Composition for sealing material film and sealing material film containing the same

Abstract

The present invention relates to a composition for an encapsulant film, which contains an ethylene / alpha-olefin copolymer, an encapsulant film, and a solar cell module.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0165772 filed on November 26, 2021, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a composition for an encapsulant film containing an ethylene / alpha-olefin copolymer, an encapsulant film, and a solar cell module. [Background technology]

[0003] As global environmental and energy issues become increasingly serious, solar cells are gaining attention as a means of generating energy without the risk of environmental pollution or depletion. When solar cells are used outdoors, such as on the roof of a building, they are generally used in the form of a solar cell module. To manufacture a solar cell module, a crystalline solar cell module is obtained by laminating the following in this order: front glass / solar cell encapsulant / crystalline solar cell element / solar cell encapsulant / rear glass (or rear protective sheet). The solar cell encapsulant is typically made of ethylene / vinyl acetate copolymer or ethylene / alpha-olefin copolymer, which have excellent transparency, flexibility, and adhesiveness.

[0004] Solar cell modules are made by protecting solar cell elements such as silicon, gallium-arsenide, or copper-indium-selenium with an upper transparent protective material and a lower substrate protective material, and then fixing the solar cell elements and protective material with an encapsulant to form a package. Generally, the encapsulant for the solar cell elements in solar cell modules is made by extrusion molding an ethylene / alpha-olefin copolymer containing an organic peroxide or a silane coupling agent into a sheet, and the solar cell elements are encapsulated using the resulting sheet-shaped encapsulant to produce a solar cell module.

[0005] In order to improve productivity during the manufacture of such solar cell modules, one possible solution is to increase the affinity between the various raw materials contained in the encapsulant film composition and the ethylene / alpha-olefin copolymer to enhance water absorption. In particular, crosslinking agents and crosslinking dispersants, which are essential for the manufacture of encapsulant films, reduce the volume resistivity of the encapsulant film, which is considered to be one of the factors that ultimately leads to a deterioration in physical properties. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Published Patent 2015-211189 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a composition for an encapsulant film having excellent volume resistivity and light transmittance, and an encapsulant film containing the same. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a composition for an encapsulant film, an encapsulant film, and a solar cell module.

[0009] (1) The present invention provides a composition for an encapsulant film, comprising an ethylene / alpha-olefin copolymer and polyethylene glycol, wherein the polyethylene glycol has a number average molecular weight of 1,000 to 50,000 g / mol, and the content of the polyethylene glycol is 0.05 to 0.7 wt % based on the total weight of the ethylene / alpha-olefin copolymer and the polyethylene glycol.

[0010] (2) The present invention provides the composition for an encapsulant film according to (1), wherein the polyethylene glycol has a number average molecular weight of 2,000 to 30,000 g / mol.

[0011] (3) The present invention provides a composition for an encapsulant film according to (1) or (2), wherein the content of the polyethylene glycol is 0.1 to 0.6% by weight based on the total weight of the ethylene / alpha-olefin copolymer and the polyethylene glycol.

[0012] (4) The present invention provides a composition for an encapsulant film according to any one of (1) to (3) above, further comprising at least one selected from the group consisting of a crosslinking agent, a crosslinking agent, a silane coupling agent, an unsaturated silane compound, an aminosilane compound, a light stabilizer, a UV absorber, and a heat stabilizer.

[0013] (5) The present invention provides a composition for an encapsulant film according to any one of (1) to (4), wherein the alpha-olefin comprises one or more selected from the group consisting of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicosene.

[0014] (6) The present invention provides a composition for an encapsulant film according to any one of (1) to (5) above, wherein the alpha-olefin is contained in an amount of more than 0 to 99 mol % based on an ethylene / alpha-olefin copolymer.

[0015] (7) The present invention provides an encapsulant film comprising the composition for an encapsulant film according to any one of (1) to (6) above.

[0016] (8) The present invention provides a solar cell module including the encapsulant film of (7) above. [Effects of the Invention]

[0017] The composition for an encapsulant film of the present invention exhibits excellent volume resistivity and light transmittance, and can be widely used for various purposes in the electric and electronic industry. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will now be described in more detail to aid in understanding the invention.

[0019] Here, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary and dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, in accordance with the principle that the inventor himself / herself can appropriately define the concept of terms in order to explain the invention in the best possible way.

[0020] <Composition for sealing film> The composition for an encapsulant film of the present invention comprises an ethylene / alpha-olefin copolymer and polyethylene glycol, wherein the polyethylene glycol has a number average molecular weight of 1,000 to 50,000 g / mol, and the content of the polyethylene glycol is 0.05 to 0.7 wt % based on the total weight of the ethylene / alpha-olefin copolymer and the polyethylene glycol.

