An isocyanate polyolefin prepolymer, a preparation method thereof, a resin composition containing the same, an encapsulating adhesive film, a solar cell module and applications

Abstract

An isocyanate polyolefin prepolymer, a preparation method thereof, a resin composition containing the same, an encapsulation film and a solar cell module, and an application thereof belong to the technical field of solar cell encapsulation materials. The number average molecular weight of the isocyanate polyolefin prepolymer is 550 to 20,000 g / mol, its viscosity at 40 °C is 10 to 5000 Pa•s, and it contains unsaturated side groups and unsaturated end groups chemically bonded to the carbon chain. The resin composition containing the isocyanate polyolefin prepolymer can be used as an encapsulation film for solar cell modules, and can enhance the water vapor barrier ability and environmental stability of solar cell modules.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell packaging materials, and in particular, to an isocyanate polyolefin prepolymer, a preparation method thereof, a resin composition containing the same, an encapsulation film, a solar cell module, and the application of this grafted polyurethane prepolymer material in the field of solar cells. Background Art

[0002] High-efficiency crystalline silicon solar cells are becoming increasingly mature, such as PERC (Passivated Emitter Rear Cell) cells, TOPCon (Tunnel Oxide Passivated Contact) solar cells, HJT (Heterojunction with Intrinsic Thin-film) double-sided cells, and IBC (Interdigitated Back Contact) cells. These new types of cells have multiple advantages such as high conversion efficiency, low attenuation, and high bifaciality. Since the silver paste used in these new types of cells is relatively special, under the action of water vapor, a potential difference is easily generated, causing corrosion of the paste, and thus easily leading to a significant decrease in the power generation efficiency of the cells. Therefore, high-performance barrier materials are required to encapsulate the cell wafers. After ethylene-vinyl acetate copolymer and polyolefin elastomer materials are mixed with a silane coupling agent, a crosslinking agent, etc., they are cast into a film and laminated with a photovoltaic cell for encapsulation, which can play a certain degree of protective role for the photovoltaic cell. Due to the cold crystallization of the packaging material, the surface wettability of the packaging material with the cell wafer or glass is reduced. The photovoltaic module is exposed outdoors for a long time, and water vapor is easily introduced into the module through the edge part of the glass or the backplane part, thereby corroding the cell grid lines and reducing the power generation performance of the module.

[0003] Currently, medium and low molecular weight olefin polymers or liquid olefin polymers (CN117467050A, CN114933873B, CN117987035A) have been developed to alleviate the problems of insufficient wettability of the encapsulation adhesive film of solar cells on the surface of the battery chips and glass, and easy intrusion of water vapor. The side groups of these materials contain carbon-carbon double bonds that can graft with the matrix resins EVA (ethylene-vinyl acetate copolymer, Ethylene Vinyl Acetate Copolymer) or POE (Poly Olefin Elastomer). However, unmodified olefin polymers often have relatively low polarity and poor compatibility with additives such as crosslinking agents and coupling agents. On the other hand, liquid olefin polymers are inconvenient to use in the processes of mixing, processing, and casting. Medium and high molecular weight olefin polymers (CN116769425A, CN104081540B, CN112437787A), such as low-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-octene copolymer, ethylene-hexene copolymer, binary ethylene-propylene rubber, or ternary ethylene-propylene rubber, have also been reported to be used in the barrier layer of photovoltaic modules. However, compared with EVA or POE, these materials often have relatively high melting points. On the other hand, these materials generally do not contain unsaturated double bonds themselves and have insufficient antioxidant ability.

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

[0005] In view of the above-mentioned defects or improvement requirements of the prior art, the present invention provides an isocyanate polyolefin prepolymer, a preparation method thereof, a resin composition containing the same, an encapsulation adhesive film, and a solar cell module, so as to improve the problems of difficult processing, weak material polarity, and poor water vapor barrier performance of existing materials.

[0006] To achieve the above object, according to one aspect of the present invention, the technical solution of the present invention lies in providing an isocyanate polyolefin prepolymer having a number average molecular weight of 550 to 20,000 g / mol, a viscosity of 10 to 5000 Pa•s at 40 °C, a glass transition temperature lower than -20 °C, and containing unsaturated side groups and unsaturated end groups chemically bonded to the carbon chain, and the molar amounts of the unsaturated side groups and end groups account for 2.5% to 99.5% of the total number of carbon-carbon bonds of the isocyanate polyolefin prepolymer. Specifically, in addition to the above two end values, it can also be 5.0%, 10.0%, 30.0%, 50.0%, 60.0%, 80.5%, 90.0%.

[0007] Furthermore, its number-average molecular weight is 700 g / mol, 1000 g / mol, 2000 g / mol, 5000 g / mol, 8000 g / mol, 10000 g / mol, 12000 g / mol, 15000 g / mol, 18000 g / mol.

[0008] Furthermore, its viscosity at 40 °C is 11 Pa•s, 50 Pa•s, 100 Pa•s, 500 Pa•s, 800 Pa•s, 1000 Pa•s, 1500 Pa•s, 2000 Pa•s, 2500 Pa•s, 3000 Pa•s, 3500 Pa•s, 4000 Pa•s, 4900 Pa•s.

[0009] Furthermore, the isocyanate polyolefin prepolymer is obtained by prepolymerization reaction of an isocyanate compound containing unsaturated olefin units and an olefin polymer under the action of a catalyst.

[0010] Furthermore, the number-average molecular weight of the olefin polymer is 500 - 20000 g / mol, and the olefin polymer contains one or more of hydroxyl, carboxyl, primary amino, secondary amino, aldehyde, carbonyl, epoxy groups.

[0011] Furthermore, the number-average molecular weight of the olefin polymer is 505 g / mol, 800 g / mol, 1000 g / mol, 2000 g / mol, 5000 g / mol, 8000 g / mol, 10000 g / mol, 15000 g / mol, 18000 g / mol, 19500 g / mol.

