Ethylene-alpha-olefin copolymer, process for its preparation and use in photovoltaic encapsulants

Abstract

The present application relates to the field of olefin polymerization, in particular to an ethylene-alpha-olefin copolymer, a preparation method thereof and application in photovoltaic adhesive film, research finds that the ethylene-alpha-olefin copolymer with moderate or relatively more high molecular weight polymer chains in the range specified in the present application has moderate or relatively more high molecular weight polymer chains, which can improve the crosslinking degree of the polymer, and the viscosity is relatively low, avoiding the influence of high molecular weight polymer on the processing performance, so that the ethylene-alpha-olefin copolymer has good crosslinking ability and excellent processing performance.

Description

Technical Field

[0001] This invention relates to the field of olefin polymerization, specifically to an ethylene-α-olefin copolymer, its preparation method, and its application in photovoltaic films. Background Technology

[0002] In the field of polymer materials, polyolefins occupy a pivotal position, accounting for the largest share of production. Compared to other types of materials, they possess significant advantages such as low cost, low density, and ease of molding and processing. These characteristics have led to their widespread application in various fields, including industry, agriculture, military, and medicine. Among them, polyethylene holds a particularly crucial position in the polyolefin industry, currently being the most widely produced general-purpose synthetic resin globally. Copolymers obtained through the copolymerization of ethylene and α-olefins combine the excellent plasticity of plastics with the high elasticity of rubber, and are considered one of the mainstream trends for future development.

[0003] With the increasing severity of global environmental problems and the energy crisis, solar cells have received growing attention due to their environmentally friendly, pollution-free, and inexhaustible energy characteristics. Modular solar cells have become the preferred choice, especially in outdoor applications such as building rooftops. These modules typically employ a multi-layered stacking structure, consisting of a front glass layer, a solar cell encapsulant layer, crystalline solar cell units, another layer of solar cell encapsulant, and finally a rear glass layer (or rear protective sheet).

[0004] In the encapsulation process of solar cells, ethylene-vinyl acetate copolymers or ethylene-α-olefin copolymers, which possess good transparency, flexibility, and adhesion properties, are typically chosen as key encapsulation materials. In particular, ethylene-α-olefin copolymers, due to their excellent anti-PID properties, are gradually becoming dominant in photovoltaic cell encapsulation technology and foreshadow future development trends. However, when fabricating them into photovoltaic encapsulants, sufficient mechanical strength and heat resistance must be ensured.

[0005] To improve mechanical strength and heat resistance, the conventional approach is to add crosslinking agents to achieve crosslinking of the material. However, the problem is that commonly used crosslinking agents and auxiliaries have low affinity with ethylene-α-olefin copolymers, resulting in a lower allowable amount of crosslinking auxiliaries to be added. Therefore, it is required that ethylene-α-olefin copolymers achieve high crosslinking with a low amount of crosslinking auxiliaries to meet the requirements for mechanical strength and heat resistance. Furthermore, as described in CN202210272154.0, the continuous development of encapsulation film equipment and molding methods has further increased the processing speed of encapsulation films. This places higher demands on the processing performance of ethylene-α-olefin copolymers, namely, requiring ethylene-α-olefin copolymers to be easier to plasticize and have lower viscosity at the same molecular weight.

[0006] Therefore, in response to this challenge, the industry urgently needs to continuously develop new ethylene-α-olefin copolymer materials with special properties, especially those ethylene-α-olefin copolymers with high crosslinking degree, easy processing and excellent casting film-forming properties, in order to promote their further application and development in the field of photovoltaic packaging. Summary of the Invention

[0007] Therefore, the technical problem to be solved by the present invention is to overcome the defects of low crosslinking degree and poor casting film performance in the prior art, thereby providing an ethylene-α-olefin copolymer, its preparation method and its application in photovoltaic films.

[0008] Therefore, in a first aspect, this application provides an ethylene-α-olefin copolymer, wherein the ethylene-α-olefin copolymer satisfies the following conditions (1) to (3):

[0009] (1) The density is 0.850 g / cm³ 3 ~0.910g / cm 3 For example, it could be 0.850 g / cm³. 3 0.855 g / cm 3 0.860 g / cm 3 0.865 g / cm 3 0.870 g / cm 3 0.875 g / cm 3 0.880 g / cm 3 0.885 g / cm 3 0.890 g / cm 3 0.895 g / cm 3 0.900 g / cm 3 0.905 g / cm 3 0.910 g / cm 3 Or it falls within the range of any two of the above values;

[0010] (2) The weight-average molecular weight is 20,000 g / mol to 200,000 g / mol, and the molecular weight distribution width (PDI) is 2.0 to 4.1; for example, it can be 20,000 g / mol, 30,000 g / mol, 40,000 g / mol, 50,000 g / mol, 60,000 g / mol, 70,000 g / mol, 80,000 g / mol, 90,000 g / mol, 100,000 g / mol, 110,000 g / mol, 120,000 g / mol, 130,000 g / mol, 140,000 g / mol, 150,000 g / mol, 160,000 g / mol, 170,000 g / mol, 180,000 g / mol, 190,000 g / mol, 20 ... g / mol or within any two of the above values; for example, the molecular weight distribution width (PDI) can be 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.1 or within any two of the above values.

[0011] (3) The values ​​of Mz, Mp, and Iv satisfy: 0.82≤Mz / Mp-Iv≤2.70; where Mz is the z-average molecular weight in g / mol; Mp is the molecular weight at the highest peak of the GPC curve in g / mol; and Iv is the intrinsic viscosity in dL / g. For example, Mz / Mp-Iv can be 0.82, 0.86, 0.90, 0.94, 0.98, 1.02, 1.06, 1.10, 1.14, 1.18, 1.22, 1.26, 1.30, 1.34, 1.38, 1.42, 1.46, 1.50, 1.54, 1.58, 1.62, 1.66, 1.70, 1.74, 1. 78, 1.82, 1.86, 1.90, 1.94, 1.98, 2.02, 2.06, 2.10, 2.14, 2.18, 2.22, 2.26, 2.30, 2.34, 2.38, 2.42, 2.46, 2.50, 2.54, 2.58, 2.62, 2.66, 2.70, or within the range of any two of the above values.

