An ethylene / alpha-olefin copolymer, and a method for preparing and using the same

Abstract

This invention provides an ethylene / α-olefin copolymer, its preparation method, and its applications. The ethylene / α-olefin copolymer contains 4.5%-13% molar percentage of the α-olefin ternary sequence EXXXE, as determined by carbon NMR spectroscopy; where E represents an ethylene-based structural unit and X represents an α-olefin-based structural unit. Through a special design of its intrinsic fine chain structure, this invention achieves high crosslinking reactivity, high crosslinking vulcanization reaction rate, and high crosslinking degree, while also maintaining good melt flowability. It can be widely used in photovoltaic module encapsulation materials. Without requiring control over the composition and amount of crosslinking aids during the crosslinking process and without relying on the crosslinking process itself, it significantly improves the processing speed and film strength of photovoltaic encapsulation materials, while reducing the use of crosslinking aids, which is of great significance for cost reduction and efficiency improvement in photovoltaic modules.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to an ethylene / α-olefin copolymer, its preparation method, and its application. Background Technology

[0002] In recent years, photovoltaic demand has grown rapidly, leading to a corresponding increase in global demand for encapsulant films. With the rise of double-glass modules and N-type cell technology, POE (polyolefin elastomer, including POE and EPE) encapsulant films have seen a significant increase in demand due to their superior encapsulation performance. Photovoltaic encapsulant films play a crucial role in the photovoltaic industry chain. Although their cost accounts for only about 6% of the total cost of photovoltaic modules, they are essential for ensuring the durability and power generation efficiency of the modules. POE is a thermoplastic polyolefin elastomer obtained by copolymerizing ethylene and α-olefins using a solution polymerization process. Its excellent water vapor barrier properties, weather resistance, and anti-PID capabilities make it more compatible with N-type TOPCon photovoltaic modules. EPE encapsulant films combine the advantages of POE and EVA (ethylene-vinyl acetate copolymer) resins and represent an important direction for encapsulant film development.

[0003] With the development of photovoltaic technology, higher requirements have been placed on the production efficiency and product stability of photovoltaic modules. Based on the actual processing needs of module encapsulant films, how to improve the vulcanization speed of photovoltaic encapsulant films, thereby shortening the processing time of lamination crosslinking reaction and achieving greater cost reduction and efficiency improvement, has significant application value. To accelerate the vulcanization speed of POE photovoltaic encapsulant films, the main solutions in the industry currently lie in optimizing the encapsulant film formulation, optimizing the crosslinking process, or modifying POE particles through silane grafting. For example, CN116023891A discloses a modified POE composition for photovoltaic films, the raw material composition of which includes: 50-75% POE resin, 15-40% crosslinking sensitized polymer, 1-3% vinyl silane, 1-3% glycidyl methacrylate, 0.1-0.5% initiator, 0.5% antioxidant, 0.5% light stabilizer, and 1-5% liquid co-crosslinking agent; the film is modified by chemical grafting silane monomers onto the POE macromolecular chain to form a high molecular weight tackifier, thereby contributing to the degree of crosslinking of the film through silane crosslinking, improving the crosslinking speed of the film, and shortening the curing cycle. CN115873528A discloses a rapid crosslinking encapsulation material comprising the following components: 90-99% matrix material, 0.6-1.5% crosslinking agent, 0.5-2% co-crosslinking agent, 0.1-1% coupling agent, 0.1-0.5% antioxidant, and 0.1-0.5% light stabilizer; the crosslinking agent includes tert-amyl peroxide-2-ethylhexyl carbonate, which, in combination with other components, optimizes the crosslinking formulation of the film, thereby accelerating the crosslinking speed and improving the production efficiency of the component. CN110713798A discloses a rapid crosslinking encapsulating film for photovoltaic modules, comprising the following components: 0-30 parts by weight of a base resin, 30-100 parts by weight of a first modified resin, 0-50 parts by weight of a second modified resin, 0.01-3 parts by weight of an organic peroxide, 0.02-2 parts by weight of a silane coupling agent, 0.005-2 parts by weight of a light stabilizer, and 0-20 parts by weight of a pigment; the first modified resin is a mixture of one or more copolymers of ethylene with vinyl acetate, propylene, butene, hexene, or octene containing at least two active groups in any proportion, wherein the active groups are selected from amino, carboxyl, hydroxyl, mercapto, acid anhydride, sulfonic acid, epoxy, cyano, isocyanate, silane coupling group, and acyl chloride group; this film utilizes modified resin to replace small molecule co-crosslinking agents, improving the crosslinking reaction of the film, and combined with radiation or heat pretreatment, can shorten the module lamination time and effectively improve the module manufacturing efficiency.

[0004] Although the industry has proposed solutions to improve the crosslinking rate by adjusting additive components, chemical modification, and improving crosslinking processes, these solutions all require matching specific formulation systems or processes. This not only imposes significant limitations on the preparation of encapsulant films and the encapsulation of photovoltaic modules, increasing costs, but also the addition of modified additives may adversely affect the long-term stability of photovoltaic modules. Therefore, developing a new material with universal applicability that is not dependent on specific crosslinking additives and crosslinking processes to improve the processing efficiency of photovoltaic modules is an urgent problem to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an ethylene / α-olefin copolymer, its preparation method, and its applications. The ethylene / α-olefin copolymer has a specific α-olefin ternary sequence content, which improves the crosslinking vulcanization rate and crosslinking degree from the perspective of intrinsic fine chain structure, while also taking into account good melt flowability. It can be widely used as an encapsulation material for photovoltaic modules, and significantly improves module processing efficiency and yield without requiring control of crosslinking aids and crosslinking processes.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides an ethylene / α-olefin copolymer, wherein the molar percentage of the α-olefin ternary sequence EXXXE, as determined by carbon nuclear magnetic resonance spectroscopy, in the ethylene / α-olefin copolymer is 4.5%-13%; wherein E represents an ethylene-based structural unit and X represents an α-olefin-based structural unit.

