Ethylene copolymers for photovoltaic cells

Abstract

Ethylene copolymers capable of producing films having excellent optical properties, including moisture resistance, creep resistance, tensile strength, and tear strength, at wavelengths of 280 to 1,100 nm. The ethylene copolymer is at least 50% by weight of ethylene-derived units and at least 20% by weight of at least one C3 to C20 comonomer, and has branching indices g '(Mz) and g' (Mz + 1) coupled to trisubstituted olefins and reaction reactivity (r1r2), which are significantly different from other ethylene copolymers of similar density. The ethylene copolymer also has significantly improved processability properties and a high volume resistivity (gt; 1015 Ohm * cm) such that these copolymers are particularly suitable for PV cell applications.

Description

Inventors: Huan Chen, Giriprasath Gururajan, Hamidreza Khakdaman, Alexandra K. Valdez, Zhifeng Bai, Narayanaswami Dharmarajan, Peijun Jiang, and Ru Xie Cross - Reference to Related Applications

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 377,365, filed on September 28, 2022, the entire content of which is incorporated herein by reference. Technical Field

[0002] Embodiments of the present invention generally relate to ethylene copolymers and electronic device modules comprising such copolymers. More specifically, the embodiments provided herein relate to ethylene copolymers suitable for the preparation of photovoltaic cell applications. Background Art

[0003] Polyolefin plastomers, mainly copolymers of ethylene with butene or octene, are increasingly used as polymer encapsulants in photovoltaic (PV) cell applications. These polymers are replacing ethylene vinyl acetate (EVA) copolymers, where studies have shown that plastomer - based encapsulant materials have increased power generation over a 30 - year service life compared to EVA. Compared to EVA films, plastomer films used as encapsulant materials have a high barrier to potential - induced degradation (PID) and lower power degradation, both of which contribute to lower power loss. Power loss in EVA - based encapsulants is increased due to acetic acid release during maintenance use and discoloration due to yellowing.

[0004] Polymer film encapsulants for PV cell applications need to meet several functional properties. Electrical properties, represented by a high volume resistivity, are useful for lower power loss. Good optical properties (usually measured by high transmittance at wavelengths from 280 to 1100 nm), enhanced moisture resistance represented by a low water vapor transmission rate (WVTR), a high cross - link density providing creep resistance, and good mechanical properties represented by tensile strength, flexural modulus, and tear strength are considered important. The problem to be solved is how to obtain all these functional properties in a single polyolefin polymer.

[0005] Several patents disclose the use of plastomeric resins as encapsulant materials in PV cells. For example, US 9,349,895 B2 and its counterpart CN 103189996 B describe ethylene α-olefin copolymers suitable as PV cell encapsulants, having a density in the range of 0.865 to 0.884 g / cc, an MI (190 °C) in the range of 2 to 10, and a Shore A hardness in the range of 60 to 85. US 8,581,094 B2 and its counterpart CN101563786 B describe PV cell devices having a polyolefin copolymer encapsulant with a density less than 0.9 g / dd, a melting point less than 95 °C, an α-olefin content of 15 to 50 wt%, an SCBDI of at least 50, and optionally a free radical initiator and additives. KR 101191126 B1 describes an encapsulant sheet for solar cells, wherein the sheet comprises an ultra-low density ethylene α-olefin copolymer (0.850 to 0.890 g / cc), a low density ethylene α-olefin copolymer (0.890 to 0.920 g / cc), and a silane-grafted ultra-low density copolymer. KR101723708 B1 describes a polyolefin resin terpolymer used as an encapsulant material, wherein the polyolefin has a first crystallization temperature in the range of 45 °C to 60 °C and a second crystallization temperature lower than the first crystallization temperature of the resin.

[0006] US 8,329,848 B2 describes an ethylene-butene copolymer having vinyl groups in the range of 0.06 to 1 per 1,000 C atoms, a density in the range of 0.850 to 0.910 g / cc, MIR (I10 / I2.16) < 7.7, an MI in the range of 0.1 to 25 dg / min, and an ethylene content in the range of 80 to 95 mol%. US10,774,205 B2 describes polymers having a multimodal composition distribution, each polymer having distinct crystallization peaks in TREF in the range of 40 °C to 110 °C.

[0007] However, there is still a need for novel ethylene-based copolymers that can produce films having excellent optical properties, good processability, moisture resistance, creep resistance, tensile strength, flexural modulus, and tear strength at wavelengths in the range of 200 to 900 nm. Such films would be particularly suitable for meeting the requirements of PV cell applications. SUMMARY OF THE INVENTION

[0008] The present invention provides ethylene copolymers, electronic device modules, and methods for preparing both. The ethylene copolymer comprises at least 50 wt% of ethylene-derived units and at least 20 wt% of at least one C3 to C20 comonomer. The ethylene copolymer has a melt index of 0.5 g / 10 min to about 50 g / 10 min as measured according to ASTM D1238 (190 °C / 2.16 kg) and a density of about 0.860 g / cc to 0.880 g / cc as measured according to ASTM D792. The copolymer has a first long-chain branching index (g'(Mz)) of 0.80 to 0.93, a second long-chain branching index (g'(Mz+1)) of 0.80 to 0.93, and less than 0.7 vinyl groups / total unsaturated moieties. The unsaturation level of the trisubstituted olefin is 50 to 500, and the volume resistivity at 23 °C is 4×10 15 Ω·cm or higher. Such ethylene copolymers can be prepared using metallocene and post-metallocene catalysts in a solution polymerization process, as further provided herein.

[0009] It has been surprisingly found that these ethylene-based copolymers have significantly improved processability properties and high volume resistivity (>10 15 Ohm·cm), and are capable of producing films having excellent optical properties, moisture resistance, creep resistance, tensile strength, flexural modulus, and tear strength at wavelengths from 200 to 900 nm, making these copolymers particularly suitable for electronic device modules, such as PV cell applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] To understand in detail the features enumerated above of the present invention, a more specific description of the invention briefly outlined above can be obtained by reference to some of the embodiments shown in the drawings. However, it should be noted that the drawings illustrate only typical embodiments of the invention and are therefore not considered to limit the scope of the invention, as the invention can be implemented with other equally effective embodiments.

[0011] Figure 1A Shows the volume resistivity plotted against the g'(Mz+1) / g'-average for Samples 1-6 and other commercially available ethylene copolymers of similar density.

[0012] Figure 1B Shows the volume resistivity plotted against the g'(Mz+1) / g'-average for Samples 1-6 and other commercially available ethylene copolymers of similar density.

[0013] Figure 1C Shows the g'(Mz+1) / g'-average plotted against the g'(Mz+1) value from GPC for Samples 1-6 and other commercially available ethylene copolymers of similar density.

[0014] Figure 2A The trisubstituted olefins to g'(Mz+1) determined by HNMR of Samples 1-6 and other commercially available ethylene copolymers of similar density are shown.

[0015] Figure 2B The trisubstituted olefins to g'(Mz) from GPC determined by HNMR of Samples 1-6 and other commercially available ethylene copolymers of similar density are shown.

[0016] Figure 3 The number of vinyl groups / total unsaturated moieties determined by HNMR to g'(Mz) from GPC of Samples 1-6 and other commercially available ethylene copolymers of similar density are shown.

[0017] Figure 4A The r1r2 values from NMR tests to g'(Mz+1) of Samples 1-6 and other commercially available ethylene copolymers of similar density are shown.

[0018] Figure 4B The r1r2 values from NMR tests to g'Mz of Samples 1-6 and other commercially available ethylene copolymers of similar density are shown.

[0019] Figure 5A The phase angles at a complex modulus of 10,000 Pa of Samples 1-6 and other commercially available ethylene copolymer grades are shown.