[0012] In the calculation of the formula “Mz / Mp-Iv”, only the numerical value of the parameter is substituted into the formula, and its unit is not substituted.

[0013] In some preferred embodiments, 1.01 ≤ Mz / Mp-Iv ≤ 1.46.

[0014] In some embodiments, the melt flow index (MFR) of the ethylene-α-olefin copolymer at 190°C and under a load of 2.16 kg is 0.1 g / 10 min to 30.1 g / 10 min. For example, the melt flow index (MFR) of the ethylene-α-olefin copolymer at 190°C and under a load of 2.16 kg can be 0.1 g / 10 min, 0.2 g / 10 min, 0.4 g / 10 min, 0.6 g / 10 min, 0.8 g / 10 min, 1.0 g / 10 min, 1.2 g / 10 min, 1.4 g / 10 min, 1.6 g / 10 min, 1.8 g / 10 min, 2.0 g / 10 min, 2.4 g / 10 min, 2.8 g / 10 min, 3.2 g / 10 min, 4 g / 10 min, 5 g / 10 min, 6 g / 10 min, 7 g / 10 min, 8 g / 10 min, 9 g / 10 min, etc. 10 min, 10 g / 10 min, 11 g / 10 min, 12 g / 10 min, 13 g / 10 min, 14 g / 10 min, 15 g / 10 min, 16 g / 10 min, 17 g / 10 min, 18 g / 10 min, 19 g / 10 min, 20 g / 10 min, 21 g / 10 min, 22 g / 10 min, 23 g / 10 min, 24 g / 10 min, 25 g / 10 min, 26 g / 10 min, 27 g / 10 min, 28 g / 10 min, 29 g / 10 min, 30 g / 10 min, 30.1 g / 10 min, or within any two of the above values.

[0015] In some embodiments, the melting peak temperature Tm of the ethylene-α-olefin copolymer is 30°C to 100°C. For example, it can be 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, or a range consisting of any two of the above values.

[0016] In some embodiments, the α-olefin used in the ethylene-α-olefin copolymer is a C3-C20 α-olefin or a mixture thereof.

[0017] In some specific embodiments, the α-olefin used in the ethylene-α-olefin copolymer is 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.

[0018] In some embodiments, Mz is 55000 g / mol to 280000 g / mol. For example, it can be 55000 g / mol, 58000 g / mol, 60000 g / mol, 62000 g / mol, 65000 g / mol, 70000 g / mol, 75000 g / mol, 80000 g / mol, 85000 g / mol, 90000 g / mol, 100000 g / mol, 120000 g / mol, 140000 g / mol, 160000 g / mol, 180000 g / mol, 200000 g / mol, 220000 g / mol, 240000 g / mol, 260000 g / mol, 280000 g / mol, or within any two of the above values.

[0019] In some embodiments, Mp is 30,000 g / mol to 120,000 g / mol. For example, it can be 30,000 g / mol, 40,000 g / mol, 50,000 g / mol, 60,000 g / mol, 70,000 g / mol, 80,000 g / mol, 90,000 g / mol, 100,000 g / mol, 110,000 g / mol, 120,000 g / mol, or within any two of the above values.

[0020] In some implementations, Iv is 0.5 dL / g to 1.64 dL / g. For example, it can be 0.5 dL / g, 0.6 dL / g, 0.7 dL / g, 0.8 dL / g, 0.9 dL / g, 1.0 dL / g, 1.1 dL / g, 1.2 dL / g, 1.3 dL / g, 1.4 dL / g, 1.5 dL / g, 1.6 dL / g, 1.64 dL / g, or a range consisting of any two of the above values.

[0021] In some preferred embodiments, the ethylene-α-olefin copolymer has a melt flow rate (MFR) of 3 g / 10 min to 16 g / 10 min at 190 °C and under a load of 2.16 kg.

[0022] In some preferred embodiments, the melting peak temperature Tm of the ethylene-α-olefin copolymer is 40~75°C.

[0023] Secondly, this application also provides a method for preparing any of the above-described ethylene-α-olefin copolymers, comprising the following steps:

[0024] The ethylene-α-olefin copolymer is obtained by polymerizing ethylene with one or more α-olefins in the presence of a catalyst and optional chain transfer agent;

[0025] The polymerization is either solution polymerization or gas-phase polymerization; the maximum temperature difference in the reactor for solution polymerization is 0.3~4℃; the maximum temperature difference in the reactor for gas-phase polymerization is 0.4~4.5℃.

[0026] In some embodiments, the maximum temperature difference within the reactor for solution polymerization is 0.3 to 4°C. For example, it can be 0.3°C, 0.5°C, 0.7°C, 0.9°C, 1.1°C, 1.3°C, 1.5°C, 1.7°C, 1.9°C, 2.1°C, 2.3°C, 2.5°C, 2.7°C, 2.9°C, 3.1°C, 3.3°C, 3.5°C, 3.7°C, 3.9°C, 4.0°C, or a range consisting of any two of the above values.

[0027] In some embodiments, the maximum temperature difference within the gas-phase polymerization reactor is 0.4 to 4.5°C. For example, it can be 0.4°C, 0.5°C, 0.7°C, 0.9°C, 1.1°C, 1.3°C, 1.5°C, 1.7°C, 1.9°C, 2.1°C, 2.3°C, 2.5°C, 2.7°C, 2.9°C, 3.1°C, 3.3°C, 3.5°C, 3.7°C, 3.9°C, 4.0°C, 4.1°C, 4.2°C, 4.3°C, 4.4°C, 4.5°C, or a range consisting of any two of the above values.

[0028] In some embodiments, the reactor for solution polymerization is one or both of a stirred tank reactor and a loop reactor.

[0029] In some embodiments, the reaction temperature of the solution polymerization is 120~200°C and the pressure is 2~10 MPa.

[0030] In some preferred embodiments, the reaction temperature of the solution polymerization is 125~195°C and the pressure is 2.5~9.5 MPa.

[0031] In some embodiments, the catalyst for the solution polymerization is a metallocene catalyst or a metallocene catalyst.

[0032] In some embodiments, the catalyst for the gas-phase polymerization is a supported metallocene catalyst.

[0033] In some embodiments, the solvent used in the solution polymerization or gas-phase polymerization process is a hydrocarbon solvent.

