratio of the monomer to the initiator is 1:0.025.

[0062] Example 3

[0063] The preparation method of Example 3 is the same as that of Example 1, except that in Example 3, the molar ratio of the monomer to the initiator is 1:0.05.

[0064] Example 4

[0065] The preparation method of Example 4 is the same as that of Example 1, except that in Example 4, the molar ratio of the monomer to the initiator is 1:0.075.

[0066] Comparative Example 1

[0067] The preparation method of Comparative Example 1 is the same as that of Example 1, except that in Comparative Example 1, the molar ratio of the monomer to the initiator is 1:0.1.

[0068] A tensile test was performed on the above-mentioned Example 1, Example 2, Example 3, Example 4 and Comparative Example 1. The method of the tensile test is: the battery cell together with the welding ribbon is cut off, and a tensile test is performed using a welding ribbon-battery cell tensile testing machine for photovoltaic modules, and the welding ribbon is stretched 180° in the opposite direction to make the welding ribbon fall off the battery cell and the tensile value is read and recorded.

[0069] Table 1 The tensile forces corresponding to samples with different monomer to initiator molar ratios

[0070] Example Monomer to initiator molar ratio Tension(N) Example 1 1:0.005 1.33 Example 2 1:0.025 1.61 Example 3 1:0.05 1.58 Example 4 1:0.075 1.17 Comparative Example 1 1:0.1 0.74

[0071] Figure 1 This is a graph of the change in tensile force corresponding to samples with different monomer to initiator molar ratios provided in the examples of the present application.

[0072] Combined with reference table 1 and Figure 1 Based on the tensile test results of Example 1, Example 2, Example 3, Example 4 and Comparative Example 1, it can be seen that when the molar ratio of the monomer to the initiator in the photocuring adhesive increases, the tensile force provided by the cured photocuring adhesive to the soldering tape and the battery cell first increases and then weakens. Among them, when the molar ratio of the monomer to the initiator is 1:0.025, the maximum tensile force provided by the cured photocuring adhesive to the soldering tape and the battery cell is 1.61N.

[0073] Comparative Example 2

[0074] The preparation method of Comparative Example 2 is the same as that of Example 1, except that in Comparative Example 2, the molar ratio of the monomer to the oligomer is 1:0.05.

[0075] Example 6

[0076] The preparation method of Example 6 is the same as that of Example 1, except that in Example 6, the molar ratio of the monomer to the oligomer is 1:0.65.

[0077] Example 7

[0078] The preparation method of Example 7 is the same as that of Example 1, except that in Example 7, the molar ratio of the monomer to the oligomer is 1:1.

[0079] Comparative Example 3

[0080] The preparation method of Comparative Example 3 is the same as that of Example 1, except that in Comparative Example 3, the molar ratio of the monomer to the oligomer is 1:2.

[0081] The above-mentioned comparative example 2, embodiment 6, embodiment 7 and comparative example 3 were subjected to a tensile test.

[0082] Table 2 Tensile forces corresponding to samples with different monomer to oligomer molar ratios

[0083] Example Monomer to oligomer molar ratio Tension(N) Comparative Example 2 1:0.05 1.17 Example 1 1:0.25 1.33 Example 6 1:0.65 1.67 Example 7 1:1 1.43 Comparative Example 3 1:2 1.21

[0084] Figure 2 This is a graph of the tensile force variation corresponding to samples with different monomer to oligomer molar ratios provided in the examples of the present application.

[0085] Combined with reference table 2 and Figure 2 Based on the tensile test results of Comparative Example 2, Example 1, Example 6, Example 7 and Comparative Example 3, it can be seen that when the molar ratio of monomers to oligomers in the photocurable adhesive increases, the tensile force provided by the cured photocurable adhesive to the soldering tape and the battery cell first increases and then weakens. Among them, when the molar ratio of monomers to oligomers is 1:0.65, the maximum tensile force provided by the cured photocurable adhesive to the soldering tape and the battery cell is 1.67N.

[0086] Example 8

[0087] The preparation method of Example 8 is the same as that of Example 1, except that the monomer in Example 8 includes 40 parts of methyl acrylate.