[0021] The composition for an encapsulant film of the present invention includes an ethylene / alpha-olefin copolymer. The ethylene / alpha-olefin copolymer is produced by copolymerizing ethylene with an alpha-olefin monomer. The alpha-olefin, which refers to the portion of the copolymer derived from the alpha-olefin monomer, is an alpha-olefin having 3 to 20 carbon atoms, specifically, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, or 1-eicosene, and may be used alone or in combination of two or more thereof.

[0022] Among these, the alpha-olefin may be 1-butene, 1-hexene, or 1-octene, and preferably 1-butene, 1-hexene, or a combination thereof.

[0023] In addition, the content of the alpha-olefin in the ethylene / alpha-olefin copolymer may be appropriately selected within a range that satisfies the physical property requirements, specifically, it may be more than 0 and not more than 99 mol%, or 10 to 50 mol%, but is not limited thereto.

[0024] In the present invention, the method or route for preparing the ethylene / alpha-olefin copolymer is not limited, and a person skilled in the art may select and use an appropriate one in consideration of the properties and purpose of the composition for the encapsulant film.

[0025] The composition for a sealant film of the present invention contains polyethylene glycol.

[0026] The number average molecular weight of the polyethylene glycol is 1,000 to 50,000 g / mol, and specifically may be 2,000 g / mol or more, 2,500 g / mol or more, 3,000 g / mol or more, 30,000 g / mol or less, 20,000 g / mol or less, or 15,000 g / mol or less, for example, 2,000 to 30,000 g / mol.

[0027] When polyethylene glycol is included in a composition for an encapsulant film, the blending of the highly polar polyethylene glycol with the non-polar ethylene / alpha-olefin copolymer hinders the movement of charges, resulting in a decrease in electrical conductivity and an increase in volume resistivity. On the other hand, when polyethylene glycol is included in a composition for an encapsulant film using a highly polar polymer, the electrical conductivity increases and the volume resistivity decreases.

[0028] In particular, in order to preferably realize the above effects, the number average molecular weight of polyethylene glycol should be 1,000 to 50,000 g / mol.

[0029] If the number average molecular weight of the polyethylene glycol is less than 1,000 g / mol, the haze increases, which leads to impaired optical properties, making it unsuitable for use as an encapsulant film. If the number average molecular weight of the polyethylene glycol is more than 50,000 g / mol, the polarity of the composition becomes too high, which may result in a decrease in volume resistivity.

[0030] The content of the polyethylene glycol may be 0.05 to 0.7 wt % based on the total weight of the ethylene / alpha-olefin copolymer and the polyethylene glycol, and specifically, 0.1 to 0.6 wt %.

[0031] If the polyethylene glycol is less than 0.05 wt % based on the total weight of the ethylene / alpha-olefin copolymer and polyethylene glycol, the effect of improving volume resistivity cannot be reliably achieved, and if it exceeds 0.7 wt %, the haze increases, causing a deterioration in optical properties, making it unsuitable for use as an encapsulant film.

[0032] The composition for an encapsulant film of the present invention may further contain one or more selected from the group consisting of a crosslinking agent, a crosslinking agent, a silane coupling agent, an unsaturated silane compound, an aminosilane compound, a light stabilizer, a UV absorber, and a heat stabilizer.

[0033] The crosslinking agent can act as a radical initiator to initiate a reaction in which an unsaturated silane compound is grafted onto a resin composition during the preparation of the silane-modified resin composition, and can improve the heat resistance and durability of a final product, such as an encapsulant sheet, by forming crosslinks between the silane-modified resin compositions or between the silane-modified resin composition and an unmodified resin composition during the lamination step in the manufacture of an optoelectronic device.

[0034] The crosslinking agent may be any crosslinking compound known in the art that can initiate radical polymerization of a vinyl group or form a crosslinking bond. For example, one or more crosslinking agents selected from the group consisting of organic peroxides, hydroperoxides, and azo compounds may be used.

[0035] Specifically, dialkyl peroxides such as t-butylcumyl peroxide, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne; hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethyl-2,5-di(hydroperoxy)hexane, and t-butyl hydroperoxide; diacyl peroxides such as bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, benzoyl peroxide, o-methylbenzoyl peroxide, and 2,4-dichlorobenzoyl peroxide; t-butyl peroxyisobutyrate, t-butyl peroxyacetate, and t-butyl Examples of the peroxyesters include peroxy-2-ethylhexyl carbonate (TBEC), t-butyl peroxy-2-ethylhexanoate, t-butyl peroxypivalate, t-butyl peroxyoctoate, t-butyl peroxyisopropyl carbonate, t-butyl peroxybenzoic acid, di-t-butyl peroxyphthalate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, and 2,5-dimethyl-2,5-di(benzoylperoxy)-3-hexyne; and ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; and azo compounds such as lauryl peroxide, azobisisobutyronitrile, and azobis(2,4-dimethylvaleronitrile), but are not limited thereto.