[0034] In some embodiments, the solvent used in the solution polymerization is selected from one or more of C5-C12 alkanes or C5-C12 cycloalkanes.

[0035] In some embodiments, the solvent used in the gas-phase polymerization process is a hydrocarbon solvent, specifically a C2-C5 alkane.

[0036] The catalyst used in the solution polymerization in this application is a homogeneous catalyst conventionally used in the art, such as a metallocene catalyst or a metallocene catalyst. Preferred components include dimethicyl(N-tert-butylamino)(tetramethylcyclopentadienyl)titanium chloride, dimethicyl(N-tert-butylamino)(tetramethylcyclopentadienyl)dimethyltitanium, dimethicyl(N-tert-butylamino)(fluorenyl)titanium chloride, (pentamethylcyclopentadienyl)trimethoxytitanium, diphenylmethylene(cyclopentadiene)(9-fluorenyl)zirconium chloride, dimethylmethylenesilylbis(2-methyl-4-phenyl-1-indenyl)zirconium chloride, racemic dimethylsilylbis(1-indenyl)zirconium chloride, bis(methylcyclopentadiene)zirconium chloride, (bis(1,3-dimethylcyclopentadienyl)zirconium chloride, (cyclopentadienyl)(1,2-dimethoxyethane)zirconium trichloride, and diphenylsilyl(cyclopentadiene) (9-fluorenyl)zirconia, racemic dimethylsilylbis(2-methyl-1-indene)zirconia, diphenylmethylenecyclopentadiene(2,7-di-tert-butyl-fluorenyl)zirconia, di-p-tolymethylenecyclopentadiene(2,7-di-tert-butyl-fluorenyl)zirconia, dimethylbis(propylcyclopentadienyl)hafnium, bis(n-butylcyclopentadiene)hafnium, dimethylsilylbis(2-methyl-4-phenylindene)zirconia, and compounds represented by the following formula.

[0037]

[0038]

[0039]

[0040] .

[0041] In solution polymerization, the solvent is in a liquid or supercritical state under polymerization conditions. The solvent is typically and preferably a hydrocarbon solvent. The liquid hydrocarbon solvent used is preferably one or more of C5-12 alkanes or C5-12 cycloalkanes, which may be unsubstituted or substituted with C1-C4 alkyl groups (e.g., pentane, methylpentane, hexane, heptane, octane, cyclohexane, methylcyclohexane, and hydrogenated naphtha), more preferably hexane, C6 mixed alkanes, methylcyclohexane, or IsoparE, etc.

[0042] In solution polymerization, the chain transfer agent can be a chain transfer agent commonly used in the art, such as hydrogen.

[0043] In the solution polymerization process described in this application, a co-catalyst may also be added.

[0044] In some embodiments, the cocatalyst is one or more of aluminoxane, alkylaluminum compound, and alkylaluminum chloride, or a combination of one or more of aluminoxane, alkylaluminum compound, and alkylaluminum chloride with one or more organoborides;

[0045] In some embodiments, the aluminum oxane includes methylaluminoxane (MAO) and modified methylaluminoxane (MMAO); the alkylaluminum compound includes triethylaluminum, triisobutylaluminum (TIBA), and trioctylaluminum, etc.; the alkylaluminum chloride includes monochloroethylaluminum, sesquiethylaluminum, and dichloroethylaluminum, etc.; the organoboronide is triphenylmethyltetra(pentafluorophenyl)borate, tri(pentafluorophenyl)boron, N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate, bis(octadecylmethyl)tertiaryamine tetra(pentafluorophenyl)borate, and dihydrotallowylmethyl)tertiaryamine tetra(pentafluorophenyl)borate.

[0046] In one embodiment, the molar ratio Al / M of aluminum in the co-catalyst to transition metal M in the main catalyst is 5 to 1000, for example, it can be 5, 10, 20, 50, 80, 100, 120, 140, 160, 180, 200, 300, 400, 500, 600, 700, 800 or 1000, more preferably 10 to 100.

[0047] In one embodiment, the molar ratio B / M of boron in the organoboride to transition metal M in the main catalyst is 0 to 10, for example, it can be 0, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9 or 10, preferably 1 to 3.

[0048] In some embodiments, the reactor for gas-phase polymerization is selected from one or more of a fluidized bed reactor, a stirred bed reactor, and a loop gas-phase reactor.

[0049] In some embodiments, the reaction temperature of the gas-phase polymerization is 25~110°C and the pressure is 1~3MPa.

[0050] In some preferred embodiments, the reaction temperature of the gas-phase polymerization is 30~105°C and the pressure is 1.3~2.8 MPa.

[0051] The catalyst used in the gas-phase polymerization in this application is a conventionally used supported metallocene catalyst in the art. Preferred metallocene catalysts include zirconium dichlorodi ... (1,2-Dimethoxyethane)zirconium trichloride, diphenylsilyl(cyclopentadiene)(9-fluorenyl)zirconium dichloride, racemic dimethylsilylbis(2-methyl-1-indene)zirconium dichloride, diphenylmethylenecyclopentadiene(2,7-di-tert-butyl-fluorenyl)zirconium dichloride, di-p-tolymethylenecyclopentadiene(2,7-di-tert-butyl-fluorenyl)zirconium dichloride, dimethylbis(propylcyclopentadienyl)hafnium, bis(n-butylcyclopentadiene)hafnium dichloride, dimethylsilylbis(2-methyl-4-phenylindene)zirconium dichloride.

[0052] In the gas-phase polymerization process, the solvent is in a gaseous state under polymerization conditions and is used as an inducing condenser. The solvent is typically and preferably a hydrocarbon solvent. The liquid hydrocarbon solvent used is preferably a C2-C5 alkane, which may be an unsubstituted or C1-C2 alkyl-substituted alkane (e.g., ethane, propane, butane, isobutane, pentane, isopentane, 2-ethylpropane), more preferably propane, isobutane, or isopentane, etc.

[0053] In the gas-phase polymerization process, the chain transfer agent can be a chain transfer agent commonly used in the art, such as hydrogen.

[0054] In the gas-phase polymerization process described in this application, a co-catalyst may also be added.

