Ethylene / α-olefin copolymer and its use for solar cell encapsulation adhesive films

Abstract

The present invention provides an ethylene / α-olefin copolymer for solar cell encapsulation adhesive films and its use. When the ethylene / α-olefin copolymer according to the present invention is used in a solar cell encapsulation adhesive film, it is possible to achieve both a relatively fast vulcanization reaction rate and excellent PID prevention performance for the solar cell encapsulation adhesive film. The ethylene / α-olefin copolymer for solar cell encapsulation adhesive films satisfies the following conditions (a) to (c): (a) a characteristic relaxation time at 190°C of 200.0 to 500.0 ms under angular frequency conditions of 0.1 to 500 rad / s, (b) a weight-average molecular weight of 20,000 to 200,000 g / mol and a density of 0.850 g / cc to 0.910 g / cc, and (c) a molecular weight distribution of 1.5 to 3.

Description

[Technical Field]

[0001] The present invention relates to the technical field of solar cell encapsulation adhesive films, and more specifically to ethylene / α-olefin copolymers for solar cell encapsulation adhesive films and their use. [Background technology]

[0002] Solar power is one of the most competitive forms of new energy and is expected to expand rapidly in the future. Although ethylene vinyl acetate (EVA) and ethylene / alpha-olefin copolymer (POE), which are the encapsulating adhesive film materials used in solar power generation, account for only about 7% of the total cost of solar power generation modules, they are important factors that affect the quality and lifespan of solar power generation module products. When yellowing or cracking begins to occur in the adhesive film or back panel of a battery module, the battery is more likely to be discarded prematurely. Solar power generation modules operate and are used for long periods in high-voltage environments, and wet leakage current paths are likely to occur between the encapsulating material, back panel, glass, and frame. A large amount of charge accumulates on the surface of the battery cells, the battery surface becomes severely deactivated, and as a result the module's performance deteriorates significantly, a phenomenon known as PID (Potential Inertial Degradation).

[0003] Currently, the mainstream methods for achieving PID-preventing adhesive films are (1) using polyolefin elastomer (POE) material with low water permeability instead of EVA material, and (2) adding and compounding PID-preventing additives. However, both of the above methods have drawbacks, and there is still room for improvement in the inherent PID-preventing performance of POE adhesive films. The addition of inorganic additives affects the optical properties of the adhesive film and leads to an increase in the haze of the adhesive film. Chinese Patent Application Publication No. 112898920, Chinese Patent Application Publication No. 113234402, and Chinese Patent No. 113122164 achieve the objective of PID prevention in adhesive films by adding inorganic and organic small molecule additives, but the addition of additives is always accompanied by the problem of additive precipitation, which affects the long-term usability of the sealing adhesive film. Chinese Patent Application Publication No. 112824466 describes how adding a crosslinking agent to the formulation of a photovoltaic adhesive film increases the crosslinking density of the crosslinked encapsulating adhesive film, improving its barrier ability against metal ions and thereby achieving a PID prevention effect. However, this is still an improvement to the formulation system and does not lead to an improvement to the encapsulating material itself.

[0004] Another important point is that, based on the needs of downstream adhesive film processing, how to accelerate the vulcanization rate of photovoltaic adhesive films, shorten the processing time for lamination and crosslinking reactions, and further reduce costs and improve efficiency is an urgent issue that the industry must address. Existing solutions for accelerating the vulcanization rate of POE photovoltaic adhesive films mainly involve modifying POE particles by means of formulation optimization or silane grafting. Chinese Patent Application Publication No. 116023891 describes grafting silane monomers onto POE polymer chains by chemical grafting to form a high molecular weight tackifier, thereby contributing to the degree of crosslinking for curing of the adhesive film by silane crosslinking, accelerating the crosslinking rate of the adhesive film and shortening the curing cycle. Chinese Patent Application Publication No. 115873528 describes accelerating the crosslinking rate and improving the production efficiency of modules by optimizing the crosslinking formulation of the adhesive film. Chinese Patent Application Publication No. 116004126 describes how to improve crosslinking properties by changing the number of layers and structure of the sealing adhesive film, thereby comprehensively enhancing the sealing effect of using POE in modules. Overall, there are few reports or applications of accelerating the crosslinking vulcanization rate and improving PID prevention performance of photovoltaic adhesive films, starting from pure POE particles.

[0005] Given this background, it is extremely important to provide a solution that can achieve both a faster vulcanization reaction rate and superior PID prevention performance without upgrading the formulation of the solar cell encapsulation adhesive film. [Overview of the project]

[0006] This invention provides an ethylene / α-olefin copolymer for solar cell encapsulation adhesive films and its use. When the ethylene / α-olefin copolymer according to the present invention is used in solar cell encapsulation adhesive films, it is possible to achieve both a faster vulcanization reaction rate and excellent PID prevention performance in the solar cell encapsulation adhesive film.

[0007] To achieve its objective, the present invention provides the following technical solutions.

[0008] In a first aspect of the present invention, an ethylene / α-olefin copolymer for a solar cell encapsulation adhesive film, wherein the copolymer is (a) Under conditions of angular frequency of 0.1 to 500 rad / s, the characteristic relaxation time at 190°C is 200.0 to 500.0 ms. (b) The weight-average molecular weight is 20,000 to 200,000 g / mol, and the density is 0.850 g / cc to 0.910 g / cc. (c) The present invention provides an ethylene / α-olefin copolymer for solar cell encapsulation adhesive films that satisfies conditions (a) to (c), wherein the molecular weight distribution is 1.5 to 3.

[0009] Preferably, the characteristic relaxation time is 350.0 to 500.0 ms, more preferably 400 to 500 ms.

[0010] Furthermore, the melt index of the copolymer under the conditions of 190°C and a 2.16 kg load is 1 g / 10 min to 50 g / 10 min.

[0011] In some embodiments, the weight-average molecular weight is 40,000 to 100,000 g / mol.

[0012] In some embodiments, the α-olefin comprises one or more of the following: propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicosene.

[0013] A second aspect of the present invention provides a method for preparing an ethylene / α-olefin copolymer for the above-mentioned solar cell encapsulation adhesive film, wherein the preparation method is: Step (S1) involves polymerizing ethylene and α-olefin to obtain a copolymer product, The step (S2) involves post-treating the copolymer product to separate an ethylene / α-olefin copolymer that simultaneously satisfies conditions (a) to (c), (a) Under conditions of an angular frequency of 0.1 to 500 rad / s, the characteristic relaxation time at 190°C is 200.0 to 500.0 ms, preferably 350.0 to 500.0 ms, more preferably 400 to 500 ms. (b) The weight-average molecular weight is 20,000 to 200,000 g / mol, and the density is 0.850 g / cc to 0.910 g / cc. (c) The molecular weight distribution is 1.5 to 3.

[0014] A third aspect of the present invention provides a solar cell encapsulation adhesive film composition comprising the above-described ethylene / α-olefin copolymer or the ethylene / α-olefin copolymer prepared by the above-described preparation method.

[0015] Furthermore, the composition further comprises one or more of the following: a crosslinking agent, a co-crosslinking agent, a coupling agent, and an antioxidant.

[0016] A fourth aspect of the present invention provides a solar cell encapsulation adhesive film, the encapsulation adhesive film being prepared using the above-mentioned composition.

