Three-layer composite EVA packaging adhesive film, preparation method thereof and photovoltaic module

Abstract

The invention relates to the technical field of photovoltaic adhesive films, in particular to a three-layer composite EVA packaging adhesive film, a preparation method thereof and a photovoltaic module. The three-layer composite EVA packaging adhesive film comprises a first adhesive layer, a second adhesive layer and a third adhesive layer, the first adhesive layer comprises EVA resin, a first anti-PID agent and a second anti-PID agent; the second adhesive layer comprises EVA resin, a composite self-crosslinking agent and a water-binding agent; and the third adhesive layer comprises EVA resin and a composite acid-binding agent. According to the EVA packaging adhesive film, through the design of the three-layer structure, the Na ion capturing and blocking capacity and the free water vapor and acetate ion absorbing and binding capacity of the EVA packaging adhesive film are sequentially improved, the EVA packaging adhesive film has the performance characteristics of being high in adhesive force, high in light transmittance, resistant to damp and hot corrosion, resistant to PID attenuation and the like, meanwhile, the three layers of base materials are all made of EVA, compatibility of all the layers is good, and the packaging effect is good. And the production cost is low, and the method is more suitable for large-scale production and packaging application at a double-glass TOPCon battery assembly end.

Description

Technical Field

[0001] The invention relates to the technical field of photovoltaic adhesive films, and in particular to a three-layer composite EVA encapsulation adhesive film and a preparation method thereof, and a photovoltaic module. Background Art

[0002] As the size of solar cells increases, PERC solar cells have become the mainstream of the market. However, due to the limitations of existing technologies, the efficiency of PERC solar cells is difficult to continue to improve. Therefore, TOPCon solar cells with higher efficiency have become a hot topic of research. N-type TOPCon solar cells have the advantages of high minority carrier lifetime, no light-induced decay, good weak light response and low temperature coefficient. In the production process of traditional TOPCon solar cells, in order to reduce the contact resistance between the screen-printed silver electrode and the boron-doped P+ emitter, Ag / Al slurry is generally used to print the electrode. However, the Ag / Al electrode is easily corroded by water vapor, resulting in poor reliability of TOPCon solar cells, which in turn puts higher requirements on the encapsulation of the components, and most of them need to use POE or EPE film for encapsulation protection on the front and back sides. However, although POE or EPE film can meet the encapsulation requirements, POE materials are expensive; and, due to the poor polarity of POE materials, the film additives will precipitate and migrate, resulting in the problems of POE film slipping, EPE film bubble generation and low lamination crosslinking degree in the actual production process of the components.

[0003] With the update and iteration of market technology, the LECO (Laser Enhanced Contact Optimization) sintering technology using pure Ag paste is used to replace the traditional sintering technology. Thanks to the use of pure Ag paste in LECO technology, the possible gate line corrosion is reduced to a certain extent, making the packaging material more selective.

[0004] However, the existing encapsulation films are relatively poorly compatible with TOPCon solar cells under LECO technology, and it is difficult to achieve both anti-PID, corrosion resistance and low cost.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] An object of the present invention is to provide a three-layer composite EVA packaging film with excellent anti-PID and corrosion resistance.

[0007] Another object of the present invention is to provide a method for preparing a three-layer composite EVA packaging film.

[0008] Another object of the present invention is to provide a photovoltaic module, comprising the above-mentioned three-layer composite EVA packaging film.

[0009] In order to achieve the above-mentioned object of the present invention, the present invention provides a three-layer composite EVA encapsulation film on one hand, comprising a first adhesive layer, a second adhesive layer and a third adhesive layer arranged in sequence;

[0010] The first adhesive layer comprises the following components by weight: 85-95 parts of EVA resin, 5-15 parts of a first anti-PID agent, 0.6-1 parts of a second anti-PID agent, and 1-5 parts of a first auxiliary agent; the first auxiliary agent comprises a cross-linked silane oligomer;

[0011] The second adhesive layer comprises the following components by weight: 100 parts of EVA resin, 1 to 3 parts of composite self-crosslinking agent, 0.1 to 0.5 parts of water-binding agent and 0.5 to 4 parts of second auxiliary agent;

[0012] The third adhesive layer comprises the following components by weight: 85-95 parts of EVA resin, 5-15 parts of composite acid binding agent and 1-5 parts of third auxiliary agent;

[0013] The first anti-PID agent comprises EVA resin and phosphate in a mass ratio of (85-95):(5-15); the second anti-PID agent comprises a multifunctional acrylate substance;

[0014] The composite self-crosslinking agent is mainly prepared from an NCO-containing acrylic ester substance, an NCO-containing silane substance and an acrylic ester diluent in a mass ratio of 1: (0.5-2): (0.5-2);

[0015] The composite acid-binding agent comprises EVA resin, aminosilane coupling agent, oxide or hydroxide of alkaline metal and carbodiimide compound in a mass ratio of (80-97) : (1-5) : (1-10) : (1-5).

[0016] In a specific embodiment of the present invention, in the third adhesive layer, the EVA resin includes a first EVA resin and a second EVA resin in a mass ratio of (3-7):(7-3); the VA content of the second EVA resin is lower than the VA content of the first EVA resin. Furthermore, the VA content of the second EVA resin is 15%-20%; the first EVA resin is photovoltaic-grade EVA particles, and the VA content is 25%-30%.

[0017] In a specific embodiment of the present invention, the phosphate includes at least one of aluminum phosphate, zirconium phosphate, bismuth phosphate, titanium phosphate and tin phosphate.

[0018] In a specific embodiment of the present invention, the multifunctional acrylate material includes at least one of 3 (ethoxy) trimethylolpropane triacrylate, 6 (ethoxy) trimethylolpropane triacrylate, 3 (propoxy) trimethylolpropane triacrylate, 6 (propoxy) trimethylolpropane triacrylate, 3 (propoxy) propylene glycol triacrylate, di (trimethylolpropane) tetraacrylate and ethoxylated pentaerythritol tetraacrylate.

[0019] In a specific embodiment of the present invention, the NCO-containing acrylate material includes at least one of NCO-containing aliphatic polyurethane acrylate and NCO-containing acrylate monomer. Further, the NCO-containing acrylate monomer includes isocyanate ethyl acrylate.

[0020] In a specific embodiment of the present invention, the NCO-containing silane substance includes at least one of 3-isocyanate propyl triethoxy silane, 3-isocyanate propyl trimethoxy silane and methyl ethyl ketoxime-terminated 3-isocyanate propyl trimethoxy silane.

[0021] In a specific embodiment of the present invention, the acrylate diluent includes at least one of 1,6-hexanediol diacrylate and tripropylene glycol diacrylate. Further, the acrylate diluent includes 1,6-hexanediol diacrylate and tripropylene glycol diacrylate in a mass ratio of (3-7):(7-3).

[0022] In a specific embodiment of the present invention, the water-binding agent includes at least one of cellulose and its derivatives. Further, the water-binding agent includes at least one of hydroxyethyl cellulose, hydroxypropyl methyl cellulose, microcrystalline cellulose, hydroxypropyl cellulose, carboxymethyl cellulose and ethyl cellulose.

[0023] In a specific embodiment of the present invention, the aminosilane coupling agent includes at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane and N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane.