[0055] In some embodiments, the cocatalyst is one or more of aluminoxane, alkylaluminum compound, and alkylaluminum chloride;

[0056] In one embodiment, the aluminum oxane includes methylaluminoxane (MAO) and modified methylaluminoxane (MMAO); the alkylaluminum compound includes triethylaluminum, triisobutylaluminum (TIBA), and trioctylaluminum, etc.; the alkylaluminum chloride includes monochloroethylaluminum, sesquiethylaluminum, and dichloroethylaluminum, etc.

[0057] In one embodiment, the molar ratio Al / M of aluminum in the co-catalyst to transition metal M in the main catalyst is 0 to 1000, for example, it can be 0, 5, 10, 20, 50, 80, 100, 120, 140, 160, 180, 200, 300, 400, 500, 600, 700, 800 or 1000, more preferably 10 to 100.

[0058] In some embodiments, the solution polymerization or gas-phase polymerization also uses a co-catalyst.

[0059] In some embodiments, the cocatalyst is selected from one or more of aluminoxanes, alkylaluminum compounds, and alkylaluminum chlorides, or from one or more of aluminoxanes, alkylaluminum compounds, and alkylaluminum chlorides combined with one or more organoborides.

[0060] Thirdly, this application provides an encapsulating composition comprising an ethylene-α-olefin copolymer according to any of the first aspects of this application or an ethylene-α-olefin copolymer prepared by any of the preparation methods described in any of the second aspects of this application.

[0061] By using the encapsulating agent composition, modified resin compositions, such as silane-modified resin compositions or aminosilane-modified resin compositions, can be prepared.

[0062] In one embodiment, the encapsulating agent composition is used to encapsulate a solar cell.

[0063] The encapsulating agent composition according to this application can be used to improve the degree of crosslinking or shorten the mixing time of the additives and copolymers.

[0064] The encapsulating agent composition may also include other components conventionally added in the art, specifically, for example, one or more of crosslinking agents, antioxidants, coupling agents, and co-crosslinking agents. Of course, other additional components permitted in the art may also be included.

[0065] For example, the crosslinking agent can be a peroxide-based crosslinking agent, comprising, but not limited to, one or more combinations of the following compounds: tert-butyl peroxycarbonate isopropyl ester, 2,5-dimethyl-2,5-(bis-tert-butylperoxy)hexane, tert-butyl peroxycarbonate-2-ethylhexyl ester, 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, 1,1-bis(tert-pentylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, 2,2-bis(tert-butylperoxy)butane, tert-butyl peroxy-2-ethylhexyl carbonate, tert-pentyl peroxy-(2-ethylhexyl) carbonate, tert-pentyl peroxycarbonate, and tert-butyl peroxy-3,3,5-trimethylhexanoate. The amount of crosslinking agent can be conventionally set by those skilled in the art as needed.

[0066] For example, the antioxidant may be one or more combinations of hindered phenolic antioxidants and phosphate ester antioxidants, including but not limited to compositions of one or more of the following compounds: β-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate n-octadecyl alcohol ester, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], bis(3,5-di-tert-butyl-4-hydroxypropionyl)hydrazine, 2,2'-oxamido-bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate, N,N'-hexamethylenebis( 3,5-Di-tert-butyl-4-hydroxyphenylpropionamide), 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-tert-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, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate. Based on 100 parts by weight of the ethylene-α-olefin copolymer, the amount of antioxidant can be 0.01-1 parts by weight, preferably 0.05-0.5 parts by weight.

[0067] For example, the coupling agent can be a silane coupling agent, including but 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, anilinemethyltriethoxysilane, and octyltrimethoxysilane. The amount of the coupling agent can be conventionally set by those skilled in the art as needed.

[0068] For example, the co-crosslinking agent is selected from one or more of acrylates and isocyanurates, including but not limited to combinations of one or more of the following substances: triallyl isocyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, tri(2-hydroxyethyl)isocyanurate triacrylate, ethoxylated trimethylolpropane triacrylate, propionylated trimethylolpropane triacrylate, ethoxylated glycerol triacrylate, propionylated glycerol triacrylate, pentaerythritol tetrapropylene. The crosslinking agents include esters, pentaerythritol tetraacrylate ethoxylate, trimethylolpropane tetraacrylate, bis(trimethylolpropane) tetraacrylate, bis(trimethylolpropane) tetramethacrylate, pentaerythritol tetraacrylate propionate, tricyclodecanediethanol diacrylate, neopentyl glycol diacrylate propionate, bisphenol A diacrylate ethoxylate, bisphenol A dimethacrylate ethoxylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate. The amount of the crosslinking agent can be conventionally set by those skilled in the art as needed.

[0069] In some embodiments, based on 100 parts by weight of the ethylene-α-olefin copolymer, the encapsulating agent composition comprises: 100 parts by weight of the ethylene-α-olefin copolymer; 0.1 to 5 parts by weight, preferably 0.5 to 2 parts by weight of a crosslinking agent; 0.01 to 1 part by weight, preferably 0.05 to 0.5 parts by weight of an antioxidant; 0.1 to 3 parts by weight, preferably 0.1 to 0.6 parts by weight of a coupling agent; and 0.1 to 5 parts by weight, preferably 0.1 to 2 parts by weight of a co-crosslinking agent.

[0070] According to another aspect of this application, an adhesive film is provided, which is prepared using the encapsulating agent composition described in this application.

[0071] In one embodiment, the adhesive film is a solar cell encapsulation film.

[0072] According to another aspect of this application, a method for preparing the encapsulating film described above is also provided, comprising the following steps: mixing and melting the components of the composition, extruding and casting them into a film, and then cooling and slitting the film. Specifically, a winding step may also be included. The specific process operations and process conditions of this preparation method can be performed with reference to conventional methods in the art, and there are no particular limitations thereto.

[0073] In this application, the maximum temperature difference inside the reactor refers to the maximum temperature difference at different locations inside the reactor, specifically the temperature difference between the two ends of the straight section of the reactor, calculated according to the following formula: Maximum temperature difference inside the reactor = Temperature at the top of the straight section of the reactor - Temperature at the bottom of the straight section of the reactor.

[0074] In this application, solution polymerization or gas-phase polymerization can control the mixing effect by controlling the mixing speed, circulation ratio, etc., thereby achieving the regulation of the maximum temperature difference in the reactor.