[0012] Furthermore, the olefin polymer is polybutadiene, or polyisoprene, or a copolymer of isoprene and styrene, or a copolymer of ethylene and vinyl acetate, or a copolymer of ethylene and acrylonitrile, or a copolymer of ethylene and propylene, or a terpolymer of ethylene, propylene and ethylidene norbornene, or a copolymer of ethylene, propylene and 1, 4 - hexadiene, or a copolymer of propylene and isoprene.

[0013] Further, the mass ratio of the olefin polymer to the isocyanate compound is 1:(0.0001~0.1000), and for example, it can be 1:0.0001, 1:0.0003, 1:0.0005, 1:0.0008, 1:0.0009, 1:0.0015, 1:0.0023, 1:0.0041, 1:0.0052, 1:0.0071, 1:0.0093, 1:0.0121, 1:0.0365, 1:0.0558, 1:0.0723, 1:0.0818, 1:0.0943, 1:0.1000, etc.

[0014] Further, the unsaturated isocyanate compound is selected from any one or a combination of two of the compounds represented by Formula I and the compounds represented by Formula II:

[0015] Formula I Formula II

[0016] Wherein, R1 is selected from C2~C6 linear or branched alkenyl, and the carbon chain includes C2, C3, C4, C5, C6; R2 is selected from C1~C6 linear or branched alkyl, and the carbon chain includes C1, C2, C3, C4, C5, C6, R3 is selected from C2~C6 linear or branched alkenyl, and the carbon chain includes C2, C3, C4, C5, C6, and X is selected from an oxygen atom or a sulfur atom.

[0017] Further, the catalyst used in the preparation process of the isocyanate polyolefin prepolymer includes a first catalyst and / or a second catalyst; the first catalyst is a metal catalyst, preferably any one or a combination of at least two of dibutyltin dilaurate, dimethyltin diacetate, dibutyltin diacetate, monobutyltin triisooctoate, stannous octoate or stannous oxalate; the second catalyst is an electron-donating organic catalyst, preferably any one or a combination of at least two of linear aliphatic amines, cycloaliphatic amines, polythiols, acid anhydride compounds.

[0018] Further, the addition amount of the catalyst is 0.001%~5% of the mass of the isocyanate compound, and for example, it can be 0.001%, 0.051%, 0.084%, 0.097%, 0.11%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. The mass ratio of the first catalyst to the second catalyst is 1:(0.0001~10000), and for example, it can be 1:0.0001, 1:0.1000, 1:0.2000, 1:0.5000, 1:1.0000, 1:1, 1:10, 1:100, 1:1000, 1:2000, 1:3000, 1:4000, 1:5000, 1:8000, etc.

[0019] Furthermore, the reaction temperature for preparing the isocyanate polyolefin prepolymer is 40 to 150 °C. Besides the above two end values, it can also be 50 °C, 70 °C, 80 °C, 100 °C, 120 °C; the reaction time is 0.5 to 10 h. Besides the above two end values, it can also be 1.0 h, 2.0 h, 5.0 h, 8.0 h, 9.0 h.

[0020] The present invention also provides a method for preparing the above isocyanate polyolefin prepolymer, in which an isocyanate compound containing unsaturated olefin units and an olefin polymer are subjected to a prepolymerization reaction under the action of a catalyst. The reaction temperature is 40 to 150 °C. Besides the above two end values, it can also be 50 °C, 70 °C, 80 °C, 100 °C, 120 °C; the reaction time is 0.5 to 10 h. Besides the above two end values, it can also be 1.0 h, 2.0 h, 5.0 h, 8.0 h, 9.0 h.

[0021] Furthermore, a solvent is used in the prepolymerization reaction, and the solvent is removed by vacuum after the reaction.

[0022] The present invention also provides a resin composition, which comprises the above isocyanate polyolefin prepolymer, a vinyl polymer, an initiator, a crosslinking agent, and a compatibilizer.

[0023] Furthermore, the vinyl polymer is one or more of polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer, ethylene-1-decene copolymer; preferably, the vinyl polymer is one or more of ethylene-propylene copolymer, EVA, and POE; preferably, the number average molecular weight of the vinyl polymer is 10,000 to 200,000 g / mol. Besides the above two end values, the number average molecular weight can also be 20,000 g / mol, 30,000 g / mol, 50,000 g / mol, 80,000 g / mol, 100,000 g / mol, 150,000 g / mol, 180,000 g / mol.

[0024] Furthermore, the weight percentage content of the isocyanate polyolefin prepolymer in the above resin composition is 0.05% to 18%. Besides the above two end values, it can also be 0.1%, 0.2%, 0.5%, 1.0%, 4.0%, 6.0%, 17%.

[0025] Furthermore, the initiator contained in the resin composition is selected from one or a combination of two of azo initiators, peroxide initiators, or redox initiators. The mass of the initiator contained in the resin composition is 0.01% to 6% of the total mass of the resin composition. In addition to the above two end values, it can also be 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 2%, 5%. The mass of the crosslinking agent contained in the resin composition is 0.01% to 6% of the total mass of the resin composition. In addition to the above two end values, it can also be 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 2%, 5%. The mass of the compatibilizer contained in the resin composition is 0.01% to 6% of the total mass of the resin composition. In addition to the above two end values, it can also be 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 2%, 5%.

[0026] According to another aspect of the present invention, there is also provided an encapsulating film. The encapsulating film is formed by melting and mixing the aforementioned resin composition, extruding it through an extruder, and then calendering and embossing to form a film-like material. The encapsulating film composition is a single-layer structure or a multi-layer structure, and the material of at least one layer in the encapsulating film includes the above-mentioned isocyanate polyolefin prepolymer.

