Method for producing an ethylene-α-olefin copolymer, an ethylene-α-olefin copolymer, a resin composition for solar cell encapsulation containing the same, and a solar cell encapsulation

Abstract

The present invention provides a method for producing an ethylene-α-olefin copolymer, an ethylene-α-olefin copolymer, a resin composition for solar cell encapsulation containing the same, and an encapsulation material for solar cells. The ethylene-α-olefin copolymer can be produced by a method for producing an ethylene-α-olefin copolymer, which includes the step of reacting ethylene with an α-olefin copolymer in the presence of a catalyst composition containing a transition metal compound represented by chemical formula 1. [Formula 1] JPEG2026521846000019.jpg69166

Description

[Technical Field]

[0001] The present invention relates to a method for producing an ethylene-α-olefin copolymer, an ethylene-α-olefin copolymer, a resin composition for solar cell encapsulating materials, and a solar cell encapsulating material. [Background technology]

[0002] Recently, along with the expansion of the new renewable energy market, the solar power market has also grown explosively. Among these, olefin materials are widely used as encapsulants for solar panels.

[0003] Currently, the most commonly used encapsulating material is EVA (ethylene vinyl acetate)-based material, used to attach and encapsulate photocells or photocell arrays to a ferroelectric material. However, EVA has poor adhesion to glass and other components of the module, which easily induces delamination between the layers of the module after prolonged use, leading to decreased module efficiency and corrosion due to moisture penetration.

[0004] Furthermore, known encapsulants lose their durability against ultraviolet (UV) light, and prolonged use can lead to problems such as discoloration or fading, as well as PID (Potential Induced Degradation), which also reduces module efficiency. Additionally, encapsulants made from resins such as EVA have the problem of generating stress during curing, which can damage the module.

[0005] To address these issues, the use of ethylene-α-olefin copolymers has recently gained attention. This material protects the solar energy-producing cells, provides adhesion to the glass and backsheet, and protects them from moisture and external impacts.

[0006] However, ethylene-α-olefin copolymers have the problem of degrading and decreasing power generation efficiency when exposed to the elements for extended periods. To prevent this, it is necessary to improve their volume resistivity and light transmittance.

[0007] Furthermore, ethylene-α-olefin copolymers have a relatively slower crosslinking rate compared to EVA. When conventional module manufacturing processes are applied to ethylene-α-olefin copolymer products, the slow crosslinking rate can lead to insufficient crosslinking, resulting in adhesion problems. While high-temperature, long-duration molding has been proposed as a way to compensate for this, this method carries the risk of deformation such as yellowing or thermal shrinkage.

[0008] Therefore, there is a need for a method that enables crosslinking of ethylene-α-olefin copolymers to occur as quickly as possible, even at low temperatures. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] As one finding, this invention aims to provide a method for producing ethylene-α-olefin copolymers that enables crosslinking to occur as quickly as possible, even at low temperatures.

[0010] Furthermore, as a first finding, the present invention aims to provide an ethylene-α-olefin copolymer having high volume resistivity, excellent light transmittance, and a fast crosslinking rate.

[0011] Furthermore, as another finding of the present invention, we aim to provide a resin composition for solar cell encapsulants containing the ethylene-α-olefin copolymer.

[0012] Furthermore, the present invention also aims to provide a encapsulant for solar cells that exhibits excellent crosslinking ratio and transparency. [Means for solving the problem]

[0013] The present invention provides a method for producing an ethylene-α-olefin copolymer, the method comprising the step of reacting ethylene with an α-olefin copolymer in the presence of a catalyst composition containing a transition metal compound represented by Chemical Formula 1.

[0014]

Chemical Formula

[0015] The transition metal compound represented by chemical formula 1 may be the transition metal compound represented by chemical formula 1-1.

[0016] [ka]

[0017] The transition metal compound represented by the chemical formula 1 may have catalytic activity of 200 kg / g-cat or more.

[0018] The catalyst composition may further include at least one co-catalyst selected from the group consisting of compounds represented by chemical formula 2 and compounds represented by chemical formula 3.

[0019] [ka]

[0020] [ka]

[0021] In chemical formulas 2 and 3, L is a neutral or positively ionic Lewis acid, Z is a group 13 element, and A is (C6-C 20 )aryl or (C1-C 20 ) It may be alkyl.

[0022] The α-olefin may include at least one selected from the group consisting of propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-aitocene, 4,4-dimethyl-1-pentene, 4,4-diethyl-1-hexene, and 3,4-dimethyl-1-hexene.

[0023] In other findings, the present invention provides an ethylene-α-olefin copolymer, which may be any one produced by the method described above.

[0024] The ethylene-α-olefin copolymer may have a weight-average molecular weight of 10,000 to 1,000,000, a molecular weight distribution of 1 to 10, and a density of 0.868 to 0.880 g / mL.

[0025] Furthermore, the ethylene-α-olefin copolymer may contain α-olefin in an amount of 20 to 40% by weight.

[0026] Furthermore, as another finding, the present invention provides a resin composition for solar cell encapsulants, the resin composition comprising an ethylene-α-olefin copolymer produced by any one of the above methods, a crosslinking agent, and optionally further comprising a crosslinking aid.

[0027] The aforementioned resin composition for solar cell encapsulation may have a time (T90) of 600 to 700 seconds until the torque value reaches 90% saturation at 150°C during crosslinking.

[0028] The ethylene-α-olefin copolymer may have a weight-average molecular weight of 10,000 to 1,000,000, a molecular weight distribution of 1 to 10, and a density of 0.860 to 0.885 g / mL.

[0029] The ethylene-α-olefin copolymer may be produced by adding α-olefin in a content of 19 to 40% by weight.

[0030] Furthermore, the present invention also provides a solar cell encapsulant comprising an ethylene-α-olefin copolymer produced by any one of the above methods and a crosslinking agent.

[0031] Furthermore, the sealing material must either i) have a Yellow Index of 2 or less for a 3 mm thick film, or ii) have a volume resistivity of 0.1 × 10⁻⁶ when measured according to ASTM D257. 16 It can be greater than Ω·cm.