[0075] In this application, "optional" means that the matter or event described thereafter may or may not occur, and the description includes both the scenario in which the event occurs and the scenario in which the event does not occur.

[0076] The technical solution of this invention has the following advantages:

[0077] 1. The ethylene-α-olefin copolymer provided by the present invention, wherein the ethylene-α-olefin copolymer satisfies the following conditions (1) to (3); (1) the density is 0.850 g / cm³. 3 ~0.910g / cm 3 (2) The weight-average molecular weight is 20000 g / mol to 200000 g / mol, and the molecular weight distribution width (PDI) is 2.0 to 4.0. (3) The values ​​of Mz, Mp and Iv satisfy: 0.82≤Mz / Mp-Iv≤2.7. Among them, Mz is the z-average molecular weight, in g / mol; Mp is the molecular weight at the highest peak of the GPC curve, in g / mol; Iv is the intrinsic viscosity, in dL / g. It has been found that ethylene-α-olefin copolymers with density, weight-average molecular weight and Mz / Mp-Iv within the above range have moderate or relatively more high molecular weight polymer chains, which can improve the crosslinking degree of the polymer, and its viscosity is relatively low, avoiding the influence of high molecular weight polymer on processing performance, thus making ethylene-α-olefin copolymers have both good crosslinking ability and excellent processing performance.

[0078] When Mz / Mp-Iv is too high (greater than 2.7), the molecular weight of the high-molecular-weight polymer chains differs significantly from the molecular weight of the polymer at the peak of the GPC curve, resulting in excessively low overall viscosity. This makes crosslinking difficult or requires more crosslinking aids to ensure a high degree of crosslinking, thus increasing costs. When Mz / Mp-Iv is too low (less than 0.82), the molecular weight of the high-molecular-weight polymer chains differs too little from the molecular weight of the polymer at the peak of the GPC curve, resulting in a relatively narrow distribution and making processing difficult, leading to a decrease in processing rates for downstream applications.

[0079] Therefore, if the ethylene-α-olefin copolymer of the present invention, which is within the above range of Mz / Mp-Iv, is used in the encapsulant composition, the copolymer has a high degree of crosslinking and a high processing speed, which meets the application requirements of photovoltaic films. It has high mechanical properties, high degree of crosslinking, and is easier to process and cast into films.

[0080] 2. The preparation method of the ethylene-α-olefin copolymer provided by the present invention is simple and convenient to operate. By controlling the maximum temperature difference in the reactor of the solution polymerization to be 0.3~4℃ and the maximum temperature difference in the reactor of the gas-phase polymerization to be 0.4~4.5℃, the values ​​of Mz, Mp and Iv satisfy: 0.82≤Mz / Mp-Iv≤2.7, thereby enabling the ethylene-α-olefin copolymer to have both good crosslinking ability and excellent processing performance. Detailed Implementation

[0081] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0082] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0083] The materials and reagents used in the following examples are all commercially available, as detailed below:

[0084] IsoparE, 100% hydrogenated naphtha, Mobil;

[0085] C6 mixed alkanes (industrial hexane), 100% alkanes, Shandong Jingbo Petrochemical Co., Ltd.;

[0086] 1-Octenene, 98%, INEOS Group;

[0087] 1-Hexene, 99%, Hubei Lingyan Biotechnology Co., Ltd.;

[0088] Ethylene, polymer grade, Air Liquide (France).

[0089] 1-Butene, 99%, Air Liquide (France).

[0090] Isopentane, 99.6%, Heze Xileng Chemical Co., Ltd.;

[0091] UL0588, Ethylene-Butene Copolymer, Dushanzi Petrochemical Company;

[0092] UL1488, Ethylene-Butene Copolymer, Dushanzi Petrochemical Company;

[0093] 2,7-di-tert-butylfluorenyl zirconium dichloride, 99%, Wuxi Yaodexin Chemical Products Co., Ltd., designated as M1;

[0094] Dimethicone (N-tert-butylamino) (tetramethylcyclopentadienyl)dimethyltitanium, 99%, Strem Reagent Company, designated as M2;

[0095] Modified methylaluminoxane (MMAO), 7wt% aluminum solution (MMAO-7 in Isopar E solution), Norin;

[0096] Triisobutylaluminum (TIBA), using a 1 mol / L hexane solution of triisobutylaluminum, Inokai;

[0097] N,N-Dimethylphenylammonium tetra(pentafluorophenyl)borate, 99%, Inokai, soluble in toluene, designated as B1;

[0098] Diphenylmethylene (cyclopentadiene) (9-fluorenyl)zirconium dichloride, Wuxi Yaodexin Chemical Products Co., Ltd., 98%, designated as M3;

[0099] (M4)

[0100] Compound (M4) was synthesized according to Example 16 of patent CN202010798198.8;

[0101] SLD-MG01, supported metallocene catalyst, Shanghai Lide Catalyst Co., Ltd., designated as M5;

[0102] SLCM-100G, supported metallocene catalyst, Shanghai Lide Catalyst Co., Ltd., designated as M6;

[0103] 2-Ethylhexyl tert-butyl peroxide, Akzo Corporation, purity >95%;

[0104] Triallyl isocyanurate, Acros, 98% purity;

[0105] γ-Methacryloxypropyltrimethoxysilane, Aladdin, 95% purity;

[0106] γ-(2,3-epoxypropoxy)propyltrimethoxysilane, Aladdin, purity 95%;

[0107] Bis[2,4-di-tert-butylphenyl]pentaerythritol diphosphite, Acros, 95% purity;

[0108] β-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate n-octadecyl alcohol ester, ark, purity 95%;

[0109] 1,1-Bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, Acros, 95% purity;

[0110] (2-Ethylhexyl) tert-amyl peroxide carbonate, ARK, purity 95%;

[0111] Trimethylolpropane triacrylate, Aladdin, 98% purity;

[0112] Antioxidant 1076, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate n-octadecyl alcohol ester, Lianlong New Materials Co., Ltd., industrial grade;

[0113] Antioxidant 1010, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], Lianlong New Materials Co., Ltd., industrial grade.