[0027] Furthermore, the encapsulating film can be a three-layer structure, including a first film layer, a second film layer, and a third film layer stacked in sequence. The materials of the first film layer and the third film layer include the aforementioned resin composition, and the material of the second film layer can include a conventional EVA composition or a POE composition (i.e., not including the isocyanate polyolefin prepolymer); or, the materials of the first film layer, the second film layer, and the third film layer all include the aforementioned resin composition; or, the encapsulating film can also be a two-layer structure, and the material of at least one layer in the two-layer structure includes the above-mentioned resin composition.

[0028] According to yet another aspect of the present invention, there is also provided a solar cell module, including a first glass plate or an organic backplane, a front encapsulating film, a battery cell array, a rear encapsulating film, and a second glass plate arranged in sequence; at least one of the rear encapsulating film and the front encapsulating film adopts the aforementioned encapsulating film; the battery cell array can be any one of PERC, TOPCon, HJT, and IBC cells.

[0029] The present invention also provides an application of the above-mentioned isocyanate polyolefin prepolymer or the above-mentioned encapsulation film in improving the performance of a photovoltaic cell encapsulation film, including improving the polarity of vinyl resins (such as EVA resin or POE resin) in the photovoltaic cell encapsulation film, enhancing the wettability of the photovoltaic cell encapsulation film with the cell array and the surface of the photovoltaic encapsulation glass, enhancing the adhesion between the photovoltaic cell film and the cell array and the photovoltaic encapsulation glass, enhancing the water vapor barrier performance of the photovoltaic encapsulation material, and enhancing the protection effect of the photovoltaic cell encapsulation film on the cell and the cell grid lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 FIG. is a schematic structural diagram of a double-glass type solar cell module according to an embodiment of the present invention.

[0032] Figure 2 FIG. is a schematic structural diagram of a single-glass type solar cell module according to an embodiment of the present invention.

[0033] Figure 3 FIG. is an infrared spectrum diagram of the isocyanate polyolefin prepolymer masterbatch prepared in Example 1.

[0034] Description of reference numerals: 25, organic backplane; 24, first glass plate; 23, rear encapsulation film; 231, first sub-rear encapsulation film; 232, second sub-rear encapsulation film; 22, cell array; 21, front encapsulation film; 211, first sub-front encapsulation film; 212, second sub-front encapsulation film; 213, third sub-front encapsulation film; 20, second glass plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] To better illustrate the objectives, technical solutions, and advantages of the present invention, the present invention will be further described below in conjunction with the drawings and specific embodiments. The test methods used in the embodiments of the present invention are all conventional methods unless otherwise specified; the materials, reagents, etc. used in the embodiments of the present invention can all be obtained from commercial sources unless otherwise specified.

[0036] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0037] As described in the background art section, the polarity of the existing solar cell encapsulation adhesive film is low, and the contact wetting property with the cell array and the photovoltaic encapsulation glass is insufficient, so water vapor is likely to invade during long-term outdoor use. In order to improve the insufficient barrier ability of the current photovoltaic adhesive film, according to one aspect of the present invention, the technical solution of the present invention is to provide an isocyanate polyolefin prepolymer. Adding the isocyanate polyolefin prepolymer to the photovoltaic cell encapsulation adhesive film can effectively improve the polarity of the vinyl resin (such as POE resin, EVA resin) in the photovoltaic cell encapsulation adhesive film, thereby enhancing the wetting property of the adhesive film with the cell array and the surface of the photovoltaic encapsulation glass, and enhancing the adhesion between the photovoltaic cell encapsulation adhesive film and these materials. On the other hand, the isocyanate polyolefin prepolymer can enhance the water vapor barrier property of the photovoltaic encapsulation material and improve the protection effect of the adhesive film material on the cell and the cell grid line.

[0038] The isocyanate polyolefin prepolymer provided by the present invention has a number average molecular weight of 550 to 20,000 g / mol, a viscosity at 40 °C of 10 to 5000 Pa•s, a glass transition temperature lower than -20 °C, and contains unsaturated side groups and unsaturated end groups chemically bonded to the carbon chain, and the molar amounts of the unsaturated side groups and end groups account for 2.5% to 99.5% of the total number of carbon-carbon bonds of the isocyanate polyolefin prepolymer. Specifically, in addition to the above two end values, it can also be 2.8%, 3.2%, 9.7%, 25.7%, 32.5%, 49.8%, 59.3%, 60.4%, 73.5%, 86.2%, 99.1%, etc.

[0039] The isocyanate polyolefin prepolymer provided by the present invention is obtained by carrying out a prepolymerization reaction for a certain time at a certain temperature under the action of a catalyst between an isocyanate compound containing an unsaturated olefin functional group and an isocyanate functional group and a medium- and low-molecular-weight olefin polymer containing a hydroxyl group, a carboxyl group, a primary amino group, a secondary amino group, an aldehyde group, a carbonyl group, and an epoxy group.

[0040] For the isocyanate polyolefin prepolymer provided by the present invention, the mass ratio of the medium- and low-molecular-weight olefin polymer to the unsaturated isocyanate compound is 1:(0.0001~0.1000).

[0041] The unsaturated isocyanate compound described in the present invention is a straight-chain or branched-chain difunctional compound, and at least contains an unsaturated double bond and an isocyanate group. Further, the unsaturated isocyanate compound is selected from any one or a combination of two of the compounds shown in Formula I and Formula II:

[0042] Formula I Formula II

[0043] Among them, R1 is selected from C2-C6 linear or branched alkenyl groups, R2 is selected from C1-C6 linear or branched alkyl groups, R3 is selected from C2-C6 linear or branched alkenyl groups, and X is selected from an oxygen atom or a sulfur atom.

