Composition for an encapsulating film and encapsulating film comprising the same

Abstract

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

Description

Technical Field

[0001] Cross-reference to related applications

[0002] This application claims the benefit of Korean Patent Application No. 2021-0165772, filed with the Korean Intellectual Property Office on November 26, 2021, the contents of which are incorporated herein by reference.

[0003] This invention relates to a composition comprising an ethylene / α-olefin copolymer for encapsulation, the encapsulation film, and a solar cell module. Background Technology

[0004] With the increasing severity of global environmental and energy issues, solar cells have gained attention as a means of energy generation that does not involve concerns about environmental pollution or depletion. If solar cells are used outdoors, such as on building rooftops, module-type solar cells are typically used. To obtain crystalline solar cell modules during manufacturing, the following sequence is stacked: front glass / solar cell encapsulant / crystalline solar cell device / solar cell encapsulant / back glass (or back protective sheet). As encapsulants for solar cells, ethylene / vinyl acetate copolymers or ethylene / α-olefin copolymers, which possess excellent transparency, flexibility, and adhesion, are commonly used.

[0005] A solar cell module is obtained by protecting solar cell devices such as silicon, gallium-arsenide, and copper-indium-selenide (CIGS) cells with an upper transparent protective material and a lower substrate protective material, and then encapsulating the solar cell devices and protective materials with an encapsulating agent. Typically, the encapsulating agent for the solar cell devices in a solar cell module is formed by extruding an ethylene / α-olefin copolymer mixed with an organic peroxide or silane coupling agent into a sheet shape, and the solar cell devices are encapsulated using this sheet encapsulating agent to manufacture the solar cell module.

[0006] In manufacturing the aforementioned solar cell modules, increasing the affinity between the ethylene / α-olefin copolymer and the various materials contained in the composition used for the encapsulation film to improve absorption can be a way to increase productivity. Specifically, crosslinking agents, crosslinking aids, etc., which must be used to manufacture the encapsulation film, reduce the volume resistivity of the encapsulation film and are considered to be one of the factors leading to the deterioration of physical properties.

[0007] [Existing technical documents]

[0008] [Patent Literature]

[0009] (Patent Document 1) Japanese Patent Publication No. 2015-211189 Summary of the Invention

[0010] Technical issues

[0011] One object of the present invention is to provide a composition for an encapsulation film having excellent volume resistivity and light transmittance, and an encapsulation film comprising the composition.

[0012] Technical solution

[0013] To address the aforementioned issues, the present invention provides a composition for an encapsulation film, the encapsulation film, and a solar cell module.

[0014] (1) The present invention provides a composition for encapsulating film comprising an ethylene / α-olefin copolymer and polyethylene glycol, wherein the number average molecular weight of the polyethylene glycol is from 1,000 g / mol to 50,000 g / mol, and the content of the polyethylene glycol is from 0.05% by weight to 0.7% by weight based on the total weight of the ethylene / α-olefin copolymer and the polyethylene glycol.

[0015] (2) The present invention provides a composition for encapsulating film according to (1), wherein the number average molecular weight of polyethylene glycol is from 2,000 g / mol to 30,000 g / mol.

[0016] (3) The present invention provides a composition for encapsulating film according to (1) or (2), wherein the content of polyethylene glycol is from 0.1% by weight to 0.6% by weight based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol.

[0017] (4) The present invention provides a composition for encapsulating film according to any one of (1) to (3), further comprising one or more selected from crosslinking agents, crosslinking aids, silane coupling agents, unsaturated silane compounds, aminosilane compounds, light stabilizers, UV absorbers and heat stabilizers.

[0018] (5) The present invention provides a composition for encapsulating film according to any one of (1) to (4), wherein the α-olefin comprises one or more selected from 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.

[0019] (6) The present invention provides a composition for encapsulating film according to any one of (1) to (5), wherein, based on the ethylene / α-olefin copolymer, the α-olefin is contained in greater than 0 to 99 mol%.

[0020] (7) The present invention provides an encapsulating film comprising a composition for encapsulating film according to any one of (1) to (6).

[0021] (8) The present invention provides a solar cell module including (7) an encapsulation film.

[0022] Beneficial effects

[0023] The composition for encapsulation films of the present invention exhibits excellent volume resistivity and light transmittance, and can be widely used in a variety of applications in the electrical and electronic industries. Detailed Implementation

[0024] The invention will be described in more detail below to aid in understanding it.

[0025] It should be understood that the words or terms used in this disclosure and claims should not be construed as having the meanings defined in common dictionaries. It will be further understood that, based on the principle that the inventors can appropriately define the meanings of words or terms to best illustrate the invention, the words or terms should be understood to have meanings consistent with their meanings in the context of the relevant art and the technical concept of the invention.

[0026] <Compositions for Encapsulating Films>

[0027] The composition for encapsulating films of the present invention is characterized by comprising an ethylene / α-olefin copolymer and polyethylene glycol, wherein the number average molecular weight of the polyethylene glycol is from 1,000 g / mol to 50,000 g / mol, and the content of polyethylene glycol is from 0.05% by weight to 0.7% by weight based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol.

[0028] The composition for encapsulating films of the present invention comprises an ethylene / α-olefin copolymer. The ethylene / α-olefin copolymer is prepared by copolymerizing ethylene with an α-olefin monomer, wherein the α-olefin refers to a portion of the α-olefin monomer in the copolymer, which can be an α-olefin with 4 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, 1-eicosene, etc., and any one of them or a mixture of two or more of them can be used.

[0029] The α-olefin can be 1-butene, 1-hexene, or 1-octene, preferably 1-butene, 1-hexene, or a combination thereof.