[0036] The organic peroxide may be an organic peroxide having a one-hour half-life temperature of 120 to 135°C, for example, 120 to 130°C, 120 to 125°C, and preferably 121°C. The "one-hour half-life temperature" refers to the temperature at which the half-life of the crosslinking agent is one hour. Since the temperature at which a radical initiation reaction efficiently occurs varies depending on the one-hour half-life temperature, when an organic peroxide having a one-hour half-life temperature within the aforementioned range is used as a crosslinking agent, the radical initiation reaction, i.e., the crosslinking reaction, can proceed effectively at the temperature of a lamination process for manufacturing an optoelectronic device.

[0037] The crosslinking agent is included in an amount of 0.01 to 1 part by weight, for example, 0.05 to 0.55, 0.1 to 0.5, or 0.15 to 0.45 parts by weight, relative to 100 parts by weight of the composition for an encapsulant film. When the crosslinking agent is included in an amount of less than 0.01 part by weight, the effect of improving heat resistance is negligible. When the crosslinking agent is included in an amount of more than 1 part by weight, the formability of the encapsulant sheet is reduced, which may cause problems such as process limitations and may affect the physical properties of the encapsulant.

[0038] In addition to the crosslinking agent, a crosslinking agent may be contained in the resin composition. When the crosslinking agent is contained in the resin composition, the degree of crosslinking between the resin components by the crosslinking agent can be increased, and therefore the heat resistance durability of the final product, for example, the encapsulant sheet, can be further improved.

[0039] The crosslinking agent may be any of various crosslinking agents known in the art. For example, the crosslinking agent may be a compound containing at least one unsaturated group such as an allyl group or a (meth)acryloxy group.

[0040] Examples of the compound containing an allyl group include polyallyl compounds such as triallyl isocyanurate (TAIC), triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate, and examples of the compound containing a (meth)acryloxy group include poly(meth)acryloxy compounds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate, but are not particularly limited thereto.

[0041] The crosslinking agent is included in an amount of 0.01 to 0.5 parts by weight, for example, 0.01 to 0.3, 0.015 to 0.2, or 0.016 to 0.16 parts by weight, relative to 100 parts by weight of the composition for an encapsulant film. If the crosslinking agent is included in an amount less than 0.01 part by weight, the effect of improving heat resistance is negligible. If the crosslinking agent is included in an amount more than 0.5 parts by weight, problems may arise that affect the properties of the final product, for example, the encapsulant sheet, and the production cost may increase.

[0042] As the silane coupling agent, for example, one or more selected from the group consisting of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane (MEMO) may be used.

[0043] The silane coupling agent may be included in an amount of 0.1 to 0.4 parts by weight based on 100 parts by weight of the composition for encapsulant film. If used in an amount of less than 0.1, adhesion to glass during the fabrication of a solar module is poor, moisture penetration is easy, and long-term performance of the module cannot be guaranteed. If used in an amount of 1 part by weight or more, it acts as a factor increasing YI, which is undesirable.

[0044] The composition for an encapsulant film may further contain an unsaturated silane compound and an aminosilane compound.

[0045] The unsaturated silane compound may be grafted onto a main chain containing polymerized units of the monomer of the copolymer of the present invention in the presence of a radical initiator or the like, and may be included in the silane-modified resin composition or aminosilane-modified resin composition in a polymerized form.

[0046] The unsaturated silane compound may be vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrippropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentoxysilane, vinyltriphenoxysilane, or vinyltriacetoxysilane, and among these, vinyltrimethoxysilane or vinyltriethoxysilane may be used, but is not limited thereto.

[0047] In addition, the aminosilane compound acts as a catalyst to promote the hydrolysis reaction that converts reactive functional groups, such as alkoxy groups of unsaturated silane compounds, e.g., vinyltriethoxysilane, grafted to the main chain of the copolymer into hydroxy groups during the graft modification step of the ethylene / alpha-olefin copolymer, thereby further improving the adhesive strength with the upper and lower glass substrates or backsheets made of fluororesin, etc. At the same time, the aminosilane compound also participates as a reactant in the direct copolymerization reaction, thereby providing the aminosilane-modified resin composition with moieties having amine functional groups.