[0044] More preferably, the unsaturated isocyanate compound is selected from any one or a combination of at least two of the compounds in Table 1 below.

[0045] Table 1 Unsaturated Isocyanate Compounds

[0046]

[0047] Among them, CAS (Chemical Abstracts Servic) represents the Chemical Substance Registry Number, also known as the Substance Digital Identification Number. CAS no. represents its specific number.

[0048] In the present invention, the low molecular weight olefin polymer has an appropriate molecular weight, and the number average molecular weight is 500-20000 g / mol, ensuring that the material has good processing ability. In a preferred embodiment, the polymerization unit of the medium and low molecular weight olefin polymer is a conjugated diene, or a conjugated diene and a vinyl aromatic hydrocarbon, or a non-conjugated diene and a vinyl aromatic hydrocarbon; further preferably, the olefin polymer is polybutadiene, or polyisoprene, or a copolymer of isoprene and styrene, or a copolymer of ethylene and vinyl acetate, or a copolymer of ethylene and acrylonitrile, or a copolymer of ethylene and propylene, or a terpolymer of ethylene, propylene and ethylidene norbornene, or a copolymer of ethylene, propylene and 1,4-hexadiene, or a copolymer of propylene and isoprene.

[0049] In the preparation process of the isocyanate polyolefin prepolymer of the present invention, two catalysts, a first catalyst and / or a second catalyst, can be used. The first catalyst is mainly applicable to the reaction and polymerization of an isocyanate compound with a medium and low molecular weight olefin polymer containing a hydroxyl group, a carboxyl group, a primary amino group or a secondary amino group; the second catalyst mainly acts on the ring-opening or activation of an aldehyde group, a carbonyl group or an epoxy group, and then polymerizes with the isocyanate compound.

[0050] Furthermore, the first catalyst is a metal catalyst, preferably selected from any one or a combination of at least two of dibutyltin dilaurate, tin dimethyl diacetate, dibutyltin diacetate, monobutyltin triisooctoate, stannous octoate and stannous oxalate. The second catalyst is an electron-donating organic catalyst, preferably selected from any one or a combination of at least two of linear aliphatic amines, cycloaliphatic amines, polythiols and acid anhydride compounds.

[0051] Furthermore, the addition amount of the catalyst is 0.001% - 5% of the mass of the isocyanate compound. For example, it can be 0.001%, 0.051%, 0.084%, 0.097%, 0.11%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. According to the types of medium and low molecular weight olefin polymers and isocyanates, the first catalyst and the second catalyst can be used simultaneously or separately; when the first catalyst and the second catalyst are used simultaneously, the mass ratio of the first catalyst to the second catalyst is 1:(0.0001 - 10000). For example, it can be 1:0.0001, 1:0.0008, 1:0.005, 1:0.007, 1:0.03, 1:1, 1:20, 1:345, 1:4546, 1:8679, 1:10000.

[0052] The preparation method of the isocyanate polyolefin prepolymer of the present invention can adopt bulk polymerization or solution polymerization, and the foregoing catalyst is used in the polymerization process. Typical polymerization processes include mixing the isocyanate compound, medium and low molecular weight polyolefin polymer, and catalyst in proportion, then heating to 40 - 150°C. For example, it can be 40°C, 53°C, 62°C, 77°C, 86°C, 90°C, 110°C, 150°C, and reacting for 0.5 - 10 h. For example, it can be 0.5 h, 0.9 h, 1.2 h, 2.3 h, 3.5 h, 4.6 h, 5.5 h, 6.2 h, 8.9 h, 10 h, mixing through kneading equipment such as a kneader and a mixer, and then removing bubbles under vacuum to form the isocyanate polyolefin prepolymer.

[0053] Furthermore, a reaction solvent with a mass fraction of 5% - 200% relative to the olefin polymer can be added in the foregoing reaction process. For example, it can be 5%, 12%, 21%, 32%, 40%, 52%, 64%, 72%, 85%, 100%, 130%, 175%, 182%, 200%. Preferably, the reaction solvent is selected from any one or a combination of at least two of chloroform, dichloromethane, acetonitrile, ethanol, methanol, n-butanol, benzene, toluene, xylene, chlorobenzene, acetone, butanone, dimethyl sulfoxide, N,N-dimethylformamide, water, dioxane, tetrahydrofuran, methyl ethyl ketone, ethyl acetate, ether, isopropyl ether, carbon tetrachloride, bromoethane, cyclohexane, and hexane.

[0054] According to another aspect of the present invention, the present invention also provides a resin composition, which comprises the above-mentioned isocyanate polyolefin prepolymer, medium and low molecular weight vinyl polymer, initiator, crosslinking agent, and compatibilizer. Adding this resin composition to the photovoltaic cell encapsulation film can effectively improve the polarity of vinyl resins (such as POE resin and EVA resin) in the photovoltaic cell encapsulation film, thereby enhancing the wettability of the film with the cell array and the surface of the photovoltaic cell encapsulation glass, and strengthening the adhesion between the photovoltaic cell encapsulation film and these materials. On the other hand, the isocyanate polyolefin prepolymer can enhance the water vapor barrier performance of the photovoltaic encapsulation material and improve the protection effect of the film material on the cell and the cell grid lines.

[0055] Further, the vinyl polymer is one or more of polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer, and ethylene-1-decene copolymer; preferably, the vinyl polymer is one or more of ethylene-propylene copolymer, EVA, and POE; preferably, the number average molecular weight of the vinyl polymer is 20,000 - 200,000 g / mol.

[0056] Further, the weight percentage content of the isocyanate polyolefin prepolymer in the above resin composition is 0.05% - 18%.