[0017] A fifth aspect of the present invention provides a method for manufacturing a solar cell encapsulating adhesive film, which includes the steps of mixing and melting the components in the composition, extruding and casting to form a film, and then cooling and slitting.

[0018] A sixth aspect of the present invention provides a solar cell module including the solar cell encapsulation adhesive film. [Effects of the Invention]

[0019] The technical solution according to the present invention has the following beneficial effects.

[0020] The ethylene / α-olefin copolymer for a solar cell encapsulation adhesive film according to the present invention simultaneously satisfies the above conditions (a) to (c) and has a relatively long characteristic relaxation time. With this copolymer, the solar cell encapsulation adhesive film can achieve both a relatively fast vulcanization reaction rate and excellent PID prevention performance.

Embodiments for Carrying out the Invention

[0021] For the ease of understanding the present invention, the following further describes the present invention with reference to examples. It should be understood that the examples described below are for facilitating the understanding of the present invention and are not intended to limit the present invention to the following embodiments.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention pertains. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0023] Where specific experimental steps or conditions are not specified in the examples, they may be carried out based on the operations or conditions of the corresponding normal experimental steps in the technical field. The reagents or equipment used are not specified by the manufacturer, and all are common commercially available products.

[0024] The ethylene / α-olefin copolymer for a solar cell encapsulation adhesive film according to the present invention is (a) Under the condition of an angular frequency of 0.1 to 500 rad / s, the characteristic relaxation time at 190°C is 200.0 to 500.0 ms, (b) The weight average molecular weight is 20,000 to 200,000 g / mol, and the density is 0.850 g / cc to 0.910 g / cc, (c) The molecular weight distribution is 1.5 to 3, and simultaneously satisfies the conditions (a) to (c) as described above.

[0025] The ethylene / α-olefin copolymer for solar cell encapsulation adhesive films of the present invention has the following characteristic (a): Under conditions of an angular frequency of 0.1 to 500 rad / s, the characteristic relaxation time at 190°C is 200.0 ms or more and 500.0 ms or less, for example, 200.0 ms, 250.0 ms, 300.0 ms, 350.0 ms, 400.0 ms, 450.0 ms, 500.0 ms, etc. Preferably, the characteristic relaxation time is 350.0 to 500.0 ms, more preferably 400 to 500 ms.

[0026] The ethylene / α-olefin copolymer for solar cell encapsulation adhesive films of the present invention has the above-mentioned characteristic relaxation time, as well as the following characteristics (b) and (c): (b) a weight-average molecular weight of 20,000 to 200,000 g / mol and a density of 0.850 g / cc to 0.910 g / cc, and (c) a molecular weight distribution of 1.5 to 3.

[0027] By using an ethylene / α-olefin copolymer that simultaneously possesses the above characteristics (a) to (c), it is possible to manufacture a solar cell encapsulation adhesive film that achieves both a relatively short vulcanization reaction time and excellent PID prevention performance.

[0028] In the ethylene / α-olefin copolymer for solar cell encapsulation adhesive films according to the present invention, the weight-average molecular weight (M w ) are 20,000 to 200,000 g / mol, for example, 40,000 to 100,000 g / mol, for example, 40,000 to 90,000 g / mol, and further, for example, 45,000 to 75,000 g / mol.

[0029] The ethylene / α-olefin copolymer for solar cell encapsulation adhesive films according to the present invention has a density of 0.850 g / cc to 0.910 g / cc, for example, 0.850 g / cc, 0.860 g / cc, 0.870 g / cc, 0.880 g / cc, 0.890 g / cc, 0.900 g / cc, 0.905 g / cc, 0.910 g / cc, etc.

[0030] In the ethylene / α-olefin copolymer for solar cell encapsulation adhesive films according to the present invention, the molecular weight distribution (PDI) is 1.5 to 3, for example, 1.5, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, and further, for example, 2.1 to 2.8.

[0031] Furthermore, in the ethylene / α-olefin copolymer for solar cell encapsulation adhesive film according to the present invention, the melt index (MI) under load conditions of 190°C and 2.16 kg may be 1 g / 10 min to 50 g / 10 min, for example 1 g / 10 min, 2 g / 10 min, 3 g / 10 min, 5 g / 10 min, 10 g / 10 min, 15 g / 10 min, 17 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 40 g / 10 min, 45 g / 10 min, 50 g / 10 min, for example 2 g / 10 min to 40 g / 10 min, for example 2 g / 10 min to 20 g / 10 min, and even for example 3 g / 10 min to 17 g / 10 min.

[0032] The ethylene / α-olefin copolymer of the present invention may be a random or block polymer, where α-olefin is derived from α-olefin as a copolymer monomer, and α-olefin may include one or more of the following: propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicosene.

[0033] Characteristic relaxation time refers to the time it takes for a polymer to recover its stress equilibrium state after being subjected to a certain deformation. Characteristic relaxation time is related to the entanglement structure of the polymer chains. When a polymer has long chain branches, the degree of chain entanglement increases as the branched chain structure increases, thereby lengthening the polymer's characteristic relaxation time. Furthermore, the increased degree of chain entanglement increases the free volume of the polymer chains, solvation of this portion of the polymer occurs more easily in the solvent, improving solubility and thus providing separation capabilities in actual production applications. That is, polymers with the desired characteristics can be obtained by dissolution-precipitation-separation methods.

[0034] The present invention also provides a method for preparing an ethylene / α-olefin copolymer for the aforementioned solar cell encapsulation adhesive film, the ethylene / α-olefin copolymer according to the present invention can be prepared by a preparation method comprising the steps of polymerizing ethylene and α-olefin to obtain an ethylene / α-olefin copolymer product (S1), and post-treating the copolymer product to separate an ethylene / α-olefin copolymer that simultaneously satisfies conditions (a) to (c) (S2).

[0035] (a) Under conditions of an angular frequency of 0.1 to 500 rad / s, the characteristic relaxation time at 190°C is 200.0 to 500.0 ms, preferably 350.0 to 500.0 ms, more preferably 400 to 500 ms. (b) The weight-average molecular weight is 20,000 to 200,000 g / mol, and the density is 0.850 g / cc to 0.910 g / cc. (c) The molecular weight distribution is 1.5 to 3.

[0036] In some embodiments, in step (S2), the post-treatment of the copolymer product is, specifically, The process includes first dissolving the prepared copolymer product in a first good solvent, then adding the resulting solution to a first poor solvent to precipitate and separate it to obtain a first liquid phase, and removing the solvent from the first liquid phase to obtain the desired product (S2a). Furthermore, the process may include dissolving the precipitate separated by precipitation in step (S2a) in a second good solvent, then adding the resulting solution to a second poor solvent to precipitate and separate it to obtain a second liquid phase, and removing the solvent from the second liquid phase to obtain the desired product (S2b).

[0037] Step (S1): Step (S1) is a step of polymerizing ethylene and α-olefin to prepare an ethylene / α-olefin copolymer product.