[0114] The testing methods for the parameters involved in this invention are as follows:

[0115] (1) Melting peak temperature (Tm) test: DSC was used, with data obtained from the second heating cycle at a rate of 10 °C / min. The specific test procedure was as follows: after cutting the sample granules, DSC analysis was performed on a METTLER DSC 3 differential scanning calorimeter using an FRS6+ sensor. Programmed temperature control was employed: initial temperature 25 °C, increased to 160 °C at 10 °C / min, then decreased to -100 °C at 10 °C / min, held for 3 minutes, and then increased to 160 °C at 10 °C / min. Nitrogen flow rate was 50 mL / min, and sample volume was 5-10 mg. Calibration was performed using In and Zn standard substances.

[0116] (2) Density: Tested using a densitometer. The density of the sample pieces cut from the tablet press was tested using a Mettler XS204 densitometer, employing the impregnation method with anhydrous ethanol (AR) as the impregnation solution. The ambient temperature was 23℃±2℃; the test temperature required internal calibration. The sample mass was greater than 1g, and there were no air bubbles. The mass of the sample in air and in the impregnation solution were weighed separately, and the sample density was calculated using Archimedes' principle.

[0117] (3) The weight-average molecular weight Mw, z-average molecular weight Mz, peak molecular weight Mp, intrinsic viscosity Iv and molecular weight distribution were tested by gel permeation chromatography (GPC). Specifically, the analysis was performed using a polymer char GPC-IR instrument (high-temperature gel permeation chromatograph). This instrument has three MIXED columns connected in series, with a size of 300*7.5mm. It is equipped with infrared, viscosity and laser detectors. The IR5 MCT infrared detector for polyolefins is commonly used for detection. 8 mg of the sample to be tested was automatically injected with 8 ml of trichlorobenzene solvent in the high-temperature zone (160℃) of the instrument's autosampler. After shaking and dissolving for one hour, 200 μL was extracted for testing. The infrared detector temperature was 150℃. The molecular weight standard used was polystyrene (PS). The monomer standard was established using a series of polyolefin elastomers (POE) with different monomer content gradients.

[0118] Examples A1-A4, Comparative Examples A1-A2

[0119] Examples A1-A4 and Comparative Examples A1-A2 each provide a method for preparing an ethylene-α-olefin copolymer, and the preparation methods are as follows:

[0120] Solution polymerization of ethylene and α-olefins was carried out on a continuous solution polymerization platform. The solvent, α-olefin comonomers (1-octene, 1-hexene, or 1-butene), and ethylene were continuously fed into a 25L reactor at the feed rates shown in Tables 1 and 2 after deoxygenation and dehydration in a fixed bed. Simultaneously, hydrogen was supplied to the reactor in gaseous form through a mass controller, and the main catalyst and co-catalyst were prepared into solutions and then supplied to the reactor. Solution polymerization was carried out at different maximum temperature differences in the reactor. The maximum temperature difference in the reactor was adjusted by adjusting the stirring speed or the circulation ratio (the stirring speed was adjusted for stirred tank reactors, and the circulation ratio was adjusted for loop reactors; the circulation ratio is the ratio of the total mass flow rate of the material that leaves the reactor and is then circulated back to the reactor by the circulation pump (referred to as "circulation amount") to the mass flow rate of the fresh material (including solvent, ethylene, and α-olefins) flowing into the reactor (referred to as "total feed amount"). The maximum temperature difference in the reactor was obtained by measuring the difference between the thermocouples at both ends of the straight section of the reactor. The product was then obtained by devolatilization and granulation, and samples were taken for analysis. The reactor's inlet heat exchanger and reaction jacket control the reaction to proceed at a specified temperature. The polymerization temperature in the reactor kettle is obtained through thermocouple testing in the middle of the reactor's cylindrical section. Pressure is controlled and measured via a pneumatic proportional control valve at the reactor outlet; the pressure is hydraulic.

[0121] Table 1 Reaction conditions of Examples A1-A4 and Comparative Examples A1-A2

[0122]

[0123] In the table, "—" indicates that it has not been added.

[0124] Table 2 Reaction conditions of Examples A1-A4 and Comparative Examples A1-A2

[0125]

[0126] In the table, "—" indicates that it has not been added.

[0127] Examples A5-A7, Comparative Examples A3-A4

[0128] Examples A5-A7 and Comparative Examples A3-A4 respectively provide a method for preparing ethylene-α-olefin copolymers, and the preparation methods are as follows:

[0129] Ethylene and α-olefin gas-phase polymerization was carried out on a continuous gas-phase polymerization platform. The solvent (inducing condenser), α-olefin comonomer (1-hexene or 1-butene), and ethylene were continuously fed into a 120L reactor at the feed rates shown in Tables 3 and 4 after deoxygenation and dehydration in a fixed bed. Hydrogen and nitrogen were simultaneously fed into the reactor in gas phase through a mass controller, and the partial pressure of nitrogen was controlled to be 0.2MPa by gas chromatography. The main catalyst was fed into the reactor in powder form, and the co-catalyst was prepared into a solution. The gas-phase polymerization reaction was carried out under different maximum temperature differences in different reactors. The maximum temperature difference in the reactor was controlled by adjusting the gas phase circulation ratio. The maximum temperature difference in the reactor was obtained by measuring the difference between the thermocouples at both ends of the straight section of the reactor. The unreacted monomer, solvent, and nitrogen gas phase exited from the top of the reactor, cooled by a circulating compressor and a circulating heat exchanger, and then re-entered the reactor. The powder obtained from the bottom of the reactor was degassed and granulated to obtain particle products, which were then sampled for analysis. The polymerization temperature of the reactor is controlled by adjusting the temperature of the circulating gas. The polymerization temperature in the reactor is obtained through thermocouple testing in the middle of the straight section of the reactor. The pressure is controlled and measured by a pneumatic proportional control valve at the reactor's gas phase outlet, and the pressure is the gas phase pressure.

[0130] Table 3 Reaction conditions of Examples A5-A7 and Comparative Examples A3-A4

[0131]

[0132] In the table, "—" indicates that it has not been added.

[0133] Table 4 Reaction conditions for Examples A5-A7 and Comparative Examples A3-A4

[0134]

[0135] In the table, "—" indicates that it has not been added.

[0136] The performance test results of the ethylene-α-olefin copolymers prepared in Examples A1-A7 and Comparative Examples A1-A4, as well as two commercially available products (referred to as Comparative Examples 5 and 6, respectively) are shown in Table 5 below.