[0020] Figure 5B The phase angles at a complex modulus of 50,000 Pa of Samples 1-6 and other commercially available ethylene copolymer grades are shown.

[0021] Figure 6 The TREF-IR data (differential and cumulative) of Samples 1-4 are shown.

[0022] Figure 7 The cooling cycle data of Samples 1 to 4 are compared.

[0023] Figure 8 The water vapor transmission rate (WVTR) performance of Samples 1-4 is shown.

[0024] Figure 9 The curing performance of the single reactor composition and the dual reactor composition of Samples 1-4 is shown.

[0025] Figure 10 The melt pressure and screw torque during extrusion at a melt temperature of 100 °C of 0.5 mm thick films made from Samples 2 and 4 and two other comparative polymers of similar density commercially available are shown. DETAILED DESCRIPTION OF THE INVENTION

[0026] An ethylene copolymer capable of producing a film having excellent optical properties at wavelengths from 280 to 1,100 nm is provided, the optical properties including moisture resistance, creep resistance, tensile strength and tear strength. The ethylene copolymer has a branching index g'(Mz) and g'(Mz+1) measured by GPC-4D coupled trisubstituted olefins and a reactivity ratio (r1r2) determined using HNMR, which is significantly different from other ethylene copolymers of similar density. It has been surprisingly found that these ethylene copolymers provided herein also have significantly improved processability properties and a high volume resistivity (> 10 15 Ohm*cm), making these copolymers particularly suitable for electronic device modules, such as PV cell applications.

[0027] It should be understood that the disclosure provided herein provides several exemplary embodiments for implementing different features, structures, and / or functions of the present invention. Exemplary embodiments describing components, arrangements, and configurations are provided to simplify the present disclosure; however, these exemplary embodiments are provided only as examples and are not intended to limit the scope of the present invention. Additionally, the present disclosure may repeat reference numerals and / or letters in the various exemplary embodiments and in the drawings provided herein. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate a relationship between the various exemplary embodiments and / or configurations discussed in the drawings. Furthermore, the exemplary embodiments provided herein may be combined in any manner, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment without departing from the scope of the disclosure.

[0028] Additionally, certain terms are used in the following description and claims to refer to particular components. As those skilled in the art will appreciate, various entities may refer to the same component by different names, and thus, unless specifically defined otherwise herein, the naming convention for the elements described herein is not intended to limit the scope of the present invention. Moreover, the naming convention used herein is not intended to distinguish between components that have different names but different functions.

[0029] In the following discussion and claims, the terms "comprising" and "including" are meant to be open-ended and should therefore be interpreted to mean "including but not limited to". The phrase "consisting essentially of" means that the described / claimed composition does not contain any other component that would substantially alter its properties by more than 5% of said properties, and in any case, does not contain any other component to a level greater than 3 mass%.

[0030] The term "or" is intended to cover both exclusive and inclusive cases, i.e., "A or B" is intended to be synonymous with "at least one of A and B", unless expressly stated otherwise herein.

[0031] The indefinite articles "a" and "an" refer to singular forms (i.e., "one") and plural referents (i.e., one or more), unless the context clearly dictates otherwise. For example, embodiments using "olefins" include embodiments in which one, two, or more olefins are used, unless otherwise stated or the context clearly indicates that only one olefin is used.

[0032] The term "wt%" refers to weight percentage, "vol%" refers to volume percentage, "mol%" refers to mole percentage, "ppm" refers to parts per million, and "ppm wt" and "wppm" are used interchangeably and refer to parts per million by weight. Unless otherwise stated, all concentrations are expressed based on the total amount of the composition under discussion.

[0033] The term "polymer" refers to any two or more identical or different repeating / monomeric units. The term "homopolymer" refers to a polymer having the same units. The term "copolymer" refers to a polymer having two or more units that are different from each other and includes terpolymers, etc. The term "terpolymer" refers to a polymer having three monomeric units that are different from each other. The term "different" refers to units that differ from each other by at least one atom or are isomerically different. Similarly, the definition of polymer used herein includes homopolymers, copolymers, and the like. For example, when a copolymer is said to have a "propylene" content of 10 wt% to 30 wt%, it should be understood that the repeating / monomeric units or simply units in the copolymer are derived from propylene in the polymerization reaction and the derived units are present at 10 wt% to 30 wt% based on the weight of the copolymer.

[0034] As used herein, "Mn" refers to the number-average molecular weight of different polymers in a polymer material, "Mw" refers to the weight-average molecular weight of different polymers in a polymer material, and "Mz" refers to the z-average molecular weight of different polymers in a polymer material. The terms "molecular weight distribution" (MWD) and "polydispersity index" (PDI) are used interchangeably and refer to the ratio of Mw to Mn. Unless otherwise stated, all molecular weights (e.g., Mw, Mn, Mz) are reported in g / mol.

[0035] The nomenclature of elements and their groups used herein follows the periodic table used by the International Union of Pure and Applied Chemistry after 1988. An example of the periodic table is shown on the inner page of the cover of the sixth edition of Advanced Inorganic Chemistry edited by F. Albert Cotton et al. (John Wiley & Sons, Inc., 1999).

[0036] Considering the ethylene copolymer in more detail, the ethylene copolymer can be a single-peak or bimodal composition, and the ethylene copolymer can be prepared with a single reactor or a dual reactor. The single reactor ethylene copolymer can have a TREF elution temperature peak of about 30 °C. In the case of the dual reactor copolymer, the first reactor can produce a lower crystalline component having a TREF peak typically at about 20 °C, and the second reactor can produce a copolymer having a TREF peak greater than 40 °C. Compared to the single reactor product, the dual reactor copolymer has a higher crystallization temperature (Tc) as measured by differential scanning calorimetry (DSC), a lower WVTR, and enhanced tear strength. The crystalline component helps to improve pellet stability, provides a water ingress barrier reflected in the lower WVTR performance, and a higher Tc that enhances the crosslink density, all of which are required for applications as a polymer encapsulant in PV cells.

[0037] The ethylene copolymer contains ethylene and at least one other C3-C20 comonomer. Preferred ethylene copolymers are ethylene-butene and ethylene-octene plastomers. The ethylene content of the lower ethylene content fraction can range from a lower limit of 55 wt% to an upper limit of 76 wt%. The ethylene content of the higher ethylene content fraction can range from a lower limit of 60 wt% to an upper limit of 90 wt%. The ethylene content of the total polymer can range from a lower limit of 60 wt% to an upper limit of 85 wt%.

[0038] The ethylene copolymer can have a melt index of 0.5 g / 10 min to about 50 g / 10 min as measured according to ASTM D1238 (190 °C / 2.16 kg). The melt index can also range from a lower limit of about 0.5, 1.0 or 2.0 to an upper limit of about 30, 40 or 50 g / 10 min. The melt index can also range from a lower limit of about 0.5, 3.0 or 5.0 to an upper limit of about 20, 35 or 45 g / 10 min.

[0039] The ethylene copolymer can also have a broad melt index ratio (MIR) or (MI 21.6 / MI 2.16 ) of 20.0 to about 100.0 as measured according to ASTM D1238 (190 °C / 2.16 kg). The MIR can also range from a lower limit of about 25, 30 or 40 to an upper limit of about 60, 80 or 95.

[0040] Ethylene copolymers can have a density of 0.850 g / cc to 0.920 g / cc measured according to ASTM D792, indicating that they can be used as a plastomer with a combined property of an elastomer and a polymer. Ethylene copolymers can also have a density of about 0.860 g / cc to 0.880 g / cc. Density can be in the range of a lower limit of about 0.850, 0.855, 0.860, 0.865 or 0.870 to an upper limit of about 0.874, 0.876, 0.880, 0.900 or 0.920 g / cc.