[0008] The ethylene / α-olefin copolymer provided by this invention contains a specific proportion of EXXXE sequence structures in the polymer chain segments, exhibiting a more uneven distribution of α-olefins. Due to the uneven insertion of α-olefins, the crosslinking active sites of the polymer are more active under the same or similar insertion rate conditions, allowing for faster vulcanization and crosslinking reactions under the same conditions. Simultaneously, the uneven insertion of α-olefins reduces the damage to the ethylene crystal chain segments caused by α-olefins, resulting in a higher degree of crosslinking under the same or similar insertion rate conditions. This invention designs the polymer from the perspective of intrinsic fine chain structure, providing an ethylene / α-olefin copolymer with high crosslinking reactivity, high crosslinking vulcanization reaction rate, and high degree of crosslinking, while also maintaining good melt flowability. When used in photovoltaic encapsulation materials, it significantly improves the processing speed and film strength of photovoltaic encapsulation materials (e.g., encapsulation films) without requiring control over the composition and amount of crosslinking aids during the crosslinking process or depending on the crosslinking process itself. It also reduces the use of crosslinking aids, which is of great significance for cost reduction and efficiency improvement in photovoltaic modules.

[0009] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0010] In this invention, the ethylene / α-olefin copolymer is analyzed by carbon nuclear magnetic resonance (NMR) spectroscopy. 13 The molar percentage of the α-olefin ternary sequence EXXXE measured by C-NMR is 4.5%-13%, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11% or 12%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the range, but 4.5%-11% is preferred.

[0011] Preferably, the melt index (MI) of the ethylene / α-olefin copolymer at 190°C and 2.16 kg is 1-30 g / 10 min, for example, it can be 2 g / 10 min, 3 g / 10 min, 5 g / 10 min, 7 g / 10 min, 8 g / 10 min, 10 g / 10 min, 13 g / 10 min, 15 g / 10 min, 17 g / 10 min, 20 g / 10 min, 23 g / 10 min, 25 g / 10 min, 27 g / 10 min or 29 g / 10 min, more preferably 1.5-24 g / 10 min, and more preferably 3-22 g / 10 min.

[0012] Preferably, the density of the ethylene / α-olefin copolymer is 0.860-0.880 g / cm³. 3 For example, it could be 0.862 g / cm³. 3 0.865g / cm 3 0.868 g / cm 3 0.870 g / cm 3 0.872 g / cm 3 0.875g / cm 3 Or 0.878 g / cm 3 And the specific point values ​​between the above-mentioned point values, due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range, and further preferably 0.862-0.880 g / cm³. 3 More preferably 0.865-0.877 g / cm³ 3 .

[0013] Preferably, the ethylene / α-olefin copolymer is spectrally analyzed by carbon nuclear magnetic resonance (NMR) spectroscopy. 13The molar percentage of EXXE in the sequence measured by C-NMR is 9%-16%, for example, it can be 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15% or 15.5%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0014] Preferably, the ethylene / α-olefin copolymer is spectrally analyzed by carbon nuclear magnetic resonance (NMR) spectroscopy. 13 The molar percentage of EXE in the sequence measured by C-NMR is 46%-69%, for example, it can be 47%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 64%, 65%, 66% or 68%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0015] Preferably, the weight-average molecular weight (M) of the ethylene / α-olefin copolymer is... w ) is 4.0×10 4 -15.0×10 4 g / mol, for example, could be 5.0 × 10⁻⁶ g / mol. 4 g / mol, 6.0×10 4 g / mol, 7.0×10 4 g / mol, 8.0×10 4 g / mol, 9.0×10 4 g / mol, 10.0×10 4 g / mol, 11.0×10 4 g / mol, 12.0×10 4 g / mol, 13.0×10 4 g / mol or 14.0 × 10 4 g / mol, and specific values ​​between the above-mentioned points. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range, but 4.5 × 10 g / mol is further preferred. 4 -13.0×10 4 g / mol, more preferably 4.6 × 10 g / mol 4 -9.0×10 4 g / mol.

[0016] Preferably, the molecular weight distribution index (PDI, M) of the ethylene / α-olefin copolymer is... w / M nThe value is 2.0-3.0, for example, it can be 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8 or 2.9, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range. It is further preferred to be 2.0-2.7, and more preferably 2.1-2.6.

[0017] For example, the weight-average molecular weight (M) of the present invention w Number-average molecular weight (M) n The molecular weight distribution (PDI) was determined by gel permeation chromatography (GPC); the PDI was M. w / M n .

[0018] Preferably, the α-olefin is selected from any one or a combination of at least two of the α-olefins from C3 to C20; wherein the α-olefins from C3 to C20 are specifically α-olefins of C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, and C20.

[0019] Preferably, the α-olefin comprises any one or a combination of at least two 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.

[0020] Preferably, the α-olefin is selected from any one or a combination of at least two of the C3-C12 α-olefins, and more preferably from any one or a combination of at least two of the following: propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, and 1-decene.

[0021] Preferably, the mass percentage of α-olefin-based structural units in the ethylene / α-olefin copolymer is 20%-38%, for example, it can be 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, or 37%, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0022] Preferably, the molar insertion rate of α-olefin in the ethylene / α-olefin copolymer is 5%-50%, for example, it can be 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, or 48%, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0023] In a second aspect, the present invention provides a method for preparing an ethylene / α-olefin copolymer as described in the first aspect, the method comprising: polymerizing ethylene and α-olefin under the catalysis of a catalytic system to obtain the ethylene / α-olefin copolymer.