[0057] Further, in order to make the encapsulation material have better elongation at break and tensile strength, it is necessary to crosslink the resin material. Preferably, an initiator with a mass fraction of 0.01% - 6% is added to the above resin composition, which can be a composition of one or two of azo initiators, peroxide initiators, and redox initiators, and more preferably tert-amyl peroxy-2-ethylhexyl carbonate, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, and tert-butyl peroxy-2-ethylhexyl carbonate.

[0058] Further, in order to improve the anti-aging ability of the encapsulation material, it is necessary for the resin material to have a better crosslinking degree. Preferably, a polyfunctional crosslinking agent with a mass fraction of 0.01% - 6% is added to the above resin composition, and more preferably triallyl isocyanurate, trimellitic acid triallyl ester, trimethylolpropane trimethacrylate, and ethoxylated trimethylolpropane triacrylate.

[0059] Further, in order to improve the adhesion and anti-aging performance of the encapsulation material, a compatibilizer with a mass fraction of 0.01% - 6% is preferably added, and the compatibilizer can include at least one of silane compounds containing silane structures and unsaturated olefin structures, hindered phenol compounds, hindered amine compounds, and ultraviolet absorbing compounds.

[0060] According to another aspect of the present invention, there is also provided an encapsulant film, which is formed by melting and mixing the aforementioned resin composition, extruding it through an extruder, and casting and embossing it into a film-like material. The encapsulant film composition is a single-layer structure or a multi-layer structure, and the material of at least one layer in the encapsulant film includes the above resin composition. Using this encapsulant film for encapsulating a photovoltaic cell module can effectively improve the polarity of vinyl resins (such as POE resin and EVA resin) in the photovoltaic cell encapsulant film, thereby enhancing the wettability of the film with the cell array and the surface of the photovoltaic encapsulation glass, and strengthening the adhesion between the photovoltaic cell encapsulant film and these materials. On the other hand, the isocyanate polyolefin prepolymer can enhance the water vapor barrier performance of the photovoltaic encapsulation material and improve the protection effect of the film material on the cell and the cell grid lines.

[0061] Furthermore, the encapsulant film is a single-layer or multi-layer structure. In some embodiments, the encapsulant film is a three-layer structure, including a first film layer, a second film layer, and a third film layer stacked in sequence. The materials of the first film layer and the third film layer are the aforementioned resin composition, and the material of the second film layer is a conventional EVA composition or POE composition that does not contain an isocyanate polyolefin prepolymer; alternatively, the materials of the first film layer, the second film layer, and the third film layer are all the aforementioned resin composition. In some embodiments, the encapsulant film is a two-layer structure, and the material of at least one layer in the two-layer structure includes the above isocyanate polyolefin prepolymer.

[0062] According to still another aspect of the present invention, there is also provided a solar cell module. In some embodiments, as Figure 1 shown, the solar cell module may include a first glass plate 24, a rear encapsulant film 23, a cell array 22, a front encapsulant film 21, and a second glass plate 20 (photovoltaic glass plate) stacked in sequence; wherein, the rear encapsulant film 23 is a single-layer structure, and the front encapsulant film 21 is a two-layer structure, including a stacked first sub-front encapsulant film 211 and a second sub-front encapsulant film 212.

[0063] In other embodiments, as Figure 2 shown, the solar cell module may include an organic backplane 25, a rear encapsulant film 23, a cell array 22, a front encapsulant film 21, and a second glass plate 20 (photovoltaic glass plate) stacked in sequence; wherein, the rear encapsulant film 23 may be a two-layer structure, including a first sub-rear encapsulant film 231 and a second sub-rear encapsulant film 232; the front encapsulant film 21 may be a three-layer structure, including a first sub-front encapsulant film 211, a second sub-front encapsulant film 212, and a third sub-front encapsulant film 213.

[0064] At least one of the front encapsulation film and the rear encapsulation film in the embodiments of the present invention uses the aforementioned encapsulation film; wherein the cell array can be any one of PERC, TOPCon, HJT, and IBC cells.

[0065] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0066] Example 1

[0067]

[0068] Preparation of polymer (isocyanate polyolefin prepolymer): Add 200 g of acetonitrile (solvent) and 0.28 g of dibutyltin dilaurate to a reactor, add 100 g of hydroxyl-terminated polybutadiene with a number average molecular weight of about 3000 g / mol and a hydroxyl value of about 0.75 mmol / g, stir and mix well, then add 9.5 g of 2-isocyanatoethyl acrylate, degas under vacuum, then ultrasonically vibrate for 30 min, heat up to 70 °C, keep warm and stir for 2 h, and remove the solvent under vacuum to obtain isocyanate polyolefin prepolymer A with a number average molecular weight of about 3300 g / mol and a viscosity (40 °C) of about 65 Pa•s.

[0069] Masterbatch preparation: Mix isocyanate polyolefin prepolymer A and EVA resin (Formosa Plastics EVA7760) according to a mass ratio of 11:89, and granulate at a temperature of 85 °C through a twin-screw extruder to produce isocyanate polyolefin prepolymer EVA masterbatch A with a concentration of 11%. Figure 3 The infrared spectrum of isocyanate polyolefin prepolymer EVA masterbatch A is shown, from which the main absorption peaks of EVA can be seen; in addition, the absorption peak at 1900 - 2300 cm -1 indicates that the isocyanate polyolefin prepolymer has undergone a graft reaction with the EVA resin.

[0070] Film preparation: Weigh 15 parts of isocyanate polyolefin prepolymer EVA masterbatch A, 85 parts of EVA resin (Zhejiang Petrochemical), 0.47 part of tert-butyl peroxycarbonate-2-ethylhexyl ester, 0.58 part of triallyl isocyanurate, 0.32 part of vinyltriethoxysilane, 0.41 part of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 0.43 part of distearyl thiodipropionate, place them in a mixing kettle for stirring and mixing until the particle surface is dry. Extrude the mixed material into a film using a single-screw extruder, and obtain a rolled encapsulation film through embossing, traction, and winding. The film thickness is 0.42 mm. Among them, the above parts are all parts by weight.