[0032] Furthermore, the sealing material may have a light transmittance of 90% or more and 99% or less for light with a wavelength of 550 nm on a 3 mm thick film. [Effects of the Invention]

[0033] The ethylene-α-olefin copolymer provided in this invention has high volume resistivity and excellent light transmittance, and exhibits a fast crosslinking rate.

[0034] When using the ethylene-α-olefin copolymer with a shortened crosslinking rate provided in the present invention as a encapsulant for solar cells, the speed at which it reaches the same degree of crosslinking is faster, which can significantly reduce the working time in the production of solar panels. [Brief explanation of the drawing]

[0035] [Figure 1] This graph shows the results of the low-temperature TGIC analysis of the ethylene-α-olefin copolymer obtained in Example 1. [Figure 2]This graph shows the results of the low-temperature TGIC analysis of the ethylene-α-olefin copolymer obtained in Comparative Example 1. [Modes for carrying out the invention]

[0036] The present invention will be described in detail below. However, embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0037] As used in this invention, the term "alkyl" refers to a monovalent linear or branched saturated hydrocarbon radical composed only of carbon and hydrogen atoms. Examples of such alkyl radicals include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, octyl, dodecyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl.

[0038] Furthermore, the term "alkenyl" as used in this invention refers to a linear or branched hydrocarbon radical containing one or more carbon-carbon double bonds, and includes, but is not limited to, ethenyl, propenyl, butenyl, and pentenyl.

[0039] Furthermore, the term "alkynyl" as used in this invention refers to a linear or branched hydrocarbon radical containing one or more carbon-carbon triple bonds, and includes, but is not limited to, methynyl, ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, and octinyl.

[0040] Furthermore, the term "aryl" as used in this invention refers to an organic radical derived from an aromatic hydrocarbon by removing one hydrogen atom, and includes single or fused ring systems. Specific examples include, but are not limited to, phenyl, naphthyl, biphenyl, anthryl, fluorenyl, phenanthryl, triphenylenyl, pyrenyl, perilenyl, crisenyl, naphthacenyl, and fluoranthenyl.

[0041] Furthermore, the term "alkylaryl" as used in this invention refers to an organic group in which one or more hydrogen atoms of an aryl group are substituted by an alkyl group, and includes, but is not limited to, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, and t-butylphenyl.

[0042] Furthermore, the term "arylalkyl" as used in this invention refers to an organic group in which one or more hydrogen atoms of an alkyl group are substituted with an aryl group, and includes, but is not limited to, phenylpropyl and phenylhexyl.

[0043] Furthermore, the term "amide" as used in this invention means an amino group (-NH2) bonded to a carbonyl group (C=O), "alkylamide" means an organic group in which at least one hydrogen in the -NH2 of an amide group is substituted with an alkyl group, and "arylamide" means an organic group in which at least one hydrogen in the -NH2 of an amide group is substituted with an aryl group. The alkyl group in the alkylamide group and the aryl group in the arylamide group may be the same as the examples of alkyl and aryl groups described above, but are not limited to these.

[0044] Furthermore, the term "alkylidene" as used in this invention refers to a divalent aliphatic hydrocarbon group in which two hydrogen atoms are removed from the same carbon atom of an alkyl group, and includes, but is not limited to, ethylidene, propylidene, isopropylidene, butylidene, and pentylidene.

[0045] Furthermore, the term "acetal" as used in this invention refers to an organic group formed by the bonding of an alcohol and an aldehyde, that is, a substituent having two ether (-OR) bonds to one carbon, and includes, but is not limited to, methoxymethoxy, 1-methoxyethoxy, 1-methoxypropyloxy, 1-methoxybutyloxy, 1-ethoxyethoxy, 1-ethoxypropyloxy, 1-ethoxybutyloxy, 1-(n-butoxy)ethoxy, 1-(iso-butoxy)ethoxy, 1-(sec-butoxy)ethoxy, 1-(tert-butoxy)ethoxy, 1-(cyclohexyloxy)ethoxy, 1-methoxy-1-methylmethoxy, 1-methoxy-1-methylethoxy, and the like.

[0046] Furthermore, the term "ether" as used in this invention refers to an organic group having at least one ether linkage (-O-), and includes, but is not limited to, 2-methoxyethyl, 2-ethoxyethyl, 2-butoxyethyl, 2-phenoxyethyl, 2-(2-methoxyethoxy)ethyl, 3-methoxypropyl, 3-butoxypropyl, 3-phenoxypropyl, 2-methoxy-1-methylethyl, 2-methoxy-2-methylethyl, 2-methoxyethyl, 2-ethoxyethyl, 2-butoxyethyl, and 2-phenoxyethyl.

[0047] Furthermore, the term "silyl" as used in this invention refers to a -SiH3 radical derived from silane, in which at least one of the hydrogen atoms in the silyl can be substituted with various organic groups such as alkyl and halogen, and more specifically includes, but is not limited to, trimethylsilyl, triethylsilyl, t-butyldimethylsilyl, vinyldimethylsilyl, propyldimethylsilyl, triphenylsilyl, diphenylsilyl, phenylsilyl, trimethoxysilyl, methyldimethoxysilyl, ethyldiethoxysilyl, triethoxysilyl, vinyldimethoxysilyl, and triphenoxysilyl.

[0048] Furthermore, the term "alkoxy" as used in this invention means an -O-alkyl radical, where "alkyl" is defined as described above. Examples of such alkoxy radicals include, but are not limited to, methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, and t-butoxy.

[0049] Furthermore, the term "halogen" as used in this invention refers to a fluorine, chlorine, bromine, or iodine atom.

[0050] Furthermore, the term "C" as described in the present invention n " means that there are n carbon atoms.

[0051] The present invention provides a method for producing an ethylene-α-olefin copolymer by polymerizing ethylene and at least one α-olefin monomer in the presence of a catalyst composition comprising a main catalyst compound and a co-catalyst compound, and an ethylene-α-olefin copolymer produced by the said method.

