Insulating paste for solar cell and preparation method and application thereof

Abstract

The invention provides insulation paste for solar cells and a preparation method and application thereof, and relates to the technical field of insulation paste for solar cells, and the insulation paste is prepared from the following raw materials: acrylic acid modified epoxy resin, a monomer, a photoinitiator, a coupling agent and a flatting agent; wherein the acrylic acid modified epoxy resin is prepared from the following raw materials: 1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane and a carboxylic acid reaction component. The insulating glue for the solar cell provided by the invention has the advantages of lower viscosity, high reaction activity and excellent edge covering and gluing performance, the edge film surface is neat, the coating thickness (10-15 microns) can be thinner and is close to the height (10-12 microns) of an electroplated grid line, and after cell pieces are stacked and packaged, the fragment rate is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of insulating adhesive for solar cells, and in particular to an insulating adhesive for solar cells, a preparation method thereof, and an application thereof. Background Art

[0002] In the manufacture of traditional photovoltaic cells, grid lines are usually formed by screen-printing silver paste. Due to the high price of silver paste, the market currently expects to replace the silver paste process with electroplating copper. The electroplating copper process uses laser film opening technology and electroplating to produce the grid lines of photovoltaic cells. First, laser film opening is used to form a patterned groove. After high-temperature annealing, nickel, copper, tin and other metals are plated on the patterned groove using electroplating to form the grid lines of the cell. In order to reduce the risk of short-circuit defects caused by the electroplating process, the metal grid lines on the front and back of the cell edges are connected, which is a short-circuit defect. Before electroplating, an edge wrapping process is added. The four sides of the cell are wrapped with insulating glue to prevent metal deposition around the cell. Electroplating is then carried out.

[0003] However, the insulating adhesive used in the prior art is typically 15-20mm thick after curing, while the grid line height formed by electroplating is only 10-12μm. Because the edge adhesive thickness is much higher than the grid line height, the edge area of ​​the stacked battery cells is significantly higher than the middle area after packaging. This can easily lead to mechanical stress concentration during transportation and unpacking, causing the battery cells to break and resulting in a high fragmentation rate. In addition, although the existing insulating adhesive has a certain degree of heat resistance, its acid resistance will be significantly reduced in high temperature and high humidity environments, resulting in reduced insulation performance of the battery.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] One of the objectives of the present invention is to provide an insulating adhesive for solar cells that addresses at least one of the technical problems existing in the prior art. The insulating adhesive for solar cells provided by the present invention has the advantages of low viscosity, high reactivity, and excellent edge coating performance. It also provides a smooth edge film surface and can be applied to a thin thickness (10-15 μm), close to the height of electroplated grid lines (10-12 μm). After stacking and packaging solar cells, the fragmentation rate is significantly reduced.

[0006] A second object of the present invention is to provide a method for preparing an insulating adhesive for solar cells.

[0007] A third object of the present invention is to provide an insulating adhesive for solar cells or the use of the insulating adhesive for solar cells prepared by the preparation method in the preparation of solar cells.

[0008] A fourth object of the present invention is to provide a solar cell.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0010] In a first aspect, the present invention provides an insulating adhesive for solar cells, the raw materials for preparing the insulating adhesive include: acrylic modified epoxy resin, monomer, photoinitiator, coupling agent and leveling agent;

[0011] The raw materials for preparing the acrylic modified epoxy resin include 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane and a carboxylic acid reaction component.

[0012] Furthermore, the raw materials for its preparation include, by mass percentage:

[0013] 20% to 40% monomer, 2% to 10% photoinitiator, 0.2% to 2% coupling agent, 0.05% to 0.5% leveling agent and the balance acrylic acid modified epoxy resin;

[0014] Preferably, the monomer includes one or more of tripropylene glycol diacrylate, dipropylene glycol diacrylate, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, tricyclodecane dimethanol diacrylate, pentaerythritol triacrylate and propoxylated glycerol triacrylate;

[0015] Preferably, the photoinitiator includes one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, hydroxycyclohexane phenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone and ethyl 2,4,6-trimethylbenzoylphenylphosphonate;

[0016] Preferably, the coupling agent includes one or more of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, vinyltriethoxysilane and vinyltrimethoxysilane;

[0017] Preferably, the leveling agent includes one or more of polyoxyethylene alcohol acrylate, nano-silica acrylate and polydimethylsiloxane acrylate;

[0018] Preferably, the viscosity of the insulating adhesive for solar cells is 500-2000 mPa.s.

[0019] Further, the carboxylic acid reaction component includes α-methacrylic acid;

[0020] Preferably, the mass ratio of the α-methacrylic acid to 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is 6-10:1-2.