[0071] Fabrication of solar cell module: Stack in the order of the first glass plate 24 (photovoltaic glass), rear encapsulation adhesive film 23, cell array 22, front encapsulation adhesive film 21, and the second glass plate (photovoltaic glass), and then laminate using a vacuum laminator at a lamination temperature of 148 °C and a lamination time of 18 minutes. After cooling, perform edge sealing to obtain the solar cell module.

[0072] Example 2

[0073]

[0074] Preparation of polymer (isocyanate polyolefin prepolymer): Add 200 g of methyl ethyl ketone (solvent), 0.28 g of stannous octoate, and 100 g of hydroxyl-terminated nitrile liquid rubber with a number average molecular weight of about 5000 g / mol and a hydroxyl value of about 0.45 mmol / g to the reactor, stir and mix well, then add 7.7 g of 2-isocyanatoethyl methacrylate, degas under vacuum, then ultrasonically vibrate for 30 min, raise the temperature to 70 °C, keep warm and stir for 2 h, and remove the solvent under vacuum to obtain isocyanate polyolefin prepolymer B with a number average molecular weight of about 5180 g / mol and a viscosity (40 °C) of about 180 Pa•s.

[0075] Masterbatch preparation: Mix isocyanate polyolefin prepolymer B and EVA resin (Formosa Plastics EVA7760) in a mass ratio of 11:89, and granulate at a temperature of 85 °C using a twin-screw extruder to produce an isocyanate polyolefin prepolymer EVA masterbatch B with a concentration of 11%.

[0076] Adhesive film preparation: Weigh 15 parts of isocyanate polyolefin prepolymer EVA masterbatch B, 85 parts of EVA resin (Formosa Plastics EVA7760), 0.47 part of tert-amyl peroxy 2-ethylhexyl carbonate, 0.58 part of triallyl cyanurate, 0.39 part of 3-mercaptopropyltrimethoxysilane, 0.41 part of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 0.43 part of distearyl thiodipropionate, place them in a mixing kettle and stir and mix until the particle surface is dry. Extrude the mixed material into a film using a single-screw extruder, and obtain a rolled encapsulation adhesive film through embossing, traction, and winding. The film thickness is 0.42 mm. Among them, the above parts are all parts by weight.

[0077] The subsequent fabrication process of the solar cell module is the same as that in Example 1.

[0078] Example 3

[0079]

[0080] Preparation of polymer (isocyanate polyolefin prepolymer): Add 200 g of methyl ethyl ketone (solvent), 0.28 g of stannous octoate, 0.98 g of maleic anhydride, and 100 g of epoxidized hydroxyl-terminated polybutadiene liquid rubber with a number average molecular weight of about 1500 g / mol into the reactor. Stir well to mix, then add 7.3 g of allyl isothiocyanate, degas under vacuum, then ultrasonically vibrate for 30 min, heat up to 70 °C, keep warm and stir to react for 2 h, and remove the solvent under vacuum to obtain isocyanate polyolefin prepolymer C with a number average molecular weight of about 1600 g / mol and a viscosity (at 40 °C) of about 12 Pa•s.

[0081] Preparation of masterbatch: Mix isocyanate polyolefin prepolymer C and EVA resin (Sirbon Petrochemical) according to a mass ratio of 11:89, and granulate at a temperature of 85 °C through a twin-screw extruder to produce isocyanate polyolefin prepolymer EVA masterbatch C with a concentration of 11%.

[0082] Preparation of adhesive film: Weigh 15 parts of isocyanate polyolefin prepolymer EVA masterbatch C, 85 parts of EVA resin (Zhejiang Petrochemical), 0.47 part of tert-butyl peroxycarbonate-2-ethylhexyl ester, 0.58 part of trimethylolpropane trimethacrylate, 0.32 part of 3-(methacryloyloxy)propyltrimethoxysilane, 0.41 part of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 0.43 part of distearyl thiodipropionate, place them in a mixing kettle for stirring and mixing until the particle surface is dry. Extrude the mixed material into a film using a single-screw extruder, and obtain a rolled encapsulation adhesive film through embossing, traction, and winding. The film thickness is 0.42 mm. Among them, the above parts are all parts by weight.

[0083] The subsequent production process of the solar cell module is the same as that in Example 1.

[0084] Example 4

[0085] Preparation of polymer (isocyanate polyolefin prepolymer): Add 200 g of acetonitrile (solvent) and 0.8 g of dicyandiamide into the reactor, stir well to mix, then add 100 g of epoxy-terminated polybutadiene liquid rubber with a number average molecular weight of about 6000 g / mol and 5.2 g of isobutyl isothiocyanate, degas under vacuum, then ultrasonically vibrate for 30 min, heat up to 75 °C, keep warm and stir to react for 4 h, and remove the solvent under vacuum to obtain isocyanate polyolefin prepolymer D with a number average molecular weight of about 6170 g / mol and a viscosity (at 40 °C) of about 300 Pa•s.

[0086] Masterbatch preparation: Mix the isocyanate polyolefin prepolymers D and EVA resin (Formosa Plastics EVA7760) in a mass ratio of 11:89, and granulate them through a twin-screw extruder at a temperature of 85 °C to produce an isocyanate polyolefin prepolymer EVA masterbatch D with a concentration of 11%.

[0087] Adhesive film preparation: Weigh 15 parts of isocyanate polyolefin prepolymer EVA masterbatch D, 85 parts of EVA resin (Formosa Plastics EVA7760), 0.47 parts of tert-butyl peroxycarbonate-2-ethylhexyl ester, 0.58 parts of ethoxylated trimethylolpropane triacrylate, 0.32 parts of 3-mercaptopropyltrimethoxysilane, 0.41 parts of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 0.43 parts of distearyl thiodipropionate. Place them in a mixing kettle and stir to mix until the particle surface is dry. Extrude the mixed material into a film using a single-screw extruder, and obtain a rolled encapsulation adhesive film through embossing, traction, and winding. The film thickness is 0.42 mm. Among them, the above parts are all parts by weight.