[0038] In step (S1), solution polymerization may be employed, and as a reference example, step (S1) may include, for example, the following steps: In a reactor, an organic solvent and α-olefin are introduced into the reactor by solution polymerization, a main catalyst and a co-catalyst are added to the reactor at a desired reaction temperature, and ethylene gas is introduced into the reactor to cause the reaction to obtain a reactant solution. Here, by adding the polymerization monomers (α-olefin and / or ethylene) in one or multiple stages, indicator parameters of the polymer, such as weight-average molecular weight, molecular weight distribution, and the α-olefin content in the copolymer, can be controlled. The solvent is removed from the obtained reactant solution to obtain an ethylene / α-olefin copolymer product. The reactor used here may be a ring reactor, isothermal reactor, stirred tank reactor, batch reactor, circulating tubular reactor, or any other reactor commonly used in this art. The reactor may include one or more types of reactors in parallel, series, and / or any other combination of configurations. The reaction can be carried out in a continuous or batch manner.

[0039] Furthermore, the organic solvent used in the polymerization reaction in step (S1) may be one or more of aliphatic solvents and aromatic solvents. Preferably, the aliphatic solvent is one or more selected from n-butane, isobutane, n-pentane, cyclopentane, n-hexane, cyclohexane, n-heptane, n-octane, n-nonane and their alkylated compounds. Preferably, the aromatic solvent is one or more selected from benzene, toluene, xylene and their halogenated compounds, of which the halogenated compound may be a monohalogenated compound or a polyhalogenated compound.

[0040] Furthermore, the main catalyst used in the polymerization reaction in step (S1) is preferably one or more of metallocene catalysts and post-metallocene catalysts, and is preferably one or more of (tert-butylamide)dimethyl(tetramethyl-η5-cyclopentadienyl)silanthinium dichloride, bis(methylcyclopentadienyl)zirconium dichloride, bis(1,3-dimethylcyclopentadienyl)zirconium dichloride, cyclopentadienyl-(1,2-dimethoxyethane)zirconium trichloride, and (dimethylsilylene)bis(2-methyl-4-phenylindenyl)zirconium dichloride. Those skilled in the art can determine the specific amount of main catalyst used depending on the requirements of the reaction. For example, in some embodiments, the amount of main catalyst used may be 1 to 20 μmol / L relative to the amount of reaction system solvent used.

[0041] Furthermore, the co-catalyst used in the polymerization reaction in step (S1) is preferably at least one of alkylaluminum, organoboron compounds, and alkylaluminoxanes, and preferably one or more of methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, trimethylaluminum, triethylaluminum, triisobutylaluminum, and tris(pentafluorophenyl)borane compounds. Here, the molar ratio of aluminum in the co-catalyst to the metal atoms of the main catalyst may be 1 to 1000:1, and the molar ratio of boron in the co-catalyst to the metal atoms of the main catalyst may be 0 to 5:1.

[0042] Furthermore, in step (S1), the reaction temperature is, for example, 100-210°C, or for example, 120-210°C, and the reaction pressure is, for example, 20-100 bar.

[0043] Steps (S2a) and (S2b): Steps (S2a) and (S2b) are steps to post-treat the ethylene / α-olefin copolymer product obtained in step (S1) to prepare an ethylene / α-olefin copolymer for solar cell encapsulation adhesive film according to the present invention.

[0044] In step (S2a), the first good solvent used refers to a solvent capable of completely dissolving the copolymer product in step (S1). In step (S2b), the second good solvent used refers to a solvent capable of completely dissolving the precipitate obtained in step (S2a). Specifically, the first good solvent and the second good solvent may each be one or more of an aliphatic solvent and an aromatic solvent. Preferably, the aliphatic solvent is one or more selected from n-butane, isobutane, n-pentane, cyclopentane, n-hexane, cyclohexane, n-heptane, n-octane, n-nonane, and alkylated compounds thereof. Preferably, the aromatic solvent is one or more selected from benzene, toluene, xylene, and halogenated compounds thereof, of which the halogenated compound may be a monohalogenated compound or a polyhalogenated compound. The dissolution operation with the first or second good solvent may be carried out under conditions of 60 to 140°C, and the dissolution operation may be carried out with stirring. When dissolved in a first good solvent, the mass ratio of copolymer product to solvent used is, for example, 1:3 to 1:8, and when dissolved in a second good solvent, the mass ratio of the aforementioned precipitate to solvent used is, for example, 1:3 to 1:8.

[0045] In step (S2a), the first poor solvent used may be an alcohol having 2 to 20 carbon atoms. Preferably, it is one or a mixture of several of the following: ethanol, ethylene glycol, n-propanol, glycerol, n-butanol, neopentyl alcohol, 1,6-hexanediol, n-octanol, n-decanol, dodecanol, tetradecanol, and hexadecanol. The amount of the first poor solvent used may be 1 to 5 times the mass of the first good solvent in which the polymer is completely dissolved. As for the conditions for precipitation and separation with the first poor solvent, for example, at room temperature or 18 to 22°C, the first poor solvent is gradually added to the solution of the first good solvent in which the polymer is completely dissolved while continuously stirring (at a rotation speed of, for example, 200 to 400 rpm) until no more polymer precipitate precipitates from the solution. After that, the polymer precipitate in the solution is filtered and separated, and then the solvent is removed from the solution by evaporation to obtain the ethylene / α-olefin copolymer for solar cell encapsulation adhesive film according to the present invention.

[0046] In step (S2b), the second poor solvent used may be a mixed solution of an alcoholic solvent and a ketoneic solvent. Here, the alcoholic solvent may be an alcohol having 2 to 20 carbon atoms, and is preferably one or more of the following: ethanol, ethylene glycol, n-propanol, glycerol, n-butanol, neopentyl alcohol, 1,6-hexanediol, n-octanol, n-decanol, dodecanol, tetradecanol, and hexadecanol. The ketone solvent may preferably be one or a mixture of several of the following: dimethyl ketone, diethyl ketone, butanone, methyl isobutyl ketone, valerophenone, 3-methyl-2-octanone, methyl nonyl ketone, methylphenylhexanone, bicyclo[3.3.1]nona-3,7-dione, dimethylcyclohexanedione, 2,2,6-trimethyl-1,4-cyclohexanedione, diphenylethanedione, 3-methyl-2,4-nonanedione, 1-phenyl-2,4-pentanedione, and 2,4-decandione. Preferably, the mass ratio of the alcohol solvent to the ketone solvent may be 4 to 10:1. The amount of the second poor solvent used may be 1 to 5 times the mass of the second good solvent in which the polymer is completely dissolved. In step (S2b), under conditions for precipitation separation, the second poor solvent is gradually added to a solution of the second good solvent in which the polymer is completely dissolved, while continuously stirring (at a rotation speed of, for example, 200-400 rpm) at room temperature or 18-22°C, until no more polymer precipitate precipitates from the solution. Next, the polymer precipitate in the solution is filtered and separated, and then the solvent is removed from the solution portion by evaporation to obtain the ethylene / α-olefin copolymer for solar cell encapsulation adhesive film according to the present invention.

[0047] By treating the precipitated portion of step (S2a) with step (S2a) or step (S2b), an ethylene / α-olefin copolymer for solar cell encapsulation adhesive films that satisfies conditions (a) to (c) of the present invention is obtained.