[0052] This invention includes a main catalyst compound comprising a transition metal compound represented by the following chemical formula 1.

[0053] [ka]

[0054] R 1 ~R 6 These are independently hydrogen; halogen; silyl; (C1-C 20 )alkyl;(C3-C 20 )Cycloalkyl; (C2-C 20 ) Alkenyl; (C1-C 20 )alkoxy;halogen, (C1-C 12 )alkyl, (C3-C 12 )Cycloalkyl, (C1-C8)alkoxy, (C6-C 12 ) substituted or unsubstituted (C6-C 20 ) Aryl; Halogen, (C1-C 12 )alkyl, (C3-C 12)Cycloalkyl, (C1-C8)alkoxy, (C6-C 12 ) substituted or unsubstituted (C6-C 20 )aryl(C1-C 20 )alkyl; or (C1-C 20 ) is a metalloid radical of a group 14 metal substituted with hydrocarbyl; R 1 ~R 4 Two or more of these adjacent atoms can be linked to each other to form a ring. When the transition metal compound represented by chemical formula 1 contains such substituents, it is preferable because it allows for control of the electronic and steric environment around the metal.

[0055] In the above chemical formula 1, R 1 ~R 6 Each of these can be independently substituted with substituents containing acetal, ketal, or ether groups. When substituted with such substituents, it may be more advantageous to support the material on the surface of a carrier.

[0056] More preferably, the R 1 ~R 6 Each is independently hydrogen or (C1-C 20 ) can be alkyl, preferably independently of hydrogen or methyl. However, the R 3 and R 4 At least one of them can be methyl.

[0057] In the transition metal compound represented by the chemical formula 1, D may be Si or C, and more preferably Si.

[0058] In the transition metal compound represented by the chemical formula 1, M is a group 4 transition metal, more specifically titanium (Ti), zirconium (Zr), or hafnium (Hf), and more preferably Ti.

[0059] In the transition metal compound represented by the chemical formula 1, Q 1 and Q 2 These are hydrogen; halogen; (C1-C 20) Alkyl; (C3-C 20 ) Cycloalkyl; (C2-C 20 ) Alkenyl; (C6-C 20 ) Aryl; (C1-C 20 ) Alkyl (C6-C 20 ) Aryl; (C6-C 20 ) Aryl (C1-C 20 ) Alkyl; (C1-C 20 ) Alkylamino; (C6-C 20 ) Arylamino; or (C1-C 20 ) Alkylidene and may be, more specifically, the above Q 1 and Q 2 each may independently be halogen or (C1-C 20 ) alkyl and may be, more specifically, chlorine or methyl.

[0060] In the transition metal compound represented by the above Chemical Formula 1, E is -O-, -S-, -NR 7 -, or -PR 7 -, and R 7 is hydrogen, halogen; (C1-C 20 ) alkyl; (C3-C 20 ) cycloalkyl; (C2-C 20 ) alkenyl; (C1-C 20 ) alkoxy; (C6-C 20 ) aryl; (C6-C 20 ) aryl (C1-C 20 ) alkoxy; (C1-C 20 ) alkyl (C6-C 20 ) aryl; or (C6-C 20 ) aryl (C1-C 20 ) alkyl.

[0061] The transition metal compound represented by Chemical Formula 1 provided by the present invention contains a ligand with a new structure in which an amide ligand and o-phenylene form a condensed ring, and a 5-membered ring π-ligand bonded to the o-phenylene is fused with a thiophene heterocycle. Thereby, the transition metal compound can have improved copolymerization activity of ethylene-α olefin compared to a transition metal compound in which a thiophene heterocycle is not fused.

[0062] The catalyst composition of the present invention may contain a co-catalyst compound of chemical formula 2 and / or chemical formula 3.

[0063] [ka]

[0064] [ka]

[0065] In chemical formulas 2 and 3, L is a neutral or positively ionic Lewis acid, Z is a group 13 element, and A is (C6-C 20 )aryl or (C1-C 20 ) alkyl, and the above (C6-C 20 )aryl or (C1-C 20 )alkyl is a halogen, (C1-C 20 ) Hydrocarbyl, (C1-C 20 )alkoxy, or (C6-C 20 ) It may be substituted or unsubstituted with an aryloxy.

[0066] The co-catalyst compounds represented by chemical formulas 2 and 3 can activate the main catalyst compound represented by chemical formula 1.

[0067] In more detail, the co-catalyst compound represented by chemical formula 2 or chemical formula 3 has strong electrophilicity and Q is bonded to the central metal M of the main catalyst compound represented by chemical formula 1. 1 and / or Q 2 It can be rapidly dissociated. The aforementioned Q 1 and / or Q 2 Rapid dissociation of the central metal can increase the polymerization activity of ethylene and α-olefins. Furthermore, the central metal M can maintain a stable state for a longer period of time, allowing it to coordinate with the double bonds contained in ethylene and α-olefins, meaning that the number of reactable bonds can increase, thereby forming longer chains and thus yielding a higher molecular weight ethylene-α-olefin copolymer.

[0068] According to the present invention, in the co-catalyst compound represented by the chemical formula 2, the [LH] + This is the dimethylanilinium positive ion, as described above [Z(A)4] - is [B(C6F5)4] - It is preferable that this be the case.

[0069] Furthermore, in the co-catalyst compound represented by the chemical formula 3, the [L] + is [(C 18 H 37 )2N(H)(C6H5)] + And, as mentioned above [Z(A)4] - is [B(C6F5)4] - It is preferable that this be the case.