[0024] Preferably, the single-pass conversion rate of ethylene in the polymerization reaction is 80%-92%, for example, it can be 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90% or 91%, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but 85%-90% is further preferred.

[0025] Preferably, the α-olefin conversion rate in the polymerization reaction is ≥26%, for example, it can be 26.5%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 38%, or 40%, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but 26%-36% is further preferred.

[0026] As a preferred technical solution of the present invention, during the polymerization reaction, the relative concentrations of ethylene and α-olefins at the reactive center can be effectively controlled by controlling the single-pass conversion rate of ethylene. The relative concentrations of ethylene / α-olefins at the reactive center are one of the main influencing factors on the sequence distribution during the ethylene / α-olefin copolymerization process. Therefore, by controlling the single-pass conversion rate of ethylene within the range of 80%-92% and simultaneously controlling the conversion rate of α-olefins to ≥26%, the polymerization reaction activity can be improved while regulating the EXXXE sequence distribution, so that the content of the EXXXE sequence is 4.5%-13%.

[0027] Preferably, the catalytic system comprises a combination of a main catalyst and a co-catalyst.

[0028] Preferably, the main catalyst is a homogeneous catalyst, and more preferably any one or a combination of at least two of metallocene catalysts, post-metallocene catalysts, and non-metallocene catalysts.

[0029] Preferably, the main catalyst is a transition metal catalyst.

[0030] Preferably, the main catalyst comprises silyl(N-tert-butylamino)(tetramethylcyclopentadienyl)titanium chloride, dimethyl(N-tert-butylamino)(tetramethylcyclopentadienyl)dimethyltitanium, dimethyl(N-tert-butylamino)(fluorenyl)titanium chloride, (pentamethylcyclopentadienyl)trimethoxytitanium, diphenylmethylene(cyclopentadiene)(9-fluorenyl)zirconium chloride, dimethyldimethylalkylbis(2-methyl-4-phenyl-1-indenyl)zirconium chloride, mesodimethylsilylbis(1-indenyl)zirconium chloride, (bis(methylcyclopentadiene)zirconium chloride), (bis(1,3-dimethylcyclopentadienyl)zirconium chloride, (cyclopentadienyl)(1,2-dimethoxyethane)zirconium chloride, Diphenylsilyl(cyclopentadiene)(9-fluorenyl)zirconia dichloride, racemic dimethylsilylbis(2-methyl-1-indene)zirconia dichloride, diphenylmethylenecyclopentadiene(2,7-di-tert-butyl-fluorenyl)zirconia dichloride, di-p-tolymethylenecyclopentadiene(2,7-di-tert-butyl-fluorenyl)zirconia dichloride, dimethylbis(propylcyclopentadienyl)hafnium, bis(n-butylcyclopentadiene)hafnium dichloride, dimethylsilylbis(2-methyl-4-phenylindene)zirconia dichloride, rac-ethylenebis(1-indene)zirconia dichloride, any one or a combination of at least two of the compounds shown in Formula A, Formula B, Formula C, Formula D, and Formula E.

[0031]

[0032] Where Ph represents phenyl, Me represents methyl, and Et represents ethyl. i Pr represents isopropyl, and Bn represents benzyl. n Bu represents n-butyl.

[0033] M is selected from Ti, Zr, or Hf.

[0034] X is selected from halogens (e.g., F, Cl, Br, I), methyl, benzyl, dimethylamino, with Cl or methyl being more preferred.

[0035] R is selected from any one of C1-C30 alkyl and C6-C30 aryl.

[0036] Wherein, the C1-C30 alkyl group can be a straight-chain or branched alkyl group of C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C20, C22, C24, C25, C26, C28, etc., and can also be a C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C Cycloalkyl groups of C20, C22, C24, C25, C26, C28, etc., are further preferred to be C1-C10 straight-chain or branched alkyl groups and C3-C10 cycloalkyl groups. Exemplary examples include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-methylbutyl, n-pentyl, isopentyl, neopentyl, n-hexyl, neohexyl, 2-ethylhexyl, n-octyl, n-heptyl, n-nonyl, n-decyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantyl, etc.

[0037] The C6-C30 aryl group can be an aryl group of C6, C9, C10, C12, C14, C16, C18, C20, C22, C24, C26 or C28, preferably a C6-C20 aryl group, and exemplary examples include but are not limited to: phenyl, biphenyl, terphenyl, naphthyl, anthracene, phenanthryl, etc.

[0038] Preferably, the inlet flow rate of the main catalyst is 0.05-0.2 g / h, for example, it can be 0.06 g / h, 0.08 g / h, 0.1 g / h, 0.11 g / h, 0.12 g / h, 0.13 g / h, 0.14 g / h, 0.15 g / h, 0.16 g / h, 0.17 g / h, 0.18 g / h or 0.19 g / h, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, and 0.09-0.17 g / h is further preferred.

[0039] Preferably, the cocatalyst comprises an organoaluminum compound and optionally an organoboronide.

[0040] Preferably, the organoaluminum compound includes any one or a combination of at least two of aluminum oxanes, alkylaluminum compounds, and alkylaluminum chlorides.

[0041] Preferably, the aluminum oxane includes any one or a combination of at least two of methylaluminoxane (MAO), modified methylaluminoxane (MMAO), ethylaluminoxane, and butylaluminoxane.