[0024] In a specific embodiment of the present invention, the oxide or hydroxide of the alkaline metal includes at least one of aluminum hydroxide, magnesium hydroxide, sodium hydroxide, aluminum oxide, magnesium oxide, zinc oxide and magnesium aluminum hydrotalcite.

[0025] In a specific embodiment of the present invention, the carbodiimide compound is a non-aromatic carbodiimide compound. Further, the carbodiimide compound includes at least one of N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide.

[0026] In a specific embodiment of the present invention, in the composite acid binding agent, the VA content of the EVA resin is 15% to 20%.

[0027] In a specific embodiment of the present invention, in the first adhesive layer, the VA content of the EVA resin is 25% to 30%; in the second adhesive layer, the VA content of the EVA resin is 25% to 30%.

[0028] In a specific embodiment of the present invention, the thickness ratio of the first adhesive layer, the second adhesive layer and the third adhesive layer is 1:(0.5-1):(0.8-1.2).

[0029] In a specific embodiment of the present invention, the cross-linked silane oligomer accounts for 20wt% to 40wt% of the first auxiliary agent. Further, the cross-linked silane oligomer includes at least one of methacryloxysilane oligomer, vinyltrimethoxysilane oligomer, vinyltriethoxysilane oligomer, 3-(methoxypolyoxyethylene)propyltrimethoxysilane, acyloxyvinylsilane oligomer and octylsilane oligomer.

[0030] Another aspect of the present invention provides a method for preparing any one of the above three-layer composite EVA packaging films, comprising the following steps: multi-layer co-extrusion casting of raw materials for the first adhesive layer, the second adhesive layer, and the third adhesive layer.

[0031] Another aspect of the present invention provides a photovoltaic module, comprising any one of the three-layer composite EVA packaging films described above.

[0032] The three-layer composite EVA packaging film of the present invention is particularly suitable for the preparation of TOPCon double-glass components under LECO technology.

[0033] In a specific embodiment of the present invention, the photovoltaic module includes any one of a single-glass module and a double-glass module.

[0034] In a specific embodiment of the present invention, the first adhesive layer of the three-layer composite EVA encapsulation film is adhered to the glass of the photovoltaic module, and the third adhesive layer of the three-layer composite EVA encapsulation film is adhered to the battery cell of the photovoltaic module.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The EVA encapsulation film of the present invention has a three-layer functional structure design, which sequentially improves the EVA encapsulation film's ability to capture and block Na ions and its ability to absorb and bind free water vapor and acetate ions, so that the EVA encapsulation film of the present invention has excellent anti-PID and corrosion resistance, and can provide long-term reliability protection for components;

[0037] (2) The EVA encapsulation film of the present invention adopts EVA as the matrix of each layer, and the compatibility between the layers is good. Compared with EPE film, it can significantly improve the problems of lamination bubbles and additive precipitation, and compared with POE film, it can also significantly reduce the cost, and is more suitable for large-scale production and application; and it has excellent matching with the TOPCon cell double-glass solar module under LECO technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A schematic diagram of the structure of a three-layer composite EVA packaging film provided in an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of the structure of a double-glass LECO-TOPCon battery assembly provided in an embodiment of the present invention.

[0041] Reference numerals:

[0042] 1-first adhesive layer; 2-second adhesive layer; 3-third adhesive layer;

[0043] 4-Glass; 5-Battery cell. DETAILED DESCRIPTION

[0044] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0045] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0046] Figure 1 The present invention provides a three-layer composite EVA encapsulation film, comprising a first adhesive layer 1, a second adhesive layer 2 and a third adhesive layer 3 arranged in sequence.

[0047] The first adhesive layer 1 comprises the following components by weight: 85-95 parts of EVA resin, 5-15 parts of a first anti-PID agent, 0.6-1 parts of a second anti-PID agent, and 1-5 parts of a first auxiliary agent; the first auxiliary agent comprises a cross-linked silane oligomer;

[0048] The second adhesive layer 2 comprises the following components by weight: 100 parts of EVA resin, 1 to 3 parts of composite self-crosslinking agent, 0.1 to 0.5 parts of water-binding agent and 0.5 to 4 parts of second auxiliary agent;

[0049] The third adhesive layer 3 comprises the following components by weight: 85-95 parts of EVA resin, 5-15 parts of composite acid binding agent and 1-5 parts of third auxiliary agent;

[0050] The first anti-PID agent includes EVA resin and phosphate in a mass ratio of (85-95):(5-15); the second anti-PID agent includes multifunctional acrylate substances;

[0051] The composite self-crosslinking agent is mainly prepared from an NCO-containing acrylic ester substance, an NCO-containing silane substance and an acrylic ester diluent in a mass ratio of 1:(0.5-2):(0.5-2);

[0052] The composite acid-binding agent comprises EVA resin, aminosilane coupling agent, oxide or hydroxide of alkaline metal and carbodiimide compound in a mass ratio of (80-97) : (1-5) : (1-10) : (1-5).

[0053] The EVA encapsulation film of the present invention has a three-layer functional structure design, which sequentially improves the EVA encapsulation film's ability to capture and block Na ions and its ability to absorb and bind free water vapor and acetate ions, so that the EVA encapsulation film of the present invention has excellent anti-PID and corrosion resistance, can provide long-term reliability protection for components, and is suitable for the encapsulation application of TOPCon solar cell double-glass components under LECO technology. In the EVA encapsulation film of the present invention, the first adhesive layer 1 is arranged to be bonded to the glass when in use. By adding the first anti-PID agent and the second anti-PID agent to the transparent EVA resin, the first anti-PID agent can absorb Na ions conducted from one side of the glass to the adhesive film and the battery sheet through ion replacement, and the second anti-PID agent can form a denser three-dimensional cross-linked network with the EVA main chain segment in the form of long branches during thermal curing, thereby improving the cross-linking density of the first adhesive layer 1, so that the free sodium ions invaded by water vapor are chelated in situ, thereby increasing steric hindrance and being unable to pass through the cross-linked network to reach the battery surface. Through the synergy of the first anti-PID agent and the second anti-PID agent, the barrier capacity for Na ions and water vapor is significantly improved, the generation of leakage current is avoided, and the PID attenuation rate is reduced.

[0054] The first adhesive layer 1 is attached to one side of the glass. In order to further increase the bonding strength between the adhesive film and the glass after wet heat aging, a conventional amount of cross-linked silane oligomer can be added. The cross-linked silane oligomer added to the first adhesive layer 1 of the present invention can undergo a polymerization reaction with the EVA main chain segment under the action of auxiliary agents such as a cross-linking agent and a co-cross-linking agent during thermal curing of the adhesive film to increase the cross-linking degree of the first adhesive layer 1, thereby increasing the barrier effect on Na ions and water vapor; at the same time, the silane molecular structure in the cross-linked silane oligomer is compact and not easy to hydrolyze, and a siloxane film layer is formed during the cross-linking process, which has good hydrophobicity and can significantly increase the bonding strength between the adhesive film and the glass after wet heat aging.

[0055] For example, in different embodiments, in the first adhesive layer 1, the amounts of the components in parts by weight may be as follows:

[0056] The amount of EVA resin can be 85 parts, 88 parts, 90 parts, 92 parts, 95 parts or a range consisting of any two of them;

[0057] The amount of the first anti-PID agent can be 5 parts, 7 parts, 9 parts, 11 parts, 13 parts, 15 parts or a range consisting of any two of them;

[0058] The amount of the second anti-PID agent can be 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part or a range consisting of any two thereof;

[0059] The dosage of the first auxiliary agent can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts or a range consisting of any two of them.

