Patent Description:
The global demand for alternative energy has resulted in large increases in solar panel and photovoltaic (PV) module production over the last decade. The solar cells (also called PV cells) that convert solar energy into electrical energy are extremely fragile and must be surrounded by a durable encapsulant film. Two main functions of the encapsulant film are to (<NUM>) bond the solar cell to the glass coversheet and the backsheet and (<NUM>) protect the PV module from environmental stress (e.g., moisture, temperature, shock, vibration, electrical isolation, etc.).

In order to be used as an encapsulant film, a film must show (a) good lamination performance, (b) strong adhesion with glass, the PV cell, and the backsheet, (c) good electrical insulation (low leakage current, high volume resistivity), (d) good optical transparency, (e) low water vapor permeability and moisture absorption, (f) good creep resistance, (g) stability in UV exposure, and (h) good weathering. Current encapsulant films are primarily made of ethylene vinyl acetate (EVA) because EVA shows a good balance of (a)-(h). EVA is a type of ethylene/unsaturated carboxylic ester copolymer in which the unsaturated carboxylic ester comonomer is a vinyl carboxylate. Because EVA is so readily used to form encapsulant films, numerous additive packages have been developed to enhance one or more of (a)-(h).

Non-polar polyolefins, such as ethylene-based elastomers that are not ethylene/unsaturated carboxylic ester copolymers, have been used to make encapsulant films, yet require organic peroxide and a coupling agent, generally a silane coupling agent, in order to adhere to glass sufficiently. A crosslinking co-agent is typically used with the non-polar polyolefin-based encapsulant films in order to obtain sufficient glass adhesion. However, many conventional crosslinking agents are problematic because they reduce the volume resistivity of the encapsulant film. Consequently, the art recognizes the need for crosslinking co-agents that provide sufficient glass adhesion and improve volume resistivity for encapsulant films.

The disclosure provides an encapsulant film comprising a crosslinked polymeric composition, the composition comprising (A) from <NUM> wt% to <NUM> wt% of a non-polar ethylene-based polymer based on the total weight of the composition; (B) from <NUM> wt% to <NUM> wt% of an organic peroxide based on the total weight of the composition; (C) from <NUM> wt% to <NUM> wt% of a silane coupling agent based on the total weight of the composition; and (D) from <NUM> wt% to <NUM> wt% based on the total weight of the composition of a single co-agent comprising a compound of Structure I
<CHM>
wherein R<NUM>-R<NUM> is each independently selected from the group consisting of a C<NUM>-C<NUM> hydrocarbyl group, a C<NUM>-C<NUM> substituted hydrocarbyl group and combinations thereof and wherein the encapsulant film has a volume resistivity from greater than or equal to <NUM>*<NUM><NUM> ohm. cm to <NUM>*<NUM><NUM> ohm. cm at <NUM>.

In another embodiment, the disclosure provides an electronic device module comprising an electronic device, wherein the electronic device is a photovoltaic cell, and at least one encapsulant film composed of a crosslinked polymeric composition which is the reaction product of a composition comprising (A) from <NUM> wt% to <NUM> wt% of a non-polar ethylene-based polymer based on the total weight of the composition; (B) from <NUM> wt% to <NUM> wt% of an organic peroxide based on the total weight of the composition; (C) from <NUM> wt% to <NUM> wt% of a silane coupling agent based on the total weight of the composition; and (D) from <NUM> wt% to <NUM> wt% based on the total weight of the composition of a single co-agent comprising a compound of Structure I, as described herein.

<FIG> is an exploded perspective view of an exemplary photovoltaic module.

Any reference to the Periodic Table of Elements is that as published by CRC Press, Inc. , <NUM>-<NUM>. Reference to a group of elements in this table is by the new notation for numbering groups.

The numerical ranges disclosed herein include all values from, and including, the lower and upper value. For ranges containing explicit values (e.g., <NUM> or <NUM>, or <NUM> to <NUM>, or <NUM>, or <NUM>), any subrange between any two explicit values is included (e.g., <NUM> to <NUM>; <NUM> to <NUM>; <NUM> to <NUM>; <NUM> to <NUM>; <NUM> to <NUM>; etc.).

"Blend", "polymer blend" and like terms mean a composition of two or more polymers. Such a blend may or may not be miscible. Such a blend may or may not be phase separated. Such a blend may or may not contain one or more domain configurations, as determined from transmission electron spectroscopy, light scattering, x-ray scattering, and any other method used to measure and/or identify domain configurations. Blends are not laminates, but one or more layers of a laminate may contain a blend.

"Composition," as used herein, includes a mixture of materials which comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.

The terms "comprising," "including," "having," and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term "comprising" may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term, "consisting essentially of" excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability. The term "consisting of" excludes any component, step or procedure not specifically listed. The term "or," unless stated otherwise, refers to the listed members individual as well as in any combination. Use of the singular includes use of the plural and vice versa.

Crosslinking or cure is tested using a moving die rheometer. The moving die rheometer (MDR) is loaded with <NUM> grams of each sample. The MDR is run for <NUM> minutes and the time v. torque curve is produced for the samples over the given interval. The MDR is run at <NUM> and <NUM>. The <NUM> represents the maximum film fabrication temperature. The <NUM> represents the module lamination temperature. The maximum torque (MH) exerted by the MDR during the <NUM> minute testing interval is reported in dNm. The MH usually corresponds to the torque exerted at <NUM> minutes. The time it takes for torque to reach X% of MH (tx) is reported in minutes. tx is a standardized measurement to understand the curing kinetics of each resin. The time to reach <NUM>% of MH (T<NUM>) is reported in minutes.

Density of ethylene vinyl acetate (EVA) is measured in accordance with ASTM D1525). Density of the non-polar ethylene-based polymers is measured in accordance with ASTM D792. The result is recorded in grams (g) per cubic centimeter (g/cc or g/cm<NUM>).