[0048] The present invention also provides a solar cell encapsulation adhesive film composition comprising an ethylene / α-olefin copolymer for the solar cell encapsulation adhesive film or an ethylene / α-olefin copolymer for the solar cell encapsulation adhesive film prepared by the preparation method described above. Specifically, the ethylene / α-olefin copolymer is (a) Under conditions of angular frequency of 0.1 to 500 rad / s, the characteristic relaxation time at 190°C is 200 to 500 ms, preferably 350.0 to 500.0 ms, more preferably 400 to 500 ms. (b) The weight-average molecular weight is 20,000 to 200,000 g / mol, and the density is 0.850 g / cc to 0.910 g / cc. (c) The molecular weight distribution is between 1.5 and 3, and conditions (a) to (c) are satisfied simultaneously.

[0049] The specific details of the ethylene / α-olefin copolymer in the above composition can be found by referring to the corresponding descriptions of the ethylene / α-olefin copolymer for photovoltaic encapsulation adhesive films according to the present invention provided above, and will not be explained again here.

[0050] The above composition employs an ethylene / α-olefin copolymer for solar power generation sealing adhesive films according to the present invention, thereby significantly shortening the vulcanization reaction time and providing the resulting sealing adhesive film with excellent PID prevention performance.

[0051] The solar cell encapsulation adhesive film composition may contain other components conventionally added in this art, specifically, one or more of the following: crosslinking agents, co-crosslinking agents, coupling agents, and antioxidants. Of course, it may also contain other additional components permitted in this art.

[0052] Furthermore, the crosslinking agent may be a peroxide-based crosslinking agent, such as tert-butylperoxyisopropyl carbonate, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-pentylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-pentylperoxy)-3,3,5-trimethylcyclohexane, or 1,1-bis(tert-butylperoxy)hexane. The crosslinking agent may include, but is not limited to, one or more of the following compounds: rt-pentylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)butane, tert-butylperoxy 2-ethylhexyl carbonate, tert-amylperoxy 2-ethylhexyl carbonate, tert-amylperoxy carbonate, and tert-butylperoxy-3,3,5-trimethylhexanoate. Based on 100 parts by weight of ethylene / α-olefin copolymer, the amount of crosslinking agent used may be 0.1 to 5 parts by weight, preferably 0.5 to 2 parts by weight.

[0053] Furthermore, the crosslinking agent may be one or a combination of several polyfunctional acrylate substances, including triallyl isocyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl) isocyanurate triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, ethoxylated glyceryl triacrylate, propoxylated glyceryl triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate The material may contain, but is not limited to, one or more of the following substances: acrylate, ditrimethylolpropanetetraacrylate, ditrimethylolpropanetetramethacrylate, propoxylated pentaerythritol tetraacrylate, tricyclodecanedimethanol diacrylate, propoxylated neopentyl glycol diacrylate, ethoxylated bisphenol A diacrylate, ethoxylated bisphenol A dimethyl acrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, diethylene glycol dimethyl acrylate, triethylene glycol dimethyl acrylate, and polyethylene glycol dimethyl acrylate. Based on 100 parts by weight of ethylene / α-olefin copolymer, the amount of crosslinking agent used may be 0.1 to 5 parts by weight, preferably 0.1 to 2 parts by weight.

[0054] Furthermore, the coupling agent may be a silane-based coupling agent and may include, but is not limited to, one or more combinations of the following compounds: γ-methacryloyloxypropyltrimethoxysilane, γ-chloropropylmethoxysilane, vinylethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-methacryloyloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, 3-(trimethoxysilyl)propyl-2-methyl-2-acrylate, anilinomethyltriethoxysilane, and octyltrimethoxysilane. Based on 100 parts by weight of ethylene / α-olefin copolymer, the amount of the coupling agent used may be 0.1 to 3 parts by weight, preferably 0.1 to 0.6 parts by weight.

[0055] Furthermore, the antioxidant may be a combination of one or more types of hindered phenol antioxidants and phosphate antioxidants, such as n-octadecyl β-[3,5-di-t-butyl-4-hydroxyphenyl]propionate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], bis(3,5-di-tert-butyl-4-hydroxypropionyl)hydrazine, 2,2'-oxamide-bis[ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxyphenylpropionamide), The composition may include, but is not limited to, one or more of the following compounds: 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)trione, triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 4,6-bis(octylthiomethyl)-o-cresol, tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate. Based on 100 parts by weight of ethylene / α-olefin copolymer, the amount of antioxidant used may be 0.01 to 1 part by weight, preferably 0.05 to 0.5 parts by weight.

[0056] In some embodiments, the solar cell encapsulation adhesive film composition further comprises 100 parts by weight of ethylene / α-olefin copolymer, 0.1 to 5 parts by weight, preferably 0.5 to 2 parts by weight of a crosslinking agent; 0.1 to 5 parts by weight, preferably 0.1 to 2 parts by weight of a co-crosslinking agent; 0.1 to 3 parts by weight, preferably 0.1 to 0.6 parts by weight of a coupling agent; and 0.01 to 1 part by weight, preferably 0.05 to 0.5 parts by weight of an antioxidant.

[0057] The present invention also provides a solar cell encapsulation adhesive film, which is manufactured using the aforementioned composition. Specifically, the composition contains an ethylene / α-olefin copolymer for solar cell encapsulation adhesive films according to the present invention, wherein the ethylene / α-olefin copolymer is (a) Under conditions of angular frequency of 0.1 to 500 rad / s, the characteristic relaxation time at 190°C is 200 to 500 ms, preferably 350.0 to 500.0 ms, more preferably 400 to 500 ms. (b) The weight-average molecular weight is 20,000 to 200,000 g / mol, and the density is 0.850 g / cc to 0.910 g / cc. (c) The molecular weight distribution is between 1.5 and 3, and conditions (a) to (c) are satisfied simultaneously.

[0058] The specific details of the composition and the ethylene / α-olefin copolymer can be found in the description above and will not be explained again here.

[0059] The present invention also provides a method for manufacturing the aforementioned solar cell encapsulation adhesive film, comprising the steps of mixing and melting the components of the composition, extruding and casting to form a film, followed by cooling and slitting. Specifically, it may further include a winding step. The specific operation and conditions of the manufacturing method can be carried out in accordance with conventional methods in the art and are not particularly limited.

[0060] The solar cell encapsulation adhesive film manufactured based on the ethylene / α-olefin copolymer for solar cell encapsulation adhesive films of the present invention can achieve both a relatively fast vulcanization reaction rate and excellent PID prevention performance.

[0061] The present invention also provides a solar cell module including the aforementioned solar cell encapsulation adhesive film.

[0062] The inventors have found that ethylene / α-olefin copolymers with a relatively long property relaxation time have a relatively high degree of chain entanglement and, compared to ethylene / α-olefin copolymers with a relatively short property relaxation time, more readily form a three-dimensional network crosslinked structure in the crosslinking reaction. This helps to accelerate the vulcanization crosslinking reaction, shortening the processing time by laminators when applying solar power adhesive films in downstream adhesive film factories, and reducing the time required for the vulcanization crosslinking reaction of polyolefin elastomers in the adhesive film, thereby providing practical benefits to adhesive film factories. Furthermore, as the degree of chain entanglement in the polyolefin elastomer structure increases, the adhesive film becomes more likely to form a denser crosslinked structure, thereby improving the barrier ability of the encapsulating adhesive film against metal ions, reducing the rate at which metal ions migrate to the surface of battery cells, and thus improving the PID prevention performance of the solar power encapsulating adhesive film.