[0060] In some embodiments of the present invention, in the first anti-PID agent, the mass ratio of EVA resin to phosphate can be 85:15, 88:12, 90:10, 92:8, 95:5, or any two thereof. Regulating the mass ratio of EVA resin to phosphate within the above range helps to take into account the dispersibility of phosphate and ensure the replacement adsorption effect of Na ions.

[0061] In the EVA encapsulation film of the present invention, a water-binding agent and a composite self-crosslinking agent are added to the second adhesive layer 2 at the same time. The addition of the water-binding agent can bind part of the water vapor that cannot be blocked by the first adhesive layer 1 and the water vapor that enters through the edge of the component, and store the water vapor in the second adhesive layer 2; the composite self-crosslinking agent further undergoes a chemical crosslinking reaction with the water vapor in the second adhesive layer 2, which not only consumes the water vapor in the second adhesive layer 2 and reduces the amount of water vapor passing through, but also increases the crosslinking density of the second adhesive layer 2, further blocking the diffusion of Na ions and water vapor.

[0062] For example, in different embodiments, in the second adhesive layer 2, by weight, compared to 100 parts of EVA resin, the amounts of the remaining components may be as follows:

[0063] The amount of the composite self-crosslinking agent can be 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.8 parts, 3 parts or a range consisting of any two of them;

[0064] The amount of the water-binding agent can be 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part or a range consisting of any two of them;

[0065] The dosage of the second auxiliary agent can be 0.5 parts, 1 parts, 2 parts, 3 parts, 4 parts or a range consisting of any two of them.

[0066] In some embodiments of the present invention, in the composite self-crosslinking agent, the mass ratio of the NCO-containing acrylate substance to the NCO-containing silane substance can be 1:0.5, 1:1, 1:1.5, 1:2 or a range consisting of any two thereof; the mass ratio of the NCO-containing acrylate substance to the acrylate diluent can be 1:0.5, 1:1, 1:1.5, 1:2 or a range consisting of any two thereof. Regulating the distribution ratio of each component in the composite crosslinking agent within the above range helps to ensure heat curing and moisture curing, which not only meets the requirements of heat curing lamination, but also can provide sufficient moisture curing reaction during use to further increase the crosslinking density and block water vapor and Na ions.

[0067] In the composite self-crosslinking agent of the present invention, the NCO-containing acrylate substance contains both NCO (isocyanate group) and double bonds. NCO is sensitive to moisture and can undergo moisture curing reaction with water vapor; the double bond functional group can undergo heat curing reaction; the NCO-containing silane substance can also participate in moisture curing reaction on the one hand, and can also participate in the heat curing reaction of EVA on the other hand, to improve the crosslinking density and anti-aging performance of the film; the addition of acrylate diluent can reduce the viscosity of the composite self-crosslinking agent to a certain extent, so as to be smoothly added to the film system. The composite self-crosslinking agent of the present invention can achieve dual curing of heat and moisture, and a two-step curing reaction can occur during component packaging and use. First, under conventional thermal curing, the double bond functional groups of the first adhesive layer 1, the second adhesive layer 2 and the third adhesive layer 3 of the photovoltaic module can be polymerized with the EVA resin under the action of a cross-linking agent, thereby curing and cross-linking; then, in outdoor applications, due to the intrusion of water vapor at the edge or front of the module, the NCO in the composite self-cross-linking agent can be triggered to undergo a self-cross-linking moisture curing reaction with water molecules, further improving the overall cross-linking density of the film, blocking the migration of water vapor and Na ions, and playing a protective role in anti-PID and corrosion resistance.

[0068] In the EVA packaging film of the present invention, a composite acid-binding agent is added to the third adhesive layer 3 to neutralize the free acetic acid in the EVA film, thereby avoiding power attenuation of the component battery due to corrosion of the grid line.

[0069] For example, in different embodiments, in the third adhesive layer 3, the amounts of the components in parts by weight may be as follows:

[0070] The amount of EVA resin can be 85 parts, 88 parts, 90 parts, 92 parts, 95 parts or a range consisting of any two of them;

[0071] The amount of the composite acid-binding agent can be 5 parts, 6 parts, 8 parts, 10 parts, 12 parts, 15 parts or a range consisting of any two of them;

[0072] The dosage of the third auxiliary agent can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts or a range consisting of any two of them.

[0073] For example, in different embodiments, in the composite acid binding agent, the mass ratio of EVA resin to aminosilane coupling agent can be 80:5, 84:4, 89:3, 93:2, 97:1 or a range consisting of any two thereof; the mass ratio of EVA resin to oxide or hydroxide of alkaline metal can be 80:10, 84:8, 89:5, 93:3, 97:1 or a range consisting of any two thereof; the mass ratio of EVA resin to carbodiimide compound can be 80:5, 84:4, 89:3, 93:2, 97:1 or a range consisting of any two thereof.

[0074] In the composite acid-binding agent of the present invention, the oxide or hydroxide of the alkaline metal can neutralize the free acetic acid in the EVA film through an acid-base neutralization reaction, thereby avoiding the power attenuation of the solar module battery due to the corrosion of the grid line; the carbodiimide compound can react with the acetic acid in the film, the moisture generated by the side reaction, and the moisture intruded from the outside at the same time, thereby reducing the acetic acid content in the third adhesive layer 3, further blocking the intrusion of water vapor, and avoiding the battery cell from being corroded and damaged. At the same time, in order to better exert the synergistic effect of the oxide or hydroxide of the alkaline metal and the carbodiimide compound, the composite acid-binding agent of the present invention uses EVA resin as a carrier and uses an aminosilane coupling agent to compound the two.

[0075] In a specific embodiment of the present invention, in the third adhesive layer 3, the EVA resin includes a first EVA resin and a second EVA resin in a mass ratio of (3-7):(7-3); the VA content of the second EVA resin is lower than the VA content of the first EVA resin.

[0076] The present invention further adopts some EVA resin with low VA content in the third adhesive layer 3, which can significantly reduce the release of acetic acid in the third adhesive layer 3 during wet heat aging compared with the EVA resin with high VA content. Since the third adhesive layer 3 is directly attached to the battery cell, the release of acetic acid in the long-term wet heat aging of EVA is reduced from the source, providing better reliability protection for the component. For example, in different embodiments, in the third adhesive layer 3, the mass ratio of the first EVA resin to the second EVA resin can be 3:7, 4:6, 6:4, 5:5, 7:3 or a range consisting of any two of them.

[0077] In a specific embodiment of the present invention, the VA content in the second EVA resin is 15% to 20%; and the VA content in the first EVA resin is 25% to 30%.

[0078] For example, in different embodiments, in the second EVA resin, the VA content may be 15%, 16%, 17%, 18%, 19%, 20% or a range consisting of any two thereof; in the first EVA resin, the VA content may be 25%, 26%, 27%, 28%, 29%, 30% or a range consisting of any two thereof.

[0079] In a specific embodiment of the present invention, the phosphate includes at least one of aluminum phosphate, zirconium phosphate, bismuth phosphate, titanium phosphate and tin phosphate.