[0041] Ethylene copolymers can have 8×10 15 23°C volume resistivity of at least 8.5×10 15 Ωcm; 9.5×10 15 Ωcm, 1×10 16 Ωcm or 1.5×10 16 Ωcm.

[0042] The ethylene copolymer may have a ratio of g'Mz+1 to g'-average of 0.9 to 1.0. This ratio may also range from a lower limit of 0.91, 0.92 or 0.93 to an upper limit of 0.97, 0.98 or 0.99.

[0043] The ethylene copolymer may have less than 0.7 vinyl groups / total unsaturated portions estimated by H-NMR. The number of vinyl groups / total unsaturated portions may be in the range of a lower limit of about 0.01, 0.02, or 0.03 to an upper limit of about 0.5, 0.6, or 0.7. The number of vinyl groups / total unsaturated portions may also be in the range of a lower limit of about 0.1, 0.2, or 0.3 to an upper limit of about 0.5, 0.6, or 0.7.

[0044] The ethylene copolymer may have a tri-substituted olefin unsaturation level of 50 to 500 as determined by H-NMR. The tri-substituted olefin unsaturation level may also range from a lower limit of about 50, 80, or 100 to an upper limit of about 300, 400, or 500. The tri-substituted olefin unsaturation level may also range from about 60 to 480; 80 to 420; or 100 to 300.

[0045] The ethylene copolymer may have a reactivity ratio of 0.8 or less. The reactivity ratio may also be in the range of 0.2 to 0.8. The reactivity ratio may also be in the range of a lower limit of 0.2, 0.3 or 0.35 to an upper limit of 0.5, 0.65 or 0.8. The reactivity ratio may also be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 or 0.8. Aggregation methods

[0046] The ethylene copolymer can be prepared using a solution polymerization method. Preferably, the solution polymerization method is a bulk polymerization method, which refers to a polymerization method in which the polymerizing monomer and / or comonomer is used as a solvent or diluent, and little or no inert solvent is used as a liquid or diluent. A small portion of the inert solvent can be used as a carrier for the catalyst and scavenger.

[0047] The term "solution polymerization" refers to a polymerization method in which the polymer is dissolved in a liquid polymerization medium such as an inert solvent, monomer(s), or a blend thereof. Solution polymerization is generally homogeneous, which refers to a polymerization method in which the polymer product is dissolved in the polymerization medium. Such a system is preferably not turbid, as described in J. Vladimir Oliveira, C. Dariva, and J. C. Pinto, Ind. Eng, Chem. Res. 29, 2000, 4627. A homogeneous polymerization method is generally a method in which at least 90 wt% of the product is soluble in the reaction medium.

[0048] Suitable solution polymerization methods for preparing the polymer blend compositions disclosed herein are generally described in more detail in U.S. Patent Nos. 9,359,535, 7,470,118, 7,226,553, and 7,033,152, which are incorporated herein by reference in their entirety. WO 2017 / 058385A1 describes a solution polymerization method using a single or multiple coil heat exchanger system for the continuous polymerization of C2 to C40 olefins, which can also be used and is also incorporated herein by reference in its entirety.

[0049] The ethylene copolymer can exhibit a low level of long chain branching (LCB). In particular, the ethylene copolymer can have a first long chain branching index (g'(Mz)) of 0.30 to 1.00, preferably 0.70 to 0.97. The first long chain branching index (g'(Mz)) can also be in the range of 0.80 to 0.93. The first long chain branching index (g'(Mz)) can also be in the range from a lower limit of 0.80, 0.82, or 0.85 to an upper limit of 0.90, 0.92, or 0.93. The first long chain branching index (g'(Mz)) can also be 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, or 0.93.

[0050] The ethylene copolymer may have a second long-chain branching index (g'(Mz+1)) of from 0.30 to 1.00, preferably from 0.70 to 0.97. The second long-chain branching index (g'(Mz+1)) may also be in the range of from 0.80 to 0.93. The second long-chain branching index (g'(Mz+1))) may also be in the range of from a lower limit of 0.80, 0.82 or 0.85 to an upper limit of 0.90, 0.92 or 0.93. The second long-chain branching index (g'(Mz+1)) may also be 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92 or 0.93. comonomer

[0051] At least one other comonomer may include any one or more C4 to C20 olefins. The C4 to C20 comonomer may be linear, branched or cyclic. Suitable C4 to C20 cyclic olefins may be strained or unstrained, monocyclic or polycyclic, and may optionally include heteroatoms and / or one or more functional groups. The reactor C2 concentration may be in the range of from 0.1 to 40.0 wt%, while the reactor comonomer concentration may be in the range of from 0.1 to 40.0 wt%.

[0052] Specific examples of comonomers include butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, norbornene, norbornadiene, dicyclopentadiene, cyclopentene, cycloheptene, cyclooctene, cyclooctadiene, cyclododecene, 7-oxanorbornene, 7-oxanorbornadiene, their substituted derivatives and their isomers, preferably hexene, heptene, octene, nonene, decene, dodecene, cyclooctene, 1,5-cyclooctadiene, 1-hydroxy-4-cyclooctene, 1-acetoxy-4-cyclooctene, 5-methylcyclopentene, cyclopentene, dicyclopentadiene, norbornene, norbornadiene and their respective homologues and derivatives, preferably norbornene, norbornadiene and dicyclopentadiene.

[0053] In a preferred embodiment, one or more dienes (diene comonomers) are added to the polymerization process. Based on the total weight of the composition, the diene may be present in the polymer prepared herein at up to 10 wt%, preferably from 0.00001 to 8.0 wt%, preferably from 0.002 to 8.0 wt%, even more preferably from 0.003 to 8.0 wt%. In some embodiments, 500 ppm or less of the diene is added to the polymerization, preferably 400 ppm or less, preferably 300 ppm or less. In other embodiments, at least 50 ppm or 100 ppm or more or 150 ppm or more of the diene is added to the polymerization.

[0054] Suitable diolefin comonomers include any hydrocarbon structure having at least two unsaturated bonds, preferably C4 to C30, wherein at least one unsaturated bond is readily incorporated into the polymer chain during chain growth. Further preferably, the diolefin comonomer is selected from α,ω-diene monomers (i.e., divinyl monomers). More preferably, the diolefin comonomer is a linear divinyl comonomer, and very preferably, those containing 4 to 30 carbon atoms. Specific examples of preferred dienes include butadiene, pentadiene, hexadiene, heptadiene, octadiene, nonadiene, decadiene, undecadiene, dodecadiene, tridecadiene, tetradecadiene, pentadecadiene, hexadecadiene, heptadecadiene, octadecadiene, nonadecadiene, eicosadiene, heneicosadiene, docosadiene, tricosadiene, tetracosadiene, pentacosadiene, hexacosadiene, heptacosadiene, octacosadiene, nonacosadiene, triacontadiene, and particularly preferred dienes include 1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 1,10-undecadiene, 1,11-dodecadiene, 1,12-tridecadiene, 1,13-tetradecadiene, and low molecular weight polybutadiene (Mw less than 1000 g / mol). Preferred cyclic dienes include cyclopentadiene, 5-vinyl-2-norbornene, norbornadiene, 5-ethylidene-2-norbornene, divinylbenzene, and dicyclopentadiene or higher ring-containing diolefins with or without substituents at various ring positions. Catalyst system