[0070] Here, the co-catalyst compound represented by chemical formula 2 is not particularly limited, but non-limiting examples include trimethylammonium tetrakis(pentafluorophenyl)borate, triethylammonium tetrakis(pentafluorophenyl)borate, tripropylammonium tetrakis(pentafluorophenyl)borate, tri(n-butyl)ammonium tetrakis(pentafluorophenyl)borate, tri(sec-butyl)ammonium tetrakis(pentafluorophenyl)borate, and N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate. tetrakis(pentafluorophenyl)borate), N,N-dimethylanilinium n-butyltris(pentafluorophenyl)borate, N,N-dimethylanilinium benzyltris(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(4-(t-butyldimethylsilyl)-2,3,5,6-tetrafluorophenyl)borate, N,N-dimethylanilinium tetrakis(4-(t-triisopropylsilyl)-2,3,5,6-tetrafluorophenyl) borate (N,N-dimethylanilinium tetrakis(4-(triisopropylsilyl)-2,3,5,6-tetrafluorophenyl) borate), N,N-dimethylanilinium pentafluorophenoxytris(pentafluorophenyl) borate, N,N-diethylanilinium tetrakis(pentafluorophenyl) borate, N,N-dimethyl-2,4,6-trimethylanilinium tetrakis(pentafluorophenyl) borate, N,N-dimethylammonium tetrakis(2,3,5,6-tetrafluorophenyl) borate (dimethylammonium tetrakis(2,3,5,6-tetrafluorophenyl)borate), N,N-diethylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, tripropylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, tri(n-butyl)ammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, dimethyl(t-butyl)ammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, N,N,N-dimethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate, N,N-diethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate, N,N-dimethyl-2,4,6-trimethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate, N,N-dioctadecylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate N,N-(Dihexadecylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate), N,N-(Ditetradecylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate), N,N-(Ditetradecylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate), N,N-(Dioctadecylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate), N,N-(Dihexadecylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate) tetrakis(2,3,4,6-tetrafluorophenyl)borate), N,N-ditetradecylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate N,It may be one or more selected from the group consisting of N-(Ditetradecylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate), bis(hydrogenated-tallowalkyl)methylammonium tetrakis(pentafluorophenyl)borate, and dialkylammonium.

[0071] Examples of the aforementioned dialkylammonium include, but are not limited to, di-(i-propyl)ammonium tetrakis(pentafluorophenyl)borate or dicyclohexylammonium tetrakis(pentafluorophenyl)borate.

[0072] Furthermore, the co-catalyst compound represented by chemical formula 3 is not limited to this, but may be one or more selected from the group consisting of trialkylphosphonium, dialkyloxonium, dialkylsulfonium, and carbonium salts.

[0073] Examples of the aforementioned trialkylphosphonium include, but are not limited to, triphenylphosphonium tetrakis(pentafluorophenyl)borate, tri(o-tolyl)phosphonium tetrakis(pentafluorophenyl)borate, or tri(2,6-dimethylphenyl)phosphonium tetrakis(pentafluorophenyl)borate.

[0074] Examples of the aforementioned dialkyloxonium include, but are not limited to, diphenyloxonium tetrakis(pentafluorophenyl)borate, di(o-tolyl)oxonium tetrakis(pentafluorophenyl)borate, or di(2,6-dimethylphenyl)oxonium tetrakis(pentafluorophenyl)borate.

[0075] Examples of the aforementioned dialkylsulfonium include, but are not limited to, diphenylsulfonium tetrakis(pentafluorophenyl)borate, di(o-tolyl)sulfonium tetrakis(pentafluorophenyl)borate, or bis(2,6-dimethylphenyl)sulfonium tetrakis(pentafluorophenyl)borate.

[0076] Examples of the carbonium salts mentioned above, without limitation, include tropylium tetrakis(pentafluorophenyl)borate, triphenylmethylcarbenium tetrakis(pentafluorophenyl)borate, or benzene(diazonium)tetrakis(pentafluorophenyl)borate.

[0077] Such co-catalyst compounds may further contain trialkylaluminum such as trimethylaluminum, triethylaluminum, tributylaluminum, trihexylaluminum, trioctylaluminum, and tridecylaluminum.

[0078] On the other hand, the amount of the co-catalyst compound added can be determined by considering the amount of the main catalyst compound added and the amount necessary to sufficiently activate the co-catalyst compound. According to the present invention, the co-catalyst compound may be present in an amount of 1 to 100,000 moles per mole of the main catalyst compound, preferably 1 to 10,000 moles, and more preferably 1 to 5,000 moles.

[0079] More specifically, the co-catalyst compound represented by chemical formula 2 or chemical formula 3 may be included in a ratio of 1 to 100 moles, preferably 1 to 10 moles, and more preferably 1 to 4 moles, per mole of the main catalyst compound represented by chemical formula 1.

[0080] On the other hand, the catalyst of the present invention, which includes the main catalyst compound and the co-catalyst compound, may further include a support.

[0081] Here, the carrier may be one that is commonly used in the production of catalysts in the art to which the present invention belongs, and may be an inorganic or organic material carrier.

[0082] In one embodiment of the present invention, the support is not limited to, but may be, for example, SiO2, Al2O3, MgO, MgCl2, CaCl2, ZrO2, TiO2, B2O3, CaO, ZnO, BaO, ThO2, SiO2-Al2O3, SiO2-MgO, SiO2-TiO2, SiO2-V2O5, SiO2-Cr2O3, SiO2-TiO2-MgO, bauxite, zeolite, starch, cyclodextrin, or synthetic polymer.

[0083] Preferably, the support has a hydroxyl group on its surface and may be one or more selected from the group consisting of silica (SiO2), silica-alumina (SiO2-Al2O3), and silica-magnesia (SiO2-MgO).

[0084] Methods for supporting the main catalyst compound and the co-catalyst compound on the carrier include directly supporting the main catalyst compound on a dehydrated carrier, pre-treating the carrier with the co-catalyst compound before supporting the main catalyst compound, supporting the main catalyst compound on the carrier and then post-treating it with the co-catalyst compound, and reacting the main catalyst compound and the co-catalyst compound before adding the carrier and allowing the reaction to proceed.

[0085] The solvents usable in the aforementioned supporting method may be aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated aliphatic hydrocarbon solvents, or mixtures thereof.

[0086] Examples of the aforementioned aliphatic hydrocarbon solvents include, but are not limited to, pentane, hexane, heptane, octane, nonane, decane, undecane, or dodecane.