[0080] In a specific embodiment of the present invention, the multifunctional acrylate material includes at least one of 3 (ethoxy) trimethylolpropane triacrylate, 6 (ethoxy) trimethylolpropane triacrylate, 3 (propoxy) trimethylolpropane triacrylate, 6 (propoxy) trimethylolpropane triacrylate, 3 (propoxy) propylene glycol triacrylate, di (trimethylolpropane) tetraacrylate and ethoxylated pentaerythritol tetraacrylate.

[0081] In a specific embodiment of the present invention, in the first auxiliary agent, the proportion of cross-linked silane oligomer is 20wt% to 40wt%, such as 20wt%, 25wt%, 30wt%, 35wt%, 40wt% or any two thereof, but not limited thereto.

[0082] In a specific embodiment of the present invention, the cross-linked silane oligomer includes but is not limited to: at least one of methacryloxysilane oligomer, vinyltrimethoxysilane oligomer, vinyltriethoxysilane oligomer, 3-(methoxypolyethylene oxide)propyltrimethoxysilane, acyloxyvinylsilane oligomer and octylsilane oligomer.

[0083] In a specific embodiment of the present invention, the first auxiliary agent includes at least one of a crosslinking agent, a co-crosslinking agent, a crosslinking silane oligomer, an antioxidant and a light stabilizer. Further, the first auxiliary agent includes the following components by weight: 0.5 to 1 part of a crosslinking agent, 0.2 to 0.8 parts of a co-crosslinking agent, 0.2 to 0.6 parts of a crosslinking silane oligomer, 0.1 to 0.15 parts of an antioxidant and 0.05 to 0.09 parts of a light stabilizer.

[0084] In a specific embodiment of the present invention, the NCO-containing acrylate material includes at least one of NCO-containing aliphatic polyurethane acrylate and NCO-containing acrylate monomer. Further, the NCO-containing acrylate monomer includes isocyanate ethyl acrylate.

[0085] In a specific embodiment of the present invention, the NCO-containing silane material includes at least one of 3-isocyanate propyl triethoxy silane, 3-isocyanate propyl trimethoxy silane and methyl ethyl ketoxime-terminated 3-isocyanate propyl trimethoxy silane.

[0086] In a specific embodiment of the present invention, in the NCO-containing acrylate material, the mass ratio of the NCO-containing aliphatic polyurethane acrylate to the NCO-containing acrylate monomer is (3-7):(7-3).

[0087] For example, in different embodiments, the mass ratio of the NCO-containing aliphatic polyurethane acrylate to the NCO-containing acrylate monomer can be 3:7, 4:6, 5:5, 6:4, 7:3 or a range consisting of any two of them.

[0088] In a specific embodiment of the present invention, the acrylate diluent includes at least one of 1,6-hexanediol diacrylate and tripropylene glycol diacrylate. Further, the acrylate diluent includes 1,6-hexanediol diacrylate and tripropylene glycol diacrylate in a mass ratio of (3-7):(7-3).

[0089] For example, in different embodiments, the mass ratio of 1,6-hexanediol diacrylate to tripropylene glycol diacrylate can be 3:7, 4:6, 5:5, 6:4, 7:3 or a range of any two thereof.

[0090] In a specific embodiment of the present invention, the preparation of the composite self-crosslinking agent includes: mixing the substances in proportion, and stirring at 40-60° C. for more than 0.5 h until there are no bubbles in the mixing aid.

[0091] For example, in different embodiments, in the preparation of the composite self-crosslinking agent, the mixing temperature can be 40°C, 45°C, 50°C, 55°C, 60°C or a range consisting of any two thereof; the stirring time can be 0.5h, 1h, 2h, etc. to ensure uniform mixing.

[0092] In a specific embodiment of the present invention, the water-binding agent includes at least one of cellulose and its derivatives. Further, the water-binding agent includes at least one of hydroxyethyl cellulose, hydroxypropyl methyl cellulose, microcrystalline cellulose, hydroxypropyl cellulose, carboxymethyl cellulose and ethyl cellulose.

[0093] In a specific embodiment of the present invention, the second auxiliary agent includes at least one of a crosslinking agent, a co-crosslinking agent, an antioxidant and a light stabilizer. Further, the second auxiliary agent includes the following components by weight: 0.5 to 1 part of a crosslinking agent, 0.2 to 0.8 part of a co-crosslinking agent, 0.1 to 0.15 part of an antioxidant and 0.05 to 0.09 part of a light stabilizer.

[0094] In a specific embodiment of the present invention, the aminosilane coupling agent includes at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane and N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane.

[0095] In a specific embodiment of the present invention, the oxide or hydroxide of the alkaline metal includes at least one of aluminum hydroxide, magnesium hydroxide, sodium hydroxide, aluminum oxide, magnesium oxide, zinc oxide and magnesium aluminum hydrotalcite.

[0096] In a specific embodiment of the present invention, the carbodiimide compound is a non-aromatic carbodiimide compound. Further, the carbodiimide compound includes at least one of N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide.

[0097] In a specific embodiment of the present invention, in the composite acid binding agent, the VA content of the EVA resin is 15% to 20%.

[0098] In a specific embodiment of the present invention, the preparation of the composite acid-binding agent comprises: mixing various substances in proportion, and extruding and granulating at 90-130°C.

[0099] In a specific embodiment of the present invention, the third auxiliary agent includes at least one of a crosslinking agent, a co-crosslinking agent, a silane coupling agent, an acrylic monomer, an antioxidant and a light stabilizer. Further, the third auxiliary agent includes the following components by weight: 0.5-1 part of a crosslinking agent, 0.2-0.8 part of a co-crosslinking agent, 0.2-0.8 part of a silane coupling agent, 0.6-1 part of an acrylic monomer, 0.1-0.15 part of an antioxidant and 0.05-0.09 part of a light stabilizer.

[0100] In a specific embodiment of the present invention, in the first adhesive layer 1, the VA content of the EVA resin is 25% to 30%; in the second adhesive layer, the VA content of the EVA resin is 25% to 30%.

[0101] In a specific embodiment of the present invention, the thickness ratio of the first adhesive layer 1, the second adhesive layer 2 and the third adhesive layer 3 is 1:(0.5-1):(0.8-1.2).

[0102] For example, in different embodiments, the thickness ratio of the first adhesive layer 1 to the second adhesive layer 2 can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1 or a range consisting of any two thereof; the thickness ratio of the first adhesive layer 1 to the third adhesive layer 3 can be 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2 or a range consisting of any two thereof.