"Direct Contact" means a layer configuration whereby a first layer is located immediately adjacent to a second layer and no intervening layers or no intervening structures are present between the first layer and the second layer.

An "ethylene-based polymer" is a polymer that contains more than <NUM> weight percent polymerized ethylene monomer (based on the total amount of polymerizable monomers) and, optionally, may contain at least one comonomer. Ethylene-based polymer includes ethylene homopolymer, and ethylene copolymer (meaning units derived from ethylene and one or more comonomers). The terms "ethylene-based polymer" and "polyethylene" may be used interchangeably. Non-limiting examples of ethylene-based polymer (polyethylene) include low density polyethylene (LDPE) and linear polyethylene. Non-limiting examples of linear polyethylene include linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE), very low density polyethylene (VLDPE), multi-component ethylene-based copolymer (EPE), ethylene/α-olefin multi-block copolymers (also known as olefin block copolymer (OBC)), single-site catalyzed linear low density polyethylene (m-LLDPE), substantially linear, or linear, plastomers/elastomers, medium density polyethylene (MDPE), and high density polyethylene (HDPE). Generally, polyethylene may be produced in gas-phase, fluidized bed reactors, liquid phase slurry process reactors, or liquid phase solution process reactors, using a heterogeneous catalyst system, such as Ziegler-Natta catalyst, a homogeneous catalyst system, comprising Group <NUM> transition metals and ligand structures such as metallocene, non-metallocene metal-centered, heteroaryl, heterovalent aryloxyether, phosphinimine, and others. Combinations of heterogeneous and/or homogeneous catalysts also may be used in either single reactor or dual reactor configurations.

Glass adhesion strength (maximum glass adhesion strength and average glass adhesion strength from <NUM> (<NUM>") to <NUM> (<NUM>") is measured by the <NUM>° peel test. Cuts are made through the backsheet and film layers of each of the laminated samples (e.g., comparative example and inventive example formulations) to divide each laminated sample into three <NUM> (<NUM>-inch) wide strip specimens, with the strips still adhered to the glass layer. The <NUM>° peel test is conducted on an Instron TM <NUM> under controlled ambient conditions. The initial glass adhesion and the glass adhesion after aging (Damp Heating (DH) aging test) at <NUM> and <NUM>% humidity for <NUM> hours and <NUM> hours are tested. Results are reported in Newtons/cm. Three specimens are tested to get the average glass adhesion strength for each sample at each condition.

Glass transition temperature (Tg) is measured according to ASTM-D3418-<NUM>.

"Hydrocarbyl group" and "hydrocarbon" refer to substituents containing only hydrogen and carbon atoms, including branched or unbranched, saturated or unsaturated, cyclic, polycyclic or acyclic species, and combinations thereof. Non-limiting examples of hydrocarbyl groups include alkyl-, cycloalkyl-, alkenyl-, alkadienyl-, cycloalkenyl-, cycloalkadienyl-, aryl-, aralkyl, alkylaryl, and alkynyl- groups. "Substituted hydrocarbyl group" and "substituted hydrocarbon" refer to a hydrocarbyl group that is substituted with one or more nonhydrocarbyl substituent groups. A non-limiting example of a nonhydrocarbyl substituent group is a heteroatom. A "heteroatom" refers to an atom other than carbon or hydrogen. The heteroatom can be a non-carbon atom from Groups IV, V, VI and VII of the Periodic Table. Non-limiting examples of heteroatoms include: F, N, O, P, B, S, and Si. "Alkyl group" refers to a saturated linear, cyclic, or branched hydrocarbon group. Non-limiting examples of suitable alkyl groups include, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, i-butyl (or <NUM>-methylpropyl), etc. In one embodiment, the alkyls have <NUM> to <NUM> carbon atoms.

"Interpolymer," as used herein, refers to polymers prepared by the polymerization of at least two different types of monomers. The generic term interpolymer thus includes copolymers (employed to refer to polymers prepared from two different types of monomers), and polymers prepared from more than two different types of monomers.

Melt index (Ml) is measured in accordance with ASTM D1238 at <NUM>, <NUM> and reported in grams per <NUM> minutes (g/<NUM>).

Melting point (Tm) is measured according to ASTM D3418-<NUM>.

"Non-polar ethylene-based polymer" and like terms refer to an ethylene-based polymer that does not have a permanent dipole, i.e., the polymer does not have a positive end and a negative end, and is void of heteroatoms and functional groups. "Functional group" and like terms refer to a moiety or group of atoms responsible for giving a particular compound its characteristic reactions. Non-limiting examples of functional groups include heteroatom-containing moieties, oxygen-containing moieties (e.g., alcohol, aldehyde, ester, ether, ketone, and peroxide groups), and nitrogen-containing moieties (e.g., amide, amine, azo, imide, imine, nitratie, nitrile, and nitrite groups). A "heteroatom" is an atom other than carbon or hydrogen, as defined above.

"Photovoltaic cell", "PV cell" and like terms is a structure that contains one or more photovoltaic effect materials of any of several inorganic or organic types which are known in the art and from prior art photovoltaic module teachings. For example, commonly used photovoltaic effect materials include one or more of the known photovoltaic effect materials including but not limited to crystalline silicon, polycrystalline silicon, amorphous silicon, copper indium gallium (di)selenide (CIGS), copper indium selenide (CIS), cadmium telluride, gallium arsenide, dye-sensitized materials, and organic solar cell materials. As shown in <FIG>, PV cells are typically employed in a laminate structure and have at least one light-reactive surface that converts the incident light into electric current. Photovoltaic cells are generally packaged into photovoltaic modules that protect the cell(s) and permit their usage in their various application environments, typically in outdoor applications. PV cells may be flexible or rigid in nature and include the photovoltaic effect materials and any protective coating surface materials that are applied in their production as well as appropriate wiring and electronic driving circuitry.