[0055] Suitable catalyst systems for preparing the ethylene copolymers provided herein may include one or more bridged metallocene compounds having two ancillary monoanionic ligands that bridge the metallocene metal center, such as substituted or unsubstituted cyclopentadienyl (Cp)-containing ligands and / or a single substituted carbon or silicon atom of substituted and unsubstituted Group 13-16 heteroatom ligands. The bridge substituents may be substituted aryls, with the substituents including at least one solubilizing hydrocarbylsilyl substituent located on at least one aryl bridge substituent. The substituents present on the cyclopentadienyl and / or heteroatom ligands may include C1-C30 hydrocarbyls, hydrocarbylsilyls, or fluorohydrocarbyls as replacements for one or more hydrogen groups on these ligands or on fused aromatic rings on the cyclopentadienyl ring. The aromatic rings may be substituents on the cyclopentadienyl ligand and include indenyl and fluorenyl derivatives of cyclopentadienyl and their hydrogenated counterparts. These aromatic rings typically include one or more aromatic ring substituents selected from linear, branched, cyclic, aliphatic, aromatic, or combinatorial structural groups, including fused ring or pendant configurations. Examples include methyl, isopropyl, n-propyl, n-butyl, isobutyl, tert-butyl, neopentyl, phenyl, n-hexyl, cyclohexyl, benzyl, and adamantyl. As used herein, the term "hydrocarbon" or "hydrocarbyl" refers to those compounds or groups that include substantially hydrocarbon character but optionally contain no more than about 10 mole % of non-carbon heteroatoms (such as boron, silicon, oxygen, nitrogen, sulfur, and phosphorus). Additionally, the term is intended to include fluorohydrocarbyl-substituted groups. Examples of "hydrocarbylsilyl" are, but not limited to, dihydrocarbylsilyl and trihydrocarbylsilyl, where the preferred hydrocarbyl is C1-C 30 Substituent hydrocarbyl, hydrocarbylsilyl, or fluorohydrocarbyl substituents are used for the bridging group phenyl. For heteroatom-containing catalysts, see International Publication No. WO 92 / 00333. Additionally, the use of heteroatom-containing rings or fused rings, where a Group 13, 14, 15, or 16 non-carbon atom replaces one of the ring carbons, is considered herein to be within the terms "cyclopentadienyl", "indenyl", and "fluorenyl". See, for example, the background and teachings of International Publication Nos. WO 98 / 37106 and WO 98 / 41530, which are incorporated herein by reference.

[0056] Particularly suitable cyclopentadienyl-based complexes are dimethyl·(p-trimethylsilylphenyl)(p-n-butylphenyl)methylene(fluorenyl)(cyclopentadienyl)hafnium, dimethyl·bis(p-trimethylsilylphenyl)methylene(2,7-di-tert-butylfluorenyl)(cyclopentadienyl)hafnium, dimethyl·bis(p-triethylsilylphenyl)methylene(2,7-di-tert-butylfluorenyl)(cyclopentadienyl)hafnium, dimethyl·or dibenzyl·(p-triethylsilylphenyl)(p-tert-butylphenyl)methylene(2,7-di-tert-butylfluorenyl)(cyclopentadienyl)hafnium and dimethyl·or dibenzyl·bis(p-triethylsilylphenyl)methylene(2,7-dimethylfluorenyl)(cyclopentadienyl)hafnium compound isomers or mixtures. Other suitable cyclopentadienyl-based complexes are described in WO / 2000 / 024793, which is also incorporated herein by reference. Activator

[0057] The bridged metallocene compounds can be activated in any manner sufficient to permit coordination or cationic polymerization for use in polymerization catalysis. This can be achieved in coordination polymerization when one ligand can be abstracted and another ligand will permit insertion of an unsaturated monomer or will similarly be abstractable to be replaced by a ligand (labile ligand) that permits insertion of an unsaturated monomer, such as an alkyl, silyl or hydrogen group. Conventional activators in the field of coordination polymerization are suitable, such as Lewis acids like aluminoxane compounds, and ionizing anionic precursor compounds that abstract one in order to ionize the bridged metallocene metal center to a cation and provide a counter non-coordinating anion.

[0058] For example, suitable activators can include a cationic component. In any embodiment, the cationic component can have the formula [R 1 R 2 R 3 AH] + , where A is nitrogen, and R 1 and R 2 together are a -(CH2) a - group, where a is 3, 4, 5 or 6 and together with the nitrogen atom forms a 4, 5, 6 or 7-membered non-aromatic ring, optionally one or more aromatic or heteroaromatic rings may be fused to the non-aromatic ring via adjacent ring carbon atoms, and R 3 is a C1, C2, C3, C4 or C5 alkyl group, or N-methylpyrrolidine or N-methylpiperidine Alternatively, in any embodiment, the cationic component can have the formula [R n AH4_ n + ​, where A is nitrogen, n is 2 or 3, and all Rs are the same and are C1-C3 alkyl groups, such as trimethylammonium, trimethylbenzylammonium, triethylammonium, dimethylbenzylammonium, and dimethylammonium.

[0059] Suitable activators can also be or include anionic component [Y]. The anionic component can be a non-coordinating anion (NCA) having the formula [B(R 4 )4] - , where R 4 is aryl or substituted aryl, where one or more substituents are the same or different and are selected from alkyl, aryl, halogen atoms, haloaryl, and haloalkylaryl. The substituents can be perhalogenated aryl or perfluorinated aryl, including perfluorophenyl, perfluoronaphthyl, and perfluorobiphenyl.

[0060] The cationic and anionic components of the catalyst system disclosed herein can together form an activator compound. In any embodiment, the activator can be N,N-dimethylbenzylammonium tetrakis(perfluorophenyl)borate, N,N-dimethylbenzylammonium tetrakis(perfluoronaphthyl)borate, N,N-dimethylbenzylammonium tetrakis(perfluorobiphenyl)borate, N,N-dimethylbenzylammonium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate, triphenylcarbenium tetrakis(perfluorophenyl)borate triphenylcarbenium tetrakis(perfluoronaphthyl)borate triphenylcarbenium tetrakis(perfluorobiphenyl)borate and / or triphenylcarbenium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate

[0061] A particularly advantageous activator is dimethylbenzylammonium (heptafluoronaphthyl)borate. For a detailed description of suitable catalyst systems and activators, also see International Publication Nos. WO / 2021 / 162748; WO / 2013 / 134038; WO / 2000 / 024793. Each of which is incorporated herein by reference.

[0062] As noted, suitable polymerization methods use a polymerization catalyst system, particularly a polymerization catalyst system comprising at least one activator, at least one support, and at least one catalyst composition. A "catalyst composition" or "catalyst system" is a combination of at least two catalyst compounds, a support material, an optional activator, and an optional co-activator. It is believed that due to the specific catalyst system used for polymerizing the copolymer, the high volume resistivity of the ethylene-based copolymer provided herein can be achieved or enhanced. In a photovoltaic cell, a viable way to mitigate potential-induced degradation (PID) is to impede the flow of ionic current through the encapsulant. Volume resistivity is an inherent property of the encapsulant polymer material and is characterized by the strength with which a given material resists the flow of current.

[0063] For a given catalyst system, once the cation of the activator activates the catalyst, the activator can remain in the polymer composition. As a result, the cations and anions can affect the polymer conductivity. Since not all ions diffuse equally, different ions affect the polymer composition differently. In particular, the size of the ion, the charge of the ion, the interaction of the ion with the surrounding medium, and the dissociation energy of the ion with the available counterions will all affect the ability of the ion to diffuse through the surrounding medium (such as a polymer material).