[0063] The ethylene / α-olefin copolymer for photovoltaic encapsulation adhesive films according to the present invention is an ethylene / α-olefin copolymer having a long property relaxation time and simultaneously satisfying conditions (a) to (c). The encapsulation adhesive film containing this copolymer can achieve both a relatively fast vulcanization reaction rate and excellent PID prevention performance, and can be widely used in the electrical and electronics industry.

[0064] The present invention will be described in further detail below with reference to examples. The provided examples are for illustrative purposes only and should not be understood as limiting the scope of the invention.

[0065] The main ingredients are described below. tert-butylperoxy-2-ethylhexyl carbonate, Akzo, purity >95% Triallyl isocyanurate, Acros, 98% purity γ-Methacryloyloxypropyltrimethoxysilane, Aladdin, 95% purity γ-(2,3-epoxypropoxy)propyltrimethoxysilane, Aladdin, 95% purity Bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, Acros, 95% purity n-octadecyl β-[3,5-di-t-butyl-4-hydroxyphenyl]propionic acid, ark, purity 95% 1,1-Bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, Acros, 95% purity tert-amyl peroxycarbonate, ark, 95% purity Trimethylolpropane triacrylate, Aladdin, 98% purity Antioxidant 1076, β-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid n-octadecyl, Lianlong New Materials Co., Ltd., Industrial Grade Antioxidant 1010, Pentaerythritol Tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], Lianlong New Materials Co., Ltd., Industrial Grade 1-Octene, Aladdin, 99% purity 1-Butene, Aladdin, 99% purity 1-Hexene, Aladdin, 99% purity 1-Decene, Aladdin, 99% purity Ethylene, Meikyo Gas Co., Ltd., 99.99% purity Methylaluminoxane, Akzo, 10% wt toluene solution Modified methylaluminoxane (MMAO-3A), Nouryon, 7 wt% toluene solution (Dimethylsilylene)bis(2-methyl-4-phenylindenyl)zirconium dichloride, Jiangsu Xinnuoke Catalysts Co., Ltd., 98% purity. (tert-butylamide)dimethyl(tetramethyl-η5-cyclopentadienyl)silanthitanium dichloride, Suzhou Yuanqi Materials Technology Co., Ltd., purity 98% Bis(methylcyclopentadienyl)zirconium dichloride, Shanghai Mairui Biochemical Technology Co., Ltd., 97% purity. Bis(1,3-dimethylcyclopentadienyl)zirconium dichloride, Baoji Funuokang Industrial Co., Ltd., purity >95% n-Heptane, Aladdin Biochemical Technology Co., Ltd. (Shanghai), purity >99.5% n-Octane, Aladdin Biochemical Technology Co., Ltd. (Shanghai), purity >99.5% Methylphenylhexanone, Jinan Hongli Chemical Industry Co., Ltd., purity>99% Bicyclo[3.3.1]nona-3,7-dione, Zhengzhou Hui Chemical Co., Ltd., purity 98% 3-Methyl-2-Octanone, Shanghai Haohong Biomedical Technology Co., Ltd., Purity >98% 1-Phenyl-2,4-pentanedione, Beijing Gonghe Technology Co., Ltd., Purity >98% Alkane solvent, Tianjin Tairong, industrial grade Ethanol, Tianjin Tairong, Industrial Grade PERC battery, Tongwei 182 double-sided battery

[0066] Equipment, devices, and detection methods: The extruder is a single-screw extruder with a screw diameter of 30 mm (L / D=35). Test equipment for property relaxation time: ARES-G2 rheometer manufactured by TA Corporation. At 190°C, with angular frequencies from 0.1 rad / s to 500 rad / s and a strain of 5%, complex viscosity is obtained from the change in copolymer stress with respect to angular frequency, and the property relaxation time λ is calculated by fitting it using the Carreau-Yasuda equation below. η(γ)=η ∞ +(η0-η ∞ )[1+(λγ) α ] (n-1) / α η(γ): viscosity, unit Pa·s η ∞ Infinite viscosity, unit Pa·s η0: Zero shear viscosity, unit Pa·s λ: Relaxation time, unit s γ: Shear rate, unit: s -1 α: Material constant, a dimensionless parameter representing the viscosity transition from the Newtonian region to the non-Newtonian region. In the case of the Carreau model, α = 2. n: Shear thinning index. PID aging device: Environmental chamber manufactured by Shanghai Zhiwei Co., Ltd., model EW-EC03PID02-021220. PID performance test: Conduct an experiment to obtain the PID prevention performance of the manufactured multi-layer glass solar power generation module under the conditions of 96h - 85°C / 85% RH / -1500V. PID power test device used to test the degradation of PID prevention performance: Manufactured by Nanjing Lixi Co., Ltd., model LXT-CELL. Test of characteristic vulcanization times Ts1, Ts2: Use a rotorless vulcanizer Alpha, MDR to test the characteristic vulcanization times Ts1, Ts2 of the copolymer under the conditions of 145°C and 15 min. Melt index of the copolymer: Measured using a melt index meter (CEAST melt index meter, Italy) according to the national standard GB / T3682.1-2018 method at 190°C and a load of 2.16 kg. Weigh the mass of the extrudate every 6 seconds, perform 5 parallel operations, obtain the average value, convert it to the mass of the extrudate per 10 min, and express it in g / 10 min. Weight average molecular weight (M w ) and molecular weight distribution (PDI) of the copolymer: Measured by high-temperature gel permeation chromatography (GPC, Agilent PL-GPC 220, USA). The dissolution temperature of the sample is 160°C, the mobile phase is 1,2,4-trichlorobenzene containing 500 ppm of BHT (2,6-di-tert-butyl-p-cresol), and the flow rate is 1 mL / min. Universal calibration is performed using monodisperse polystyrene standard substances (M -4 ) with K values of 1.016×10 w and α values of 0.7220 (M -4 are 3.1, 9.6, 27.8, 70.5, 187.7, 729.5, 2189.0, and 3507.0 kg / mol, respectively). The K value and α value of the ethylene / α-olefin copolymer (test sample) are 4.416×10 Copolymer density: Measured using a densimeter (METTLER TOLEDO densimeter) according to ASTM-D792.

[0067] Preparation of ethylene / α-olefin copolymers: Preparation of ethylene-octene copolymer A: In a 2.0 L continuous process reactor, hexane was injected at 4.50 kg / h and 1-octene at 2.91 kg / h, and the reactor temperature was controlled to 150°C. Simultaneously, (dimethylsilylene)bis(2-methyl-4-phenylindenyl)zirconium dichloride (0.35 μmol / min, main catalyst) and a toluene solution of methylaluminoxane at a concentration of 10 wt% (3.5 μmol / min, co-catalyst) were injected into the reactor. Subsequently, ethylene was introduced into the reactor at a rate of 1.38 kg / h, and the reactor was operated continuously under controlled pressure of 60 bar. Once the operation stabilized (system temperature and pressure were stable), the reaction mixture was continuously withdrawn for approximately 2 hours, and the solvent in the reaction mixture was removed by evaporation to obtain the polymerization product. The obtained polymerization product was completely dissolved in n-heptane solvent at 80°C with stirring to obtain a polymer solution. Here, the mass ratio of polymerization product to solvent used was 1:5. Once the temperature had cooled to room temperature, the polymer solution was added dropwise to ethanol with stirring, here, the mass ratio of polymer solution to ethanol was 1:1. A precipitate formed during the dropwise addition. After the addition was complete, the solvent was removed from the liquid phase by evaporation, and the polymer was dried in a vacuum oven at 60°C to a constant weight to obtain ethylene-octene copolymer A. The measured property relaxation time was 492.2 ms.