"Photovoltaic module", "PV module" and like terms refer to a structure including a PV cell. A PV module may also include a cover sheet, front encapsulant film, rear encapsulant film and backsheet, with the PV cell sandwiched between the front encapsulant film and rear encapsulant film.

"Polymer," as used herein, refers to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term polymer thus embraces the term homopolymer (employed to refer to polymers prepared from only one type of monomer, with the understanding that trace amounts of impurities can be incorporated into the polymer structure), and the term interpolymer as previously defined. Trace amounts of impurities, for example, catalyst residues, may be incorporated into and/or within the polymer.

The volume resistivity is tested according to a Dow method, which is based on ASTM D257. The measurement is made using a Keithley <NUM> B electrometer, combined with the Keithley <NUM> test fixture. The Keithley model <NUM> test chamber is located inside the forced air oven and is capable of operating at elevated temperatures (the maximum temperature of the oven is <NUM>). The leakage current is directly read from the instrument and the following equation is used to calculate the volume resistivity: <MAT> where ρ is the volume resistivity (ohm. cm), V is applied voltage (volts), A is electrode contact area (cm<NUM>), I is the leakage current (amps) and t is the average thickness of the sample. To get the average thickness of the samples, the thickness of each sample is measured before the tests, with five points of the sample measured to get an average thickness. The volume resistivity test is conducted at <NUM> voltage at room temperature (RT) and <NUM>. Two compression molded films are tested to get the average.

In an embodiment, the disclosure provides an encapsulant film comprising a crosslinked polymeric composition, the composition comprising (A) from <NUM> wt% to <NUM> wt% of a non-polar ethylene-based polymer based on the total weight of the composition; (B) from <NUM> wt% to <NUM> wt% of an organic peroxide based on the total weight of the composition; (C) from <NUM> wt% to <NUM> wt% of a silane coupling agent based on the total weight of the composition; and (D) from <NUM> wt% to <NUM> wt% based on the total weight of the composition of a co-agent comprising a compound of Structure I
<CHM>
wherein R<NUM>-R<NUM> each is independently selected from the group consisting of a C<NUM>-C<NUM> hydrocarbyl group, a C<NUM>-C<NUM> substituted hydrocarbyl group, and combinations thereof and wherein the encapsulant film has a volume resistivity from greater than or equal to <NUM>*<NUM><NUM> ohm. cm to <NUM>*<NUM><NUM> ohm. cm at <NUM>.

A composition comprising (A) a non-polar ethylene-based polymer; (B) an organic peroxide; (C) a silane coupling agent; and (D) a co-agent comprising a compound having Structure I, as described above, is used to form an encapsulant film.

The composition comprises a non-polar ethylene-based polymer.

In an embodiment, the non-polar ethylene-based polymer has a density from <NUM>/cc, or <NUM>/cc, or <NUM>/cc, or <NUM>/cc, or <NUM>/cc to <NUM>/cc, or <NUM>/cc, or <NUM>/cc, or <NUM>/cc, or <NUM>/cc.

In an embodiment, the non-polar ethylene-based polymer has a melting point from <NUM>, or <NUM>, or <NUM>, or <NUM> to <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>.

In an embodiment, the glass transition temperature (Tg) of the non-polar ethylene-based polymer is from -<NUM>, or -<NUM>, or -<NUM> or -<NUM> to -<NUM>, or -<NUM>, or -<NUM>, or -<NUM>, or -<NUM>.

In an embodiment, the melt index (Ml) of the non-polar ethylene-based polymer is from <NUM>/<NUM>, or <NUM>/<NUM>, or <NUM>/<NUM>, or <NUM>/<NUM> to <NUM>/<NUM>, or <NUM>/<NUM>, or <NUM>/<NUM>, or <NUM>/<NUM>, or <NUM>/<NUM>.

In an embodiment, the non-polar ethylene-based polymer is an ethylene/alpha-olefin interpolymer. Ethylene/alpha-olefin interpolymers can be random or block interpolymers.

Alpha-olefins are hydrocarbon molecules composed of hydrocarbon molecules comprising (i) only one ethylenic unsaturation, this unsaturation located between the first and second carbon atoms, and (ii) at least <NUM> carbon atoms, or of <NUM> to <NUM> carbon atoms, or in some cases of <NUM> to <NUM> carbon atoms and in other cases of <NUM> to <NUM> carbon atoms. Non-limiting examples of suitable α-olefins from which the copolymers are prepared include propylene, <NUM>-butene, <NUM>-pentene, <NUM>-hexene, <NUM>-octene, <NUM>-dodecene, and mixtures of two or more of these monomers.

Non-limiting examples of suitable ethylene/alpha-olefin interpolymers include ethylene/propylene, ethylene/butene, ethylene/<NUM>-hexene, ethylene/<NUM>-octene, ethylene/propylene/<NUM>-octene, ethylene/propylene/butene, and ethylene/butene/<NUM>-octene interpolymers. In an embodiment, the ethylene/alpha-olefin interpolymer is a copolymer. Non-limiting examples of suitable ethylene/alpha-olefin copolymers include ethylene/propylene copolymers, ethylene/butene copolymers, ethylene/<NUM>-hexene copolymers, and ethylene/<NUM>-octene copolymers.

In an embodiment, the non-polar ethylene-based polymer is an ethylene/alpha-olefin interpolymer. The ethylene/alpha-olefin interpolymer has one, some, or all of the following properties:.

In an embodiment, the ethylene/alpha-olefin interpolymer has at least <NUM>, or all <NUM> of properties (i)-(iii).

The non-polar ethylene-based polymer is present in the composition in an amount of from <NUM> wt% to <NUM> wt%, based on the total weight of the composition.

Blends of non-polar ethylene-based polymers may also be used, and the non-polar ethylene-based polymers may be blended or diluted with one or more other polymers to the extent that the polymers are (i) miscible with one another, (ii) the other polymers have little, if any, impact on the desirable properties of the non-polar ethylene-based polymers, and (iii) the non-polar ethylene-based polymers(s) constitute from <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt% to <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or less than <NUM> wt% of the blend.