[0064] Conventional olefin polymerization activators include weakly coordinating or non-coordinating anions. It has been shown that the weak coordination of the anion leads to an increase in the catalytic efficiency of the cationic catalyst. However, since the non-nucleophilic nature of the non-coordinating anion also increases diffusion, the residual activator anions in the resulting polymer will reduce the resistance of the polymer, thereby increasing the electrical loss and reducing the insulating ability of the resulting polymer.

[0065] It has surprisingly been found that the volume resistivity of ethylene-based copolymers can be enhanced (increased) by reducing the level of residual ions and achieving a low ion diffusion rate. The transition metal bis(phenolate) complexes according to formula (I) shown and described in U.S. Patent No. 11,225,539 have the ability to produce ethylene copolymers with high catalyst activity (about 3 times higher than conventional bridged metallocene compounds such as those mentioned in paragraph

[0055] ). The high catalyst activity results in low residual ions in the polymer. Particularly suitable catalysts include: dimethylzirconium [2',2'''-(pyridine-2,6-diyl)bis(3-adamantan-1-yl)-5-(tert-butyl)-[1,1'-biphenyl]-2-olate] (Cat-Zr) or dimethylhafnium [2',2'''-(pyridine-2,6-diyl)bis(3-adamantan-1-yl)-5-(tert-butyl)-[1,1'-biphenyl]-2-olate] (Cat-Hf).

[0066] It has also surprisingly been found that bulky activators, such as those compatible with the above-mentioned Cat-Zr and Cat-Hf catalysts, slow down the ion diffusion rate during polymerization. Such activators can include: N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (DMAH-BF20) or N,N-dimethylanilinium tetrakis(heptafluoronaphthyl)borate (DMAH-BF28).

[0067] Ethylene copolymers can have a unique combination of the following properties: a. Volume resistivity at 23 °C > 8*10 15 Ωcm; b. g'Mz+1 / g'-average < 1, for g'Mz+1 (branching) < 0.931; c. For g'Mz (branched) < 0.93 and g'Mz+1 (branched) < 0.93, significantly higher trisubstituted olefins; d. For g'Mz < 0.94, < 0.2 vinyl groups / total unsaturated moieties; e. For any g'Mz < 0.94, reactivity ratio ≤ 0.7; and / or f. As shown in Figure 4, lower r1r2 values compared to the comparative copolymers (most > 1 and up to ~1.5), indicating a lower chain blockiness level.

[0068] These unique properties distinguish the ethylene copolymers provided herein from other comparative ethylene copolymers. Examples

[0069] The foregoing discussion can be further described with reference to the following non-limiting examples. Six (6) different ethylene copolymers were prepared. Samples 1 - 4 are ethylene - butene copolymers and Samples 5 - 6 are ethylene - octene copolymers. All 6 copolymers were prepared in a pilot - scale solution reactor using dimethyl·bis(p - triethylsilylphenyl)methylene(2,7 - di - tert - butylfluorenyl)(cyclopentadienyl)hafnium as the catalyst and dimethylanilinium tetrakis(heptafluoronaphthyl)borate as the cocatalyst, both of which are available from ExxonMobil Product Solutions Company.

[0070] Tables 1 and 2 provide more information on each reactor component and the total copolymers for Samples 1 - 6. Tables 3 and 4 provide similar information for comparative commercially available copolymers. Table 5 reports the tensile strength and flexural modulus of compression - molded samples from Samples 1 - 4.

[0071] Table 1: Properties of Samples 1 - 6

[0072] Table 2: Additional Properties of Samples 1 - 6

[0073] Table 3: Properties of Comparative Commercially Available Copolymers

[0074] Table 4: Properties of Comparative Commercially Available Copolymers.

[0075] Table 5: Tensile and Flexural Properties of Compression - Molded Samples 1 - 4

[0076] For Samples 1-6 and other commercially available ethylene copolymers of similar density, Figure 1A Volume resistivity plotted against the g'Mz+1 value is shown, Figure 1B Volume resistivity plotted against the g'(Mz+1) / g'-average value is shown. Figure 1C The g'(Mz+1) / g'-average value plotted against the g'(Mz+1) value from GPC is shown for the same copolymer. As Figure 1A - 1C shown, for both the copolymers of the present invention and the comparative commercially available copolymers, the volume resistivity at 23 °C > 4×10 15 Ωcm & the g'Mz+1 / g'-average value < 1 for g'Mz+1 (branching) < 0.93.

[0077] Figure 2A The trisubstituted olefin vs. g'(Mz+1) determined by HNMR is shown for Samples 1-6 and other commercially available ethylene copolymers of similar density, Figure 2B The trisubstituted olefin vs. g'(Mz) determined by HNMR is shown. As Figure 2A and 2B shown, Samples 1-6 show significantly higher trisubstituted olefins for g'Mz (branching) < 0.93 and g'Mz+1 (branching) < 0.93.

[0078] Figure 3 The number of vinyl groups / total unsaturated moieties determined by HNMR vs. g'(Mz) from GPC is shown for Samples 1-6 and other commercially available ethylene copolymers of similar density. Figure 3 The resin of the present invention has < 0.2 vinyl groups / total unsaturated moieties for g'Mz < 0.94.

[0079] Figure 4A The r1r2 value from the NMR test vs. g'(Mz+1) is shown for Samples 1-6 and other commercially available ethylene copolymer grades, and Figure 4B the r1r2 value from the NMR test vs. g'Mz is shown. The reactivity ratios of the copolymers of the present invention are ≤ 0.7 for any g'Mz < 0.94 and have much lower r1r2 values than the comparative copolymers (most > 1 and up to ~1.5), which means a lower level of chain blockiness.

[0080] Figure 5A The phase angle at a complex modulus of 10,000 Pa is shown for Samples 1-6 and other commercially available ethylene copolymer grades, and Figure 5B the phase angle at a complex modulus of 50,000 Pa is shown. As shown, the phase angles measured at ~5 MI and ~14 MI at 10,000 & 50,000 Pa complex moduli are significantly lower than those of the comparative examples at similar MI.

[0081] Figure 6 The TREF-IR data (differential and cumulative) of Samples 1-4 are shown. The TREF data contain a soluble fraction below 0 °C and an insoluble fraction with distinct elution temperatures. For Samples 1 and 3, there is a distinct peak elution temperature near 30 °C. For Samples 3 and 4, there are two peak elution temperatures corresponding to the densities of the components in each reactor. The elution peak of the lower density component appears near 20 °C, while the elution peak of the higher density fraction is between 45 and 50 °C.

[0082] Figure 7 The cooling cycle data of Samples 1 to 4 were compared separately. The peak crystallization temperature and the corresponding heat of crystallization were plotted for each sample. Comparing Sample 3 with Sample 1, a higher Tc was observed (56 °C vs. 45 °C), and the same was true when comparing Sample 4 with Sample 2 (61 °C vs. 49 °C). The heat of crystallization of Sample 3 was lower compared to Sample 1 (32 J / g vs. 34 J / g), and when comparing Sample 4 with Sample 2, the heat of crystallization was higher (36 J / g vs. 33 J / g). The increase in Tc is particularly significant for maintaining stable pellets at lower polymer densities due to the higher crystallinity in the second reactor component. Figure 7 It is also shown that the dual-reactor Sample 4 has a higher modulus.

[0083] Figure 8 The water vapor transmission rate (WVTR) performance of Samples 1 to 4 is shown. The transmission rate is typically considered in g / m 2 *days. Lower values indicate enhanced barrier to water permeation. Sample 3 and Sample 4 have lower WVTR values compared to the single-reactor analogs of Sample 1 and Sample 3, respectively. The lower WVTR values of the dual-reactor grades can be attributed to the higher crystalline fraction in the second reactor component.