[0042] Preferably, the alkylaluminum compound includes any one or a combination of at least two of triethylaluminum, triisobutylaluminum, trioctylaluminum, trimethylaluminum, tripropylaluminum, tri-n-butylaluminum, and trisec-butylaluminum.

[0043] Preferably, the alkylaluminum chloride includes any one or a combination of at least two of monochloroethylaluminum, sesquiethylaluminum chloride, and dichloroethylaluminum.

[0044] Preferably, the molar ratio of Al in the organoaluminum compound to the transition metal in the main catalyst is (10-1000):1, for example, it can be 15:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, 120:1, 140:1, 150:1, 160:1, 180:1, 200:1, 250:1, 300:1, 350:1, 400:1, 450:1, 500:1, 550:1, 600:1, 650:1, 700:1, 750:1, 800:1, 850:1, 900:1 or 950:1, etc., and more preferably (20-100):1.

[0045] Preferably, the organoboronide comprises any one or a combination of at least two of the following: triphenylmethyltetra(pentafluorophenyl)borate, tri(pentafluorophenyl)boron, N,N-dimethylanilinetetra(pentafluorophenyl)borate, bis(octadecylmethyl)tertiaryaminetetra(pentafluorophenyl)borate, and dihydrotallowylmethyl)tertiaryaminetetra(pentafluorophenyl)borate.

[0046] Preferably, the molar ratio of B in the organoboride to the transition metal in the main catalyst is ≤10:1, for example, it can be 0 (i.e., no organoboride is used), 0.1:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1 or 9.5:1, etc., and more preferably (1-3):1.

[0047] Preferably, the polymerization reaction is carried out in the presence of a solvent, i.e., the polymerization reaction is a solution polymerization reaction.

[0048] Optionally, the solution polymerization reaction is carried out in one reactor or several (≥2) reactors connected in series.

[0049] The solvent is in a liquid or supercritical state under the conditions of the polymerization reaction, preferably in a liquid state.

[0050] Preferably, the solvent includes any one or a combination of at least two of the following: alkane solvents, haloalkane solvents, cycloalkane solvents, and aromatic solvents.

[0051] For alkane solvents and cycloalkanes, preferably C5-C12 (e.g., C6, C7, C8, C9, C10, C11, etc.) alkanes and C5-C12 (e.g., C6, C7, C8, C9, C10, C11, etc.) cycloalkanes, which are unsubstituted or substituted by C1-C4 (e.g., C2, C3, C4) straight-chain or branched alkyl groups; such solvents include, but are not limited to, any one or at least a combination of two of the following: pentane, methylpentane, hexane, heptane, octane, cyclohexane, methylcyclohexane, hydrogenated naphtha, C6 mixed alkanes, and isoalkanes (e.g., Isopar E).

[0052] Preferably, the solvent comprises any one or a combination of at least two of the following: pentane, methylpentane, n-butane, isobutane, methylcyclopentane, methylenecyclopentane, n-hexane, cyclohexane, methylcyclohexane, n-heptane, n-octane, isoparaffins (e.g., IsoparE), hydrogenated naphtha, benzene, toluene, and xylene.

[0053] Preferably, the polymerization reaction is carried out in the presence of a chain transfer agent.

[0054] Preferably, the chain transfer agent includes any one or a combination of at least two of methane, ethane, propane, and hydrogen, with hydrogen being more preferred.

[0055] Preferably, the hydrogen flow rate is 0.005-0.5 g / h, for example, it can be 0.008 g / h, 0.01 g / h, 0.02 g / h, 0.05 g / h, 0.08 g / h, 0.1 g / h, 0.15 g / h, 0.2 g / h, 0.25 g / h, 0.3 g / h, 0.35 g / h, 0.4 g / h, 0.45 g / h, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range, but 0.01-0.3 g / h is further preferred.

[0056] Preferably, the ethylene flow rate is 5-15 kg / h, for example, it can be 6 kg / h, 7 kg / h, 8 kg / h, 9 kg / h, 10 kg / h, 11 kg / h, 12 kg / h, 13 kg / h or 14 kg / h, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0057] Preferably, the α-olefin is introduced at a rate of 10-30 kg / h, for example, 12 kg / h, 15 kg / h, 18 kg / h, 20 kg / h, 22 kg / h, 25 kg / h or 28 kg / h, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0058] Preferably, the ratio of the amount of ethylene fed to the amount of α-olefin fed is 1:(1-3), for example, it can be 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.2, 1:2.5, 1:2.8, etc., and more preferably 1:(1.2-2.2).

[0059] Preferably, the polymerization reaction temperature is 110-200℃, for example, it can be 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃ or 190℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but 120-190℃ is further preferred.

[0060] Preferably, the pressure of the polymerization reaction is 1-10 MPa, for example, it can be 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa or 9 MPa, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, and 3-7 MPa is further preferred.

[0061] As a preferred embodiment of the present invention, the polymerization reaction temperature is 110-200℃, and / or the polymerization reaction pressure is 1-10MPa, so as to maintain high catalytic and polymerization reaction activity of the catalytic system.

[0062] Preferably, the polymerization reaction time is 2-20 min, for example, it can be 3 min, 4 min, 5 min, 6 min, 8 min, 10 min, 12 min, 14 min, 15 min, 16 min or 18 min, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but 3-12 min is further preferred.

[0063] Preferably, the polymerization reaction further includes quenching, devolatilization, and extrusion granulation steps after completion.

[0064] In a preferred embodiment, the preparation method includes the following steps:

[0065] Ethylene and α-olefins are polymerized in the presence of a catalytic system, hydrogen, and a solvent to obtain the ethylene / α-olefin copolymer.