[0103] The auxiliary agents involved in the first adhesive layer 1, the second adhesive layer 2 and the third adhesive layer 3 of the EVA encapsulating film of the present invention, such as a cross-linking agent, a co-cross-linking agent, a silane coupling agent, a cross-linking silane oligomer, an antioxidant, a light stabilizer, an acrylate monomer, etc., can be selected according to the conventional types of encapsulating films, and are listed here, but not limited to:

[0104] Crosslinking agents include but are not limited to tert-butyl peroxy-2-ethylhexyl carbonate, tri-pentyl peroxy (2-ethylhexyl) carbonate, bis (2-ethylhexyl) peroxy dicarbonate, bis (2-ethylhexyl) peroxy dicarbonate;

[0105] Auxiliary crosslinking agents include but are not limited to triallyl isocyanurate, triallyl cyanurate, ethylene glycol dimethacrylate;

[0106] Silane coupling agents include but are not limited to KH-570 (Kashida), O174S (Jianghan Chemical), and KBM-503 (Shin-Etsu Chemical);

[0107] The antioxidant includes but is not limited to at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl, tris(2,4-di-tert-butylphenyl) phosphite, tris[2,4-di-tert-butylphenyl]phosphite and dioctadecyl pentaerythritol diphosphite;

[0108] The light stabilizer includes but is not limited to at least one of bis(1,2,2,6,6-pentamethylpiperidinol) sebacate, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, diphenylaminourea and dimethyl azobisisobutyrate;

[0109] Acrylate monomers include but are not limited to trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, polyethylene glycol (400) dimethacrylate, neopentyl glycol (2) PO diacrylate, polypropylene glycol (1000) EO (3) dimethacrylate, ethoxylated bisphenol A diacrylate, ethoxylated bisphenol A dimethacrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate and neopentyl glycol diacrylate.

[0110] Another aspect of the present invention provides a method for preparing any one of the above three-layer composite EVA packaging films, comprising the following steps: multi-layer co-extrusion casting of raw materials for the first adhesive layer, raw materials for the second adhesive layer, and raw materials for the third adhesive layer.

[0111] In a specific embodiment of the present invention, in the co-extrusion casting, the extrusion section temperature of the first rubber layer is 70-80°C; the extrusion section temperature of the second rubber layer is 70-80°C; the extrusion section temperature of the third rubber layer is 70-80°C; and the die head temperature is 80-85°C.

[0112] Another aspect of the present invention provides a photovoltaic module, comprising any one of the above three-layer composite EVA packaging films.

[0113] In a specific embodiment of the present invention, the photovoltaic module includes any one of a single-glass module and a double-glass module.

[0114] In a specific embodiment of the present invention, the first adhesive layer of the three-layer composite EVA encapsulation film is attached to the glass of the photovoltaic module, and the third adhesive layer of the three-layer composite EVA encapsulation film is attached to the battery cell of the photovoltaic module.

[0115] Figure 2 The schematic diagram of the structure of the double-glass LECO-TOPCon battery module provided in an embodiment of the present invention shows that the first adhesive layer 1 of the three-layer composite EVA encapsulation film is adhered to the glass 4 of the photovoltaic module, and the third adhesive layer 3 of the three-layer composite EVA encapsulation film is adhered to the battery cell 5 of the photovoltaic module.

[0116] Example 1

[0117] This embodiment provides an EVA encapsulation film, including a first adhesive layer, a second adhesive layer and a third adhesive layer arranged in sequence; the total thickness of the EVA encapsulation film is 500 μm; the thickness ratio of the first adhesive layer, the second adhesive layer and the third adhesive layer is 1:0.6:1.

[0118] The raw materials of the first adhesive layer mainly include: 90 parts by weight of EVA resin (V2825 / Sulbon Chemical), 10 parts of the first anti-PID agent, 0.8 parts of the second anti-PID agent, 0.5 parts of the crosslinking agent 2-ethylhexyl carbonate tert-butyl peroxide, 0.6 parts of the auxiliary crosslinking agent triallyl isocyanurate, 0.4 parts of crosslinking silane oligomer, 0.1 parts of antioxidant 1010 and 0.06 parts of light stabilizer UV-770. The crosslinking silane oligomer includes methacryloyloxysilane oligomer (7270T / Aikopu) and 3-(methoxypolyoxyethylene)propyltrimethoxysilane (JH-PEG100 / Jianghan New Materials) in a mass ratio of 1:1. The first anti-PID agent is obtained by twin-screw extrusion granulation of EVA resin (V2825 / Sailbon Chemical) and zirconium phosphate in a mass ratio of 9:1. The twin-screw extruder includes 10 zone temperatures, and the temperatures of each zone are: the temperature of the first zone is 80°C, the temperature of the second zone is 90°C, the temperature of the third zone is 100°C, the temperature of the 4th to 7th zones is 110°C, the temperature of the 8th zone is 100°C, the temperature of the 9th zone is 90°C, and the temperature of the 10th zone is 80°C. The second anti-PID agent includes 6 (propoxy) trimethylolpropane triacrylate and di (trimethylolpropane) tetraacrylate in a mass ratio of 2:1.

[0119] The raw materials of the second adhesive layer mainly include: 100 parts of EVA resin (V2825 / Sailbon Chemical), 2 parts of composite self-crosslinking agent, 0.4 parts of water-binding agent, 0.5 parts of crosslinking agent 2-ethylhexyl carbonate tert-butyl peroxide, 0.6 parts of auxiliary crosslinking agent triallyl isocyanurate, 0.1 parts of antioxidant 1010 and 0.06 parts of light stabilizer UV-770. The preparation of the composite self-crosslinking agent includes: weighing aliphatic polyurethane acrylate (EBECRYL 4250 / allnex), ethyl isocyanate acrylate, methyl ethyl ketoxime-terminated 3-isocyanate propyl trimethoxysilane (HJ-IC13P / Shin-Etsu Chemical), tripropylene glycol diacrylate and 1,6-hexanediol diacrylate in a mass ratio of 0.8﹕0.2﹕1.5﹕1﹕1 respectively, placing them in a container, and then stirring at 50°C for 1 hour, defoaming to obtain the composite self-crosslinking agent. The water-binding agent is hydroxypropyl methylcellulose.

[0120] The raw materials of the third adhesive layer mainly include: 50 parts by weight of EVA resin (V2825 / Sulbang Chemical), 40 parts of EVA resin with low VA content (19F16 / Yanshan Petrochemical), 10 parts of composite acid binding agent, 0.5 parts of cross-linking agent 2-ethylhexyl peroxide tert-butyl carbonate, 0.6 parts of auxiliary cross-linking agent triallyl isocyanurate, 0.4 parts of silane (KH-570 / Kashda), 0.6 parts of trimethylolpropane triacrylate, 0.1 parts of antioxidant 1010 and 0.06 parts of light stabilizer UV-770. The composite acid-binding agent is obtained by extruding and granulating EVA resin (19F16 / Yanshan Petrochemical) with a low VA content in a mass ratio of 90:2:5:3, 3-aminopropyltriethoxysilane, oxides or hydroxides of alkaline metals, and N,N'-dicyclohexylcarbodiimide through a twin-screw extruder. The twin-screw extruder has 10 zone temperatures, and the temperatures of each zone are: the temperature of the first zone is 90°C, the temperature of the second zone is 100°C, the temperature of the third zone is 120°C, the temperature of the fourth to seventh zones is 130°C, the temperature of the eighth zone is 120°C, the temperature of the ninth zone is 100°C, and the temperature of the tenth zone is 80°C. Among them, the oxides or hydroxides of alkaline metals include magnesium hydroxide and magnesium aluminum hydrotalcite in a mass ratio of 3:2.

[0121] The preparation method of the EVA packaging film of this embodiment comprises the following steps:

[0122] A certain proportion of the raw materials of the first adhesive layer, the raw materials of the second adhesive layer, and the raw materials of the third adhesive layer (corresponding to the first adhesive layer, the second adhesive layer, and the third adhesive layer, respectively) are subjected to multi-layer co-extrusion casting, cooling, and winding to obtain an EVA encapsulation film. In the multi-layer co-extrusion casting, the extrusion section temperature of the first adhesive layer is 70-80°C; the extrusion section temperature of the second adhesive layer is 70-80°C; the extrusion section temperature of the third adhesive layer is 70-80°C; and the die head temperature is 80-85°C.