[0084] Samples 1-4 were compounded with peroxide (Luperox 101) at 2.5 phr. The peroxide was added to the polymer using a 270 gm batch in a Brabender Plasticorder. The melt temperature in the Brabender was maintained at 70 °C to mitigate premature crosslinking. The samples were added to the Brabender with the rotor running at 50 rpm until the polymer flowed and homogenized in the chamber. The peroxide was added to the polymer, and the mixture was compounded for an additional 3 minutes and then discharged from the chamber.

[0085] The curing properties of the samples were tested using an oscillating disk rheometer (ODR) at 180 °C, 3-degree arc, and 30-minute test time. The curing state determined by MH-ML, the difference between the maximum torque value (MH) and the minimum torque value (ML), and the maximum curing rate were determined as [(MH-ML)×0.9-2] / (Tc90 - Ts2), where Tc 90 is the time to reach 90% of the maximum HF, and Ts2 is the curing time to a 2 - torque - unit increase.

[0086] Figure 9 Shows the ODR parameters (curing rate and curing state) comparing the single - reactor samples (Sample 1 and Sample 2) with the corresponding dual - reactor analogs of Sample 3 and Sample 4, respectively. Both the maximum curing rate and the curing state in the dual - reactor polymers are higher compared to the single - reactor candidates.

[0087] Samples 2 and 4 (14 MI) were extruded in a sheet extruder to form a 0.5 - mm - thick film, where the melt temperature was at 100 °C. Figure 10 Shows the melt pressure and screw torque during extrusion of 0.5 - mm - thick films made from Samples 2 and 4 and two other commercially available comparative polymers of similar density at a melt temperature of 100 °C. These copolymer samples showed lower torque than the commercially available reference copolymers, indicating better processability for this particular application. Further, it was found that, compared to single - reactor polymers produced at a fixed MI, tailoring of the individual molecular weight provided an advantage in terms of processability, especially during film extrusion. Test Procedure

[0088] In the above - mentioned embodiments, the following test methods and procedures were used:

[0089] Density was measured according to ASTM D792, and the MI value and MIR value (MI 21.6 / MI 2.16 ) were measured according to ASTM D1238 (190 °C / 2.16 kg).

[0090] The distributions and moments of molecular weight (Mw, Mn, Mz, Mw / Mn, Mz / Mn, etc.), comonomer content (C8), and long chain branching index (g') are determined by high temperature gel permeation chromatography (Polymer Char GPC-IR) equipped with a multi-channel band-pass filter based infrared detector IR5, an 18-angle light scattering detector, and a viscometer. Three Agilent PLgel 10μm Mixed-B LS columns are used to provide polymer separation. The detailed analytical principles and methods for molecular weight determination are described in paragraphs

[0044] -

[0051] of International Publication No. WO2019 / 246069A1, which is incorporated herein by reference (it should be noted that the equation for c in terms of the concentration I at each point in the chromatogram cited in paragraph

[0044] thereof is c = βI, where β is a mass constant and I is the IR5 broadband signal intensity (I) minus the baseline). Unless otherwise specifically mentioned, all molecular weight moments used or mentioned in this disclosure are determined according to conventional molecular weight (IR molecular weight) determination methods (e.g., as cited in paragraphs

[0044] -

[0045] of the disclosure just mentioned), it should be noted that for the equation in this paragraph

[0044] , a = 0.695 and K = 0.000579(1 - 0.75Wt) are used, where Wt is the weight fraction of the hexane comonomer, and it should also be noted that the comonomer composition is determined by the ratio of the IR5 detector intensities corresponding to the CH2 and CH3 channels, said channels being calibrated with a series of PE and PP homopolymer / copolymer standard samples, the nominal values of which are pre-determined by NMR or FTIR (providing methyl groups per 1000 total carbons (CH3 / 1000TC)), as indicated in paragraph

[0045] of the international publication just mentioned).

[0091] The TREF technique is carried out as described in Wild et al., J. Poly. Sci., Poly. Phys. Ed., Vol. 20, p. 441 (1982) and U.S. Patent No. 5,008,204, which are incorporated herein by reference.

[0092] The SDBI measures the width of the solubility distribution curve of a given polymer. The procedure used herein for calculating the SDBI is described in International Publication No. WO 93 / 03093 (pages 16 to 18), which is incorporated herein by reference.

[0093] The long chain branching index (g') was measured using GPC-4D. A typical GPC-4D curve has log M vs g', and is used to estimate the average g' based on the average across molecular weights. The average branching index g' ranges from 1 to 0, where 1 is linear (no branching) and 0 is fully branched. The average g' cannot clearly distinguish branching changes at low levels (0.85 to 1), so g'(Mz) and g'(Mz+1) are estimated at higher molecular weight fractions (Mz, Mz+1). The branching index g'(Mz) is the g' from the GPC-4D curve estimated at the z-average (third moment) molecular weight average. This calculation is performed by fitting the g' vs molecular weight data curve to an nth order polynomial using a MATLAB program. The value of n is typically between 3 and 4. The Mz value obtained from GPC-IR measurement is inserted into the curve fitting to calculate the g' associated with the molecular weight. of C2% and r1r2 13 13C NMR

[0094] The sample was dissolved in deuterated 1,1,2,2-tetrachloroethane-d2 (tce-d2) at a concentration of 67 mg / mL at 140 °C. The spectrum was recorded at 120 °C using a Bruker NMR spectrometer with at least 600 MHz and a 10 mm cryoprobe. A 90° pulse, 10 s delay, 512 transients, and gated decoupling were used to measure 13 13C NMR. The polymer resonance peak was referenced to the polyethylene main peak at 29.98 ppm.

[0095] Randall described the chemical shift assignments of ethylene-octene copolymers in "A Review Of High Resolution Liquid Carbon Nuclear Magnetic Resonance Characterization of Ethylene-Based Polymers", Polymer Reviews, 29:2, 201-5317 (1989). The copolymer content, mole % and weight %, triad sequences, and dyad calculations were also calculated and described in this work using the methods established by Randall. The calculation of the reactivity ratios (r1r2) is based on the equation r1r2 = 4*[EE]*[OO] / [EO] 2 ; where [EE], [EO], [OO] are the dyad molar concentrations; E is ethylene and O is octene.

[0096] The reactivity ratios of the product r1r2 are more fully described in the Textbook of Polymer Chemistry, F.W. Billmeyer, Jr., Interscience Publishers, New York, pages 221 et seq. (1957). The reactivity ratio product r1r2 (where r1 is the reactivity of ethylene and r2 is the reactivity of propylene) can be calculated from the measured dyad distribution (OO, EE, EO, and OE in the nomenclature) by applying the following formula: r1r2 = 4(EE)(OO) / (EO) 2 r1 = K 11 / K 12 = [2(EE) / EO]X r2 = K 22 / K 21 = [2(PP) / (EO)]X O = (OO)+(EO / 2) E = (EE)+(EO / 2) where Mol% E = [(E) / (E + O)]*100 and X = E / O in the reactor; K 11 and K 12 are the kinetic insertion constant of ethylene and K 21 and K 22 are the kinetic insertion constant of propylene.

[0097] As is known to those skilled in the art, a reactivity ratio product r1r2 of zero (0) can define an "alternating" copolymer, and a reactivity ratio product of one (1) is said to define a "statistically random" copolymer. In other words, copolymers with a reactivity ratio product r1r2 of 0.6 to 1.5 are generally considered random copolymers (strictly speaking, generally only copolymers with a reactivity ratio product r1r2 greater than 1.5 contain longer homopolymer sequences and are considered "blocky").