[0066] The catalytic system comprises a combination of a transition metal catalyst and a co-catalyst, wherein the co-catalyst comprises an organoaluminum compound and optionally an organoboride;

[0067] The polymerization reaction is carried out at a temperature of 110-200℃, a pressure of 1-10MPa, and a time of 2-20min.

[0068] The single-pass conversion rate of ethylene in the polymerization reaction is 80%-92%, and the conversion rate of α-olefins is 26%-36%.

[0069] Thirdly, the present invention provides an application of the ethylene / α-olefin copolymer as described in the first aspect in photovoltaic encapsulation materials.

[0070] Fourthly, the present invention provides a photovoltaic encapsulation material, wherein the raw materials for preparing the photovoltaic encapsulation material include the ethylene / α-olefin copolymer as described in the first aspect.

[0071] Preferably, the photovoltaic encapsulation material includes an encapsulation film.

[0072] Preferably, the raw materials for preparation further include crosslinking agents, co-crosslinking agents, and optionally other additives.

[0073] Preferably, the crosslinking agent comprises an organic peroxide.

[0074] Preferably, the crosslinking agent comprises any one or a combination of at least two of the following: tert-amyl peroxide (2-ethylhexyl) carbonate, di(4-methylbenzoyl) peroxide, cumene peroxide, di-tert-butyl peroxide, dicumene hydrogen peroxide, 2,5-dimethyl-2,5-di-tert-butyl peroxide, tert-butyl peroxide (2-ethylhexyl) carbonate, benzoyl peroxide, cyclohexanone peroxide, tert-butyl peroxybenzoate, tert-butyl peracetate, and tert-butyl peroxide-3,5,5-trimethylhexanoate.

[0075] Preferably, based on 100 parts by weight of the ethylene / α-olefin copolymer, the mass of the crosslinking agent is 0.1-2 parts, for example, 0.2 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.5 parts, 1.6 parts, or 1.8 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0076] Preferably, the crosslinking agent comprises any one or a combination of at least two of the following: triallyl isocyanurate, trimethylolpropane trimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, tri(2-hydroxyethyl)isocyanurate triacrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylolpropane triacrylate.

[0077] Preferably, based on 100 parts by weight of the ethylene / α-olefin copolymer, the mass of the co-crosslinking agent is 0.1-2 parts, for example, 0.2 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.5 parts, 1.6 parts, or 1.8 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0078] Preferably, the other additives include any one or a combination of at least two of the following: silane coupling agents, antioxidants, light stabilizers, ultraviolet absorbers, anti-precipitation additives, and anti-PID additives.

[0079] This invention does not limit the specific types of other additives such as silane coupling agents, antioxidants, light stabilizers, ultraviolet absorbers, anti-precipitation agents, and anti-PID agents. Other additives known in the art that can be used in encapsulation materials are also applicable to this invention.

[0080] Preferably, based on 100 parts by weight of the ethylene / α-olefin copolymer, the mass of the silane coupling agent is 0.1-1 parts, for example, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, or 0.9 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0081] Preferably, based on 100 parts by weight of the ethylene / α-olefin copolymer, the antioxidant is 0.1-1 parts by weight, for example, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, or 0.9 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0082] Preferably, the antioxidant includes any one or a combination of at least two of hindered amine antioxidants, hindered phenolic antioxidants, and phosphite antioxidants.

[0083] As a preferred embodiment of the present invention, the ethylene / α-olefin copolymer provided by the present invention possesses high crosslinking reactivity, high crosslinking vulcanization reaction rate, and high crosslinking degree. Photovoltaic encapsulation materials (e.g., encapsulation films) prepared using this copolymer exhibit faster crosslinking vulcanization speed and higher crosslinking degree, resulting in faster processing speed and higher film strength during processing. Simultaneously, it can reduce the use of crosslinking aids and co-crosslinking agents, which is of great significance for reducing costs and increasing output in photovoltaic module production. Based on the high crosslinking degree of the photovoltaic encapsulation material, the efficiency and performance stability of the encapsulated product are ensured under long-term use, for example, enabling photovoltaic modules to achieve high power generation efficiency.

[0084] As a preferred embodiment of the present invention, the degree of crosslinking of the photovoltaic encapsulation material is >80%, preferably ≥82%, and can be 82.5%-86.1%.

[0085] As a preferred embodiment of the present invention, the crosslinking vulcanization time T90 of the photovoltaic encapsulation material is ≤12.5 min, and can be 11.6-12.31 min.

[0086] For example, the method for preparing the photovoltaic encapsulation material includes: blending an ethylene / α-olefin copolymer, a crosslinking agent, a co-crosslinking agent, and optionally other additives, and molding them to obtain the photovoltaic encapsulation material.

[0087] Preferably, the molding method includes cast extrusion or twin-screw extrusion.

[0088] Compared with the prior art, the present invention has the following beneficial effects:

[0089] (1) The ethylene / α-olefin copolymer provided by the present invention has high crosslinking reactivity, high crosslinking vulcanization reaction rate and high crosslinking degree through the special design of intrinsic fine chain structure, especially the design of EXXXE sequence structure, while taking into account good melt flowability. It can be widely used in the encapsulation material of photovoltaic modules. Without requiring the control of the composition and amount of crosslinking aids in the crosslinking process and without depending on the crosslinking process, the processing speed and film strength of photovoltaic encapsulation material are significantly improved.