[0021] Furthermore, the raw materials for preparing the acrylic modified epoxy resin also include: a catalyst and a polymerization inhibitor;

[0022] Preferably, the catalyst comprises one or more of triethylamine, N,N-dimethylaniline, trimethylbenzylammonium chloride, tetra-n-butylammonium bromide, 2-methylpyridine, triphenylphosphine and triphenylantimony;

[0023] Preferably, the amount of the catalyst added is 0.1% to 1% of the total amount of reactants;

[0024] Preferably, the polymerization inhibitor comprises one or more of p-hydroxyphenylmethane, p-benzoquinone, p-hydroxyanisole, hydroquinone, 2,5-dimethylhydroquinone, 2,6-di-tert-butyl-p-quinone and p-hydroxyanisole;

[0025] Preferably, the addition amount of the polymerization inhibitor is 0.05% to 0.5% of the total amount of reactants.

[0026] In a second aspect, the present invention provides a method for preparing an insulating adhesive for solar cells, comprising: mixing an acrylic modified epoxy resin, a monomer, a photoinitiator, a coupling agent and a leveling agent to obtain the insulating adhesive for solar cells.

[0027] Furthermore, the method further comprises: after the mixing, sequentially performing vacuum degassing treatment and filtering treatment;

[0028] Preferably, the vacuum degree of the vacuum degassing is 0.05-0.2 MPa;

[0029] Preferably, the vacuum degassing temperature is 20-50°C;

[0030] Preferably, the vacuum degassing time is 20 to 60 minutes;

[0031] Preferably, the pore size of the filter during the filtration is 5 to 50 μm;

[0032] Preferably, the stirring speed during the mixing is 500 to 2000 r / min;

[0033] Preferably, the mixing temperature is 20-30°C;

[0034] Preferably, the mixing time is 30 to 60 minutes.

[0035] Furthermore, the acrylic acid modified epoxy resin is prepared by the following steps:

[0036] (a) mixing a catalyst, a polymerization inhibitor and α-methacrylic acid to obtain an acrylic acid mixture;

[0037] (b) mixing the acrylic acid mixture and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane;

[0038] (c) measuring the acid value of the reaction system, and stopping the reaction when the acid value in the system drops to below 2 to 4 mgKOH / g to obtain the acrylic acid-modified epoxy resin;

[0039] Preferably, the mixing temperature in step (a) is 20 to 50°C;

[0040] Preferably, the mixing process in step (b) comprises: stirring 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane at a speed of 200 to 600 r / min and heating to 60 to 90° C.; then adding the acrylic acid mixture within 45 to 75 minutes; heating to 100 to 120° C. and then conducting a constant temperature reaction;

[0041] Preferably, in step (c), the acid value of the reaction system is measured every 3 to 6 minutes.

[0042] In a third aspect, the present invention provides an insulating adhesive for solar cells or use of the insulating adhesive for solar cells prepared by the preparation method in preparing solar cells.

[0043] In a fourth aspect, the present invention provides a solar cell, wherein the preparation method thereof comprises:

[0044] The insulating adhesive for solar cells or the insulating adhesive for solar cells prepared by the preparation method is used to coat the four sides of the solar cell silicon substrate; then a metal layer is prepared in the patterned groove of the solar cell silicon substrate to obtain a solar cell.

[0045] Furthermore, before the glue coating, the solar cell silicon substrate is thermally repaired;

[0046] Preferably, the temperature of the thermal repair is 600-800°C;

[0047] Preferably, the thermal repair time is 60 to 120 seconds;

[0048] Preferably, after the glue coating and before the metal layer is prepared, a curing treatment is performed;

[0049] Preferably, the curing is performed by irradiation with ultraviolet light;

[0050] Preferably, the wavelength of the ultraviolet lamp is 250-420 nm;

[0051] Preferably, the irradiation intensity of the ultraviolet lamp is 1000-3000 mW / cm 2 ;

[0052] Preferably, the curing time is 1 to 3 seconds;

[0053] Preferably, the material of the metal layer is a combination of nickel-copper, nickel-copper-tin and nickel-copper-silver;