[0098] HNMR data were collected at an H frequency of at least 600 MHz using a Bruker spectrometer with a 10 mm cold probe at 120 °C. The maximum pulse width was 45°, with a 5-second interval between pulses and 512 transient signals averaged for signal recording. Samples were prepared by dissolving 80 - 100 mg of the sample in 3 mL of solvent heated to 140 °C. For the present invention and the appended claims, the unsaturated portion in the polymer is by 1 H frequency to collect 1 HNMR data. Using a maximum pulse width of 45°, 5 seconds between pulses, and 512 transient signals averaged for signal recording. Samples were prepared by dissolving 80 - 100 mg of the sample in 3 mL of solvent heated to 140 °C. For the present invention and the appended claims, the unsaturated portion in the polymer is by 11H NMR was determined with reference to Macromolecules, 2014, 47, 3782 and Macromolecules, 2005, 38, 6988, but in case of conflict, Macromolecules, 2014, 47, 3782 shall prevail. The peak assignments were determined with reference to a 1,1,2,2-tetrachloroethane-d2 solvent at 5.98 ppm. US2018162973A1 provides additional details, which are incorporated herein by reference.

[0099] The volume resistivity (VR) was tested according to the ExxonMobil method based on ASTM D257. Measurements were made using a Keithley 6517B electrometer and a Keithley 8009 test fixture. The leakage current was directly measured with the said instrument, and the volume resistivity was calculated using the following equation, where ρ is the volume resistivity (Ω.cm), V is the applied voltage (volts), A is the electrode contact area (cm 2 ), I is the leakage current (amperes), and t is the average thickness of the sample. The volume resistivity test was carried out at 500 volts at room temperature, and three compression-molded films were tested to obtain an average value.

[0100] Differential scanning calorimetry (DSC) was performed using a Perkin Elmer instrument with 5 mg to 10 mg samples, where two melting cycles and one cooling cycle were carried out at a rate of 10 °C / min between -80 °C and 200 °C. The melting temperature (Tm) and the crystallization temperature (Tc) are reported in °C.

[0101] Small amplitude oscillatory shear (SAOS) measurements were carried out at 190 °C between 0.01 s -1 and 500 s -1 shear rates. A van Gurp-Palmen plot was constructed by plotting the phase angle (δ) as a function of the constant modulus (G*). The phase angles at 10000 Pa and 50000 Pa complex moduli were reported.

[0102] To estimate the water vapor transmission rate (WVTR, g / m 2 -day) on the compression-molded film, an in-house method was used. A PermatranW-700 manufactured by Mocon was used for the measurement. The test was carried out at 37.8 °C, 760 mm Hg atmospheric pressure, and 100% relative humidity. The WVTR values reported in gm / m 2 -day were converted to permeance in metric perm (gm.mil / m 2 -day).

[0103] The ethylene copolymers provided herein are particularly suitable for manufacturing solar cells (also known as photovoltaic cells), photovoltaic (PV) modules, and other low-current electronic devices or modules, such as liquid crystal panels, electroluminescent devices, and plasma display units. Solar cell modules typically have one or more cells made of silicon, gallium-arsenic, and copper-iridium-selenium, which have a top transparent protective material and a bottom protective substrate material, wherein the solar cells and the protective materials are fixed by using an encapsulating material. The ethylene copolymers provided herein can be used as the top protective material, the bottom protective material, or both. The ethylene copolymer can provide a film with excellent flexibility, transparency, and heat resistance, making such a film particularly suitable for PV modules.

[0104] The ethylene copolymers can also be used for packaging. Such modules as described above typically utilize electronic devices combined with one or more substrates, and the one or more substrates provide protection and / or support for their manufacture, transportation, and use. For example, these types of devices are typically positioned behind one or more glass cover plates and / or between two substrates, wherein one or both substrates are made of glass, metal, plastic, rubber, or other materials. In these cases, the ethylene copolymer can be used as an encapsulant or sealant for the devices within the module, or directly used as a cover layer or skin layer of the module depending on the design of the module, such as the back skin layer in a solar cell module. List of embodiments

[0105] The present disclosure may also include any one or more of the following non-limiting embodiments:

[0106] Embodiment 1. An ethylene copolymer, comprising: at least 50 wt% of ethylene-derived units; and at least 20 wt% of at least one C3 to C20 comonomer, wherein the copolymer has a melt index of 0.5 g / 10 min to about 50 g / 10 min measured according to ASTM D1238 (190 °C / 2.16 kg); a density of about 0.860 g / cc to 0.880 g / cc measured according to ASTM D792; a first long-chain branching index (g'(Mz)) of 0.80 to 0.93; a second long-chain branching index (g'(Mz+1)) of 0.80 to 0.93; less than 0.7 vinyls / total unsaturation; an unsaturation level of trisubstituted olefins of 50 to 500 and a 23 °C volume resistivity of 4×10 15 Ω·cm or higher.

[0107] Embodiment 2. The ethylene copolymer of Embodiment 1, further comprising a g'Mz+1 / g'-average ratio of 0.9 to 1.0.

[0108] Embodiment 3. The ethylene copolymer of Embodiment 1 or 2, wherein the copolymer has less than 0.6 vinyls / total unsaturation.

[0109] Embodiment 4. The ethylene copolymer according to any one of Embodiments 1 to 3, wherein the unsaturation level of the trisubstituted olefin is 60 to 450.

[0110] Embodiment 5. The ethylene copolymer according to any one of Embodiments 1 to 4, further comprising two or more TREF elution temperature peaks.

[0111] Embodiment 6. The ethylene copolymer according to any one of Embodiments 1 to 5, further comprising a first peak elution temperature of less than 30 °C and a second peak elution temperature of greater than 40 °C.

[0112] Embodiment 7. The ethylene copolymer according to any one of Embodiments 1 to 6, further comprising an r1r2 reactivity ratio of less than or equal to 0.8.

[0113] Embodiment 8. The ethylene copolymer according to any one of Embodiments 1 to 7, further comprising an r1r2 reactivity ratio of 0.2 to 0.8.

[0114] Embodiment 9. The ethylene copolymer according to any one of Embodiments 1 to 8, further comprising less than 10 wt% of diene-derived units.

[0115] Embodiment 10. The ethylene copolymer according to any one of Embodiments 1 to 9, wherein the at least one C3 to C20 comonomer is butene or octene or a combination thereof.

[0116] Embodiment 11. An electronic device module, comprising at least one electronic device and an ethylene copolymer film in direct contact with at least one surface of the electronic device, the ethylene copolymer comprising at least 50 wt% ethylene-derived units; and at least 20 wt% of at least one C3 to C20 comonomer, wherein the copolymer has a melt index of 0.5 g / 10 min to about 50 g / 10 min measured according to ASTM D1238 (190 °C / 2.16 kg); a density of about 0.860 g / cc to 0.880 g / cc measured according to ASTM D792; a first long-chain branching index (g'(Mz)) of 0.80 to 0.93; a second long-chain branching index (g'(Mz+1)) of 0.80 to 0.93; less than 0.7 vinyls / total unsaturation moiety; an unsaturation level of the trisubstituted olefin of 50 to 500 and a 23 °C volume resistivity of 4×10 15 Ωcm or higher.

[0117] Embodiment 12. The electronic device module according to Embodiment 11, wherein the copolymer further comprises a g'Mz+1 / g'-average ratio of 0.9 to 1.0.

[0118] Embodiment 13. The electronic device module of Embodiment 11 or 12, wherein the copolymer further comprises a first peak elution temperature of less than 30 °C and a second peak elution temperature of greater than 40 °C.

[0119] Embodiment 14. The electronic device module of any one of Embodiments 11 to 13, wherein the copolymer further comprises an r1r2 reactivity ratio of 0.2 to 0.8.