[0088] The subsequent production process of the solar cell module is the same as that in Example 1.

[0089] Example 5

[0090] Polymer (isocyanate polyolefin prepolymer) preparation: Add 200 g of methyl ethyl ketone (solvent) and 0.18 g of dibutyltin dilaurate to the reactor, stir and mix well, then add 100 g of carboxyl-terminated liquid nitrile rubber with a number-average molecular weight of about 18000 g / mol and a hydroxyl value of about 0.25 mmol / g, 0.95 g of allyl isocyanate, degas under vacuum, then ultrasonically vibrate for 30 min, heat up to 65 °C, keep warm and stir for 2 h, and remove the solvent under vacuum to obtain a viscous solid isocyanate polyolefin prepolymer E with a number-average molecular weight of about 18100 g / mol and a viscosity (40 °C) of about 4200 Pa•s.

[0091] Masterbatch preparation: Mix the isocyanate polyolefin prepolymer E and EVA resin (Zhejiang Petrochemical) in a mass ratio of 11:89, and granulate them through a twin-screw extruder at a temperature of 85 °C to produce an isocyanate polyolefin prepolymer EVA masterbatch E with a concentration of 11%.

[0092] Production of the adhesive film: Weigh 15 parts of isocyanate polyolefin prepolymer EVA masterbatch E, 85 parts of EVA resin (Sirbon Petrochemical), 0.47 parts of tert-butyl peroxycarbonate-2-ethylhexyl ester, 0.58 parts of ethoxylated trimethylolpropane triacrylate, 0.32 parts of 3-(methacryloyloxy)propyltrimethoxysilane, 0.41 parts of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 0.43 parts of distearyl thiodipropionate. Place them in a mixing kettle and stir to mix until the surface of the particles is dry. Extrude the mixed material into a film using a single-screw extruder, and obtain a rolled encapsulation adhesive film through embossing, traction, and winding. The film thickness is 0.42 mm. Among them, the above parts are all parts by weight.

[0093] The subsequent production process of the solar cell module is the same as that in Example 1.

[0094] Table 2 Components added during the preparation of isocyanate polyolefin prepolymer in Examples 1-5

[0095]

[0096] Comparative Example 1

[0097] The difference from Example 1 is only that: during the production of the masterbatch, the isocyanate polyolefin prepolymer is not contained, but Taizhou Plastics EVA7760 is used instead.

[0098] Comparative Example 2

[0099] The difference from Example 1 is only that: during the production of the masterbatch, the isocyanate polyolefin prepolymer is not contained, but Dow POE8660 is used instead. During the production of the adhesive film, EVA7760 is also replaced by Dow POE8660.

[0100] Comparative Example 3

[0101] The difference from Example 1 is only that: the number-average molecular weight of the isocyanate polyolefin prepolymer is 500 g / mol, and the viscosity is 5 Pa•s.

[0102] Comparative Example 4

[0103] The difference from Example 1 is only that: the number-average molecular weight of the isocyanate polyolefin prepolymer is 48000 g / mol, and the viscosity is 8000 Pa•s.

[0104] Performance test:

[0105] Water vapor transmission rate test: After casting, the adhesive film is hot-pressed at 150 °C for 18 minutes to obtain a laminated adhesive film sample. Refer to the test method provided in "GB / T 26253-2010" to test the water vapor transmission rate, with the unit g / (m2 • day)

[0106] Adhesion test with glass: Prepare test specimens according to the standard of 《GB / T29848-2018》. The test specimens are subjected to DH aging test (Damp heat, temperature is 85°C, humidity is 85%RH), taken out after 3000 hours, and the peel strength test is carried out according to the standard of 《GB / T2790-1995》, with the unit of N / cm.

[0107] Coefficient of static friction test: The cast film is hot-pressed at 150°C for 18 minutes to obtain a laminated film sample, and the coefficient of static friction is tested with reference to the test method provided by 《GB / T 10006-2021》. The test results are shown in Table 3 below.

[0108] Table 3 Test Results

[0109]

[0110] In the above tests, in Comparative Example 1, no isocyanate polyolefin prepolymer was added as a blank control group; in Example 1, an isocyanate hydroxyl-terminated polybutadiene prepolymer was used, in Example 2, an isocyanate terminal hydroxyl nitrile liquid rubber prepolymer was used, in Example 3, an isocyanate epoxidized terminal hydroxyl polybutadiene liquid rubber prepolymer was used, in Example 4, an isocyanate terminal epoxy group polybutadiene liquid rubber prepolymer was used, and in Example 5, an isocyanate terminal carboxyl liquid nitrile rubber prepolymer was used.

[0111] The test results well reflect the advantages of the isocyanate polyolefin prepolymer. Compared with Comparative Examples 1-4, the water vapor transmission rate of Examples 1-5 has been reduced to varying degrees, and the adhesion to glass has been improved to a certain extent. Among them, the strongly polar isocyanate terminal hydroxyl nitrile liquid rubber prepolymer in Example 2 shows the lowest water vapor transmission rate, and the isocyanate epoxidized terminal hydroxyl polybutadiene liquid rubber prepolymer in Example 3 shows the best adhesion to glass. The coefficient of static friction of the films in Comparative Examples 1-4 is generally low, indicating that the films modified without isocyanate polyolefin prepolymer have low polarity, poor compatibility with polar additives, and are prone to additive precipitation, resulting in film slippage.