[0048] The aminosilane compound is not particularly limited as long as it is a silane compound containing an amine group and is a primary amine or a secondary amine. For example, aminotrialkoxysilane, aminodialkoxysilane, etc. may be used as the aminosilane compound, such as 3-aminopropyltrimethoxysilane (APTMS), 3-aminopropyltriethoxysilane (APTES), bis[(3-triethoxysilyl)propyl]amine, bis[(3-trimethoxysilyl)propyl]amine, 3-aminopropylmethyldiethoxysilane, 3-aminopropylmethyldimethoxysilane, N-[3-(trimethoxysilyl)propyl]ethylenediamine (DAS), aminoethylaminopropyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, aminoethylaminopropylmethyldiethoxysilane, Examples of suitable aminosilane compounds include at least one selected from the group consisting of silane, aminoethylaminomethyltriethoxysilane, aminoethylaminomethylmethyldiethoxysilane, diethylenetriaminopropyltrimethoxysilane, diethylenetriaminopropyltriethoxysilane, diethylenetriaminopropylmethyldimethoxysilane, diethyleneaminomethylmethyldiethoxysilane, (N-phenylamino)methyltrimethoxysilane, (N-phenylamino)methyltriethoxysilane, (N-phenylamino)methylmethyldimethoxysilane, (N-phenylamino)methylmethyldiethoxysilane, 3-(N-phenylamino)propyltrimethoxysilane, 3-(N-phenylamino)propyltriethoxysilane, 3-(N-phenylamino)propylmethyldimethoxysilane, 3-(N-phenylamino)propylmethyldiethoxysilane, and N-(N-butyl)-3-aminopropyltrimethoxysilane. The aminosilane compounds may be used alone or in combination.

[0049] The content of the unsaturated silane compound and / or aminosilane compound is not particularly limited.

[0050] Furthermore, the composition for an encapsulant film may further contain one or more additives selected from a light stabilizer, a UV absorber, a heat stabilizer, and the like, as needed.

[0051] The light stabilizer may act to prevent photooxidation by capturing active species that initiate photothermalization of the resin depending on the application of the composition. The type of light stabilizer that can be used is not particularly limited, and known compounds such as hindered amine compounds or hindered piperidine compounds may be used.

[0052] The UV absorber can absorb ultraviolet rays from sunlight or the like and convert them into harmless thermal energy within the molecule, thereby preventing the excitation of photothermal-initiating active species in the resin composition, depending on the intended use of the composition. The specific type of UV absorber that can be used is not particularly limited, and for example, one or a mixture of two or more inorganic UV absorbers such as benzophenone-based, benzotriazole-based, acrylonitrile-based, metal complex salt-based, hindered amine-based, ultrafine titanium oxide, or ultrafine zinc oxide may be used.

[0053] Examples of the heat stabilizer include phosphorus-based heat stabilizers such as tris(2,4-di-tert-butylphenyl)phosphite, bis[2,4-bis(1,1-dimethylethyl)-6-methylphenyl]ethyl ester phosphorous acid, tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4′-diylbisphosphonate, and bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite; and lactone-based heat stabilizers such as a reaction product of 8-hydroxy-5,7-di-tert-butyl-furan-2-one and o-xylene, and one or more of the above may be used.

[0054] The content of the light stabilizer, UV absorber, and / or heat stabilizer is not particularly limited, and may be appropriately selected in consideration of the use of the resin composition, the shape and density of the additive, etc., and may generally be appropriately adjusted within a range of 0.01 to 5 parts by weight based on 100 parts by weight of the total solid content of the composition for encapsulant film.

[0055] In addition to the above components, the composition for an encapsulant film of the present invention may further contain various additives known in the art depending on the application of the resin component.

[0056] In addition, the composition for an encapsulant film may be used as various molded products by molding using methods such as injection molding and extrusion molding. Specifically, the composition may be used as an encapsulant for encapsulating elements in various optoelectronic devices, such as solar cells, and may also be used as an industrial material applied to a temperature-raised lamination process, but is not limited thereto.

[0057] <Sealing film> The present invention also provides an encapsulant film comprising the encapsulant film composition.

[0058] The encapsulant film of the present invention may be produced by molding the composition for an encapsulant film into a film or sheet. The molding method is not particularly limited, and the composition may be produced by a conventional process such as a T-die process or extrusion. For example, the encapsulant film may be produced in situ using an apparatus in which the process for producing a modified resin composition using the composition for an encapsulant film and the process for filming or sheeting are connected to each other.

[0059] The thickness of the encapsulant film may be adjusted to about 10 to 2,000 μm or about 100 to 1,250 μm in consideration of the support efficiency and breakage risk of elements in an optoelectronic device, weight reduction of the device, workability, etc., and may be changed depending on the specific application.