Non-limiting examples of suitable commercially available non-polar ethylene-based polymers include ENGAGE resins from Dow Chemical, EXACT resins from EMCC, and LUCENE resins from LG Chemical.

The composition includes an organic peroxide. Non-limiting examples of suitable organic peroxides include dicumyl peroxide, lauryl peroxide, benzoyl peroxide, tertiary butyl perbenzoate, di(tertiary-butyl) peroxide, cumene hydroperoxide, <NUM>,<NUM>-dimethyl-<NUM>,<NUM>-di(t-butylperoxy)hexyne-<NUM>, <NUM>,-<NUM>-di-methyl-<NUM>,<NUM>-di(t-butyl-peroxy)hexane, tertiary butyl hydroperoxide, isopropyl percarbonate, alpha,alpha'-bis(tertiary-butylperoxy)diisopropylbenzene, t-butylperoxy-<NUM>-ethylhexyl-monocarbonate, <NUM>,<NUM>-bis(t-butylperoxy)-<NUM>,<NUM>,<NUM>-trimethyl cyclohexane, <NUM>,<NUM>-dimethyl-<NUM>,<NUM>-dihydroxyperoxide, t-butylcumylperoxide, alpha,alpha'-bis(t-butylperoxy)-p-diisopropyl benzene, and the like.

Non-limiting examples of suitable commercially available organic peroxides include TRIGONOX(R) from AkzoNobel and LUPEROX(R) from ARKEMA.

The organic peroxide is present in the reaction composition in an amount of from <NUM> wt% to <NUM> wt% based on the total weight of the reaction composition.

The composition includes a silane coupling agent. In an embodiment, the silane coupling agent contains at least one alkoxy group. Non-limiting examples of suitable silane coupling agents include γ-chloropropyl trimethoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, vinyl-tris-(β-methoxy)silane, γ-methacryloxypropyl trimethoxysilane, β-(<NUM>,<NUM>-ethoxy-cyclohexyl)ethyl trimethoxysilane, γ-glycidoxypropyl trimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyl trimethoxysilane, N-β-(aminoethyl)- γ-aminopropyl trimethoxysilane, and <NUM>-(trimethoxysilyl)propylmethacrylate.

In an embodiment, the silane coupling agent is vinyl trimethoxysilane or <NUM>-(trimethoxysilyl)propylmethacrylate.

The silane coupling agent is present in an amount of from <NUM> wt%, or <NUM> wt% to <NUM> wt% based on the total weight of the reaction composition.

The composition includes a co-agent comprising a compound of Structure I
<CHM>
wherein R<NUM>-R<NUM> each is independently selected a C<NUM>-C<NUM> hydrocarbyl group, a C<NUM>-C<NUM> substituted hydrocarbyl group, and combinations thereof.

In an embodiment, each of R<NUM>-R<NUM> is the same.

In an embodiment, each of R<NUM>-R<NUM> is a C<NUM>-C<NUM> hydrocarbyl group. In an embodiment, each of R<NUM>-R<NUM> is the same C<NUM>-C<NUM> hydrocarbyl group.

In an embodiment, each of R<NUM>-R<NUM> is a C<NUM> hydrocarbyl group. In an embodiment, each of R<NUM>-R<NUM> is the same C<NUM> hydrocarbyl group.

In an embodiment, each of R<NUM>-R<NUM> is a C<NUM>-C<NUM> alkyl group. In an embodiment, each of R<NUM>-R<NUM> is the same C<NUM>-C<NUM>alkyl group.

In an embodiment, each of R<NUM>-R<NUM> is a C<NUM> alkyl group. In an embodiment, each of R<NUM>-R<NUM> is the same C<NUM> alkyl group and the co-agent has the Structure II (hexapropylmelamine, N2,N2,N4,N4,N6,N6-hexapropyl-<NUM>,<NUM>,<NUM>-triazine-<NUM>,<NUM>,<NUM>-triamine or HPM):
<CHM>.

In an embodiment, each of R<NUM>-R<NUM> is a C<NUM>-C<NUM> alkenyl group. In an embodiment, each of R<NUM>-R<NUM> is the same C<NUM>-C<NUM> alkenyl group.

In an embodiment, each of R<NUM>-R<NUM> is a C<NUM> alkenyl group. In an embodiment, each of R<NUM>-R<NUM> is the same C<NUM> alkenyl group and the co-agent has the Structure III (hexaallylmelamine, N,N,N',N',N",N"-hexaallyl-<NUM>,<NUM>,<NUM>-triazine-<NUM>,<NUM>,<NUM>-triamine or HAM):
<CHM>.

The preparation of HAM is described in <CIT> and <CIT>.

In an embodiment, R<NUM>, R<NUM> and R<NUM> are the same and each is a C<NUM> substituted hydrocarbyl group, R<NUM> and R<NUM> are the same and each is a C<NUM> substituted hydrocarbyl group, and R<NUM> is a C<NUM> hydrocarbyl group. In an embodiment, the co-agent has the Structure V (<NUM>,<NUM>-Hexanediamine, N,N'-bis(<NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-<NUM>-piperidinyl)-polymer with <NUM>,<NUM>,<NUM>-trichloro-<NUM>,<NUM>,<NUM>-triazine reaction products with N-butyl-<NUM>-butanamine and N-butyl-<NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-<NUM>-piperidinamine, available as Chimassorb <NUM> from BASF):
<CHM>
wherein n is <NUM>-<NUM>.

In an embodiment, the compound of Structure I is selected from HAM, HPM, Chimassorb <NUM> and UV <NUM>.

The co-agent is present in an amount of from <NUM> wt%, or <NUM> wt%, to <NUM> wt% based on the total weight of the composition.