[0112] Those skilled in the art can draw on the content of this article and appropriately modify the process parameters to achieve. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they all fall within the scope of protection of the present invention. The methods and applications of the present invention have been described through preferred embodiments, and those skilled in the art can obviously make changes or appropriate alterations and combinations to the methods and applications in this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

Claims

1. An isocyanate polyolefin prepolymer, characterized in that, The number-average molecular weight of the isocyanate polyolefin prepolymer is 550 to 20,000 g / mol, and its viscosity at 40 °C is 10 to 5000 Pa·s. It contains unsaturated side groups and unsaturated end groups chemically bonded to the carbon chain; The isocyanate polyolefin prepolymer is obtained by the prepolymerization reaction of an isocyanate compound containing unsaturated olefin units and a low-molecular-weight olefin polymer under the action of a catalyst. The number-average molecular weight of the low-molecular-weight olefin polymer is 500 to 20,000 g / mol, and the olefin polymer contains one or more of hydroxyl, carboxyl, primary amino, secondary amino, aldehyde, carbonyl, and epoxy groups; The isocyanate compound of the unsaturated olefin unit is selected from any one or a combination of at least two of the compounds shown in Formula I and the compounds shown in Formula II: Among them, R1 is selected from C2-C6 straight-chain or branched alkenyl, R2 is selected from C1-C6 straight-chain or branched alkyl, R3 is selected from C2-C6 straight-chain or branched alkenyl, and X is selected from oxygen atoms.

2. The isocyanate polyolefin prepolymer according to claim 1, wherein The molar quantity of the unsaturated side groups and the unsaturated end groups accounts for 2.5% to 99.5% of the total number of carbon-carbon bonds of the isocyanate polyolefin prepolymer.

3. The isocyanate polyolefin prepolymer according to claim 1 or 2, characterized in that The olefin polymer is polybutadiene, or polyisoprene, or a copolymer of isoprene and styrene, or a copolymer of ethylene and vinyl acetate, or a copolymer of ethylene and acrylonitrile, or a copolymer of ethylene and propylene, or a terpolymer of ethylene, propylene and ethylidene norbornene, or a copolymer of ethylene, propylene and 1,4-hexadiene, or a copolymer of propylene and isoprene.

4. The isocyanate polyolefin prepolymer according to claim 1 or 2, characterized in that, The catalyst used in the preparation process of the isocyanate polyolefin prepolymer includes a first catalyst and / or a second catalyst; the first catalyst is a metal catalyst, and the metal catalyst is selected from any one or a combination of at least two of dibutyltin dilaurate, dimethyltin diacetate, dibutyltin diacetate, monobutyltin triisooctoate, stannous octoate and stannous oxalate; the second catalyst is an electron-donating organic catalyst, and the electron-donating organic catalyst is selected from any one or a combination of at least two of straight-chain aliphatic amines, cycloaliphatic amines, polythiols, and acid anhydride compounds.

5. A method for preparing an isocyanate polyolefin prepolymer according to any one of claims 1-4, comprising: Prepolymerizing an isocyanate compound containing unsaturated olefin units and an olefin polymer under the action of a catalyst, and the reaction temperature is 40 to 150 °C; The reaction time is 0.5 to 10 h.

6. The preparation method according to claim 5, characterized in that, A solvent is used in the prepolymerization reaction, and the solvent is removed under vacuum after the reaction.

7. A resin composition, characterized in that, The resin composition is a mixture of the isocyanate polyolefin prepolymer according to any one of claims 1 to 4, a vinyl polymer, an initiator, a crosslinking agent and a compatibilizer.

8. The resin composition according to claim 7, wherein, The vinyl polymer is polyethylene, or a copolymer of ethylene and 1-butene, or a copolymer of ethylene and 1-octene, or a copolymer of ethylene and one or more of vinyl acetate, acrylic acid, maleic anhydride, and glycidyl methacrylate; the isocyanate polyolefin prepolymer is 0.05% to 18% of the total mass of the resin composition; the initiator is 0.01% to 6% of the total mass of the resin composition, and the crosslinking agent is 0.01% to 6% of the total mass of the resin composition.

9. An encapsulation adhesive film, characterized in that, The encapsulation film is a single-layer structure or a multi-layer structure, and the material of at least one layer in the encapsulation film includes the resin composition described in claim 7 or 8.

10. The encapsulation adhesive film according to claim 9, wherein, The encapsulation film is a film-like material formed by melting and mixing the resin composition, extruding it through an extruder, and calendering and embossing.

11. The encapsulation adhesive film according to claim 10, wherein, The encapsulation film is a three-layer structure, including a first film layer, a second film layer, and a third film layer stacked in sequence, wherein the materials of the first film layer and the third film layer contain the resin composition; alternatively, the materials of the first film layer, the second film layer, and the third film layer all contain the resin composition; Or the encapsulation film is a two-layer structure, and the material of at least one layer in the two-layer structure includes the resin composition.

12. A solar cell module, characterized in that, The solar cell module includes an organic backplane (25) or a first glass plate (24), a rear encapsulation film (23), a cell array (22), a front encapsulation film (21), and a second glass plate (20) stacked in sequence, wherein the front encapsulation film (21) and / or the rear encapsulation film (23) adopts the encapsulation film described in any one of claims 9-11.

13. An application of the isocyanate polyolefin prepolymer described in any one of claims 1-4 or the resin composition described in claim 7 or 8 in improving the performance of a photovoltaic cell encapsulation film, including improving the polarity of the vinyl resin in the photovoltaic cell encapsulation film, enhancing the wettability of the photovoltaic cell encapsulation film with the cell array and the surface of the photovoltaic encapsulation glass, and enhancing the water vapor barrier performance of the photovoltaic cell encapsulation film.

14. The application according to claim 13, wherein The vinyl resin is a POE resin or an EVA resin.

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