[0060] <Solar cell module> The present invention also provides a solar cell module including the encapsulant film. In the present invention, the solar cell module may have a configuration in which solar cells arranged in series or parallel are filled with the encapsulant film of the present invention, a glass surface is placed on the surface exposed to sunlight, and the back surface is protected by a backsheet, but is not limited thereto, and various types and shapes of solar cell modules manufactured using encapsulant films in the art may all be applied to the present invention.

[0061] The glass surface may be made of tempered glass to protect the solar cell from external impact and prevent breakage, or low iron tempered glass to prevent reflection of sunlight and increase the transmittance of sunlight, but is not limited thereto.

[0062] The backsheet is a weather-resistant film that protects the back surface of the solar cell module from the outside, and examples thereof include, but are not limited to, a fluorine-based resin sheet, a metal plate or foil such as aluminum, a cyclic olefin-based resin sheet, a polycarbonate-based resin sheet, a poly(meth)acrylic-based resin sheet, a polyamide-based resin sheet, a polyester-based resin sheet, and a composite sheet obtained by laminating a weather-resistant film and a barrier film.

[0063] In addition, the solar cell module of the present invention can be produced by any method known in the art without any limitations, except that it contains the above-mentioned encapsulant film.

[0064] The solar cell module of the present invention is manufactured using a sealing material film having excellent volume resistivity, and can prevent electrons in the solar cell module from moving through the sealing material film and current from flowing out to the outside. Therefore, it is possible to significantly suppress the PID (Potential Induced Degradation) phenomenon in which the insulation deteriorates, leakage current occurs, and the output of the module rapidly decreases.

[0065] Example Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are for illustrative purposes of the present invention, and the scope of the present invention is not limited only to these.

[0066] [Production of Transition Metal Compound] Production Example 1 (1) Production of Ligand Compound <Synthesis of N-tert-butyl-1-(1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophen-3-yl)-1,1-dimethylsilanamine> 4.65 g (15.88 mmol) of the compound chloro(1,2-dimethyl-6,7-dihydro-3H-benzo[b]cyclopenta[d]thiophen-3-yl)dimethylsilane was quantitatively added to a 100 mL Schlenk flask, and then 80 mL of THF was added thereto. After adding tBuNH2 (4 eq, 6.68 ml) at room temperature, the reaction was carried out at room temperature for 3 days. After the reaction, THF was removed and then filtered with hexane. After drying the solvent, a yellow liquid was obtained in a yield of 4.50 g (86%). [[ID=…]] [[ID=…]]

[0067] [[ID=…]] 1H-NMR(in CDCl3, 500MHz): 7.99(d, 1H), 7.83(d, 1H), 7.35(dd, 1H), 7.24(dd, 1H), 3.4 9(s, 1H), 2.37(s, 3H), 2.17(s, 3H), 1.27(s, 9H), 0.19(s, 3H), -0.17(s, 3H).

[0068] (2) Production of transition metal compounds [ka]

[0069] The ligand compound (1.06 g, 3.22 mmol / 1.0 eq) and 16.0 mL (0.2 M) of MTBE were placed in a 50 mL Schlenk flask and stirred. At -40 °C, n-BuLi (2.64 mL, 6.60 mmol / 2.05 eq, 2.5 M in THF) was added and reacted at room temperature for one day. Then, MeMgBr (2.68 mL, 8.05 mmol / 2.5 eq, 3.0 M in diethyl ether) was slowly added dropwise at -40 °C, followed by TiCl4 (2.68 mL, 3.22 mmol / 1.0 eq, 1.0 M in toluene) and reacted at room temperature for one day. The reaction mixture was then filtered through Celite with hexane. After drying the solvent, a brown solid was obtained in a yield of 1.07 g (82%).

[0070] 1 H-NMR(in CDCl3, 500MHz): 7.99(d, 1H), 7.68(d, 1H), 7.40(dd, 1H), 7.30(dd, 1H), 3.22(s, 1H), 2.6 7(s, 3H), 2.05(s, 3H), 1.54(s, 9H), 0.58(s, 3H), 0.57(s, 3H), 0.40(s, 3H), -0.45(s, 3H).

[0071] Manufacturing Example 2 (1) Preparation of Ligand Compounds <Synthesis of N-tert-butyl-1-(1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophen-3-yl)-1,1-(methyl)(2-methylphenyl)silanamine> (i) Preparation of chloro-1-(1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophen-3-yl)-1,1-(methyl)(2-methylphenyl)silan Into a 250 mL Schlenk flask, 2.0 g (1.0 eq, 9.985 mmol) of 1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophene and 50 mL of THF were added. 4.2 mL (1.05 eq, 10.484 mmol, 2.5 M in hexane) of n-BuLi was added dropwise at -30 °C, and then stirred at room temperature for one day. The stirred Li-complex THF solution was cannulated into a Schlenk flask containing 2.46 g (1.2 eq, 11.982 mmol) of dichloro(O-tolylmethyl)silan and 30 mL of THF at -78 °C, and then stirred at room temperature for one day. After stirring, it was dried under vacuum and then extracted with 100 mL of hexane.