[0090] (2) The photovoltaic encapsulation material provided by this invention, based on the use of ethylene / α-olefin copolymer, has a significantly improved crosslinking rate and degree of crosslinking, which can shorten processing time, improve processing speed and efficiency, and at the same time reduce the use of crosslinking aids, which is of great significance for cost reduction and efficiency improvement of photovoltaic modules. At the same time, the photovoltaic encapsulation material has a high degree of crosslinking and higher film strength, which can ensure the efficiency and performance stability of the encapsulated products for long-term use. Detailed Implementation

[0091] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0092] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not limited to those elements and may also include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0093] "Optional" or "any one" means that the matter or event described thereafter may or may not occur, and the description includes both the possibility that the event may occur and the possibility that the event may not occur.

[0094] In the following specific embodiments of the present invention, the main testing methods for the polymer are as follows:

[0095] (1) Density: Tested according to the method in standard ASTM D-792.

[0096] (2) Molecular weight (weight-average molecular weight M) w Number average molecular weight M n ), molecular weight distribution (PDI, M) w / M n The insertion rates of α-olefins were determined by gel permeation chromatography (GPC). Specifically, the chromatographic column was an Agilent Olexis; the solvent was 1,2,4-trichlorobenzene; the flow rate was 1.0 mL / min; the sample concentration was 1.0 mg / mL; the injection volume was 200 μL; the column temperature was 160 °C; the detector was an Agilent High Temperature RI detector; and the standard was polystyrene (PS) corrected for a cubic function.

[0097] (3) The molar percentages of sequences EXXXE, EXXE, and EXE were determined by carbon NMR spectroscopy. 13The results were obtained by C-NMR analysis. Specifically, 2.74 g of the sample and tetrachloroethane-d2 containing 0.025 M Cr(AcAc)3 (chromium acetylacetone) were added to a Nore II 1001-7 10 mm NMR tube. Oxygen was removed by manually purging the tube with nitrogen for 1 min using a Pasteur pipette. The tube and its contents were heated to 150 °C using a heating plate, with minimal use of a heating gun, to dissolve and homogenize the sample. The sample was thoroughly mixed immediately before analysis and should not be cooled before insertion into the heated NMR probe. This is necessary to ensure that the sample is homogeneous and representative of the whole sample. Data were collected using a Bruker 400 MHz spectrometer equipped with a Bruker cryopreservation probe. Data were acquired using 160 scans, a 6-second pulse repetition delay, and a sample temperature of 120 °C. All measurements were performed on a non-spin sample in locked mode. The sample was allowed to equilibrate for 7 min before data acquisition. The collected data were used to calculate the sequence distribution of the polymer using the randall and seger methods, which yielded the aforementioned binary and ternary sequence distributions of the ethylene / α-olefin copolymer.

[0098] For randall's method, please refer to the literature: "A review of high resolution liquid13carbon nuclear magnetic resonance characterizations of ethylene-basedpolymers", Randall J C., Journal of Macromolecular Science-Reviews inMacromolecular Chemistry and Physics.1989, 29(2-3):201-317;

[0099] For Seger's methods, please refer to the literature: "Quantitative 13 C NMR analysis of sequence distributions in poly(ethylene-co-1-hexene)", Seger MR et al., Analytical Chemistry., 2004, 76(19):5734-5747.

[0100] (4) Melt index (MI):

[0101] The mass of the extrudate was measured using a melt flow indexer (CEAST melt flow indexer, Italy) and in accordance with the method of GB / T3682.1-2018. At 190℃ and 2.16kg load, the mass of the extrudate was weighed every 6 seconds. Five parallel operations were performed, and the average value was taken and converted into the mass of the extrudate every 10 minutes, expressed in g / 10min.

[0102] (5) Ethylene single-pass conversion rate, α-olefin conversion rate:

[0103] Ethylene single-pass conversion rate = copolymer production rate × ethylene content in copolymer / ethylene feed rate;

[0104] α-Olefin conversion rate = copolymer production rate × α-olefin content in copolymer / α-olefin feed rate;

[0105] The α-olefin content (mass content) and ethylene content (mass content) in the copolymer were measured by the GPC method described above; the copolymer production rate, ethylene feed rate and α-olefin feed rate were controlled by the continuous reaction unit.

[0106] (6) Catalytic activity: Calculated according to the following formula, catalytic activity = copolymer mass (kg) / main catalyst mass (g).

[0107] The specific information of the materials used in the following specific embodiments of the present invention is as follows, all of which are commercially available chemicals:

[0108]

[0109] The following will use several examples to describe in detail the ethylene / α-olefin copolymer and its preparation method according to the present invention, but the ethylene / α-olefin copolymer and its preparation method according to the present invention are not limited to these examples.

[0110] Example 1

[0111] An ethylene / α-olefin copolymer is prepared by the following method:

[0112] Hexane solvent (80 kg / h) and 1-butene (15 kg / h) were added to a 25 L high-pressure continuous reactor, and the temperature at the top of the reactor was preheated to 145 °C. Simultaneously, the main catalyst Al (0.167 g / h) and the co-catalyst methylaluminoxane (prepared as a hexane solution with an Al element content of 10 wt%, with a solution feed rate of 0.80 g / h) were introduced into the reactor. Subsequently, ethylene (10 kg / h) and hydrogen (0.01 g / h) were added to the autoclave reactor, and the polymerization reaction was carried out continuously at 3.5 MPa and 145 °C for more than 15 min to obtain a copolymer solution. The single-pass conversion rate of ethylene was controlled at 92%, and the conversion rate of 1-butene was 32.2%. After the reaction, the reaction solution was quenched with methanol and then entered a three-stage devolatilization tank for devolatilization. After removing unreacted hexane, 1-butene, and ethylene in the devolatilization tank, the ethylene / α-olefin copolymer particles were obtained by extrusion granulation. The properties were tested and are shown in Table 2.