[0068] Preparation of ethylene-octene copolymer B: The preparation process was carried out with reference to ethylene-octene copolymer A, but with the following differences. The polymer solution was added dropwise to ethanol, and the precipitate obtained was removed. The precipitate was stirred at 80°C and completely dissolved in n-heptane, where the mass ratio of the precipitate to n-heptane was 1:6. Once the temperature had cooled to room temperature, the obtained solution was added dropwise with stirring to a mixed solvent of ethanol and methylphenylhexanone in a mass ratio of 6:1, where the mass ratio of the solution to the mixed solvent was 1:1. After the addition was complete, the solvent was removed from the liquid phase by evaporation, and the copolymer was dried in a vacuum oven at 60°C to a constant weight to obtain ethylene-octene copolymer B. The measured property relaxation time was 210.3 ms.

[0069] Preparation of ethylene-butene copolymer C: In a 2.0 L continuous process reactor, n-octane solvent was injected at 5.0 kg / h and 1-butene at 2.67 kg / h, and the reactor temperature was controlled to 146°C. Simultaneously, (tert-butylamide)dimethyl(tetramethyl-η5-cyclopentadienyl)silanthinium dichloride (0.48 μmol / min, main catalyst) and a toluene solution of methylaluminoxane at a concentration of 10 wt% (48 μmol / min, co-catalyst) were injected into the reactor. Subsequently, ethylene was introduced into the reactor at a rate of 1.55 kg / h, and the reactor was operated continuously under controlled pressure of 40 bar. Once the operation stabilized (system temperature and pressure were stable), the reaction mixture was continuously withdrawn for approximately 2 hours, and the solvent in the reaction mixture was removed by flushing to obtain the polymerization product. The obtained polymerization product was completely dissolved in n-heptane solvent at 100°C with stirring to obtain a polymer solution. Here, the mass ratio of polymerization product to solvent used was 1:5. Once the temperature had cooled to room temperature, the polymer solution was added dropwise to ethanol with stirring, here, the mass ratio of polymer solution to ethanol was 1:1. A precipitate formed during the dropwise addition. After the addition was complete, the solvent was removed from the liquid phase by evaporation, and the polymer was dried in a vacuum oven at 60°C to a constant weight to obtain ethylene-butene copolymer C. The measured property relaxation time was 387.5 ms.

[0070] Preparation of ethylene-butene copolymer D: The preparation process was carried out with reference to ethylene-butene copolymer C, but with the following differences. The polymer solution was added dropwise to ethanol, and the precipitate obtained was removed. The precipitate was completely dissolved in n-heptane with stirring at 120°C, with a mass ratio of 1:5 between the precipitate and the n-heptane. Once the temperature had cooled to room temperature, the resulting solution was added dropwise with stirring to a mixed solvent of ethanol and 3-methyl-2-octanone in a mass ratio of 8:1, with a mass ratio of 1:2 between the solution and the mixed solvent. After the addition was complete, the solvent was removed from the liquid phase, and the copolymer D was dried in a vacuum oven at 60°C to a constant weight. The measured property relaxation time was 240.4 ms.

[0071] Preparation of ethylene-hexene copolymer E: In a 2 L batch reaction vessel, the temperature was raised to 160°C using an oil bath. A vacuum pump was connected to the reaction vessel's piping to remove water vapor and oxygen gas. After 2 hours, the stirring speed was set to 500 rpm, and 800 mL of n-heptane and 300 mL of 1-hexene were added and stirred at 80°C. While stirring, bis(methylcyclopentadienyl)zirconium dichloride (4 μmol) and a toluene solution of 2 mol / L methylaluminoxane (2 mL) were added to the reactant solution. Ethylene was introduced into the reaction vessel until the pressure stabilized at 4 MPa. Polymerization continued for 10 minutes, after which the ethylene pressure was released, the solvent was removed by vacuum, and the polymerization product was obtained. The obtained polymerization product was mixed with n-heptane at 80°C by stirring, completely dissolving the polymerization product. The mass ratio of the polymerization product to n-heptane was 1:5. Once the temperature had cooled to room temperature, the obtained polymer solution was added dropwise to ethanol while stirring, with a mass ratio of polymer solution to ethanol of 1:1. A precipitate formed during the dropwise addition. After the addition was complete, the solvent was removed from the liquid phase, and the mixture was dried in a vacuum oven at 60°C to a constant weight to obtain ethylene-hexene copolymer E. The measured property relaxation time was 320.1 ms.

[0072] Preparation of ethylene-hexene copolymer F: The preparation process was carried out with reference to ethylene-hexene copolymer E, but with the following differences. The polymer solution was added dropwise to ethanol, and the precipitate obtained was removed. The precipitate was mixed with n-heptane at 80°C by stirring, completely dissolving the precipitate. Here, the mass ratio of the precipitate to n-heptane was 1:6. Once the temperature had cooled to room temperature, the obtained solution was added dropwise with stirring to a mixed solvent of ethanol and 1-phenyl-2,4-pentanedione in a mass ratio of 7:1. Here, the mass ratio of the solution to the mixed solvent was 1:1. After the addition was complete, the solvent was removed from the liquid phase, and the mixture was dried in a vacuum oven at 60°C to a constant weight to obtain ethylene-hexene copolymer F. The measured property relaxation time was 202.8 ms.

[0073] Preparation of ethylene-decene copolymer G: In a 20 L continuous circulating tubular reactor, toluene was injected at 40 kg / h and 1-decene at 20 kg / h, and the reactor temperature was controlled to 126°C. Simultaneously, bis(1,3-dimethylcyclopentadienyl)zirconium dichloride (5.0 μmol / min, main catalyst) and a 7 wt% Al-modified methylaluminoxane (Nouryon, MMAO-3A) toluene solution (200 μmol / min, co-catalyst) were injected into the reactor. Subsequently, 18.5 kg / h of ethylene was introduced into the reactor, and the reactor was operated continuously under controlled pressure of 45 bar. Once the operation stabilized (system temperature and pressure were stable), the reaction mixture was continuously withdrawn for approximately 0.5 hours, and the solvent in the reaction mixture was removed by flushing and screw extrusion to obtain the polymerization product. The obtained polymerization product was completely dissolved in n-heptane solvent at 140°C with stirring to obtain a polymer solution. Here, the mass ratio of polymerization product to solvent used was 1:4. Once the temperature had cooled to room temperature, the polymer solution was added dropwise to ethanol with stirring, here, the mass ratio of polymer solution to ethanol was 1:3. A precipitate formed during the dropwise addition. After the addition was complete, the solvent was removed from the liquid phase and dried in a vacuum oven at 60°C to a constant weight to obtain ethylene-decene copolymer G. The measured property relaxation time was 498.8 ms.