[0087] Examples of the aforementioned aromatic hydrocarbon solvents, without limitation, include benzene, monochlorobenzene, dichlorobenzene, trichlorobenzene, or toluene.

[0088] Examples of the aforementioned halogenated aliphatic hydrocarbon solvents include, but are not limited to, dichloromethane, trichloromethane, dichloroethane, or trichloroethane.

[0089] Furthermore, the loading method can be carried out at temperatures of -70 to 200°C, preferably -50 to 150°C, and more preferably 0 to 100°C, which can improve the efficiency of the loading process.

[0090] In the present invention, the ethylene-α-olefin copolymer is obtained by copolymerizing ethylene and α-olefin in the presence of the catalyst composition described above.

[0091] The α-olefin is C2-C 12 Alternatively, it may be a C2-C8 aliphatic α-olefin. More specifically, the α-olefin may be propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-aithocene, 4,4-dimethyl-1-pentene, 4,4-diethyl-1-hexene, or 3,4-dimethyl-1-hexene, and one or more of these may be used in mixtures of two or more.

[0092] The proportions of ethylene and α-olefin added to the reactor during the polymerization reaction are not particularly limited, but ethylene and α-olefin can be added in a weight ratio of 0.5 to 1.3 parts ethylene to α-olefin. When ethylene and α-olefin are added in the aforementioned weight ratio, an olefin copolymer is obtained that has a high molecular weight while also having a high comonomer content.

[0093] On the other hand, the polymerization reaction of ethylene and α-olefins according to the present invention can be carried out in the slurry phase, solution phase, gas phase, or bulk phase.

[0094] When the polymerization reaction is carried out in a liquid phase or a slurry phase, a solvent or ethylene or the α-olefin monomer itself can be used as the medium.

[0095] The solvents that can be used in polymerization reactions may be aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated aliphatic hydrocarbon solvents, or mixtures thereof.

[0096] Examples of the aforementioned aliphatic hydrocarbon solvents include butane, isobutane, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, cyclopentane, methylcyclopentane, or cyclohexane.

[0097] Examples of the aforementioned aromatic hydrocarbon solvents include, but are not limited to, benzene, monochlorobenzene, dichlorobenzene, trichlorobenzene, toluene, xylene, or chlorobenzene.

[0098] Examples of the aforementioned halogenated aliphatic hydrocarbon solvents include, but are not limited to, dichloromethane, trichloromethane, chloroethane, dichloroethane, trichloroethane, or 1,2-dichloroethane.

[0099] On the other hand, in the polymerization reaction of the present invention, the amount of catalyst added can be determined within a range in which the monomer polymerization reaction can occur sufficiently through the slurry phase, liquid phase, gas phase, or bulk phase steps, and is therefore not particularly limited.

[0100] However, in the present invention, the amount of catalyst added is 10 based on the concentration of the central metal M in the main catalyst compound per unit volume L of monomer. -11 It can be up to 1 mol / L, preferably 10 -10 〜10 -1mol / L, more preferably 10 -10 〜10 -2 It can be mol / L.

[0101] Furthermore, the polymerization reaction of the present invention can be carried out in a batch, semi-continuous, or continuous manner, and is preferably a continuous reaction.

[0102] The temperature and pressure conditions for the polymerization reaction of the present invention can be determined considering the efficiency of the polymerization reaction depending on the type of reaction to be applied and the type of reactor, and are not particularly limited, but can be carried out at a temperature of 100 to 200°C, preferably 120 to 160°C, and at a pressure of 1 to 3000 atmospheres, preferably 1 to 1000 atmospheres.

[0103] According to the present invention, the copolymer of ethylene and α-olefin of the present invention can be produced by copolymerizing ethylene and α-olefin in the presence of the catalyst composition and under polymerization conditions as described above.

[0104] The copolymerization of ethylene-α-olefin produced by the present invention can be enhanced by using a catalyst containing a main catalyst compound and the co-catalyst compound, thereby increasing the polymerization activity of ethylene and α-olefin monomers, and thereby yielding copolymerization of high molecular weight ethylene-α-olefin.

[0105] The transition metal compound represented by the chemical formula 1 has excellent catalytic activity and is preferably 200 kg / g-cat or more.

[0106] The ethylene-α-olefin copolymer obtained in the present invention may have a weight-average molecular weight (Mw) of 10,000 to 1,000,000, preferably 30,000 to 800,000, and more preferably 40,000 to 300,000.

[0107] Furthermore, the ethylene-α-olefin copolymer may have a molecular weight distribution (Mw / Mn) of 1 to 10, preferably 1.5 to 8, and more preferably 1.5 to 3.

[0108] Furthermore, the ethylene-α-olefin copolymer may have a density of 0.860 to 0.885 g / mL, and more specifically, 0.869 to 0.880 g / mL.

[0109] Furthermore, the ethylene-α-olefin copolymer provided in the present invention may have a melting index (MI) of 0.1 to 50 g / 10 min.

[0110] In the ethylene-α-olefin copolymer provided in the present invention, the content of ethylene monomer and α-olefin monomer is not particularly limited, but for example, the comonomer may be present in an amount of 19 to 40% by weight, more specifically 20 to 35% by weight, more specifically 20 to 32% by weight, and even more specifically 20 to 30% by weight.

[0111] Further findings of the present invention provide a resin composition comprising the ethylene-α-olefin copolymer as described above. The resin composition comprises the ethylene-α-olefin copolymer and a crosslinking agent, and may further comprise a crosslinking aid as needed.

[0112] The crosslinking agent can be any agent commonly used for crosslinking ethylene-α-olefin copolymers, and can be used in accordance with the present invention. For example, at least one selected from the group consisting of dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, and TBEC (tert-butylperoxy 2-ethylhexyl carbonate) can be used.

[0113] The crosslinking aid is not limited to any one other than trivinylbenzene, divinylbenzene, trivinylpropane, trivinylcyclohexane, and TAIC (Triallyl isocyanurate).

[0114] More specifically, the resin composition may contain 85 to 95% by weight of ethylene-α-olefin copolymer, 0.5 to 10% by weight of a crosslinking agent, and 0.5 to 10% by weight of a crosslinking aid, based on the total weight of the resin composition, and the resin composition may be provided as a resin composition for solar cell encapsulation material.