[0123] Example 2

[0124] This embodiment refers to the EVA packaging adhesive film and preparation method thereof of Embodiment 1, with the only difference being that the first anti-PID agent and the second anti-PID agent in the first adhesive layer are of different types.

[0125] In the preparation of the first anti-PID agent of this embodiment, an equal amount of bismuth phosphate is used to replace zirconium phosphate; the second anti-PID agent includes 3 (propoxy) trimethylolpropane triacrylate and 3 (ethoxy) trimethylolpropane triacrylate in a mass ratio of 2:1.

[0126] Example 3

[0127] This embodiment refers to the EVA packaging adhesive film and its preparation method of Example 1, the only difference is that the composite acid binding agent in the third adhesive layer is different.

[0128] In the preparation of the composite acid-binding agent of this embodiment, magnesium hydroxide and magnesium oxide in a mass ratio of 3:2 are used in equal amounts to replace magnesium hydroxide and magnesium-aluminum hydrotalcite in a mass ratio of 3:2.

[0129] Example 4

[0130] This embodiment refers to the EVA packaging film and preparation method thereof of Embodiment 1, with the only difference being that the EVA resin in the third adhesive layer is different.

[0131] The raw materials of the third adhesive layer in this embodiment mainly include: 90 parts by weight of EVA resin (V2825 / Sulbon Chemical), 10 parts of composite acid binding agent, 0.5 parts of cross-linking agent 2-ethylhexyl carbonate tert-butyl peroxide, 0.6 parts of auxiliary cross-linking agent triallyl isocyanurate, 0.4 parts of silane (KH-570 / Kashda), 0.6 parts of trimethylolpropane triacrylate, 0.1 parts of antioxidant 1010 and 0.06 parts of light stabilizer UV-770. The composite acid binding agent is the same as that in Example 1.

[0132] Example 5

[0133] This embodiment refers to the EVA encapsulation adhesive film and preparation method thereof of Embodiment 1, the only difference being that the content of the first anti-PID agent in the first adhesive layer is different and the content of the acid binding agent in the third adhesive layer is different.

[0134] In this embodiment, the first anti-PID agent in the first adhesive layer is increased from 10 parts to 15 parts, and the weight of the increased first anti-PID agent is equally reduced in the EVA resin of the first adhesive layer.

[0135] The acid binding agent in the third adhesive layer of this embodiment is increased from 10 parts to 15 parts, and the weight of the increased acid binding agent is reduced in equal amounts in the EVA resin (V2825 / Sailbon Chemical) and the EVA resin with low VA content (19F16 / Yanshan Petrochemical) in the third adhesive layer.

[0136] Example 6

[0137] This embodiment refers to the EVA encapsulation adhesive film and preparation method thereof of Embodiment 1, the only difference being that the contents of the composite self-crosslinking agent and the water-binding agent in the second adhesive layer are different.

[0138] In the second adhesive layer of this embodiment, the composite self-crosslinking agent is increased from 2 parts to 3 parts, and the water-binding agent is increased from 0.4 parts to 0.5 parts.

[0139] Example 7

[0140] This embodiment refers to the EVA encapsulation adhesive film and preparation method thereof of Embodiment 1, with the only difference being that the composition of the composite self-crosslinking agent in the second adhesive layer is different.

[0141] The raw materials of the composite self-crosslinking agent of this embodiment include aliphatic polyurethane acrylate (EBECRYL 4250 / allnex), ethyl isocyanate acrylate, methyl ethyl ketoxime-terminated 3-isocyanatepropyltrimethoxysilane, tripropylene glycol diacrylate and 1,6-hexanediol diacrylate in a mass ratio of 0.8﹕0.2﹕0.5﹕0.25﹕0.25.

[0142] Example 8

[0143] This embodiment refers to the EVA encapsulation adhesive film and preparation method thereof of Embodiment 1, with the only difference being that the composition of the composite self-crosslinking agent in the second adhesive layer is different.

[0144] The raw materials of the composite self-crosslinking agent of this embodiment include aliphatic polyurethane acrylate (EBECRYL 4250 / allnex), ethyl isocyanate acrylate, methyl ethyl ketoxime-terminated 3-isocyanate propyltrimethoxysilane, tripropylene glycol diacrylate and 1,6-hexanediol diacrylate in a mass ratio of 0.8﹕0.2﹕2﹕0.5﹕0.5.

[0145] Example 9

[0146] This embodiment refers to the EVA packaging adhesive film and its preparation method of Embodiment 1, the only difference being that the composition of the composite acid binding agent in the third adhesive layer is different.

[0147] The composite acid-binding agent of Example 9 is obtained by twin-screw extrusion granulation from EVA resin with low VA content (19F19 / Yanshan Petrochemical) in a mass ratio of 97:1:1:1, 3-aminopropyltriethoxysilane, oxide or hydroxide of alkaline metal (magnesium hydroxide and magnesium aluminum hydrotalcite in a mass ratio of 3:2), and N,N'-dicyclohexylcarbodiimide.

[0148] Example 10

[0149] This embodiment refers to the EVA packaging adhesive film and preparation method thereof of Embodiment 1, with the only difference being that the composition of the composite acid binding agent in the third adhesive layer is different.

[0150] The composite acid-binding agent of Example 10 is obtained by twin-screw extrusion granulation from EVA resin (19F19 / Yanshan Petrochemical) with a low VA content in a mass ratio of 80:5:10:5, 3-aminopropyltriethoxysilane, an oxide or hydroxide of an alkaline metal (magnesium hydroxide and magnesium aluminum hydrotalcite in a mass ratio of 3:2), and N,N'-dicyclohexylcarbodiimide.

[0151] Comparative Example 1

[0152] Comparative Example 1 is a commercially available common EVA high-transmittance adhesive film (Guangzhou Lushan, EV1050G2).

[0153] Comparative Example 2

[0154] Comparative Example 2 refers to the EVA encapsulation film and preparation method thereof of Example 1, except that: the third adhesive layer does not contain a composite acid binder and an EVA resin with a low VA content, and the reduced weight portions of the composite acid binder and the EVA resin with a low VA content are added to the EVA resin of the third adhesive layer.

[0155] Comparative Example 3

[0156] Comparative Example 3 refers to the EVA encapsulation adhesive film and preparation method thereof of Example 1, except that: the first adhesive layer does not include the first anti-PID agent and the second anti-PID agent, and the reduced weight portions of the first anti-PID agent and the second anti-PID agent are added to the EVA resin of the first adhesive layer.

[0157] Comparative Example 4

[0158] Comparative Example 4 refers to the EVA encapsulation adhesive film and preparation method thereof of Example 1, except that: the second adhesive layer does not include the composite self-crosslinking aid and the water-binding agent, and the reduced weight portions of the composite self-crosslinking aid and the water-binding agent are added to the EVA resin of the second adhesive layer.