[0054] Preferably, the solar cell silicon substrate includes one or more of TOPCon, HJT and BC cells.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The insulating adhesive for solar cells provided by the present invention comprises monomers in the raw materials that provide a cross-linked network foundation, thereby enhancing mechanical strength and chemical corrosion resistance after curing; a coupling agent in the raw materials that enhances the interfacial bonding between the resin and the silicon substrate, improves adhesive layer adhesion, and prevents shedding during electroplating or heat treatment; a leveling agent in the raw materials that improves surface flatness after colloid coating, thereby reducing coating defects such as uneven edges, stringing, and shrinkage cavities; an acrylic acid-modified epoxy resin is added to the raw materials, wherein the acrylic acid-modified epoxy resin has 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane as the main chain skeleton, and a carboxylic acid reaction component that can react with an epoxy group to obtain an insulating adhesive having excellent Modified resin with excellent adhesion and flexibility, acrylic modified epoxy resin introduces acid-resistant functional groups (such as amino and carboxyl groups) to improve the stability of insulating adhesive in electroplating acidic environment (such as sulfuric acid plating solution), prevent the adhesive layer from falling off, cracking or delamination, and at the same time enhance the bonding strength between the insulating adhesive and the silicon substrate to avoid cracking caused by thermal stress or mechanical stress; acrylic modified epoxy resin also has low viscosity characteristics, which is conducive to uniform edge coating, achieving a thinner coating thickness (10-15μm), and reducing the fragmentation rate when the battery cells are stacked; in addition, acrylic modified epoxy resin forms a good match with the photoinitiator system to achieve rapid UV curing and improve production efficiency. DETAILED DESCRIPTION

[0057] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear; however, in the event of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, the use of "or" means "and / or" unless otherwise stated. In addition, the use of the term "including" and other forms is non-limiting.

[0058] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0059] The first aspect of the present invention provides an insulating adhesive for solar cells, the raw materials for preparing the insulating adhesive include: acrylic modified epoxy resin, monomer, photoinitiator, coupling agent and leveling agent; wherein the raw materials for preparing the acrylic modified epoxy resin include 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane and carboxylic acid reaction components.

[0060] In some preferred embodiments, the raw materials for its preparation include, by mass percentage:

[0061] 20% to 40% monomer, 2% to 10% photoinitiator, 0.2% to 2% coupling agent, 0.05% to 0.5% leveling agent and the balance acrylic acid modified epoxy resin.

[0062] Among them, the amount of monomer added to the raw materials for preparing the insulating adhesive for solar cells is 20% to 40%, for example, it can be 20%, 25%, 30%, 35%, 40%, etc.;

[0063] Among them, the amount of the photoinitiator added to the raw materials for preparing the insulating adhesive for solar cells is 2% to 10%, for example, it can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.;

[0064] Among them, the addition amount of the coupling agent in the raw materials for preparing the insulating adhesive for solar cells is 0.2% to 2%, for example, it can be 0.2%, 0.5%, 1%, 1.5%, 2%, etc.;

[0065] Among them, the addition amount of the leveling agent in the preparation raw materials of the insulating adhesive for solar cells is 0.05% to 0.5%, for example, it can be 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, etc.

[0066] Preferably, the monomer includes one or more of tripropylene glycol diacrylate, dipropylene glycol diacrylate, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, tricyclodecane dimethanol diacrylate, pentaerythritol triacrylate and propoxylated glycerol triacrylate.

[0067] In the present invention, the monomer provides a cross-linked network basis, enhances the mechanical strength and chemical corrosion resistance after curing, improves the dilution effect of the resin, further reduces the viscosity, enhances the coating performance, and enhances the photocuring reaction rate, shortening the UV curing time.

[0068] Preferably, the photoinitiator includes one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, hydroxycyclohexane phenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinebenzylphenyl)butanone and ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0069] In the present invention, the photoinitiator triggers a free radical polymerization reaction, which promotes the rapid cross-linking and curing of the resin and the monomer under ultraviolet light irradiation, helps to improve the curing depth and surface curing quality, ensures that the edge coating is neat and free of sagging, and ensures that the insulating glue is cured in a short time (1 to 3 seconds), meeting the requirements of the fast electroplating process.

[0070] Preferably, the coupling agent includes one or more of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, vinyltriethoxysilane and vinyltrimethoxysilane.

[0071] In the present invention, the coupling agent enhances the interfacial bonding between the resin and the silicon substrate, improves the adhesion of the adhesive layer, prevents it from falling off during electroplating or heat treatment, and improves the moisture and heat resistance of the adhesive layer, preventing delamination or peeling between the adhesive layer and the substrate in a high temperature and high humidity environment.

[0072] Preferably, the leveling agent includes one or more of polyoxyethylene alcohol acrylate, nano-silica acrylate and polydimethylsiloxane acrylate.

[0073] In the present invention, the leveling agent can improve the surface smoothness of the colloid after coating, reduce coating defects such as uneven edges, drawing, and shrinkage, and at the same time help form a smooth and continuous film surface to prevent the plating solution from being retained or penetrated on its surface.

[0074] Preferably, the viscosity of the insulating adhesive for solar cells is 500-2000 mPa.s.