[0115] In the production of the resin composition for solar cell encapsulants according to the present invention, in order to apply the resin composition for solar cell encapsulants according to the present invention to a variety of battery module encapsulants, at least one additive other than the above-mentioned components may be used, without departing from the technical spirit of the present invention, such as a colorant, coupling agent, antioxidant, discoloration inhibitor, UV stabilizer, or UV absorber, and may be used in a content of 0.1 to 5% by weight, for example, 0.2 to 1% by weight, based on the weight of the total encapsulant composition.

[0116] Furthermore, the ethylene-α-olefin copolymer of the present invention can significantly reduce the time required for crosslinking, and because it reaches the same degree of crosslinking faster than conventional polymer resins used as solar encapsulants, it can reduce the working time when manufacturing solar panels. Specifically, when crosslinking the resin composition containing the ethylene-α-olefin copolymer and crosslinking agent of the present invention, the time required for crosslinking may be 20 minutes or less, more specifically, 15 minutes or less or 12 minutes or less.

[0117] More specifically, the resin composition containing the ethylene-α-olefin copolymer provided in the present invention may have a time (T90) of 600 to 700 seconds, or 650 or 700 seconds, until the torque value reaches 90% saturation.

[0118] According to another aspect of the present invention, a encapsulant for solar cells is provided, which is manufactured from the resin composition of the present invention.

[0119] When using the resin composition of the present invention, the encapsulant for solar cells can achieve a crosslinking ratio of 90% to 99%.

[0120] When a solar encapsulant is manufactured using the ethylene-α-olefin copolymer provided in the present invention, the light transmittance measured by ASTM D1003 on a 3 mm thick film may be 90% or more, more specifically 90% to 99%, 91% to 95%, or more specifically 91% to 93%, thereby making it suitable for use as a solar encapsulant.

[0121] Furthermore, when producing a solar encapsulant using the ethylene-α-olefin copolymer according to the present invention, a yellowing index of 2 or less, more specifically 1.9 or less, and even more specifically 1.8 or less, based on a 3 mm thick film, may be obtained.

[0122] Furthermore, when producing a solar encapsulant using the ethylene-α-olefin copolymer according to the present invention, the volume resistivity measured by ASTM D257 is 0.1 × 10⁻⁶. 16 It can be greater than Ω·cm, and for details, see 0.5 × 10 16 For values ​​greater than Ω·cm, see 1.0 × 10⁻¹⁰. 16 The volume resistivity can be Ω·cm or greater. Therefore, the ethylene-α-olefin copolymer of the present invention has high volume resistivity and can be suitable for use as a encapsulant for solar applications.

[0123] Thus, according to the present invention, a resin composition for encapsulants is provided that exhibits a high crosslinking ratio, high total light transmittance and a fast crosslinking rate, and has a low degree of yellowing, and can be used as an encapsulant for solar cells. [Examples]

[0124] The present invention will be described in more detail below with reference to examples. However, the following examples are merely illustrative of the present invention and are not intended to limit it.

[0125] Example 1 At room temperature, 5.2 kg / hr of n-hexane was continuously added to a high-pressure reactor (internal capacity: 2 L, stainless steel), followed by 0.6 kg / hr of 1-butene.

[0126] Next, ethylene gas at a rate of 0.82 kg / hr (1-butene / ethylene input ratio of 0.73 by weight) was injected, and then the reactor pressure was adjusted to 60 bar and the reactor temperature to 130°C.

[0127] Next, 13.2 μmol / hr of a transition metal compound represented by the following chemical formula 4 was injected into the reactor as the main catalyst, 0.9 mmol / hr of triisobutylaluminum co-catalyst, and 63.4 μmol / hr of dioxadecylanilinium tetrakis(pentafluorophenyl)borate co-catalyst, and the polymerization reaction was carried out for 10 minutes.

[0128] [ka]

[0129] After the polymerization reaction was complete, 1.5 mmol / hr of ethanol was added to the rear end of the reactor to stop the polymerization, and the copolymer dispersed in the solvent was dried in a vacuum oven at 80°C.

[0130] Example 2 The polymerization reaction was carried out in the same manner as in Example 1, except that 0.83 kg / hr of ethylene gas (1-butene / ethylene input ratio of 0.72 by weight) was injected, and the reactor temperature was adjusted to 140°C.

[0131] Comparative Example 1 The copolymer was produced by carrying out the polymerization reaction in the same manner as in Example 1, except that a transition metal compound represented by chemical formula 5 was used as the main catalyst.

[0132] [ka]

[0133] In the above chemical formula 5, Me represents a methyl group.

[0134] Comparative Example 2 The copolymer was produced by carrying out the polymerization reaction in the same manner as in Example 1, except that a transition metal compound represented by chemical formula 6 was used as the main catalyst.

[0135] [ka]

[0136] Comparative Example 3 The copolymer was produced by carrying out the polymerization reaction in the same manner as in Example 1, except that a transition metal compound represented by chemical formula 7 was used as the main catalyst.

[0137] [ka]

[0138] In the above chemical formula 7, Me represents a methyl group, and tBu represents tert-butyl.

[0139] Comparative Example 4 The copolymer was produced by carrying out the polymerization reaction in the same manner as in Example 2, except that a transition metal compound represented by chemical formula 5 was used as the main catalyst.

[0140] Comparative Example 5 The copolymer was produced by carrying out the polymerization reaction in the same manner as in Example 2, except that a transition metal compound represented by chemical formula 6 was used as the main catalyst.

[0141] Comparative Example 6 The copolymer was produced by carrying out the polymerization reaction in the same manner as in Example 2, except that a transition metal compound represented by chemical formula 7 was used as the main catalyst.

[0142] <Analysis of the physical properties of copolymers> The following physical properties were measured for the copolymers produced in Examples 1 and 2 and Comparative Examples 1 to 6, and the results are shown in Table 1.