[0072] (ii) Preparation of N-tert-butyl-1-(1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophen-3-yl)-1,1-(methyl)(2-methylphenyl)silanamine 4.0 g (1.0 eq, 10.0 mmol) of the extracted chloro-1-(1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophen-3-yl)-1,1-(methyl)(2-methylphenyl)silan was stirred with 10 mL of hexane, then 4.2 mL (4.0 eq, 40.0 mmol) of t-BuNH2 was added at room temperature, and then stirred at room temperature for one day. After stirring, it was dried under vacuum and then extracted with 150 mL of hexane. After drying the solvent, 4.26 g (99%, dr = 1:0.83) of a viscous liquid was obtained.

[0073] 1H-NMR (CDCl3, 500MHz): δ7.95(t, 2H), 7.70(d, 1H), 7.52(d, 1H), 7.47-7.44(m, 2H), 7.24-7.02(m, 9H), 6.97(t, 1H), 3.59(s, 1H), 3.58(s, 1H), 2.50(s, 3H), 2.44(s, 3H), 2.25(s, 3H), 2.16(s, 3H), 2.06(s, 3H), 1.56(s, 3H), 1.02(s, 9H), 0.95(s, 9H), -0.03(s, 3H), -0.11(s, 3H)

[0074] (2) Production of transition metal compounds [ka]

[0075] The ligand compound (4.26 g, 10.501 mmol) was placed in 53 mL of MTBE (0.2 M) in a 250 mL round flask and stirred. n-BuLi (8.6 mL, 21.52 mmol, 2.05 eq, 2.5 min hexane) was added at -40 °C, and the mixture was stirred at room temperature for one day.

[0076] Then, MeMgBr (8.8 mL, 26.25 mmol, 2.5 eq, 3.0 M in diethyl ether) was slowly added dropwise at -40 °C, followed by TiCl (10.50 mL, 10.50 mmol) and stirring at room temperature for one day. The reaction mixture was then filtered with hexane. DME (3.3 mL, 31.50 mmol) was added to the filtrate, and the solution was filtered with hexane and concentrated to give 3.42 g (68%, dr = 1:0.68) of a yellow solid.

[0077] 1HNMR (CDCl3, 500MHz): δ7.83(d, 1H), 7.80(d, 1H), 7.74(d, 1H), 7.71(d, 1H), 7. 68(d, 1H), 7.37(d, 1H), 7.31-6.90(m, 9H), 6.84(t, 1H), 2.54(s, 3H), 2.47(s, 3H) ), 2.31(s, 3H), 2.20(s, 3H), 1.65(s, 9H), 1.63(s, 9H), 1.34(s, 3H), 1.00(s, 3H) , 0.98(s, 3H), 0.81(s, 3H), 0.79(s, 3H), 0.68(s, 3H), 0.14(s, 3H), -0.03(s, 3H)

[0078] [Production of ethylene / alpha-olefin copolymer] A 1.5 L continuous reactor was preheated to 150°C while feeding hexane solvent at 7 kg / h and 1-butene at 0.94 kg / h. Triisobutylaluminum compound (0.05 mmol / min), a 1:1.5 molar mixture of the compounds from Preparation Examples 1 and 2, and dimethylanilinium tetrakis(pentafluorophenyl)borate cocatalyst (1.5 μmol / min) were simultaneously added to the reactor. Ethylene (0.87 kg / h) and hydrogen gas (26 cc / min) were then introduced into the reactor. The copolymerization reaction was carried out at 136.0°C for at least 60 minutes in a continuous process under a pressure of 89 bar, yielding a copolymer. The copolymer was then dried in a vacuum oven for at least 12 hours, extruded, and pelletized, and its physical properties were measured.

[0079] [Manufacturing of sealing film] Example 1 Polyethylene glycol (Sigma-Aldrich) having a number average molecular weight of 3,350 g / mol was added to the ethylene / alpha-olefin copolymer prepared as described above, so that the amount of polyethylene glycol was 0.1 wt % based on the total weight of the ethylene / alpha-olefin copolymer and polyethylene glycol. After extrusion blending, the resulting sample was pelletized.

[0080] Then, 500 g of the pellets were placed in a planetary mixer preheated to 40°C, and 0.5 phr of a crosslinking agent, 0.2 phr of a silane coupling agent, and 1.0 phr of an organic peroxide were added dropwise, followed by mixing for 1 hour to obtain a composition for an encapsulant film.