[0075] In some preferred embodiments, the carboxylic acid reaction component includes α-methacrylic acid;

[0076] Preferably, the mass ratio of the α-methacrylic acid to 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is 6-10:1-2.

[0077] Here, “6-10” can be, for example, 6, 7, 8, 9, 10, etc.;

[0078] Here, “1-2” can be, for example, 1, 1.5, 2, etc.

[0079] In some preferred embodiments, the raw materials for preparing the acrylic modified epoxy resin further include: a catalyst and a polymerization inhibitor;

[0080] Preferably, the catalyst comprises one or more of triethylamine, N,N-dimethylaniline, trimethylbenzylammonium chloride, tetra-n-butylammonium bromide, 2-methylpyridine, triphenylphosphine and triphenylantimony;

[0081] Preferably, the amount of the catalyst added is 0.1% to 1% of the total amount of reactants (total reactants for preparing acrylic modified epoxy resin), for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, etc.

[0082] Preferably, the polymerization inhibitor comprises one or more of p-hydroxyphenylmethane, p-benzoquinone, p-hydroxyanisole, hydroquinone, 2,5-dimethylhydroquinone, 2,6-di-tert-butyl-p-quinone and p-hydroxyanisole;

[0083] Preferably, the addition amount of the polymerization inhibitor is 0.05% to 0.5% of the total amount of the reactants, for example, it can be 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, etc.

[0084] A second aspect of the present invention provides a method for preparing an insulating adhesive for solar cells, comprising: mixing an acrylic modified epoxy resin, a monomer, a photoinitiator, a coupling agent and a leveling agent to obtain the insulating adhesive for solar cells.

[0085] In some preferred embodiments, the preparation method further comprises: after the mixing, sequentially performing vacuum degassing and filtering;

[0086] Preferably, the vacuum degree of the vacuum degassing is 0.05 to 0.2 MPa, for example, 0.05 MPa, 0.1 MPa, 0.15 MPa, 0.2 MPa, etc.

[0087] Preferably, the vacuum degassing temperature is 20-50°C, for example, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, etc.

[0088] Preferably, the vacuum degassing time is 20 to 60 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, etc.

[0089] Preferably, the pore size of the filter during the filtration is 5 to 50 μm;

[0090] Preferably, the stirring speed during the mixing is 500 to 2000 r / min, for example, 500 r / min, 1000 r / min, 1500 r / min, 2000 r / min, etc.;

[0091] Preferably, the mixing temperature is 20-30°C, for example, 20°C, 25°C, 30°C, etc.;

[0092] Preferably, the mixing time is 30 to 60 min, for example, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, etc.

[0093] In some preferred embodiments, the acrylic acid-modified epoxy resin is prepared by the following steps:

[0094] (a) mixing a catalyst, a polymerization inhibitor and α-methacrylic acid to obtain an acrylic acid mixture;

[0095] (b) mixing the acrylic acid mixture and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane;

[0096] (c) measuring the acid value of the reaction system, and stopping the reaction when the acid value in the system drops to below 2 to 4 mgKOH / g to obtain the acrylic acid-modified epoxy resin;

[0097] Preferably, the mixing temperature in step (a) is 20 to 50° C., for example, 20° C., 25° C., 30° C., 35° C., 40° C., 45° C., 50° C., etc.;

[0098] Preferably, the mixing process in step (b) includes: stirring 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane at a speed of 200-600 r / min, for example, 200 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, etc., and heating to 60-90°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, etc.; then adding the acrylic acid mixture within 45-75 minutes, for example, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, etc.; and heating to 100-120°C and then conducting a constant temperature reaction, for example, 100°C, 115°C, 120°C, etc.

[0099] Preferably, in step (c), the acid value of the reaction system is measured every 3 to 6 minutes.

[0100] In the present invention, the catalyst is used to promote the ring-opening esterification reaction between the epoxy group and the carboxyl group, and the polymerization inhibitor is used to suppress the self-polymerization or premature polymerization of acrylic acid before the reaction to prevent the reaction from getting out of control. 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane provides epoxy groups and a cyclic skeleton structure, and the acrylic acid mixture provides carboxylic acid groups and double bonds, participating in the esterification reaction and introducing photocuring sites. The present invention obtains a modified resin with excellent adhesion and flexibility by controlling the reaction conditions (such as dropwise addition time, temperature control, acid value monitoring, etc.) and using a specific ratio of α-methyl acrylic acid and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane to react.

[0101] A third aspect of the present invention provides an insulating adhesive for solar cells or use of the insulating adhesive for solar cells prepared by the preparation method in preparing solar cells.