[0159] Comparative Example 5

[0160] Comparative Example 5 refers to the EVA encapsulation adhesive film and preparation method thereof of Example 1, except that the first auxiliary agent in the first adhesive layer does not include a cross-linked silane oligomer, and the reduced cross-linked silane oligomer is replaced by KH-570 (Kashda) silane in equal parts by weight.

[0161] Comparative Example 6

[0162] Comparative Example 6 The EVA encapsulation film and preparation method thereof of Reference Example 1 are different in that: this comparative example only includes a two-layer structure with thicknesses of 250 μm and 250 μm, respectively; the second layer is the same as the third adhesive layer in Example 1, and the raw materials of the first adhesive layer mainly include: 90 parts by weight of EVA resin (V2825 / Sulbon Chemical), 10 parts of a first anti-PID additive, 0.6 parts of a second anti-PID additive, 2 parts of a composite self-crosslinking agent, 0.4 parts of a water-binding agent, 0.5 parts of a crosslinking agent 2-ethylhexyl carbonate peroxide, 0.6 parts of a crosslinking aid triallyl isocyanurate, 0.2 parts of a methacryloxysilane oligomer (7270T / Aikopu), 0.2 parts of 3-(methoxypolyoxyethylene)propyltrimethoxysilane (JH-PEG100 / Jianghan New Materials), 0.2 parts of silane (KH570), and 1010 parts of an antioxidant. 0.1 part, and light stabilizer UV-770 0.06 part. Wherein, the composite self-crosslinking agent, water-binding agent, first anti-PID agent, and second anti-PID agent are the same as those in Example 1.

[0163] Comparative Example 7

[0164] Comparative Example 7 refers to the EVA encapsulation film and its preparation method of Example 1, except that: this comparative example includes only one layer structure with a thickness of 500 μm; the raw materials of the adhesive layer mainly include: 45 parts of EVA resin (V2825 / Sailbon Chemical), 35 parts of EVA resin with low VA content (19F16 / Yanshan Petrochemical), 2 parts of composite self-crosslinking agent, 0.4 parts of water binding agent, 10 parts of acid binding agent, 10 parts of first anti-PID additive, and 10 parts of second anti-P ID auxiliary agent 0.6 parts, crosslinking agent peroxy 2-ethylhexyl carbonate tert-butyl ester 0.5 parts, co-crosslinking agent triallyl isocyanurate 0.6 parts, methacryloxy silane oligomer (7270T / Aikopu) 0.2 parts, 3-(methoxy polyoxyethylene) propyl trimethoxy silane (JH-PEG100 / Jianghan New Materials) 0.2 parts, silane (KH570) 0.2 parts, trimethylolpropane trimethacrylate 0.2 parts, antioxidant 1010 0.1 parts, and light stabilizer UV-7700 0.06 parts. Among them, the composite self-crosslinking agent, water binding agent, and acid binding agent are the same as in Example 1.

[0165] Comparative Example 8

[0166] Comparative Example 8 refers to the EVA encapsulation adhesive film and preparation method thereof of Example 1, except that the composition of the composite acid binding agent in the third adhesive layer is different.

[0167] The composite acid-binding agent of Comparative Example 8 is prepared by twin-screw extrusion granulation of EVA resin (19F19 / Yanshan Petrochemical) with a mass ratio of 93:2:5, an aminosilane coupling agent, and magnesium hydroxide.

[0168] Comparative Example 9

[0169] Comparative Example 9 refers to the EVA encapsulation adhesive film and preparation method thereof of Example 1, except that the composition of the composite self-crosslinking agent in the second adhesive layer is different.

[0170] The raw materials of the composite self-crosslinking agent of Comparative Example 9 include methyl ethyl ketone oxime-terminated 3-isocyanate propyl trimethoxysilane, tripropylene glycol diacrylate and 1,6-hexanediol diacrylate in a mass ratio of 1.5:1:1.

[0171] Experimental example

[0172] In order to compare and illustrate the performance differences of different EVA encapsulation films, Figure 2 The double-glass component structure is made into a component, and the double-glass component is made of the film prepared in Examples 1 to 10 and Comparative Examples 1 to 9, including glass, EVA film, LECO-TOPCon battery component sheet, EVA film, and glass arranged in sequence from top to bottom, wherein when the EVA film is a composite structure, the first adhesive layer of the EVA film is bonded to the glass, and the third adhesive layer is bonded to the battery sheet, the lamination temperature is 140°C, and the exhaust time, the filling time, and the lamination time are 6 minutes, 1 minute, and 10 minutes, respectively. The performance test of the prepared double-glass component is carried out, and the test results are shown in Table 1.

[0173] Among them, the aging test of the weather resistance, transmittance and bonding strength of the film are carried out in accordance with the GB / T29848-2018 standard.

[0174] Test method for acid content of adhesive film after PCT192H: First, use a standard cutter to cut the adhesive film to (305mm*305mm), and make a laminate according to glass / two layers of adhesive film / backboard. The lamination conditions are 140℃, and the vacuum time, inflation time, and lamination time are 6min, 1min, and 10min respectively; Second, cool after lamination and perform HAST (121℃, 100%RH, 192H) aging test. After the test, return to room temperature and take out; Third, use a utility knife to take about 8g of adhesive film (without backboard) from the laminate or other material residues), placed in a conical flask, immersed in a diluted ethanol solution (a mixed solution of 50mL water + 50mL alcohol); at the same time, prepare a bottle of 50mL water + 50mL alcohol reference solution, seal the two conical flasks and ultrasonically vibrate for 30min, cool to room temperature, add 3mL of bromothymol blue indicator to each conical flask, and then titrate with the calibrated KOH-ethanol solution, record the KOH-ethanol titration solution consumed when the conical flask changes color as V2 (with sample group) and V1 (reference group), respectively.

[0175]

[0176] In formula (1): 56.1-constant (molar mass of potassium hydroxide), unit is gram per mole (g / mol);

[0177] V1-volume of KOH solution required to titrate the sample solution, in milliliters (mL);

[0178] V2-the volume of KOH solution required for blank determination, in milliliters (mL);

[0179] The concentration of C-KOH solution is in moles per liter (mol / L);

[0180] M1-mass of the sample in grams (g).

[0181] Table 1 Performance test results of different EVA encapsulation films

[0182]

[0183]