In an embodiment, the co-agent is composed solely of the compound having Structure I. In such embodiment, the compound having Structure I is present in an amount of from <NUM> wt%, or <NUM> wt%, to <NUM> wt% based on the total weight of the composition.

In an embodiment, the co-agent comprises a blend of a compound having Structure I or Structure II and at least one other compound. In an embodiment, the co-agent comprises a blend of the compound having Structure I and at least one of (i) triallyl cyanurate (TAC) and (ii) triallyl isocyanurate (TAIC). In the blend, the compound having Structure I constitutes from greater than <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt% to <NUM> wt%, or <NUM> wt%, or less than <NUM> wt% based on the total weight of the blend. For example, in an embodiment in which the co-agent comprises a blend of the compound having Structure I and at least one of (i) TAC and (ii) TAlC, the compound having Structure I constitutes from greater than <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt% to <NUM> wt%, or <NUM> wt%, or less than <NUM> wt % based on the total weight of the blend, and the at least one of (i) TAC and (ii) constitutes from greater than <NUM> wt%, or <NUM> wt%, or <NUM> wt% to <NUM> wt%, or <NUM> wt%, or <NUM> wt% based on the total weight of the blend.

In an embodiment, the composition includes one or more optional additives. Non-limiting examples of suitable additives include antioxidants, anti-blocking agents, stabilizing agents, colorants, ultra-violet (UV) absorbers or stabilizers, flame retardants, compatibilizers, fillers and processing aids.

The optional additives are present in an amount of from greater than <NUM> wt%, or <NUM> wt%, or <NUM> wt% to <NUM> wt%, or <NUM> wt%, or <NUM> wt% based on the total weight of the composition.

The composition is formed into an encapsulant film. Compositions such as those described in any above embodiment or combination of two or more embodiments are used to form the encapsulant film.

In an embodiment, the composition forms the entirety of the encapsulant film.

The (A) non-polar ethylene-based polymer, (B) organic peroxide, (C) silane coupling agent, (D) co-agent comprising a compound of Structure I and any optional additives can be added to and compounded with each other in any order or simultaneously. In an embodiment, the organic peroxide, silane coupling agent, co-agent and any optional additives are pre-mixed and the pre-mix is added to the non-polar ethylene-based polymer before or during compounding. In an embodiment, dry pellets of the non-polar ethylene-based polymer are soaked in the pre-mix and the soaked pellets are then compounded.

Non-limiting examples of suitable compounding equipment include internal batch mixers (e.g., BANBURY and BOLLING internal mixer) and continuous single or twin screw mixers (e.g., FARREL continuous mixer, BRABENDER single screw mixer, WERNER and PFLEIDERER twin screw mixers and BUSS kneading continuous extruder). The type of mixer utilized, and the operating conditions of the mixer, can affect properties of the composition such as viscosity, volume resistivity, and extruded surface smoothness.

In an embodiment, it is desirable to avoid or limit crosslinking until lamination. Premature crosslinking and/or premature decomposition of the organic peroxide can result in the encapsulant film having decreased glass adhesion. In other words, the encapsulant film remains reactive until lamination, at which point crosslinking is completed and the encapsulant film composition of the encapsulant film becomes a reaction product comprising the non-polar ethylene-based polymer, the silane coupling agent, and the co-agent, with little if any residual organic peroxide. The compounding temperature of the composition is therefore less than the decomposition temperature of the organic peroxide. In an embodiment, the compounding temperature of the composition is from <NUM>, or <NUM> to 100ºC, or <NUM>, or <NUM>.

In an embodiment, the encapsulant film is composed of a composition comprising (A) from <NUM> wt%, or <NUM> wt%, or <NUM> wt% to <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or less than <NUM> wt%, of a non-polar ethylene-based polymer, based on the total weight of the composition, (B) from <NUM> wt%, or <NUM> wt%, or <NUM> wt% to <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt% of an organic peroxide, based on the total weight of the composition, (C) from <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt% to <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt% of a silane coupling agent, based on the total weight of the composition, (D) from <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt% to <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt%, or <NUM> wt% of a co-agent comprising a compound of any of Structures (I)-(VI), based on the total weight of the composition. It is understood that the aggregate amount of components (A), (B), (C) and (D) and any optional additives yields <NUM> wt% of the composition.

Encapuslant Film <NUM>: In an embodiment, the encapsulant film is composed of a composition comprising (A) from <NUM> wt% to <NUM> wt% of a non-polar ethylene-based polymer, based on the total weight of the composition, (B) from <NUM> wt% to <NUM> wt% of an organic peroxide, based on the total weight of the composition, (C) from <NUM> wt%, to <NUM> wt% of a silane coupling agent, based on the total weight of the composition, (D) from <NUM> wt% to <NUM> wt% of a co-agent comprising a compound of any of Structures (I)-(III) and (V), based on the total weight of the composition and wherein the encapsulant film has a volume resistivity from greater than or equal to <NUM>*<NUM><NUM> ohm. cm to <NUM>*<NUM><NUM> ohm. cm at <NUM>. It is understood that the aggregate amount of components (A), (B), (C) and (D) and any optional additives yields <NUM> wt% of the composition.

In an embodiment, the encapsulant film is according to Encapsulant Film <NUM>, having
(ii) a volume resistivity from greater than or equal to or <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm to <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm, to <NUM>*<NUM><NUM> ohm. cm at <NUM>, and optionally (ii) a volume resistivity from greater than or equal to <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm to <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm, or <NUM>*<NUM><NUM> ohm. cm at room temperature.

In an embodiment, the encapsulant film is according to Encapsulant Film <NUM> and has both properties (i) and (ii).

In an embodiment, the encapsulant film is according to Encapsulant Film <NUM> having.

In an embodiment, the encapsulant film is according to Encapsulant Film <NUM> wherein the co-agent comprises a compound of any of Structures (I)-(III) and (V) wherein R<NUM>-R<NUM> each independently is a C<NUM>-C<NUM> hydrocarbyl group and the encapsulant film has.