[0102] A fourth aspect of the present invention provides a solar cell, wherein the preparation method thereof comprises:

[0103] The insulating adhesive for solar cells or the insulating adhesive for solar cells prepared by the preparation method is applied to the four sides of the solar cell silicon substrate; then a metal layer is prepared in the patterned groove of the solar cell silicon substrate to obtain a solar cell.

[0104] In some preferred embodiments, before the glue coating, the solar cell silicon substrate is thermally repaired;

[0105] Preferably, the temperature of the thermal repair is 600-800°C, for example, 600°C, 700°C, 800°C, etc.;

[0106] Preferably, the thermal repair time is 60 to 120 seconds, for example, 60 seconds, 90 seconds, 120 seconds, etc.;

[0107] Preferably, after the glue coating and before the metal layer is prepared, a curing treatment is performed;

[0108] Preferably, the curing is performed by irradiation with ultraviolet light;

[0109] Preferably, the wavelength of the ultraviolet lamp is 250-420 nm;

[0110] Preferably, the irradiation intensity of the ultraviolet lamp is 1000-3000 mW / cm 2 , for example, it can be 1000mW / cm 2 , 2000mW / cm 2 、3000mW / cm 2 wait;

[0111] Preferably, the curing time is 1 to 3 seconds, for example, 1 second, 2 seconds, 3 seconds, etc.;

[0112] Preferably, the material of the metal layer is a combination of nickel-copper, nickel-copper-tin and nickel-copper-silver;

[0113] Preferably, the solar cell silicon substrate includes one or more of TOPCon, HJT and BC cells, and crystalline silicon solar cells are all applicable.

[0114] The insulating adhesive for solar cells provided by the present invention has the following advantages and effects:

[0115] (1) Low viscosity, high reactivity, excellent edge coating performance, neat edge film surface and can be coated with a thin thickness (10-15um), close to the height of the electroplated grid line (10-12um), and the fragmentation rate is greatly reduced after the battery cells are stacked and packaged;

[0116] (2) The present invention obtains acid-resistant functional groups (amino groups, carboxyl groups, etc.) by modifying epoxy resin with acrylic acid. The prepared insulating adhesive can resist corrosion from acidic electroplating solution (T≥50°C and t≥10min) during the electroplating process without any adverse phenomena such as falling off, cracking, and delamination. It has excellent adhesion and helps to extend the service life of the battery.

[0117] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples were prepared according to existing methods or directly purchased from the market.

[0118] Example 1

[0119] This embodiment provides an insulating adhesive for solar cells, the raw materials for its preparation include, by mass percentage: 30% monomer (pentaerythritol triacrylate), 6% photoinitiator (2-hydroxy-2-methyl-1-phenyl-1-propanone), 1% coupling agent (γ-glycidyloxypropyltrimethoxysilane), 0.3% leveling agent (polyoxyethylene alcohol acrylate) and the remainder acrylic modified epoxy resin.

[0120] The preparation process of insulating adhesive for solar cells is as follows:

[0121] The acrylic modified epoxy resin, monomer, photoinitiator, coupling agent and leveling agent were stirred and mixed uniformly according to the formula ratio at a stirring speed of 1000 r / min, a stirring temperature of 25°C and a stirring time of 45 min;

[0122] Then vacuum degassing was carried out, the vacuum degree of vacuum degassing was 0.1MPa, the temperature of vacuum degassing was 35℃, and the time of vacuum degassing was 40min;

[0123] The mixture is then filtered through a filter with a pore size of 30 μm to remove impurities and obtain insulating adhesive for solar cells.

[0124] The preparation process of acrylic acid modified epoxy resin is as follows:

[0125] A measured amount of catalyst (triethylamine) and polymerization inhibitor (p-hydroxyphenylmethane) are completely dissolved in α-methylacrylic acid for later use to obtain an acrylic acid mixture; then a measured amount of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is added to a four-necked flask, and the mixture is heated while stirring. When the temperature reaches 75°C, the acrylic acid mixture is slowly added dropwise, and the addition is completed within 60 minutes; after the temperature is raised to 110°C, a constant temperature reaction is carried out, and the acid value of the reaction system is measured every 3 to 6 minutes. When the acid value in the system drops to below 2 to 4 mgKOH / g, the reaction is stopped to obtain an acrylic acid-modified epoxy resin.

[0126] The amount of the catalyst added is 0.5% of the total amount of the reactants, the amount of the polymerization inhibitor added is 0.3% of the total amount of the reactants, and the mass ratio of α-methylacrylic acid to 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is 8:1.5.