[0143] (1)Catalytic activity The weight of polymer produced per hour was measured and then divided by the amount of catalyst input per hour to calculate the yield. Catalytic activity (kg / g-cat.) = Polymer production amount / Catalyst input amount

[0144] (2) Weight-average molecular weight and molecular weight distribution The number-average molecular weight (Mn) and weight-average molecular weight (Mw) were measured using gel transmission chromatography (GPC), and the molecular weight distribution was calculated using Mw / Mn.

[0145] (3) Density A 3mm thick, 2cm radius sheet was fabricated using a copolymer and compression molded at 180°C. After cooling to room temperature, it was measured according to ASTM D-792 (Manufacturer: Toyoseiki, Model name: T-001).

[0146] (4) Melt index (MI) Measured according to ASTM D-1238 (Condition E, 190°C, 2.16 kg load) (Manufacturer: Mirage, Model name: SD-120L).

[0147] (4) Content of the couniter Analysis was performed using 1H NMR (instrument name: Avance DRX400, manufacturer: Bruker).

[0148] [Table 1]

[0149] <Analysis of physical properties of resin composition> (1) Light transmittance A 3mm thick, 2cm radius sheet was fabricated using a copolymer and compression mold at 180°C. After cooling to room temperature, the total light transmittance for 550nm wavelength light was measured using a color and haze meter (CHN Spec., Model CS-700).

[0150] The transmittance was measured by placing a 3mm thick specimen in a specimen holder and taking three measurements, then calculating the average value. The measurements were taken under the conditions specified in JIS K 7105.

[0151] (2) Yellow Index A 3mm thick, 2cm radius sheet was fabricated using a copolymer and compression mold at 180°C. After cooling to room temperature, a 3mm thick specimen was placed in a specimen holder and measured three times using a color and haze meter (CHN Spec., Model CS-700). The average value of these measurements was then calculated, according to ASTM E313-73 specifications.

[0152] (3) Volume Resistivity A sheet with a thickness of 3 mm and a radius of 2 cm was fabricated using a copolymer and compression molding at 180°C. After cooling to room temperature, the volume resistivity was measured using the ASTM D257-based volume resistivity measurement method with an SM7120 electrometer coupled to a HIOKI SME8310 (test fixture).

[0153] (4) Bridge construction time (T90) After placing 1 kg of the ethylene-α-olefin copolymer produced in Example 1 and Comparative Examples 1 to 3 into a kneader, 5 g of TBEC (tert-butylperoxy 2-ethylhexyl carbonate) as a crosslinking agent and 5 g of TAIC (triallyl isocyanurate) as a crosslinking aid were added and mixed, and the mixture was then mixed in a roll mill at 70 to 100°C for 10 minutes to produce a resin composition.

[0154] Using the aforementioned manufactured resin composition, specimens required for each physical property evaluation were prepared, and the following physical properties were evaluated and shown in Table 2.

[0155] The aforementioned resin composition was pressurized at 150°C for 15 minutes using a 1 mm thick press mold, and then cooled to room temperature to produce a disc-shaped film weighing 5 g and with a diameter of 4 cm.

[0156] The T90 (time taken for the torque value to scorch) of the aforementioned sample was confirmed at 150°C for 20 minutes.

[0157] These crosslinking behavior characteristics were measured using Alpha Technologies' RPA2000 (Rubber process analyzer).

[0158] (5)TGIC analysis We use Polymer Char's CFC (Cross-Fractionation Chromatography) equipment. The sample to be analyzed is stirred at 150°C for 60 minutes to dissolve 1,2,4-trichlorobenzene (2.5 mg / mL). The dissolved sample is then introduced into a TGIC (Thermal Gradient Interaction Chromatography) column at a rate of 1 mL / min and stabilized at 150°C for 20 minutes.

[0159] Next, the TGIC column was cooled to -20°C at a cooling rate of 20°C / min, and then heated from -20°C to 150°C in 5°C increments, and eluted onto the GPC column at a flow rate of 1 mL / min. The elution time in this case was 5 minutes, and the analysis time for each fraction was 20 minutes.

[0160] After passing through the GPC column, the elution temperature (Te), molecular weight of the polymer in each fraction, and branched chain distribution are determined using an infrared detector (IR5). The peak area of ​​each fraction is confirmed using the analytical software "GPC calc," with n-heptane used as an internal standard.

[0161] The TGIC analysis results for Example 1 and Comparative Example 1 obtained therefrom are shown in Figures 1 and 2, respectively.

[0162] [Table 2]

[0163] The transition metal compounds represented by chemical formula 4 used in Examples 1 and 2 contain fewer resonance structures compared to the transition metal compound represented by chemical formula 5 used in Comparative Example 1. As a result, the ethylene-α-olefin copolymer produced in Example 1 exhibits high light transmittance and a low Yellow Index value. From Figures 1 and 2, which show the low-temperature TGIC analysis results for the ethylene-α-olefin copolymers produced in Example 1 and Comparative Example 1, respectively, it was found that the ethylene-α-olefin copolymer produced using the transition metal compound represented by chemical formula 5 used in Comparative Example 1 has a polymer structure with a lower density compared to the ethylene-α-olefin copolymer produced in Example 1.

[0164] The ethylene-α-olefin copolymer of Comparative Example 1, which has such a low-density polymer structure, exhibits electron flowability and relatively low volume resistivity. Due to its high comonomer content, it is sterically hindered by the introduction of crosslinking agent radicals, resulting in a relatively slow crosslinking rate.

[0165] On the other hand, the ethylene-α-olefin copolymers of Examples 1 and 2 have a lower density, higher volume resistivity, and faster crosslinking rate compared to the ethylene-α-olefin copolymers produced using the transition metal compound represented by chemical formula 6 in Comparative Examples 2 and 5. These results indicate that the copolymers in the ethylene-α-olefin copolymers of Examples 1 and 2 are uniformly distributed within the polymer chain.