In an embodiment, the encapsulant film is according to Encapsulant Film <NUM>, wherein the co-agent comprises a compound of any of Structures (I)-(III) and (V) wherein R<NUM>-R<NUM> each independently is a C<NUM>-C<NUM> hydrocarbyl group and the encapsulant film has both properties (i) and (ii).

In an embodiment, the encapsulant film is according to Encapsulant Film <NUM>, wherein the co-agent comprises a compound of Structure I wherein R<NUM>-R<NUM> each independently is a C<NUM>-C<NUM> hydrocarbyl group and the encapsulant film has.

In an embodiment, the encapsulant film is according to Encapsulant Film <NUM>, wherein the co-agent comprises a compound of Structure I wherein R<NUM>-R<NUM> each independently is a C<NUM>-C<NUM> hydrocarbyl group and the encapsulant film has both properties (i) and (ii).

In an embodiment, the encapsulant film is according to Encapsulant Film <NUM>, wherein the co-agent comprising a compound of Structure I wherein R<NUM>, R<NUM> and R<NUM> are the same and each is a C<NUM> substituted hydrocarbyl group, R<NUM> and R<NUM> are the same and each is a C<NUM> substituted hydrocarbyl group, and R<NUM> is a C<NUM> hydrocarbyl group and the encapsulant film has.

In an embodiment, the encapsulant film is according to Encapsulant Film <NUM>, wherein the co-agent comprising a compound of Structure I wherein R<NUM>, R<NUM> and R<NUM> are the same and each is a C<NUM> substituted hydrocarbyl group, R<NUM> and R<NUM> are the same and each is a C<NUM> substituted hydrocarbyl group, and R<NUM> is a C<NUM> hydrocarbyl group and the encapsulant film has both properties (i) and (ii).

In an embodiment, the encapsulant film has a thickness of from <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM> to <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>.

In an embodiment, encapsulant film is one layer, wherein the single layer is composed of the present composition. In an embodiment, the encapsulant film has two or more layers, wherein at least one layer is composed of the present composition.

The composition of this disclosure is used to construct an electronic device module, and particularly encapsulant film used in the construction of an electronic device module. The encapsulant film is used as one or more "skins" for the electronic device, i.e., applied to one or both face surfaces of an electronic device, e.g., as a front encapsulant film or rear encapsulant film, or as both the front encapsulant film and the rear encapsulant film, e.g., in which the electronic device is totally enclosed within the material.

In one embodiment, the electronic device module comprises (i) at least one electronic device, typically a plurality of such devices arrayed in a linear or planar pattern, (ii) at least one cover sheet, and (iii) at least one encapsulant film composed at least in part of a composition of the present disclosure. The encapsulant film is between the cover sheet and the electronic device, and the encapsulant film exhibits good adhesion to both the device and the sheet.

In an embodiment, the electronic device module comprises (i) at least one electronic device, typically a plurality of such devices arrayed in a linear or planar pattern, (ii) a front cover sheet, (iii) a front encapsulant film, (iv) a rear encapsulant film, and (v) a backsheet, with at least one of the (iii) front encapsulant film and (iv) rear encapsulant film is composed at least in part of a composition of the present disclosure. The electronic device is sandwiched between the front encapsulant film and the rear encapsulant film with the cover sheet and backsheet enclosing the front encapsulant film/electronic device/rear encapsulant film unit.

In an embodiment, the cover sheet is glass, acrylic resin, polycarbonate, polyester or fluorine-containing resin. In an embodiment, the cover sheet is glass.

In an embodiment, the back sheet is a single or multilayer film composed of glass, metal, or a polymeric resin. The back sheet is a film composed of glass or a polymeric resin. In a further embodiment, the back sheet is a multilayer film composed of a fluorine polymer layer and a polyethylene terephthalate layer.

The electronic device is a photovoltaic (PV) cell.

In an embodiment, the electronic device module is a PV module.

<FIG> illustrates an exemplary PV module. The rigid PV module <NUM> comprises photovoltaic cell <NUM> (PV cell <NUM>) surrounded or encapsulated by the front encapsulant film 12a and rear encapsulant film 12b. The glass cover sheet <NUM> covers a front surface of the portion of the front encapsulant film 12a disposed over PV cell <NUM>. The backsheet <NUM>, e.g., a second glass cover sheet or polymeric substrate, supports a rear surface of the portion of the rear encapsulant film 12b disposed on a rear surface of PV cell <NUM>. Backsheet <NUM> need not be transparent if the surface of the PV cell to which it is opposed is not reactive to sunlight. In this embodiment, the encapsulant films 12a and 12b fully encapsulate PV cell <NUM>. In the embodiment shown in <FIG>, the front encapsulant film 12a directly contacts the glass cover sheet <NUM> and the rear encapsulant film 12b directly contacts the backsheet <NUM>. The PV cell <NUM> is sandwiched between the front encapsulant film 12a and rear encapsulant film 12b such that the front encapsulant film 12a and rear encapsulant film 12b are both in direct contact with the PV cell <NUM>. The front encapsulant film 12a and rear encapsulant film 12b are also in direct contact with each other in locations where there is no PV cell <NUM>.

The encapsulant film of the present disclosure can be the front encapsulant film, the rear encapsulant film, or both the front encapsulant film and the rear encapsulant film. In an embodiment, the encapsulant film of the present disclosure is the front encapsulant film. In another embodiment, the encapsulant film is both the front encapsulant film and the rear encapsulant film.

In an embodiment, the encapsulant film(s) comprising the compositions of this disclosure are applied to an electronic device by one or more lamination techniques. Through lamination, the cover sheet is brought in direct contact with a first facial surface of the encapsulant film, and the electronic device is brought in direct contact with a second facial surface of the encapsulant film. In another embodiment, the cover sheet is brought into direct contact with a first facial surface of the front encapsulant film, the back sheet is brought in direct contact with a second facial surface of the rear encapsulant film, and the electronic device(s) is secured between, and in direct contact with the second facial surface of the front encapsulant film and the first facial surface of the rear encapsulant film.