[0088] Example 9

[0089] The preparation method of Example 9 is the same as that of Example 1, except that the multi-monomer in Example 9 includes 30 parts of ethyl acrylate and 10 parts of bisphenol A epoxy acrylate.

[0090] Example 10

[0091] The preparation method of Example 10 is the same as that of Example 1, except that the monomers in Example 10 include 20 parts of ethyl acrylate and 20 parts of bisphenol A epoxy acrylate.

[0092] Embodiment 11

[0093] The preparation method of Example 11 is the same as that of Example 1, except that the monomers in Example 11 include 10 parts of ethyl acrylate and 30 parts of bisphenol A epoxy acrylate.

[0094] The tensile test was performed on the above-mentioned Example 1, Example 8 to Example 10. In addition, the above-mentioned Example 1, Example 8 to Example 10 was subjected to a high pressure cooking test (PCT, Pressure Cooker Test), the test temperature was 121°C, the humidity was 100% RH, the pressure was 0.2MPa, and the time was 48 hours, and then the tensile test was performed on Example 1, Example 8 to Example 10 again.

[0095] Table 3 Tensile force corresponding to samples with different glass transition temperatures

[0096]

[0097] Figure 3 This is a graph showing the tensile force variation corresponding to samples with different glass transition temperatures provided in the examples of the present application.

[0098] Combined with reference table 3 and Figure 3 Based on the tensile test results of Example 1, Example 8 to Example 11, it can be seen that the glass transition temperature of the monomer affects the glass transition temperature of the photocurable adhesive after curing. The glass transition temperatures of methyl acrylate, ethyl acrylate and bisphenol A epoxy acrylate increase in turn. The more the monomer with a high glass transition temperature accounts for the total mass of the monomer, the higher the glass transition temperature of the corresponding photocurable adhesive after curing. However, with the increase of the glass transition temperature, the tensile retention of the cured photocurable adhesive after PCT48h first increases and then decreases. When the glass transition temperature is 95°C, the tensile retention rate of the cured photocurable adhesive reaches 77.44%.

[0099] In some embodiments, the cell may be any one of a PERC cell (Passivated Emitter and Rear Cell), a PERT cell (Passivated Emitter and Rear Totally-diffused cell), a TOPCon cell (Tunnel Oxide Passivated Contact), a HIT / HJT cell (Heterojunction Technology), or a BC cell (Back Contact). In some embodiments, the cell may be a monocrystalline silicon solar cell, a polycrystalline silicon solar cell, an amorphous silicon solar cell, or a multi-compound solar cell, and the multi-compound solar cell may specifically be a cadmium sulfide solar cell, a gallium arsenide solar cell, a copper indium selenide solar cell, or a perovskite solar cell.

[0100] In the photocurable adhesive for photovoltaic modules and the manufacturing method of photovoltaic modules provided by the embodiment of the present application, the photocurable adhesive includes oligomers, monomers and initiators. Under the irradiation of ultraviolet light in a specific band, the initiator can induce a free radical reaction between the oligomers and the active monomers, thereby curing the fluid photocurable adhesive. The cured photocurable adhesive has a certain tensile strength. The use of the photocurable adhesive to fix the solder strip and the battery cell can be beneficial to improve the tension between the solder strip and the battery cell. Among them, the molar ratio of the monomer to the initiator affects the crosslinking degree of the photocurable adhesive. When the molar ratio of the monomer to the initiator is low, the amount of the initiator is insufficient to initiate the polymerization of the monomer, which easily leads to a low crosslinking degree of the cured photocurable adhesive, a low self-adhesive force, and a small tension between the solder strip and the battery cell; when the molar ratio of the monomer to the initiator is too high, the initiation rate is fast, resulting in rapid polymerization of the monomer, and the inability to form a high molecular weight structure. The cured photocurable adhesive has a low crosslinking degree and a low self-adhesive force, and can provide a small tension between the solder strip and the battery cell. Therefore, the molar ratio of the monomer to the initiator needs to be set within an appropriate range so that the specific reaction rate is moderate, which can avoid the photocurable adhesive after curing from being too hard or too soft, thereby facilitating the photocurable adhesive after curing to improve the tension between the solder strip and the battery cell. In addition, the molar ratio of the monomer to the oligomer affects the content of the oligomer coated by the polymer structure formed by polymerization. When the molar ratio of the monomer to the oligomer is low, the content of the oligomer coated by the polymer structure formed by the monomer polymerization is too small, resulting in low self-adhesion of the photocurable adhesive after curing, which can provide less tension between the solder strip and the battery cell; when the molar ratio of the monomer to the oligomer is large, the content of the short-chain polymer in the system is high, and the content of the oligomer wrapped by the polymer structure formed by the monomer polymerization is too much, resulting in low self-adhesion of the photocurable adhesive after curing, which can provide less tension between the solder strip and the battery cell. Therefore, the molar ratio of the monomer to the oligomer needs to be set within an appropriate range so that the content of the oligomer coated by the polymer structure formed by the monomer polymerization is moderate, which can avoid low self-adhesion of the photocurable adhesive after curing, thereby facilitating the photocurable adhesive after curing to improve the tension between the solder strip and the battery cell.