[0137] Table 5. Properties of copolymers in Examples A1-A7 and Comparative Examples A1-A6

[0138]

[0139] Example B1

[0140] This embodiment provides a method for preparing an encapsulating film, including the following steps:

[0141] 7g of 2-ethylhexyl tert-butyl peroxide, 4.3g of triallyl isocyanurate, 2.2g of γ-methacryloyloxypropyltrimethoxysilane, 1g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 1g of bis[2,4-di-tert-butylphenyl]pentaerythritol diphosphite and 1g of β-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate n-octadecyl alcohol ester were added to 1000g of the ethylene-α-olefin copolymer obtained in Example A1.

[0142] The above raw materials were heated to 30℃ and mixed uniformly for 5 hours. The extruder parameters were adjusted so that the temperature from the feed port to the die head was 80℃, 90℃, 90℃, 90℃, 90℃, 95℃, 95℃, and 95℃. The screw speed was controlled at 45 rpm, the traction speed at 0.7 rpm, and the winding speed at 1.3 rpm. After extrusion, casting, cooling, slitting, and winding processes, a solar cell encapsulating film with a thickness of 0.6 mm was prepared. The screw speed, traction speed, and winding speed were then increased in a gradient of 0.1 m / min to gradually increase the processing speed (the processing speed is the ratio of film length to film time) until stable casting could no longer be achieved. The highest processing speed was recorded (the processing speed before film breakage was taken as the highest processing speed (m / min)).

[0143] Example B2

[0144] This embodiment provides a method for preparing an encapsulating film, including the following steps:

[0145] To 1000g of the ethylene-α-olefin copolymer obtained in Example A2, add 9g of 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1.2g of tert-amyl peroxy(2-ethylhexyl) carbonate, 4.3g of trimethylolpropane triacrylate, 1.8g of γ-methacryloyloxypropyltrimethoxysilane, 1g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 0.1g of antioxidant 1076 and 1g of antioxidant 1010.

[0146] The above raw materials were heated to 30℃ and mixed uniformly for 5 hours. The extruder parameters were adjusted to maintain temperatures from the feed nozzle to the die at 80℃, 90℃, 90℃, 90℃, 90℃, 95℃, 95℃, and 95℃. The screw speed was 45 rpm, the traction speed was 0.7 rpm, and the winding speed was 1.3 rpm. After extrusion, casting, cooling, slitting, and winding processes, a solar cell encapsulating film with a thickness of 0.6 mm was prepared. The screw speed, traction speed, and winding speed were increased until stable casting could no longer be achieved, and the highest processing speed was recorded.

[0147] Example B3

[0148] Except that the ethylene-α-olefin copolymer obtained in Example A3 was used to replace the ethylene-α-olefin copolymer obtained in Example A1, the solar cell encapsulation film was prepared in the same manner as in Example B1.

[0149] Example B4

[0150] Except that the ethylene-α-olefin copolymer obtained in Example A4 was used to replace the ethylene-α-olefin copolymer obtained in Example A1, the solar cell encapsulation film was prepared in the same manner as in Example B1.

[0151] Example B5

[0152] Except that the ethylene-α-olefin copolymer obtained in Example A5 was used to replace the ethylene-α-olefin copolymer obtained in Example A2, the solar cell encapsulation film was prepared in the same manner as in Example B2.

[0153] Example B6

[0154] Except that the ethylene-α-olefin copolymer obtained in Example A6 was used to replace the ethylene-α-olefin copolymer obtained in Example A2, the solar cell encapsulating film was prepared in the same manner as in Example B2.

[0155] Example B7

[0156] Except that the ethylene-α-olefin copolymer obtained in Example A7 was used to replace the ethylene-α-olefin copolymer obtained in Example A2, the solar cell encapsulating film was prepared in the same manner as in Example B2.

[0157] Comparative Example B1

[0158] Except that the ethylene-α-olefin copolymer obtained in Comparative Example A1 was used to replace the ethylene-α-olefin copolymer obtained in Example A1, the solar cell encapsulation film was prepared in the same manner as in Example B1.

[0159] Comparative Example B2

[0160] Except that the ethylene-α-olefin copolymer obtained in Comparative Example A2 was used to replace the ethylene-α-olefin copolymer obtained in Example A1, the solar cell encapsulation film was prepared in the same manner as in Example B1.

[0161] Comparative Example B3

[0162] Except that the ethylene-α-olefin copolymer obtained in Comparative Example A3 was used to replace the ethylene-α-olefin copolymer obtained in Example A2, the solar cell encapsulation film was prepared in the same manner as in Example B2.

[0163] Comparative Example B4

[0164] Except that the ethylene-α-olefin copolymer obtained in Comparative Example A4 was used to replace the ethylene-α-olefin copolymer obtained in Example A2, the solar cell encapsulation film was prepared in the same manner as in Example B2.

[0165] Comparative Example B5

[0166] Except that the ethylene-α-olefin copolymer obtained in Comparative Example A5 was used to replace the ethylene-α-olefin copolymer obtained in Example A1, the solar cell encapsulation film was prepared in the same manner as in Example B1.

[0167] Comparative Example B6

[0168] Except that the ethylene-α-olefin copolymer obtained in Comparative Example A6 was used to replace the ethylene-α-olefin copolymer obtained in Example A2, the solar cell encapsulation film was prepared in the same manner as in Example B2.

[0169] According to the requirements of the China Photovoltaic Industry Association (CPIA), the degree of crosslinking was evaluated using ASTM D276 standard 5. The obtained solar cell encapsulation film was cut into 10cm × 10cm pieces and vacuum-laminated at 150°C for 20 minutes (5 minutes of vacuum maintenance / 1 minute of pressure application / 14 minutes of decompression) to obtain crosslinked samples.

[0170] The crosslinked samples were cut into appropriate sizes, and 0.5 g was weighed onto a 200-mesh wire mesh cage and dissolved in xylene under reflux for 5 hours. Afterward, the samples were dried in a vacuum oven, and the weights before and after reflux were compared to measure the degree of crosslinking for each sample. The degree of crosslinking information obtained from each example and comparative example is shown in Table 6.

[0171] Table 6. Maximum processing speed and degree of crosslinking for ethylene-α-olefin copolymer casting films.