[0113] Examples 2-8, Comparative Examples 1-2

[0114] An ethylene / α-olefin copolymer and its preparation method are disclosed. The only difference between this copolymer and Example 1 is the catalyst and process parameters used in the polymerization reaction. Specific information is shown in Table 1. The process parameters not shown in Table 1 are the same as those in Example 1. The properties of the ethylene / α-olefin copolymer are shown in Table 2.

[0115] In Table 1, the feed rate (g / h) of organoaluminum compounds is the feed rate of their n-hexane solution (containing 10 wt% Al); the feed rate (g / h) of organoborides is the feed rate of their n-hexane solution (containing 10 wt% organoborides). "--" indicates that organoborides were not used.

[0116] Table 1

[0117]

[0118]

[0119] Table 2

[0120]

[0121]

[0122] Application examples

[0123] A photovoltaic encapsulation material, specifically an encapsulation film, comprises the following raw materials by weight: 100 parts of ethylene / α-olefin copolymer, 0.8 parts of crosslinking agent (tert-amyl peroxide (2-ethylhexyl)carbonate), 0.7 parts of co-crosslinking agent (tracene propyl isocyanurate), 0.3 parts of silane coupling agent (3-(methacryloyloxy)propyltrimethoxysilane), and 0.2 parts of antioxidant (β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester); wherein the ethylene / α-olefin copolymer is the ethylene / α-olefin copolymer provided in Examples 1-8 and Comparative Examples 1-2.

[0124] The preparation method of the encapsulating film includes: mixing the raw materials according to the formula, so that the various additives are fully absorbed by the copolymer to obtain a mixture; then adding the mixture to a single-screw casting extruder, so that the mixture is melted and plasticized and injected into a T-die, with a melting temperature of 90°C, and then proceeding through processes such as melt extrusion, casting film formation, cooling, slitting and winding to obtain the encapsulating film.

[0125] The following performance tests were performed on the encapsulating film:

[0126] (1) Crosslinking degree: The crosslinking degree was determined according to the method in the photovoltaic industry association standard T / CPIA0006-2017;

[0127] (2) Crosslinking vulcanization time T90: The optimal vulcanization time T90 of the film was measured according to the standard GB / T 16584-1996. T90 is used to characterize the speed of crosslinking. The smaller the T90 time, the faster the crosslinking speed.

[0128] The test results are shown in Table 3:

[0129] Table 3

[0130] Ethylene / α-olefin copolymer Degree of crosslinking (%) T90(min) Example 1 83.5 11.73 Example 2 84.7 11.67 Example 3 85.4 11.78 Example 4 86.2 11.9 Example 5 82.5 11.85 Example 6 83.5 11.93 Example 7 85.4 12.01 Example 8 86.1 12.31 Comparative Example 1 79 12.57 Comparative Example 2 76 13.51

[0131] Based on the data in Tables 1-3, it can be seen that the ethylene / α-olefin copolymers provided in Examples 1-8 of the present invention, under similar melt index (MI) and density conditions as Comparative Examples 1-2, achieve higher crosslinking degree and faster crosslinking speed by controlling the EXXXE sequence content within a specific range of 4.5%-13%. This significantly shortens the crosslinking time of the encapsulation material, making T90 ≤ 12.31 min, thereby improving processing efficiency. Simultaneously, the crosslinking degree of the encapsulation film is 82.5%-86.1%, and its high crosslinking degree ensures the efficiency of the encapsulated product under long-term use, for example, enabling the battery cell to have high power generation efficiency.

[0132] In summary, this invention, through the special design of the EXXXE sequence and intrinsic fine chain structure of the ethylene / α-olefin copolymer, can optimize the crosslinking performance of the copolymer during the preparation of the film.

[0133] The applicant declares that this invention illustrates the ethylene / α-olefin copolymer, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product, additions of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. An ethylene / α-olefin copolymer, characterized in that, The ethylene / α-olefin copolymer contains 20%-38% by mass of α-olefin-based structural units; the ethylene / α-olefin copolymer contains 4.5%-13% by molar percentage of the α-olefin ternary sequence EXXXE, 9%-16% by molar percentage of the sequence EXXE, and 46%-69% by molar percentage of the sequence EXE, as determined by carbon nuclear magnetic resonance spectroscopy; wherein, E represents an ethylene-based structural unit and X represents an α-olefin-based structural unit.

2. The ethylene / α-olefin copolymer according to claim 1, characterized in that, The ethylene / α-olefin copolymer has a melt index of 1-30 g / 10 min at 190°C and 2.16 kg.

3. The ethylene / α-olefin copolymer according to claim 1, characterized in that, The ethylene / alpha-olefin copolymer has a density of 0.860 to 0.880 g / cm 3 .

4. The ethylene / α-olefin copolymer according to claim 1, characterized in that, The molecular weight distribution index of the ethylene / α-olefin copolymer is 2.0-3.

0.

5. The ethylene / α-olefin copolymer according to claim 1, characterized in that, The weight-average molecular weight of the ethylene / α-olefin copolymer is 4.0 × 10⁻⁶. 4 -15.0×10 4 g / mol.

6. The ethylene / α-olefin copolymer according to claim 5, characterized in that, The weight-average molecular weight of the ethylene / α-olefin copolymer is 4.5 × 10⁻⁶. 4 -13.0×10 4 g / mol.

7. The ethylene / α-olefin copolymer according to claim 1, characterized in that, The α-olefin is selected from any one or a combination of at least two of the C3-C20 α-olefins.

8. The ethylene / α-olefin copolymer according to claim 7, characterized in that, The α-olefin is selected from any one or a combination of at least two of the C3-C12 α-olefins.

9. The ethylene / α-olefin copolymer according to claim 8, characterized in that, The α-olefin is selected from any one or a combination of at least two of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, and 1-decene.