[0184] As shown in Table 1, the LECO technology TOPCon double-glass module encapsulated by the EVA encapsulation film of the present invention has a power attenuation of <3% after DH2000h aging, a power attenuation of <4% after PID192h aging, and an acid value content of ≤200ppm after PCT192h aging. The film can achieve excellent adhesion and high light transmittance with the glass surface, with an initial peel strength of >140N / cm, a bonding force of ≥60N / cm between the film and the glass surface after PCT24h aging, and a light transmittance of >90%. As shown in Example 1 and Comparative Examples 2 to 4, when the first anti-PID agent, the second anti-PID agent, the composite self-crosslinking agent, the water-binding agent, the composite acid-binding agent and part of the low-VA EVA resin are removed from the first, second and third adhesive layers of the composite EVA film, the overall barrier capacity of the film to water vapor and the capture and barrier capacity to Na and acetate ions deteriorate, which will further deteriorate the weather resistance DH2000h and PID192h power attenuation. It can be seen from Example 1 and Comparative Example 5 that when the cross-linked silane oligomer is replaced with KH-570 silane monomer in the first adhesive layer, the silane monomer will gradually hydrolyze and become ineffective during the aging process, resulting in a low adhesion of the adhesive film after PCT aging. At the same time, the monomer silane is easily hydrolyzed and cannot form a siloxane film layer in the adhesive film, and the barrier performance to water vapor will also deteriorate. Example 1 and Comparative Examples 6-7 illustrate the importance of the three-layer composite structure. Reducing the layer structure will seriously affect the light transmittance of the adhesive film and the adhesion of PCT after 24h aging. At the same time, the reduction of the layer structure will also cause the overall barrier performance of the adhesive film to deteriorate against water vapor and Na ions, which is reflected in the final DH and PID aging power attenuation. It can be seen from Example 1 and Comparative Examples 8 to 9 that when the important components in the composite self-crosslinking agent and the composite acid-binding agent are missing, the composite self-crosslinking agent and the composite acid-binding agent will seriously affect the role of the composite self-crosslinking agent and the composite acid-binding agent in the film layer, and it is impossible to form a good barrier and adsorption effect on water vapor and acetate ions. The acetic acid content of the film PCT192H is greatly increased after aging, and the aging power attenuation of DH and PID will also increase. In summary, the EVA encapsulation film of the present invention, under the premise of ensuring high transmittance and high adhesion, is set up through a three-layer structure, which sequentially improves the capture and barrier ability of the EVA encapsulation film for Na ions, and the adsorption and binding ability of free water vapor and acetate ions, so that the EVA encapsulation film of the present invention has excellent anti-PID and corrosion resistance, can provide long-term reliability protection for components, and has excellent matching with TOPCon solar cells under LECO technology.

[0185] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned 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. Three-layer composite EVA encapsulation film, It is characterized in that It includes a first adhesive layer, a second adhesive layer and a third adhesive layer which are arranged in sequence; The first adhesive layer comprises the following components by weight: 85-95 parts of EVA resin, 5-15 parts of a first anti-PID agent, 0.6-1 parts of a second anti-PID agent, and 1-5 parts of a first auxiliary agent; the first auxiliary agent comprises a cross-linked silane oligomer; The second adhesive layer comprises the following components by weight: 100 parts of EVA resin, 1 to 3 parts of composite self-crosslinking agent, 0.1 to 0.5 parts of water-binding agent and 0.5 to 4 parts of second auxiliary agent; The third adhesive layer comprises the following components by weight: 85-95 parts of EVA resin, 5-15 parts of composite acid binding agent and 1-5 parts of third auxiliary agent; The first anti-PID agent comprises EVA resin and phosphate in a mass ratio of (85-95):(5-15); the second anti-PID agent comprises a multifunctional acrylate substance; The composite self-crosslinking agent is mainly prepared from an NCO-containing acrylic ester substance, an NCO-containing silane substance and an acrylic ester diluent in a mass ratio of 1:(0.5-2):(0.5-2); The composite acid-binding agent comprises EVA resin, aminosilane coupling agent, oxide or hydroxide of alkaline metal and carbodiimide compound in a mass ratio of (80-97) : (1-5) : (1-10) : (1-5).

2. The three-layer composite EVA encapsulation film according to claim 1, It is characterized in that In the third adhesive layer, the EVA resin includes a first EVA resin and a second EVA resin in a mass ratio of (3-7):(7-3); the VA content of the second EVA resin is lower than the VA content of the first EVA resin; Preferably, the VA content in the second EVA resin is 15% to 20%; and the VA content in the first EVA resin is 25% to 30%.

3. The three-layer composite EVA encapsulation film according to claim 1, It is characterized in that The phosphate includes at least one of aluminum phosphate, zirconium phosphate, bismuth phosphate, titanium phosphate and tin phosphate; And / or, the multifunctional acrylate substance includes at least one of 3(ethoxy)trimethylolpropane triacrylate, 6(ethoxy)trimethylolpropane triacrylate, 3(propoxy)trimethylolpropane triacrylate, 6(propoxy)trimethylolpropane triacrylate, 3(propoxy)propylene glycol triacrylate, di(trimethylolpropane) tetraacrylate and ethoxylated pentaerythritol tetraacrylate.

4. The three-layer composite EVA encapsulation film according to claim 1, It is characterized in that Having at least one of the following characteristics: (1) The NCO-containing acrylate substance includes at least one of NCO-containing aliphatic polyurethane acrylate and NCO-containing acrylate monomer; preferably, the NCO-containing acrylate monomer includes isocyanate ethyl acrylate; (2) the NCO-containing silane substance comprises at least one of 3-isocyanate propyl triethoxy silane, 3-isocyanate propyl trimethoxy silane and methyl ethyl ketoxime-terminated 3-isocyanate propyl trimethoxy silane; (3) The acrylic ester diluent includes at least one of 1,6-hexanediol diacrylate and tripropylene glycol diacrylate; preferably, the acrylic ester diluent includes 1,6-hexanediol diacrylate and tripropylene glycol diacrylate in a mass ratio of (3-7):(7-3).

5. The three-layer composite EVA packaging film according to claim 1, It is characterized in that The water-binding agent comprises at least one of cellulose and its derivatives; Preferably, the water-binding agent comprises at least one of hydroxyethyl cellulose, hydroxypropyl methyl cellulose, microcrystalline cellulose, hydroxypropyl cellulose, carboxymethyl cellulose and ethyl cellulose.

6. The three-layer composite EVA encapsulation film according to claim 1, It is characterized in that Having at least one of the following characteristics: (1) The oxide or hydroxide of the alkaline metal includes at least one of aluminum hydroxide, magnesium hydroxide, sodium hydroxide, aluminum oxide, magnesium oxide, zinc oxide and magnesium aluminum hydrotalcite; (2) The carbodiimide compound is a non-aromatic carbodiimide compound; (3) the carbodiimide compound includes at least one of N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide; (4) the aminosilane coupling agent comprises at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane and N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane; (5) In the composite acid binding agent, the VA content of the EVA resin is 15% to 20%.

7. The three-layer composite EVA packaging film according to claim 1, It is characterized in that In the first adhesive layer, the VA content of the EVA resin is 25% to 30%; in the second adhesive layer, the VA content of the EVA resin is 25% to 30%; Preferably, the thickness ratio of the first adhesive layer, the second adhesive layer and the third adhesive layer is 1:(0.5-1):(0.8-1.2).

8. The three-layer composite EVA packaging film according to claim 1, It is characterized in that In the first auxiliary agent, the cross-linked silane oligomer accounts for 20wt% to 40wt%; Preferably, the cross-linked silane oligomer includes at least one of methacryloxysilane oligomer, vinyltrimethoxysilane oligomer, vinyltriethoxysilane oligomer, 3-(methoxypolyethylene oxide)propyltrimethoxysilane, acyloxyvinylsilane oligomer and octylsilane oligomer.

9. A method for preparing a three-layer composite EVA encapsulation film according to any one of claims 1 to 8, It is characterized in that The method comprises the following steps: performing multi-layer co-extrusion casting on raw materials of a first adhesive layer, raw materials of a second adhesive layer and raw materials of a third adhesive layer.

10. A photovoltaic module, It is characterized in that The invention comprises the three-layer composite EVA encapsulation adhesive film as described in any one of claims 1 to 8 or the three-layer composite EVA encapsulation adhesive film prepared by the preparation method as described in claim 9.

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