[0074] Preparation of ethylene-decencopolymer H: The preparation process was carried out with reference to ethylene-decencopolymer G, but with the following differences. The polymer solution was added dropwise to ethanol, and the precipitate obtained was removed. The precipitate was mixed with n-heptane at 80°C by stirring, completely dissolving the precipitate. Here, the mass ratio of the precipitate to n-heptane was 1:4. Once the temperature had cooled to room temperature, the obtained solution was added dropwise with stirring to a mixed solvent of ethanol and bicyclo[3.3.1]nona-3,7-dione in a mass ratio of 6:1. The mass ratio of the solution to the mixed solvent was 1:1. After the addition was complete, the solvent was removed from the liquid phase, and the polymer was dried in a vacuum oven at 60°C to a constant weight to obtain ethylene-decencopolymer H. The measured property relaxation time was 287.6 ms.

[0075] Preparation of ethylene-octene copolymer I: It was prepared by the method described in Comparative Example 6 of Chinese Patent No. 113767118.

[0076] Preparation of ethylene-hexene copolymer J: It was prepared by the method described in Example 8 of U.S. Patent No. 1,0975,173.

[0077] Table 1 shows the parameters of the physical properties of the prepared ethylene / α-olefin copolymer.

[0078] [Table 1]

[0079] Example 1 1000 g of ethylene-octene copolymer A (ethylene / α-olefin copolymer) was mixed with 9 g of tert-butyl peroxy 2-ethylhexyl carbonate, 5 g of triallyl isocyanurate, 2 g of γ-methacryloyloxypropyltrimethoxysilane, 1 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 1 g of bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, and 1 g of n-octadecyl β-[3,5-di-t-butyl-4-hydroxyphenyl]propionic acid. The above raw materials were heated to 50°C and mixed uniformly. The parameters of the extruder were adjusted so that the temperature from the outlet to the die was 80°C, 90°C, 90°C, 90°C, 90°C, 95°C, 95°C, 95°C, the screw rotation speed was 45 rpm, the traction speed was 0.7 rpm, and the winding speed was 1.3 rpm. Through the processes of extrusion, casting, cooling slitting, and winding, a solar cell encapsulating adhesive film with a thickness of 0.6 mm was obtained. Subsequently, tempered glass, encapsulating adhesive film, crystalline silicon battery cells, encapsulating adhesive film, and float glass were arranged in this order from top to bottom, and laminated at 145°C using a laminating machine to obtain a multi-layer glass solar power generation module.

[0080] Example 2 1000 g of ethylene-octene copolymer B (ethylene / α-olefin copolymer) was mixed with 9 g of tert-butyl peroxy 2-ethylhexyl carbonate, 5 g of triallyl isocyanurate, 2 g of γ-methacryloyloxypropyltrimethoxysilane, 1 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 1 g of bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, and 1 g of n-octadecyl β-[3,5-di-t-butyl-4-hydroxyphenyl]propionic acid. The above raw materials were heated to 50°C and mixed uniformly. The parameters of the extruder were adjusted so that the temperature from the outlet to the die was 80°C, 90°C, 90°C, 90°C, 90°C, 95°C, 95°C, 95°C, the screw rotation speed was 45 rpm, the traction speed was 0.7 rpm, and the winding speed was 1.3 rpm. Through the processes of extrusion, casting, cooling slitting, and winding, a solar cell encapsulating adhesive film with a thickness of 0.6 mm was obtained. Subsequently, tempered glass, encapsulating adhesive film, crystalline silicon battery cells, encapsulating adhesive film, and float glass were arranged in this order from top to bottom, and laminated at 145°C using a laminating machine to obtain a multi-layer glass solar power generation module.

[0081] Example 3 1000 g of ethylene-butene copolymer C was mixed with 6 g of 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2 g of tert-amyl peroxycarbonate, 4 g of trimethylolpropane triacrylate, 2 g of γ-methacryloyloxypropyltrimethoxysilane, 1 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 0.1 g of antioxidant 1076, and 1 g of antioxidant 1010. The above raw materials were heated to 50°C and mixed uniformly. The parameters of the extruder were adjusted so that the temperature from the outlet to the die was 80°C, 90°C, 90°C, 90°C, 90°C, 95°C, 95°C, 95°C, the screw rotation speed was 45 rpm, the traction speed was 0.7 rpm, and the winding speed was 1.3 rpm. Through the processes of extrusion, casting, cooling slitting, and winding, a solar cell encapsulating adhesive film with a thickness of 0.6 mm was obtained. Subsequently, tempered glass, encapsulating adhesive film, crystalline silicon battery cells, encapsulating adhesive film, and float glass were arranged in this order from top to bottom, and laminated at 145°C using a laminating machine to obtain a multi-layer glass solar power generation module.

[0082] Example 4 1000 g of ethylene-butene copolymer D was mixed with 6 g of 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2 g of tert-amyl peroxycarbonate, 4 g of trimethylolpropane triacrylate, 2 g of γ-methacryloyloxypropyltrimethoxysilane, 1 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 0.1 g of antioxidant 1076, and 1 g of antioxidant 1010. The above raw materials were heated to 50°C and mixed uniformly. The parameters of the extruder were adjusted so that the temperature from the outlet to the die was 80°C, 90°C, 90°C, 90°C, 90°C, 95°C, 95°C, 95°C, the screw rotation speed was 45 rpm, the traction speed was 0.7 rpm, and the winding speed was 1.3 rpm. Through the processes of extrusion, casting, cooling slitting, and winding, a solar cell encapsulating adhesive film with a thickness of 0.6 mm was obtained. Subsequently, tempered glass, encapsulating adhesive film, crystalline silicon battery cells, encapsulating adhesive film, and float glass were arranged in this order from top to bottom, and laminated at 145°C using a laminating machine to obtain a multi-layer glass solar power generation module.

[0083] Example 5 The procedure was carried out with reference to Example 1, but with the following differences: The ethylene / α-olefin copolymer used is ethylene-hexene copolymer E, 1000 g.

[0084] Example 6 The procedure was carried out with reference to Example 1, but with the following differences: The ethylene / α-olefin copolymer used is ethylene-hexene copolymer F 1000g.

[0085] Example 7 The procedure was carried out with reference to Example 3, but with the following differences: The ethylene / α-olefin copolymer used is ethylene-hexene copolymer G 1000g.

[0086] Example 8 The procedure was carried out with reference to Example 3, but with the following differences: The ethylene / α-olefin copolymer used is ethylene-hexene copolymer H 1000g.

[0087] Comparative Example 1 1000 g of ethylene-butene copolymer I was mixed with 6 g of 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2 g of tert-amyl peroxycarbonate, 4 g of trimethylolpropane triacrylate, 2 g of γ-methacryloyloxypropyltrimethoxysilane, 1 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 0.1 g of antioxidant 1076, and 1 g of antioxidant 1010. The above raw materials were heated to 50°C and mixed uniformly. The parameters of the extruder were adjusted so that the temperature from the outlet to the die was 80°C, 90°C, 90°C, 90°C, 90°C, 95°C, 95°C, 95°C, the screw rotation speed was 45 rpm, the traction speed was 0.7 rpm, and the winding speed was 1.3 rpm. Through the processes of extrusion, casting, cooling slitting, and winding, a solar cell encapsulating adhesive film with a thickness of 0.6 mm was obtained. Subsequently, tempered glass, encapsulating adhesive film, crystalline silicon battery cells, encapsulating adhesive film, and float glass were arranged in this order from top to bottom, and laminated at 145°C using a laminating machine to obtain a multi-layer glass solar power generation module.