[0101] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present application, and in practical applications, various changes may be made to the embodiments in form and detail without departing from the spirit and scope of the present application. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application, and therefore the scope of protection of the present application shall be subject to the scope defined in the claims.

Claims

1. A photocurable adhesive for photovoltaic modules, It is characterized in that Contains the following components by mass: 45-60 parts of oligomer, 40-45 parts of monomer, 1-3 parts of initiator; wherein the molar ratio of the monomer to the initiator is 1:0.005-1:0.075; the molar ratio of the monomer to the oligomer is 1:0.25-1:

1.

2. The light-curing adhesive according to claim 1, It is characterized in that The oligomer is selected from one or more of epoxy acrylate, polyurethane acrylate, polyester acrylate or polyether acrylate.

3. The light-curing adhesive according to claim 1, It is characterized in that The monomer is selected from one or more of acrylate, styrene, ethyl acrylate or butyl acrylate.

4. The light-curing adhesive according to claim 1, It is characterized in that The initiator is selected from one or more of photoinitiator 754, photoinitiator 907, photoinitiator 184, photoinitiator 369, photoinitiator 1173, photoinitiator 819, photoinitiator BP, photoinitiator TPO, photoinitiator PBZ or photoinitiator MBF.

5. The light-curing adhesive according to claim 1, It is characterized in that The solvent is selected from one or more of methyl chloride, acetone and ethylene dichloride.

6. The light-curing adhesive according to claim 1, It is characterized in that The molar ratio of the monomer to the initiator is 1:0.025; The molar ratio of the monomer to the oligomer is 1:0.

65.

7. The light-curing adhesive according to claim 1, It is characterized in that The invention also comprises the following components in parts by weight: 0 to 3 parts of gas silicone, 0.2 to 0.3 parts of leveling agent, 0.01 to 0.15 parts of polymerization inhibitor, 0.4 to 0.5 parts of surfactant and 0 to 3 parts of plasticizer.

8. The light-curing adhesive according to claim 1, It is characterized in that The glass transition temperature of the photocurable adhesive after curing is 45°C to 120°C.

9. A method for manufacturing a photovoltaic module, It is characterized in that include: Weighing each component of the photocurable adhesive as described in any one of claims 1 to 8; The oligomer, the initiator, the solvent and a part of the monomer by mass are mixed evenly, and then the remaining part of the monomer by mass is added to the mixture and mixed evenly to obtain a ready-to-use photocurable adhesive; Pre-weld the soldering tape to the position corresponding to the grid line on the battery cell; Applying the to-be-used light-curing adhesive between the two sides of the welding strip and the surface of the battery cell; Using an ultraviolet lamp to perform radiation curing on the photocurable adhesive to be used; The cured battery cell is subjected to a lamination process.

10. The method for manufacturing a photovoltaic module according to claim 9, It is characterized in that In the step of uniformly mixing the oligomer, the initiator, the solvent and a portion of the monomer by mass, the portion of the monomer by mass accounts for 60% to 100% of the total mass of the monomer.

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