[0166] Furthermore, the transition metal compounds represented by chemical formula 4 used in Examples 1 and 2 have a bulkier ligand structure compared to the transition metal compounds of chemical formula 6 used in Comparative Examples 2 and 5, which can be evaluated as providing an appropriate solid angle for the active species and facilitating the insertion of the comonmer. In addition, the electron-donating role of the ligand is judged to contribute to the stabilization of the catalytic active species, resulting in high activity and a high molecular weight (low MI) at high temperatures.

[0167] Furthermore, the transition metal compounds of chemical formula 4 used in Examples 1 and 2 exhibit higher activity than the transition metal compounds represented by chemical formula 6 in Comparative Examples 2 and 5. This is attributed to the fact that TiMe2 forms more active species than TiCl2. While the formation of catalytic active species occurs after polymerization following the alkylation of Ti, TiMe2 can immediately form active species, whereas TiCl2 requires the alkylation step, resulting in a slower rate of active species formation relative to the same time.

Claims

1. A method for producing an ethylene-α-olefin copolymer, comprising the step of reacting ethylene with an α-olefin in the presence of a catalyst composition containing a transition metal compound represented by chemical formula 1: 【Chemistry 1】 In the aforementioned chemical formula 1, R ４ to R ６ each independently represents hydrogen; halogen; silyl; (C １ -C ２０ alkyl; (C ３ -C ２０ cycloalkyl; (C ２ -C ２０ alkenyl; (C １ -C ２０ alkoxy; halogen, (C １ -C １２ alkyl, (C ３ -C １２ cycloalkyl, (C １ -C ８ alkoxy, (C ６ -C １２ aryl-substituted or unsubstituted (C ６ -C ２０ aryl; halogen, (C １ -C １２ alkyl, (C ３ -C １２ cycloalkyl, (C １ -C ８ alkoxy, (C ６ -C １２ aryl-substituted or unsubstituted (C ６ -C ２０ aryl (C<000003​​​​​​​​​​​ D is either Si or C. M is a group 4 transition metal, Q １ and Q ２ These are hydrogen; halogen; (C) independently of each other. １ -C ２０ ) alkyl; (C ３ -C ２０ ) Cycloalkyl; (C ２ -C ２０ ) Alkenil; (C ６ -C ２０ ) Aryl; (C １ -C ２０ ) Alkyl (C ６ -C ２０ ) Aryl; (C ６ -C ２０ ) Aryl (C １ -C ２０ ) alkyl; (C １ -C ２０ ) alkylamino; (C ６ -C ２０ ) arylamino; or (C １ -C ２０ ) is an alkyridene, E is -O-, -S-, -NR ７ - or -PR ７ - and here, R ７ is hydrogen, halogen; (C １ -C ２０ ) alkyl; (C ３ -C ２０ ) Cycloalkyl; (C ２ -C ２０ ) Alkenil; (C １ -C ２０ ) Alkoxy; (C ６ -C ２０ ) Aryl; (C ６ -C ２０ ) Aryl (C １ -C ２０ ) Alkoxy; (C １ -C ２０ ) Alkyl (C ６ -C ２０ ) Aryl; or (C ６ -C ２０ ) Aryl (C １ -C ２０ It is alkyl.

2. The method for producing an ethylene-α-olefin copolymer according to claim 1, wherein the transition metal compound represented by chemical formula 1 is the transition metal compound represented by chemical formula 1-1. 【Chemistry 2】

3. The method for producing an ethylene-α-olefin copolymer according to claim 1, wherein the transition metal compound represented by chemical formula 1 has a catalytic activity of 200 kg / g-cat or more.

4. The method for producing an ethylene-α-olefin copolymer according to claim 1, wherein the catalyst composition further comprises at least one co-catalyst selected from the group consisting of compounds represented by chemical formula 2 and compounds represented by chemical formula 3. 【Transformation 3】 【Chemistry 4】 In the aforementioned chemical formulas 2 and 3, L is a neutral or positively ionic Lewis acid. Z is a group 13 element, A is (C ６ -C ２０ ) Aryl or (C １ -C ２０ A method for producing an ethylene-α-olefin copolymer that is alkyl.

5. The method for producing an ethylene-α-olefin copolymer according to claim 1, wherein the α-olefin comprises at least one selected from the group consisting of propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-aitocene, 4,4-dimethyl-1-pentene, 4,4-diethyl-1-hexene, and 3,4-dimethyl-1-hexene.

6. An ethylene-α-olefin copolymer produced by the method described in any one of claims 1 to 5.

7. The ethylene-α-olefin copolymer according to claim 6, having a weight-average molecular weight of 10,000 to 1,000,000, a molecular weight distribution of 1 to 10, and a density of 0.860 to 0.885 g / mL.

8. The ethylene-α-olefin copolymer according to claim 6, which is produced by adding α-olefin in a content of 19 to 40% by weight.

9. An ethylene-α-olefin copolymer produced by the method described in any one of claims 1 to 5, It contains a crosslinking agent, A resin composition for solar cell encapsulants that further selectively contains a crosslinking aid.

10. The resin composition for solar cell encapsulants according to claim 9, wherein the time (T90) required for the torque value to saturate to 90% at 150°C during crosslinking is 600 to 700 seconds.

11. The resin composition for solar cell encapsulant according to claim 9, wherein the ethylene-α-olefin copolymer has a weight-average molecular weight of 10,000 to 1,000,000, a molecular weight distribution of 1 to 10, and a density of 0.860 to 0.885 g / mL.

12. The resin composition for solar cell encapsulant according to claim 9, wherein the ethylene-α-olefin copolymer is produced by adding α-olefin in a content of 19 to 40% by weight.

13. An ethylene-α-olefin copolymer produced by the method described in any one of claims 1 to 5, A solar cell encapsulant containing a crosslinking agent.

14. A solar cell encapsulant according to claim 13 that satisfies any one of the following i) to ii): i) The Yellow Index of a 3mm thick film is 2 or less. ii) The volume resistivity when measured by ASTM D257 is 0.1 × 10 １６ Ω·cm or more

15. The solar cell encapsulant according to claim 13, wherein the light transmittance for light with a wavelength of 550 nm to a film with a thickness of 3 mm is 90% or more and 99% or less.

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