[0127] Example 2

[0128] This embodiment provides an insulating adhesive for solar cells, which differs from the first embodiment in that:

[0129] The raw materials for its preparation include, by mass percentage, 20% monomer (pentaerythritol triacrylate), 10% photoinitiator (2-hydroxy-2-methyl-1-phenyl-1-propanone), 0.2% coupling agent (γ-glycidyloxypropyltrimethoxysilane), 0.5% leveling agent (polyoxyethylene alcohol acrylate) and the balance acrylic acid-modified epoxy resin.

[0130] Example 3

[0131] This embodiment provides an insulating adhesive for solar cells, which differs from the first embodiment in that:

[0132] The raw materials for its preparation include, by mass percentage, 40% monomer (tripropylene glycol diacrylate), 2% photoinitiator (ethyl 2,4,6-trimethylbenzoylphenylphosphonate), 2% coupling agent (vinyl triethoxysilane), 0.05% leveling agent (polydimethylsiloxane acrylate) and the balance acrylic modified epoxy resin.

[0133] Example 4

[0134] This embodiment provides an insulating adhesive for solar cells, which differs from the first embodiment in that:

[0135] A measured amount of catalyst (triethylamine) and polymerization inhibitor (p-hydroxyphenylmethane) are completely dissolved in α-methylacrylic acid for later use to obtain an acrylic acid mixture; then a measured amount of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is added to a four-necked flask, and the mixture is heated while stirring. When the temperature reaches 60°C, the acrylic acid mixture is slowly added dropwise, and the addition is completed within 75 minutes; after the temperature is raised to 100°C, a constant temperature reaction is carried out, and the acid value of the reaction system is measured every 3 to 6 minutes. When the acid value in the system drops to below 2 to 4 mgKOH / g, the reaction is stopped to obtain an acrylic acid-modified epoxy resin.

[0136] The amount of the catalyst added is 0.1% of the total amount of the reactants, the amount of the polymerization inhibitor added is 0.5% of the total amount of the reactants, and the mass ratio of α-methylacrylic acid to 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is 6:2.

[0137] Example 5

[0138] This embodiment provides an insulating adhesive for solar cells, which differs from the first embodiment in that:

[0139] A measured amount of catalyst (triethylamine) and polymerization inhibitor (p-hydroxyphenylmethane) are completely dissolved in α-methylacrylic acid for later use to obtain an acrylic acid mixture; then a measured amount of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is added to a four-necked flask, and the mixture is heated while stirring. When the temperature reaches 90°C, the acrylic acid mixture is slowly added dropwise, and the addition is completed within 45 minutes; after the temperature is raised to 120°C, a constant temperature reaction is carried out, and the acid value of the reaction system is measured every 3 to 6 minutes. When the acid value in the system drops to below 2 to 4 mgKOH / g, the reaction is stopped to obtain an acrylic acid-modified epoxy resin.

[0140] The amount of the catalyst added is 1% of the total amount of the reactants, the amount of the polymerization inhibitor added is 0.05% of the total amount of the reactants, and the mass ratio of α-methylacrylic acid to 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is 10:1.

[0141] Example 6

[0142] This embodiment provides an insulating adhesive for solar cells, which differs from the first embodiment in that:

[0143] The raw materials for preparing the composite include, by mass percentage, 19% monomer, 11% photoinitiator, 0.1% coupling agent, 0.6% leveling agent and the balance acrylic acid modified epoxy resin.

[0144] Example 7

[0145] This embodiment provides an insulating adhesive for solar cells, which differs from the first embodiment in that:

[0146] The raw materials for preparing the composite include, by mass percentage, 41% monomer, 1% photoinitiator, 3% coupling agent, 0.03% leveling agent and the balance acrylic acid modified epoxy resin.

[0147] Example 8

[0148] This embodiment provides an insulating adhesive for solar cells, which differs from the first embodiment in that:

[0149] During the preparation of the acrylic modified epoxy resin, the amount of catalyst added was 0.05% of the total amount of reactants, the amount of polymerization inhibitor added was 0.6% of the total amount of reactants, and the mass ratio of α-methylacrylic acid to 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane was 5:3.

[0150] Example 9

[0151] This embodiment provides an insulating adhesive for solar cells, which differs from the first embodiment in that:

[0152] During the preparation of the acrylic modified epoxy resin, the amount of catalyst added was 2% of the total amount of reactants, the amount of polymerization inhibitor added was 0.03% of the total amount of reactants, and the mass ratio of α-methylacrylic acid to 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane was 11:0.5.

[0153] Application Examples 1-9

[0154] This application example provides a solar cell. Application examples 1-9 respectively use the insulating adhesive for solar cells prepared in Examples 1-9. The preparation process of the solar cell is as follows:

[0155] Step 1: providing a BC solar cell silicon substrate having patterned grooves on its surface;

[0156] Step 2: Place the solar cell silicon substrate in an annealing furnace for high-temperature thermal repair at a temperature of 700°C for 90 seconds.