[0088] Comparative Example 2 1000 g of ethylene-hexene copolymer J was mixed with 6 g of 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2 g of tert-amyl peroxycarbonate, 4 g of trimethylolpropane triacrylate, 2 g of γ-methacryloyloxypropyltrimethoxysilane, 1 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 0.1 g of antioxidant 1076, and 1 g of antioxidant 1010. The above raw materials were heated to 55°C and mixed uniformly. The parameters of the extruder were adjusted so that the temperature from the outlet to the die was 95°C, 105°C, 105°C, 105°C, 105°C, 105°C, 105°C, 105°C, 105°C, the screw rotation speed was 42 rpm, the traction speed was 0.6 rpm, and the winding speed was 1.2 rpm. Through the processes of extrusion, casting, cooling slitting, and winding, a solar cell encapsulating adhesive film with a thickness of 0.6 mm was obtained. Subsequently, tempered glass, encapsulating adhesive film, crystalline silicon battery cells, encapsulating adhesive film, and float glass were arranged in this order from top to bottom, and laminated at 145°C using a laminating machine to obtain a multi-layer glass solar power generation module.

[0089] Refer to Table 2 for the test results of the examples and comparative examples.

[0090] [Table 2]

[0091] The experimental results in Table 2 confirmed the following: The ethylene / α-olefin copolymer for solar cell encapsulation adhesive films of the present invention significantly reduces the vulcanization time of the encapsulation adhesive film compared to the ethylene / α-olefin copolymer used in the comparative example, while simultaneously possessing excellent PID prevention performance. The ethylene / α-olefin copolymer used in the comparative example does not simultaneously satisfy the conditions (a) to (c) required in the present invention. The manufactured encapsulation adhesive film struggles to achieve both a relatively short vulcanization time and excellent PID prevention performance, failing to achieve a good balance between the two.

[0092] This invention provides an ethylene / α-olefin copolymer and its composition for solar cell encapsulation adhesive films. The matrix resin has a long property relaxation time, which makes the molecular structure prone to chain entanglement. When the molecular chain lengths are similar, the degree of chain entanglement of the polymer itself increases, making it easier to form a three-dimensional network crosslink structure during lamination and crosslinking reactions. This allows the vulcanization crosslinking reaction to complete more quickly, shortening the processing time and resulting in a decrease in property vulcanization times Ts1 and Ts2. Furthermore, the increased degree of chain entanglement makes it easier for the polymer to form a denser crosslink structure, thereby improving the barrier ability of the encapsulation adhesive film against metal ions and ultimately improving the PID prevention effect of the solar power generation encapsulation adhesive film. This manifests as a reduction in the decrease in PID prevention performance over 96 hours on both the front and back sides of the module. In Comparative Example 1, the property relaxation time of the matrix resin was too short, resulting in clearly inferior vulcanization performance of the manufactured adhesive film and inferior PID prevention effect of the module. On the other hand, the matrix resin used in Comparative Example 2 has a long property relaxation time, resulting in particles that are generally hard and too dense. In the casting process, it was found that using the same temperature conditions as in Example 1 made it difficult to completely plasticize the particles, requiring a further increase in temperature to fully plasticize the particles, leading to a decrease in production capacity and hindering subsequent downstream processing. Furthermore, due to the excessively high particle density, the resin particles are closer to plastic than elastomer, resulting in difficulty for auxiliary agents to migrate into the interior of the resin particles during the curing process. Consequently, the absorption effect of auxiliary agents into the particles deteriorates, significantly reducing vulcanization performance and virtually eliminating crosslinking. In addition, because the particles are generally hard and have a weak protective effect on battery cells, hidden cracks are more likely to occur in the battery cells during lamination, resulting in a decrease in module yield.

[0093] It will be readily apparent that the above embodiments are merely illustrative for clarity and do not imply that the present invention is limited thereto. Those skilled in the art can make other different forms of variations or modifications based on the above description. It is not necessary, and impossible, to list all embodiments here. Any obvious variations or modifications resulting therefrom are also within the scope of protection of the present invention.

Claims

1. An ethylene / α-olefin copolymer for solar cell encapsulation adhesive films, wherein the copolymer is (a) Under conditions of angular frequency of 0.1 to 500 rad / s, the characteristic relaxation time at 190°C is 200.0 to 500.0 ms. (b) The weight-average molecular weight is 20,000 to 200,000 g / mol, and the density is 0.850 g / cc to 0.910 g / cc, (c) An ethylene / α-olefin copolymer for solar cell encapsulation adhesive films, characterized by satisfying conditions (a) to (c), wherein the molecular weight distribution is 1.5 to 3.

2. The ethylene / α-olefin copolymer according to claim 1, characterized in that the characteristic relaxation time is 350.0 to 500.0 ms, more preferably 400 to 500 ms.

3. The ethylene / α-olefin copolymer according to claim 1, characterized in that the melt index of the copolymer under the conditions of 190°C and a load of 2.16 kg is 1 g / 10 min to 50 g / 10 min.

4. The ethylene / α-olefin copolymer according to any one of claims 1 to 3, characterized in that the weight-average molecular weight is 40,000 to 100,000 g / mol.

5. The ethylene / α-olefin copolymer according to any one of claims 1 to 3, characterized in that the α-olefin comprises one or more of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicosene.

6. A method for preparing an ethylene / α-olefin copolymer for a solar cell encapsulation adhesive film according to any one of claims 1 to 5, wherein the preparation method is: Step (S1) involves polymerizing ethylene and α-olefin to obtain a copolymer product, The step (S2) involves post-treating the copolymer product to separate an ethylene / α-olefin copolymer that simultaneously satisfies conditions (a) to (c), (a) Under conditions of an angular frequency of 0.1 to 500 rad / s, the characteristic relaxation time at 190°C is 200.0 to 500.0 ms, preferably 350.0 to 500.0 ms, more preferably 400 to 500 ms. (b) The weight-average molecular weight is 20,000 to 200,000 g / mol, and the density is 0.850 g / cc to 0.910 g / cc, (c) A preparation method characterized by having a molecular weight distribution of 1.5 to 3.

7. A solar cell encapsulation adhesive film composition, wherein the composition comprises an ethylene / α-olefin copolymer according to any one of claims 1 to 5 or the ethylene / α-olefin copolymer prepared by the preparation method according to claim 6, Preferably, the composition further comprises one or more of the following: a crosslinking agent, a co-crosslinking agent, a coupling agent, and an antioxidant.

8. A solar cell encapsulation adhesive film, characterized in that the encapsulation adhesive film is prepared using the composition described in claim 7.

9. A method for producing a solar cell encapsulation adhesive film according to claim 8, characterized by comprising the steps of mixing and melting each component in the composition, extruding and casting to form a film, and then cooling and slitting.

10. A solar cell module comprising the solar cell sealing adhesive film described in claim 8.

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