In an embodiment, the lamination temperature is sufficient to activate the organic peroxide and crosslink the composition, that is, the composition comprising the non-polar ethylene-based polymer, organic peroxide, silane coupling agent, and co-agent remains reactive until lamination when crosslinking occurs. During crosslinking, the silane coupling agent forms a chemical bond between two or more of the molecular chains of the non-polar ethylene-based polymer by way of a silane linkage. A "silane linkage" has the structure -Si-O-Si-. Each silane linkage may connect two or more, or three or more, molecular chains of the non-polar ethylene-based polymer. The silane coupling agent also interacts with the surface of the cover sheet to increase adhesion between the encapsulant film and the cover sheet. After lamination, the composition is a reaction product of the non-polar ethylene-based polymer, the organic peroxide, the silane coupling agent, and the co-agent.

In an embodiment, the lamination temperature for producing an electronic device is from <NUM>, or <NUM>, or <NUM>, or <NUM> to <NUM>, or <NUM>, or <NUM>. In an embodiment, the lamination time is from <NUM> minutes, or <NUM> minutes, or <NUM> minutes, or <NUM> minutes to <NUM> minutes, or <NUM> minutes, or <NUM> minutes, or <NUM> minutes.

In an embodiment, the electronic device of the present disclosure includes an encapsulant film composed of a composition which is the reaction product of (A) a non-polar ethylene-based polymer, (B) an organic peroxide, (C) a silane coupling agent, and (D) a co-agent comprising a compound of the Structure I, as described herein, and the encapsulant film has a glass adhesion greater than <NUM> N/cm, or <NUM> N/cm, or <NUM> N/cm, or <NUM> N/cm, or <NUM> N/cm to <NUM> N/cm, or <NUM> N/cm, or <NUM> N/cm after the encapsulant film is subjected to damp heat (<NUM>, <NUM>% humidity, <NUM> hours) and aged at <NUM>° for <NUM> minutes.

In an embodiment, the electronic devices of the present disclosure include an encapsulant film according to Encapsulant Film <NUM> having a volume resistivity from greater than or equal to <NUM>*<NUM><NUM> ohm. cm to <NUM>*<NUM><NUM> ohm. cm at <NUM>, and optionally having one, some, or all of the following properties:.

In an embodiment, the electronic device of the present disclosure includes an encapsulant film according to Encapsulant Film <NUM> having at least <NUM> or all <NUM> of properties (i)-(iii).

In an embodiment, the electronic device of the present disclosure includes an encapsulant film according to Encapsulant Film <NUM> having a volume resistivity from greater than or equal to <NUM>*<NUM><NUM> ohm. cm to <NUM>*<NUM><NUM> ohm. cm at <NUM>, and optionally one, some, or all of the following properties:.

In an embodiment, the electronic device of the present disclosure includes an encapsulant film according to Encapsulant Film <NUM> having at least <NUM>, or all <NUM> of properties (i)-(iii).

In an embodiment, the electronic device of the present disclosure includes an encapsulant film according to Encapsulant Film <NUM> wherein the co-agent comprises a compound of Structure I wherein R<NUM>-R<NUM> each independently is a C<NUM>-C<NUM> hydrocarbyl group and the encapsulant film has a volume resistivity from greater than or equal to <NUM>*<NUM><NUM> ohm. cm to <NUM>*<NUM><NUM> ohm. cm at <NUM>, and optionally one, some, or all of the following properties:.

In an embodiment, the electronic device of the present disclosure includes an encapsulant film according to Encapsulant Film <NUM> wherein the co-agent comprises a compound of Structure I wherein R<NUM>-R<NUM> each independently is a C<NUM>-C<NUM> hydrocarbyl group and the encapsulant film has at least <NUM>, or all <NUM> of properties (i)-(iii).

In an embodiment, the electronic device of the present disclosure includes an encapsulant film according to Encapsulant Film <NUM> wherein the co-agent comprises a compound of Structure I wherein R<NUM>-R<NUM> each independently is a C<NUM>-C<NUM> hydrocarbyl group and the encapsulant film has at least <NUM> or all <NUM> of properties (i)-(iii).

In an embodiment, the electronic device of the present disclosure includes an encapsulant film according to Encapsulant Film <NUM>
wherein the co-agent comprising a compound of Structure I wherein R<NUM>, R<NUM> and R<NUM> are the same and each is a C<NUM> substituted hydrocarbyl group, R<NUM> and R<NUM> are the same and each is a C<NUM> substituted hydrocarbyl group, and R<NUM> is a C<NUM> hydrocarbyl group and the encapsulant film has.

In an embodiment, the electronic device of the present disclosure includes an encapsulant film according to Encapsulant Film <NUM> wherein the co-agent comprising a compound of Structure I wherein R<NUM>, R<NUM> and R<NUM> are the same and each is a C<NUM> substituted hydrocarbyl group, R<NUM> and R<NUM> are the same and each is a C<NUM> substituted hydrocarbyl group, and R<NUM> is a C<NUM> hydrocarbyl group and the encapsulant film has both properties (i) and (ii).

Some embodiments of the present disclosure will now be described in detail in the following examples.

EVA: an ethylene/vinyl acetate copolymer having a density of <NUM>/cc (measured according to ASTM D792), a melt index (Ml) of <NUM>/<NUM> (measured according to ASTM D1238, at <NUM>°, <NUM>), and a vinyl acetate content of <NUM> wt% based on the total weight of the copolymer, available as Elvax <NUM> from DuPont.