[0081] Thereafter, an encapsulant film having a thickness of 500±100 μm was produced under the condition of a T-die temperature of 90° C.

[0082] The number average molecular weight of the polyethylene glycol was determined by measuring under the following gel permeation chromatography (GPC) analysis conditions.

[0083] -Column: Ultrahydrogel 250+120 -Solvent: pH 6.35 phosphate buffer solution -Flow rate: 0.7ml / min -Sample concentration: 1.0mg / ml -Injection volume: 100μl -Column temperature: 35℃ -Detector: Vicsotek TDA 302 -Data processing: OmniSEC 5.0

[0084] Example 2 An encapsulant film was produced in the same manner as in Example 1, except that the polyethylene glycol was 0.3 wt % based on the total weight of the ethylene / alpha-olefin copolymer and polyethylene glycol.

[0085] Example 3 An encapsulant film was produced in the same manner as in Example 1, except that the polyethylene glycol was 0.5 wt % based on the total weight of the ethylene / alpha-olefin copolymer and polyethylene glycol.

[0086] Example 4 An encapsulant film was produced in the same manner as in Example 1, except that the polyethylene glycol was 0.6 wt % based on the total weight of the ethylene / alpha-olefin copolymer and polyethylene glycol.

[0087] Example 5 An encapsulant film was produced in the same manner as in Example 1, except that polyethylene glycol having a number average molecular weight of 6,000 g / mol was used and the polyethylene glycol was 0.5 wt % based on the total weight of the ethylene / alpha-olefin copolymer and the polyethylene glycol.

[0088] Example 6 An encapsulant film was produced in the same manner as in Example 1, except that polyethylene glycol having a number average molecular weight of 8,000 g / mol was used and the polyethylene glycol was 0.5 wt % based on the total weight of the ethylene / alpha-olefin copolymer and the polyethylene glycol.

[0089] Example 7 An encapsulant film was produced in the same manner as in Example 1, except that polyethylene glycol having a number average molecular weight of 12,000 g / mol was used and the polyethylene glycol was 0.5 wt % based on the total weight of the ethylene / alpha-olefin copolymer and the polyethylene glycol.

[0090] Example 8 An encapsulant film was produced in the same manner as in Example 1, except that polyethylene glycol having a number average molecular weight of 20,000 g / mol was used and the polyethylene glycol was 0.5 wt % based on the total weight of the ethylene / alpha-olefin copolymer and the polyethylene glycol.

[0091] Comparative Example 1 An encapsulant film was produced in the same manner as in Example 1, except that polyethylene glycol was not mixed.

[0092] Comparative Example 2 An encapsulant film was produced in the same manner as in Example 1, except that the polyethylene glycol was 0.04 wt % based on the total weight of the ethylene / alpha-olefin copolymer and polyethylene glycol.

[0093] Comparative Example 3 An encapsulant film was produced in the same manner as in Example 1, except that the polyethylene glycol was 0.8 wt % based on the total weight of the ethylene / alpha-olefin copolymer and polyethylene glycol.

[0094] Comparative Example 4 An encapsulant film was produced in the same manner as in Example 1, except that the polyethylene glycol was 1.0 wt % based on the total weight of the ethylene / alpha-olefin copolymer and polyethylene glycol.

[0095] Comparative Example 5 An encapsulant film was produced in the same manner as in Example 1, except that the polyethylene glycol was 3.0% by weight based on the total weight of the ethylene / alpha-olefin copolymer and polyethylene glycol.

[0096] Comparative Example 6 An encapsulant film was produced in the same manner as in Example 1, except that the polyethylene glycol was 5.0 wt % based on the total weight of the ethylene / alpha-olefin copolymer and polyethylene glycol.

[0097] Comparative Example 7 An encapsulant film was produced in the same manner as in Example 1, except that polyethylene glycol having a number average molecular weight of 400 g / mol was used and the amount of polyethylene glycol was 0.5 wt % based on the total weight of the ethylene / alpha-olefin copolymer and polyethylene glycol.

[0098] Comparative Example 8 An encapsulant film was produced in the same manner as in Example 1, except that polyethylene glycol having a number average molecular weight of 100,000 g / mol was used and the amount of polyethylene glycol was 0.5 wt % based on the total weight of the ethylene / alpha-olefin copolymer and polyethylene glycol.

[0099] Comparative Example 9 An encapsulant film was produced in the same manner as in Example 1, except that an ethylene / vinyl acetate copolymer was used instead of the ethylene / alpha-olefin copolymer, and polyethylene glycol was not mixed.

[0100] Comparative Example 10 An encapsulant film was produced in the same manner as in Example 1, except that ethylene / vinyl acetate copolymer was used instead of ethylene / alpha-olefin copolymer, and the amount of polyethylene glycol was 0.5 wt % based on the total weight of the ethylene / vinyl acetate copolymer and polyethylene glycol.