[0120] Embodiment 15. The electronic device module of any one of Embodiments 11 to 14, wherein the copolymer further comprises less than 10 wt% of diene-derived units and the at least one C3 to C20 comonomer is butene or octene or a combination thereof.

[0121] Embodiment 16. A method of manufacturing an electronic device module, comprising: providing at least one electronic device, and laminating an ethylene copolymer film onto at least one surface of the electronic device, the ethylene copolymer comprising: at least 50 wt% ethylene-derived units; and at least 20 wt% of at least one C3 to C20 comonomer, wherein the copolymer has a melt index of 0.5 g / 10 min to about 50 g / 10 min measured according to ASTM D1238 (190 °C / 2.16 kg); a density of about 0.860 g / cc to 0.880 g / cc measured according to ASTM D792; a first long-chain branching index (g'(Mz)) of 0.80 to 0.93; a second long-chain branching index (g'(Mz+1)) of 0.80 to 0.93; less than 0.7 vinyl groups / total unsaturated moieties; an unsaturation level of trisubstituted olefins of 50 to 500 and a 23 °C volume resistivity of 4×10 15 Ω·cm or higher.

[0122] Embodiment 17. The method of Embodiment 16, wherein the copolymer further comprises a ratio of g'Mz+1 / g'-average of 0.9 to 1.0.

[0123] Embodiment 18. The method of Embodiment 16 or 17, wherein the copolymer further comprises a first peak elution temperature of less than 30 °C and a second peak elution temperature of greater than 40 °C.

[0124] Embodiment 19. The method of any one of Embodiments 16 to 18, wherein the copolymer further comprises an r1r2 reactivity ratio of 0.2 to 0.8.

[0125] Embodiment 20. The method of any one of Embodiments 16 to 19, wherein the copolymer further comprises less than 10 wt% of diene-derived units and the at least one C3 to C20 comonomer is butene or octene or a combination thereof.

[0126] Certain embodiments and features have been described using a set of upper numerical limits and a set of lower numerical limits. It is understood that ranges including any combination of any two values, e.g., ranges including any combination of any lower value with any upper value, any combination of any two lower values, and / or any combination of any two upper values are contemplated, unless otherwise stated. Certain lower limits, upper limits and ranges appear in one or more of the claims below. All numerical values are "about" or "approximately" the indicated values, and experimental error and deviations that would be expected by a person of ordinary skill in the art are considered.

[0127] Various terms have been defined above. If a term used in a claim is not defined above, it should be given its broadest definition as the term is known to persons in the relevant art from at least one printed publication or issued patent. Additionally, all patents, test procedures and other documents cited in this application are hereby incorporated by reference in their entirety to the extent that this disclosure is consistent with the present invention and for all jurisdictions that permit such incorporation.

[0128] While the foregoing relates to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope of the invention is determined by the claims that follow.

Claims

1. An ethylene copolymer, comprising: At least 50 wt% of ethylene-derived units; and At least 20 wt% of at least one C3 to C20 comonomer, wherein the copolymer has: A melt index of 0.5 g / 10 min to about 50 g / 10 min as measured by ASTM D1238 (190 °C / 2.16 kg); A density of about 0.860 g / cc to 0.880 g / cc as measured by ASTM D792; A first long-chain branching index (g'(Mz)) of 0.80 to 0.93; A second long-chain branching index (g'(Mz+1)) of 0.80 to 0.93; Less than 0.7 vinyl groups / total unsaturated moieties; An unsaturation level of 50 to 500 for trisubstituted olefins; and 4 × 10 15 Volume resistivity at 23 °C of 4 × 10 Ωcm or higher.

2. The ethylene copolymer of claim 1, further comprising a ratio of g'Mz+1 / g'-average of 0.9 to 1.

0.

3. The ethylene copolymer of claim 1, wherein the copolymer has less than 0.6 vinyl groups / total unsaturated moieties.

4. The ethylene copolymer of claim 1, wherein the unsaturation level of the trisubstituted olefins is 60 to 450.

5. The ethylene copolymer of claim 1, further comprising two or more TREF elution temperature peaks.

6. The ethylene copolymer of claim 1, further comprising a first peak elution temperature of less than 30 °C and a second peak elution temperature of greater than 40 °C.

7. The ethylene copolymer of claim 1, further comprising an r1r2 reactivity ratio ≤ 0.

8.

8. The ethylene copolymer of claim 1, further comprising an r1r2 reactivity ratio of 0.2 to 0.

8.

9. The ethylene copolymer of claim 1, further comprising less than 10 wt% of diene-derived units.

10. The ethylene copolymer of claim 1, wherein the at least one C3 to C20 comonomer is butene or octene or a combination thereof.

11. An electronic device module, comprising: At least one electronic device, and An ethylene copolymer film in direct contact with at least one surface of the electronic device, the ethylene copolymer comprising: At least 50 wt% of ethylene-derived units; and At least 20 wt% of at least one C3 to C20 comonomer, wherein the copolymer has: A melt index of 0.5 g / 10 min to about 50 g / 10 min as measured by ASTM D1238 (190 °C / 2.16 kg); A density of about 0.860 g / cc to 0.880 g / cc as measured by ASTM D792; A first long-chain branching index (g'(Mz)) of 0.80 to 0.93; A second long-chain branching index (g'(Mz+1)) of 0.80 to 0.93; Less than 0.7 vinyl groups / total unsaturated moieties; An unsaturation level of 50 to 500 for trisubstituted olefins; And 4 × 10 15 Volume resistivity at 23 °C of 4 × 10 15 Ω·cm or higher.

12. The electronic device module of claim 11, wherein the copolymer further comprises a ratio of g'Mz+1 / g'-average of 0.9 to 1.

0.

13. The electronic device module of claim 12, wherein the copolymer further comprises a first peak elution temperature of less than 30 °C and a second peak elution temperature of greater than 40 °C.

14. The electronic device module of claim 13, wherein the copolymer further comprises a r1r2 reactivity ratio of from 0.2 to 0.

8.

15. The electronic device module of claim 14, wherein the copolymer further comprises less than 10 wt% of diene-derived units, and the at least one C3 to C20 comonomer is butene or octene or a combination thereof.

16. A method of manufacturing an electronic device module, comprising: providing at least one electronic device, and laminating an ethylene copolymer film onto at least one surface of the electronic device, the ethylene copolymer comprising: at least 50 wt% of ethylene-derived units; and at least 20 wt% of at least one C3 to C20 comonomer, wherein the copolymer has: a melt index of from 0.5 g / 10 min to about 50 g / 10 min as measured according to ASTM D1238 (190 °C / 2.16 kg); a density of from about 0.860 g / cc to 0.880 g / cc as measured according to ASTM D792; a first long-chain branching index (g'(Mz)) of from 0.80 to 0.93; a second long-chain branching index (g'(Mz+1)) of from 0.80 to 0.93; less than 0.7 vinyl groups / total unsaturation; an unsaturation level of trisubstituted olefins of from 50 to 500; and 4×10 15 Volume resistivity at 23 °C of 4×10 Ωcm or higher.

17. The method of claim 16, wherein the copolymer further comprises a ratio of g'Mz+1 / g'-average of from 0.9 to 1.

0.

18. The method of claim 17, wherein the copolymer further comprises a first peak elution temperature of less than 30 °C and a second peak elution temperature of greater than 40 °C.

19. The method of claim 18, wherein the copolymer further comprises a r1 r2 reactivity ratio of from 0.2 to 0.

8.

20. The method of claim 19, wherein the copolymer further comprises less than 10 wt% of diene-derived units, and the at least one C3 to C20 comonomer is butene or octene or a combination thereof.

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