10. A method for preparing an ethylene / α-olefin copolymer as described in any one of claims 1-9, characterized in that, The preparation method includes: ethylene and α-olefin undergoing polymerization under the catalysis of a catalytic system to obtain the ethylene / α-olefin copolymer.

11. The preparation method according to claim 10, characterized in that, The ethylene single-pass conversion rate in the polymerization reaction is 80%-92%, and the ethylene single-pass conversion rate = copolymer production rate × ethylene content in the copolymer / ethylene feed rate.

12. The preparation method according to claim 10, characterized in that, The α-olefin conversion rate in the polymerization reaction is ≥26%, and the α-olefin conversion rate = copolymer production rate × α-olefin content in the copolymer / α-olefin feed rate.

13. The preparation method according to claim 12, characterized in that, The conversion rate of α-olefins in the polymerization reaction is 26%-36%.

14. The preparation method according to claim 10, characterized in that, The catalytic system comprises a combination of a main catalyst and a co-catalyst, wherein the main catalyst is a transition metal catalyst.

15. The preparation method according to claim 14, characterized in that, The cocatalyst includes organoaluminum compounds and optionally organoborides.

16. The preparation method according to claim 15, characterized in that, The organoaluminum compound includes any one or a combination of at least two of aluminum oxanes, alkylaluminum compounds, and alkylaluminum chlorides.

17. The preparation method according to claim 16, characterized in that, The aluminum oxane includes any one or a combination of at least two of methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, and butylaluminoxane.

18. The preparation method according to claim 16, characterized in that, The alkylaluminum compound includes any one or a combination of at least two of triethylaluminum, triisobutylaluminum, trioctylaluminum, trimethylaluminum, tripropylaluminum, tri-n-butylaluminum, and trisec-butylaluminum.

19. The preparation method according to claim 16, characterized in that, The alkylaluminum chloride includes any one or a combination of at least two of monochloroethylaluminum, sesquiethylaluminum chloride, and dichloroethylaluminum.

20. The preparation method according to claim 15, characterized in that, The molar ratio of Al in the organoaluminum compound to the transition metal in the main catalyst is (10-1000):

1.

21. The preparation method according to claim 20, characterized in that, The molar ratio of Al in the organoaluminum compound to the transition metal in the main catalyst is (20-100):

1.

22. The preparation method according to claim 15, characterized in that, The organoborides include triphenylmethyltetra(pentafluorophenyl)borate, tri(pentafluorophenyl)boron, N,N - Any one or a combination of at least two of the following: dimethylaniline tetra(pentafluorophenyl)borate, dioctadecylmethyl tertiary amine tetra(pentafluorophenyl)borate, and dihydrogenated tallow methyl tertiary amine tetra(pentafluorophenyl)borate.

23. The preparation method according to claim 15, characterized in that, The molar ratio of B in the organoboronide to the transition metal in the main catalyst is ≤10:

1.

24. The preparation method according to claim 10, characterized in that, The polymerization reaction is carried out in the presence of a solvent.

25. The preparation method according to claim 24, characterized in that, The solvent includes any one or a combination of at least two of the following: pentane, methylpentane, n-butane, isobutane, methylcyclopentane, methylenecyclopentane, n-hexane, cyclohexane, methylcyclohexane, n-heptane, n-octane, isoalkanes, hydrogenated naphtha, benzene, toluene, and xylene.

26. The preparation method according to claim 10, characterized in that, The polymerization reaction is carried out in the presence of a chain transfer agent.

27. The preparation method according to claim 26, characterized in that, The chain transfer agent includes any one or a combination of at least two of methane, ethane, propane, and hydrogen.

28. The preparation method according to claim 27, characterized in that, The chain transfer agent is hydrogen.

29. The preparation method according to claim 10, characterized in that, The polymerization reaction is carried out at a temperature of 110-200℃.

30. The preparation method according to claim 29, characterized in that, The polymerization reaction is carried out at a temperature of 120-190℃.

31. The preparation method according to claim 10, characterized in that, The polymerization reaction is carried out at a pressure of 1-10 MPa.

32. The preparation method according to claim 31, characterized in that, The polymerization reaction is carried out at a pressure of 3-7 MPa.

33. The preparation method according to claim 10, characterized in that, The polymerization reaction takes 2-20 minutes.

34. The preparation method according to claim 33, characterized in that, The polymerization reaction takes 3-12 minutes.

35. The application of an ethylene / α-olefin copolymer as described in any one of claims 1-9 in photovoltaic encapsulation materials.

36. A photovoltaic encapsulation material, characterized in that, The raw materials for preparing the photovoltaic encapsulation material include the ethylene / α-olefin copolymer as described in any one of claims 1-9.

37. The photovoltaic encapsulation material according to claim 36, characterized in that, The raw materials for preparation also include crosslinking agents, co-crosslinking agents, and optionally other additives.

38. The photovoltaic encapsulation material according to claim 37, characterized in that, The crosslinking agent includes organic peroxides.

39. The photovoltaic encapsulation material according to claim 37, characterized in that, Based on 100 parts by weight of the ethylene / α-olefin copolymer, the crosslinking agent comprises 0.1-2 parts by weight.

40. The photovoltaic encapsulation material according to claim 37, characterized in that, Based on 100 parts by weight of the ethylene / α-olefin copolymer, the mass of the crosslinking agent is 0.1-2 parts.

41. The photovoltaic encapsulation material according to claim 37, characterized in that, The other additives include any one or a combination of at least two of the following: silane coupling agents, antioxidants, light stabilizers, ultraviolet absorbers, anti-precipitation additives, and anti-PID additives.

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