[0101] Comparative Example 11 An encapsulant film was produced in the same manner as in Example 1, except that ethylene / vinyl acetate copolymer was used instead of ethylene / alpha-olefin copolymer, and the amount of polyethylene glycol was 1.0 wt % based on the total weight of the ethylene / vinyl acetate copolymer and polyethylene glycol.

[0102] [Table 1]

[0103] Experimental Example 1 The encapsulant films (15cm x 15cm) prepared in the examples and comparative examples were placed between two release films (thickness: about 100um), and then crosslinked by laminating them in a vacuum laminator at a process temperature of 150°C for a process time of 20 minutes.

[0104] (1) Volume resistivity Measurements were performed based on ASTM D257 standard. Specifically, samples were placed in a Keithley 8009 test fixture at a temperature of 23±1°C and humidity of 50±3%, and a voltage of 1000V was applied for 600 seconds using a Keithley 6517B electrometer connected to the fixture.

[0105] (2) Light transmittance In addition, the light transmittance at 550 nm was measured using a Shimadzu UV-3600 spectrophotometer (measurement mode: transmittance, wavelength interval: 1 nm, measurement speed: medium).

[0106] [Table 2]

[0107] As shown in Table 2, the encapsulant films prepared in Examples 1 to 8 exhibited excellent volume resistivity and light transmittance. On the other hand, in Comparative Examples 9 to 11, ethylene / vinyl acetate copolymer was used instead of ethylene / alpha-olefin copolymer, and the volume resistivity was significantly lower than that of the Examples. In addition, it was confirmed that the volume resistivity of the ethylene / vinyl acetate copolymer was not improved even when polyethylene glycol was further added.

[0108] In addition, Comparative Example 2, which used an ethylene / alpha-olefin copolymer but had a very low content of polyethylene glycol, exhibited low volume resistivity.

[0109] On the other hand, in Comparative Example 7, in which polyethylene glycol having a number average molecular weight of 400 g / mol was used, the light transmittance was low, and in Comparative Example 8, in which polyethylene glycol having a number average molecular weight of 100,000 g / mol, exceeding 50,000 g / mol, was used, the volume resistivity was found to be lowered.

[0110] Experimental Example 2 The degree of light refraction (%) was measured when light was irradiated to 1T (1 mm) of the encapsulant film according to the American Society for Testing and Materials (ASTM) D1003. Haze was measured as the transparency of the specimen by Td (refracted light) / Tt (transmitted light) x 100 (%).

[0111] [Table 3]

[0112] As shown in Table 3, Comparative Examples 3 to 6, in which polyethylene glycol was used in an extremely large amount, and Comparative Examples 7 and 8, in which the number average molecular weight was outside the range of 1,000 to 50,000 g / mol, showed high haze and were therefore unsuitable for use as an encapsulant film. Experimental Examples 1 and 2 demonstrated that a composition for an encapsulant film, which was a mixture of ethylene / alpha-olefin copolymer and polyethylene glycol having a number average molecular weight of 1,000 to 50,000 g / mol, showed excellent volume resistivity and light transmittance and low haze, and was therefore useful as an encapsulant film, when the polyethylene glycol was 0.05 to 0.7 wt % based on the total weight of the ethylene / alpha-olefin copolymer and polyethylene glycol.

[0113] In addition, it has been found that when at least one of the number average molecular weight and content of polyethylene glycol is outside the range defined in the present invention, the physical properties required for the composition for encapsulant film are reduced.

Claims

1. comprising an ethylene / alpha-olefin copolymer and polyethylene glycol; The number average molecular weight of the polyethylene glycol is 2,000 to 30,000 g / mol; The content of the polyethylene glycol is 0.1 to 0.6 wt % based on the total weight of the ethylene / alpha-olefin copolymer and the polyethylene glycol.

2. The composition for a solar cell encapsulant film according to claim 1 , further comprising at least one selected from the group consisting of a crosslinking agent, a crosslinking aid, a silane coupling agent, a light stabilizer, and a heat stabilizer.

3. 2. The composition for a solar cell encapsulant film according to claim 1, wherein the alpha-olefin comprises at least one selected from the group consisting of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicosene.

4. 2. The composition for a solar cell encapsulant film according to claim 1, wherein the alpha-olefin is contained in an amount of more than 0 to 99 mol % based on an ethylene / alpha-olefin copolymer.

5. A solar cell encapsulant film comprising the composition for a solar cell encapsulant film according to any one of claims 1 to 4.

6. A solar cell module comprising the solar cell encapsulant film according to claim 5 .

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