[0157] Step 3: Then, the insulating adhesive for solar cells prepared in Examples 1-9 is respectively used to coat the four sides of the silicon substrate of the solar cell;

[0158] Step 4: Use ultraviolet light to cure. The wavelength of the ultraviolet light is 365nm and the irradiation intensity is 2000mW / cm 2 , UV light curing time is 2s;

[0159] Step 5: electroplating nickel, copper, and tin metal to obtain an electroplated solar cell.

[0160] Comparative Example 1

[0161] This comparative example provides an insulating adhesive for solar cells, which differs from Example 1 in that epoxy resin is used instead of acrylic acid-modified epoxy resin in the formula of the insulating adhesive for solar cells.

[0162] Comparative Example 2

[0163] This comparative example provides an insulating adhesive for solar cells, which differs from Example 1 in that the formula of the insulating adhesive for solar cells does not contain a coupling agent.

[0164] Comparative Example 3

[0165] This comparative example provides an insulating adhesive for solar cells, which differs from Example 1 in that the formula of the insulating adhesive for solar cells does not contain a leveling agent.

[0166] Comparative Example 4

[0167] This comparative example provides an existing insulating adhesive for solar cells, Shanghai Delangju New Materials, model BSUN-22.

[0168] Comparative Application Examples 1-4

[0169] This comparative application example provides a solar cell. The difference between the preparation process of the solar cells of comparative application examples 1-4 and application example 1 is that comparative application examples 1-4 respectively use the insulating glue for solar cells prepared by comparative examples 1-4, and the rest of the preparation process is the same as that of application example 1.

[0170] Test Case

[0171] Test samples: The solar cells prepared in Application Examples 1-9 and Comparative Application Examples 1-4 were used as samples for testing.

[0172] Test method:

[0173] 1. Use a 3D microscope to measure the height of the adhesive layer on the four sides of the cell after electroplating (measure four points and calculate the average value). The smaller the average value, the lower the fragmentation rate of the cell after packaging, transportation and unpacking.

[0174] 2. Take the electroplated battery cell and place it in a 60℃ solution (10%wt sulfuric acid solution) for 1 hour. After cleaning and drying, use a 3D microscope to observe whether the appearance of the adhesive layer has any adverse phenomena such as delamination, shedding, bubbling, etc.

[0175] The test results are shown in Table 1.

[0176] Table 1

[0177]

[0178]

[0179] As can be seen from the data in Table 1, the thickness of the insulating adhesive layer of the application examples of the present invention is controlled within the ideal range of 10 to 15 μm, which is close to the height of the electroplated grid lines (10 to 12 μm), indicating that the insulating adhesive has good thin layer coating performance, effectively reducing the edge height difference after the battery cells are stacked, thereby significantly reducing the fragmentation rate during transportation and unpacking; while the average thickness of the insulating adhesive layer of comparative application examples 2-4 ranges from 15.03 μm to 17.67 μm, which is significantly higher than the application example group, indicating that the insulating adhesive coating thickness used in the comparative application example group is relatively thick, resulting in a large mechanical stress concentration in the edge area of ​​the battery cell during the stacking process, which in turn leads to an increase in the fragmentation rate. The result data of application examples 1 and application examples 6-9 show that the battery cell fragmentation rate is lower when insulating adhesives with specific components and specific component ranges are used.

[0180] The insulating adhesive formula in Application Example 1 is optimal, and the obtained adhesive layer thickness is the lowest, which is basically close to the height of the battery cell grid line. The fragmentation rate when unpacking after packaging and transportation is also the lowest. At the same time, the insulating adhesive has good acid resistance. After soaking in acidic solution, no adverse phenomena such as adhesive layer delamination, falling off, and bubbling occur.

[0181] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An insulating adhesive for solar cells, characterized in that: The raw materials for its preparation include: acrylic modified epoxy resin, monomer, photoinitiator, coupling agent and leveling agent; The raw materials for preparing the acrylic modified epoxy resin include 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane and a carboxylic acid reaction component.

2. The insulating adhesive for solar cells according to claim 1, characterized in that: The raw materials for its preparation include, by mass percentage: 20% to 40% monomer, 2% to 10% photoinitiator, 0.2% to 2% coupling agent, 0.05% to 0.5% leveling agent and the balance acrylic acid modified epoxy resin; Preferably, the monomer includes one or more of tripropylene glycol diacrylate, dipropylene glycol diacrylate, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, tricyclodecane dimethanol diacrylate, pentaerythritol triacrylate and propoxylated glycerol triacrylate; Preferably, the photoinitiator includes one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, hydroxycyclohexane phenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone and ethyl 2,4,6-trimethylbenzoylphenylphosphonate; Preferably, the coupling agent includes one or more of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, vinyltriethoxysilane and vinyltrimethoxysilane; Preferably, the leveling agent includes one or more of polyoxyethylene alcohol acrylate, nano-silica acrylate and polydimethylsiloxane acrylate; Preferably, the viscosity of the insulating adhesive for solar cells is 500-2000 mPa.s.