Compositions are prepared according to Table <NUM>, below, by first pre-mixing the organic peroxide, silane coupling agent and co-agent(s) at the desired percentages set forth in Table <NUM> in a sealable bottle. Dry pellets of EVA or POE, depending on the example (see Table <NUM>), are put in the bottle and the bottle is shaken <NUM> minute. The bottle is then placed in a <NUM> oven and the pellets allowed to soak for an initial <NUM> minutes, with the bottle shaken every <NUM> minutes during pellet soaking to keep a homogenous distribution of the curing package (i.e., organic peroxide, silane coupling agent and co-agent(s)). After the initial <NUM> minutes, the bottle is kept in the oven at <NUM> overnight (<NUM>-<NUM> hours).

To produce films, the soaked pellets are fed into a Brabender single screw mixer at <NUM> with a rotor speed of <NUM> rpm. Films having a thickness of approximately <NUM> are prepared and kept in an aluminum foil bag until testing.

The films are compression molded into a <NUM> film. The sample film is preheated at <NUM> for <NUM> minutes, then degassed followed by the <NUM> minute pressing process at <NUM> to insure complete curing. The samples are then ramped down to room temperature. Compression molded films are used for the volume resistivity tests.

To produce laminated articles, <NUM> (<NUM>-inch) square glass sheets are cleaned using water and dried. Pieces of backsheet material are cut into <NUM> (<NUM>-inch) squares. Prepared films are then cut into pieces to fit the size of the glass and backsheet. The materials are then layered in the following order and laminated using a PENERGY L036 laminator: (i) glass, (ii) prepared film, (iii) backsheet. Two different lamination conditions are used for comparison to test glass adhesion, as specified in Figures <NUM> and <NUM>. To produce a first set of laminated articles, the layers are laminated at <NUM> for <NUM> minutes (<NUM> minutes vacuum processing and <NUM> minutes pressing). To produce a second set of laminated articles, the layers are laminated at <NUM> for <NUM> minutes (<NUM> minutes vacuum processing and <NUM> minutes pressing).

CE1 shows the VR of EVA film without additives. The addition of HAM (a co-agent representative of the present disclosure) to EVA shows only a minor improvement in VR (see CE2). The VR of POE (a non-polar ethylene-based polymer) film without additives is shown by CE3. The addition of TAlC, a co-agent commonly used with EVA films, causes only a minor improvement in VR (see CE4).

The inventive examples show that the VR of POE in combination with a co-agent comprising a compound of Structure I or Structure II (as described herein) is improved compared to using TAIC alone. The inventive examples also show that the VR of POE in combination with a co-agent comprising a compound of Structure I or Structure II (as described herein) is improved compared to an EVA formulation using a co-agent comprising a compound of Structure I or Structure II.

IE1 uses HAM (a co-agent representative of the present disclosure) in a non-polar ethylene-based polymer film. The VR of IE1 is approximately three orders of magnitude greater than CE4 (same non-polar ethylene-based polymer film + TAlC) at room temperature and an order of magnitude greater than CE4 at <NUM> (<NUM>*<NUM><NUM> vs <NUM>*<NUM><NUM> at room temperature and <NUM>*<NUM><NUM> vs <NUM>*<NUM><NUM> at <NUM>). The improvement of IE1 at <NUM> is also significant compared to CE3 which uses the same non-polar ethylene-based polymer film with no additives (<NUM>*<NUM><NUM> vs <NUM>*<NUM><NUM>). The combination of HAM with TAIC (IE2) also results in a significant increase of the VR at both room temperature and <NUM>. The VR of IE2 at room temperature is too high and above the instrument test limit, so no value is reported in Table <NUM>. The addition of HPM to a non-polar ethylene-based polymer (IE3) also shows significant VR improvement on the scale of one order of magnitude compared to CE4 at both room temperature and <NUM>. E6 uses melamine in a non-polar ethylene-based polymer film, and the VR of E6 is similarly improved at both room temperature and <NUM>.

E4 and IE5 use oligomeric or polymeric forms of the compounds of Structure I and Structure II, respectively, as a co-agent. E4, which uses a co-agent comprising a compound of Structure I, shows significant VR improvement on the scale of one order of magnitude compared to CE4 at both room temperature and <NUM>. IE5, which uses a co-agent comprising a compound of Structure II, shows a VR improvement of about <NUM>. 7x at room temperature and approximately <NUM> at <NUM> compared to CE4.

Non-polar ethylene-based polymer materials show limited, if any, adhesion to glass surfaces when untreated. The organic peroxide and silane coupling agent are therefore used to crosslink and functionalize the non-polar polyethylene-based polymer and thereby achieve acceptable glass adhesion. The co-agent is used to promote the curing. As shown in Table <NUM>, IE1 and IE2 show generally improved adhesion compared to CE4 (non-polar ethylene-based polymer + TAlC) over the range of conditions identified. Specifically, both IE1 and IE2 show improved adhesion after aging <NUM> hours for both lamination conditions compared to CE4. Moreover, CE4 shows a significant decrease in glass adhesion after aging for both lamination conditions, while IE1 and IE2 maintain improved glass adhesion after aging.

Claim 1:
An encapsulant film comprising a crosslinked polymeric composition, the composition comprising:
(A) from <NUM> wt% to <NUM> wt% of a non-polar ethylene-based polymer based on the total weight of the composition;
(B) from <NUM> wt% to <NUM> wt% of an organic peroxide based on the total weight of the composition;
(C) from <NUM> wt% to <NUM> wt% of a silane coupling agent based on the total weight of the composition; and
(D) from <NUM> wt% to <NUM> wt% based on the total weight of the composition of a single co-agent of a compound of Structure I
<CHM>
wherein R<NUM>-R<NUM> each is independently selected from the group consisting of a C<NUM>-C<NUM> hydrocarbyl group, a C<NUM>-C<NUM> substituted hydrocarbyl group, and combinations thereof and wherein the encapsulant film has a volume resistivity from greater than or equal to <NUM>*<NUM><NUM> ohm.cm to <NUM>*<NUM><NUM> ohm.cm at <NUM>, determined according to the method disclosed in the description.