[0172]

[0173] As shown in Table 6, a comparison of Examples B1-B7 and Comparative Examples B1-B6 reveals that the processing speed of the ethylene-α-olefin copolymer cast film described in the embodiments of this application is significantly higher than that of the ethylene-α-olefin copolymers described in Comparative Examples A1-A6. The ethylene-α-olefin copolymer described in this invention is easier to melt, plasticize, and wind into shape in a screw. When using the ethylene-α-olefin copolymer of this invention to cast photovoltaic films, more films can be processed per unit time; that is, the ethylene-α-olefin copolymer of this invention can shorten processing time and improve processing efficiency in the preparation of photovoltaic films.

[0174] As shown in Table 6, a comparison between Examples B1-B7 and Comparative Examples B1-B6 reveals that the ethylene-α-olefin copolymers described in each embodiment of this application can improve the crosslinking degree of photovoltaic encapsulant products. Crosslinking can improve the strength of the material, thus making it more suitable for the photovoltaic encapsulant film field.

[0175] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An ethylene-α-olefin copolymer, characterized in that, The ethylene-α-olefin copolymer satisfies the following conditions (1) to (3): (1) The density is 0.850 g / cm³ 3 ~0.910g / cm 3 ; (2) The weight-average molecular weight is 20,000 g / mol to 200,000 g / mol, and the molecular weight distribution width (PDI) is 2.0 to 4.1; (3) The values ​​of Mz, Mp and Iv satisfy: 0.82≤Mz / Mp-Iv≤2.70; where Mz is the z-average molecular weight in g / mol; Mp is the molecular weight at the highest peak of the GPC curve in g / mol; and Iv is the intrinsic viscosity in dL / g.

2. The ethylene-α-olefin copolymer according to claim 1, characterized in that, The ethylene-α-olefin copolymer has a melt flow rate (MFR) of 0.1 g / 10 min to 30.1 g / 10 min at 190 °C and under a load of 2.16 kg. And / or, the melting peak temperature Tm of the ethylene-α-olefin copolymer is 30℃~100℃; And / or, the α-olefin used in the ethylene-α-olefin copolymer is a C3-C20 α-olefin or a mixture thereof; And / or, Mz is 55000 g / mol to 280000 g / mol; And / or, Mp is 30000 g / mol to 120000 g / mol; And / or, Iv is 0.5 dL / g to 1.64 dL / g.

3. The ethylene-α-olefin copolymer according to claim 2, characterized in that, The ethylene-α-olefin copolymer has a melt flow rate (MFR) of 3 g / 10 min to 16 g / 10 min at 190 °C and under a load of 2.16 kg. And / or, the melting peak temperature Tm of the ethylene-α-olefin copolymer is 40~75℃; And / or, 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.

4. A method for preparing an ethylene-α-olefin copolymer according to any one of claims 1-3, characterized in that, Includes the following steps: The ethylene-α-olefin copolymer is obtained by polymerizing ethylene with one or more α-olefins in the presence of a catalyst and optional chain transfer agent; The polymerization is either solution polymerization or gas-phase polymerization; the maximum temperature difference in the reactor for solution polymerization is 0.3~4℃; the maximum temperature difference in the reactor for gas-phase polymerization is 0.4~4.5℃.

5. The method for preparing the ethylene-α-olefin copolymer according to claim 4, characterized in that, The reactor for solution polymerization is one or both of a stirred tank reactor and a loop reactor; And / or, the reactor for gas-phase polymerization is selected from one or more of fluidized bed reactors, stirred bed reactors, and loop gas-phase reactors; And / or, the reaction temperature of the solution polymerization is 120~200℃, and the pressure is 2~10MPa; And / or, the reaction temperature of the gas-phase polymerization is 25~110℃, and the pressure is 1~3MPa; And / or, the catalyst for the solution polymerization is a metallocene catalyst or a post-metallocene catalyst; And / or, the catalyst for the gas-phase polymerization is a supported metallocene catalyst; And / or, in the solution polymerization or gas-phase polymerization process, the solvent used is a hydrocarbon solvent; And / or, a co-catalyst is also used in the solution polymerization or gas-phase polymerization.

6. The method for preparing the ethylene-α-olefin copolymer according to claim 4, characterized in that, In the solution polymerization, the solvent used is selected from one or more of C5-C12 alkanes or C5-C12 cycloalkanes; And / or, in the gas-phase polymerization process, the solvent used is a C2-C5 alkane; And / or, in the solution polymerization, the cocatalyst used is selected from one or more of aluminoxanes, alkylaluminum compounds and alkylaluminum chlorides, or a combination of one or more of aluminoxanes, alkylaluminum compounds and alkylaluminum chlorides with one or more organoborides; And / or, in the gas-phase polymerization, the cocatalyst used is selected from one or more of aluminoxanes, alkylaluminum compounds, and alkylaluminum chlorides; And / or, the reaction temperature for the solution polymerization is 125~195℃, and the pressure is 2.5~9.5MPa; And / or, the reaction temperature of the gas-phase polymerization is 30~105℃ and the pressure is 1.3~2.8MPa.

7. An encapsulating agent composition, characterized in that, The encapsulating agent composition comprises an ethylene-α-olefin copolymer according to any one of claims 1-3 or an ethylene-α-olefin copolymer prepared by any one of claims 4-6; The encapsulating agent composition further includes one or more selected from crosslinking agents, antioxidants, coupling agents, and co-crosslinking agents.

8. The encapsulating agent composition according to claim 7, characterized in that, The encapsulating agent composition comprises: 100 parts by weight of an ethylene-α-olefin copolymer; 0.1 to 5 parts by weight of a crosslinking agent; 0.01 to 1 part by weight of an antioxidant; and 0.1 to 3 parts by weight of a coupling agent. And 0.1 to 5 parts by weight of crosslinking agent.

9. The encapsulating agent composition according to claim 7 or 8, characterized in that, The crosslinking agent is a peroxide-based crosslinking agent; And / or, the antioxidant is one or more selected from hindered phenolic antioxidants and phosphate ester antioxidants; And / or, the coupling agent is a silane coupling agent; And / or, the crosslinking agent is selected from one or more of acrylates and isocyanurates.

10. A film, characterized in that, The film is prepared using the encapsulating agent composition according to any one of claims 7-9.

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