3. The insulating adhesive for solar cells according to claim 1, characterized in that: The carboxylic acid reaction component includes α-methacrylic acid; Preferably, the mass ratio of the α-methacrylic acid to 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is 6-10:1-2.

4. The insulating adhesive for solar cells according to claim 1, characterized in that: The raw materials for preparing the acrylic modified epoxy resin also include: a catalyst and a polymerization inhibitor; Preferably, the catalyst comprises one or more of triethylamine, N,N-dimethylaniline, trimethylbenzylammonium chloride, tetra-n-butylammonium bromide, 2-methylpyridine, triphenylphosphine and triphenylantimony; Preferably, the amount of the catalyst added is 0.1% to 1% of the total amount of reactants; Preferably, the polymerization inhibitor comprises one or more of p-hydroxyphenylmethane, p-benzoquinone, p-hydroxyanisole, hydroquinone, 2,5-dimethylhydroquinone, 2,6-di-tert-butyl-p-quinone and p-hydroxyanisole; Preferably, the addition amount of the polymerization inhibitor is 0.05% to 0.5% of the total amount of reactants.

5. The method for preparing the insulating adhesive for solar cells according to any one of claims 1 to 4, characterized in that: include: The insulating adhesive for solar cells is obtained by mixing acrylic modified epoxy resin, monomer, photoinitiator, coupling agent and leveling agent.

6. The preparation method according to claim 5, characterized in that Also includes: After the mixing, vacuum degassing and filtering are sequentially performed; Preferably, the vacuum degree of the vacuum degassing is 0.05-0.2 MPa; Preferably, the vacuum degassing temperature is 20-50°C; Preferably, the vacuum degassing time is 20 to 60 minutes; Preferably, the pore size of the filter during the filtration is 5 to 50 μm; Preferably, the stirring speed during the mixing is 500 to 2000 r / min; Preferably, the mixing temperature is 20-30°C; Preferably, the mixing time is 30 to 60 minutes.

7. The preparation method according to claim 5, characterized in that The acrylic acid modified epoxy resin is prepared by the following steps: (a) mixing a catalyst, a polymerization inhibitor and α-methacrylic acid to obtain an acrylic acid mixture; (b) mixing the acrylic acid mixture and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane; (c) measuring the acid value of the reaction system, and stopping the reaction when the acid value in the system drops to below 2 to 4 mgKOH / g to obtain the acrylic acid-modified epoxy resin; Preferably, the mixing temperature in step (a) is 20 to 50°C; Preferably, the mixing process in step (b) comprises: stirring 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane at a speed of 200 to 600 r / min and heating to 60 to 90° C.; then adding the acrylic acid mixture within 45 to 75 minutes; heating to 100 to 120° C. and then conducting a constant temperature reaction; Preferably, in step (c), the acid value of the reaction system is measured every 3 to 6 minutes.

8. Use of the insulating adhesive for solar cells according to any one of claims 1 to 4 or the insulating adhesive for solar cells prepared by the preparation method according to any one of claims 5 to 7 in the preparation of solar cells.

9. A solar cell, characterized in that: The preparation method thereof comprises: The four sides of the solar cell silicon substrate are coated with the insulating adhesive for solar cells described in any one of claims 1 to 4 or the insulating adhesive for solar cells prepared by the preparation method described in any one of claims 5 to 7; then a metal layer is prepared in the patterned groove of the solar cell silicon substrate to obtain a solar cell.

10. The solar cell according to claim 9, characterized in that Before the glue coating, the solar cell silicon substrate is thermally repaired; Preferably, the temperature of the thermal repair is 600-800°C; Preferably, the thermal repair time is 60 to 120 seconds; Preferably, after the glue coating and before the metal layer is prepared, a curing treatment is performed; Preferably, the curing is performed by irradiation with ultraviolet light; Preferably, the wavelength of the ultraviolet lamp is 250-420 nm; Preferably, the irradiation intensity of the ultraviolet lamp is 1000-3000 mW / cm 2 ; Preferably, the curing time is 1 to 3 seconds; Preferably, the material of the metal layer is a combination of nickel-copper, nickel-copper-tin and nickel-copper-silver; Preferably, the solar cell silicon substrate includes one or more of TOPCon, HJT and BC cells.

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