[0030] In addition, in ethylene / α-olefin copolymers, the α-olefin content can be appropriately selected within a range that meets the physical conditions, specifically greater than 0 to 99 mol%, or 10 mol% to 50 mol%, but not limited thereto.

[0031] In this invention, the preparation method or route of the ethylene / α-olefin copolymer is not limited, and those skilled in the art can select and use a suitable preparation method or route of obtaining it by considering the physical properties and purpose of the composition used for the encapsulation film.

[0032] The composition for encapsulating films of the present invention comprises polyethylene glycol.

[0033] The number average molecular weight of polyethylene glycol is from 1,000 g / mol to 50,000 g / mol, specifically above 2,000 g / mol, above 2,500 g / mol, and above 3,000 g / mol, and below 30,000 g / mol, below 20,000 g / mol, and below 15,000 g / mol, for example, from 2,000 g / mol to 30,000 g / mol.

[0034] If the composition used for encapsulation films contains polyethylene glycol, the mixture of highly polar polyethylene glycol and nonpolar ethylene / α-olefin copolymers inhibits charge movement, reduces conductivity, and increases volume resistivity. Conversely, if the composition for encapsulation films using highly polar polymers comes into contact with polyethylene glycol, conductivity will increase and volume resistivity will decrease.

[0035] Specifically, in order to preferably achieve such an effect, the number average molecular weight of polyethylene glycol is required to be between 1,000 g / mol and 50,000 g / mol.

[0036] If the number average molecular weight of polyethylene glycol is less than 1,000 g / mol, the haze may increase and impair optical properties, making it unsuitable for use as an encapsulation film. If the number average molecular weight of polyethylene glycol is greater than 50,000 g / mol, the polarity of the composition becomes too high, and understandably, the volume resistivity decreases further.

[0037] Based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol, the content of polyethylene glycol is from 0.05% by weight to 0.7% by weight, specifically from 0.1% by weight to 0.6% by weight.

[0038] Based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol, if the polyethylene glycol content is less than 0.05% by weight, the improvement in volume resistivity may not be satisfactory. If the content is greater than 0.7% by weight, the haze may increase, leading to a deterioration in optical performance, and it may be unsuitable for use as an encapsulation film.

[0039] The composition for encapsulating films of the present invention may further comprise one or more selected from crosslinking agents, crosslinking aids, silane coupling agents, unsaturated silane compounds, aminosilane compounds, light stabilizers, UV absorbers, and heat stabilizers.

[0040] The crosslinking agent is a free radical initiator in the preparation step of the silane-modified resin composition and can initiate a grafting reaction of the unsaturated silane composition onto the resin composition. Furthermore, in the lamination step used to manufacture optoelectronic devices, forming crosslinking bonds in the silane-modified resin composition or between the silane-modified resin composition and the unmodified resin composition can improve the heat resistance and durability of the final product, such as an encapsulated sheet.

[0041] The crosslinking agent can be any crosslinking agent known in the art, as long as it is a crosslinking compound capable of initiating free radical polymerization of vinyl groups or forming crosslinking bonds, such as one or more of organic peroxides, hydroxy peroxides, and azo compounds.

[0042] Specifically, one or more of the following may be used: dialkyl peroxides, such as tert-butyl cumene peroxide, di-tert-butyl peroxide, di-isopropylbenzene peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne; hydroperoxides, such as cumene hydroperoxide, di-isopropylbenzene hydroperoxide, 2,5-dimethyl-2,5-di(hydrogen peroxide)hexane and tert-butyl hydroperoxide; diacyl peroxides, such as bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, benzoyl peroxide, o-methylbenzoyl peroxide and 2,4-dichlorobenzoyl peroxide; peroxide esters. Examples of peroxides include tert-butyl peroxide, tert-butyl peracetic acid, tert-butyl peroxycarbonate-2-ethylhexyl peroxide (TBEC), tert-butyl peroxide-2-ethylhexanoate, tert-butyl perpentanoate, tert-butyl peroctanoate, tert-butyl perisopropyl carbonate, tert-butyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane and 2,5-dimethyl-2,5-di(benzoylperoxy)-3-hexyne; ketone peroxides, such as methyl ethyl ketone peroxide and cyclohexanone peroxide, lauroyl peroxide, and azo compounds, such as azobisisobutyronitrile and azobis(2,4-dimethylpentanonitrile), but not limited thereto.

[0043] The organic peroxide can be an organic peroxide with a one-hour half-life temperature of 120°C to 135°C, for example, 120°C to 130°C, 120°C to 125°C, preferably 121°C. "One-hour half-life temperature" refers to the temperature at which the half-life of the crosslinking agent becomes one hour. Depending on the one-hour half-life temperature, the effective temperature for free radical initiation reactions can vary. Therefore, when using an organic peroxide with a one-hour half-life temperature within the above-mentioned range, free radical initiation reactions, i.e., crosslinking reactions at the lamination process temperatures used in the manufacture of optoelectronic devices, can be effectively carried out.

[0044] Based on 100 parts by weight of the composition for encapsulating film, the content of the crosslinking agent can be from 0.01 parts by weight to 1 part by weight, for example, 0.05 parts by weight to 0.55 parts by weight, 0.1 parts by weight to 0.5 parts by weight, or 0.15 parts by weight to 0.45 parts by weight. If the content of the crosslinking agent is less than 0.01 parts by weight, the improvement in heat resistance may not be significant; if the content is greater than 1 part by weight, the formability of the encapsulated sheet may be reduced, and problems may arise that limit processing or affect the physical properties of the encapsulating agent.

[0045] In addition to crosslinking agents, crosslinking aids may also be included. By including crosslinking aids in the resin composition, the degree of crosslinking of the resin composition by the crosslinking agent can be increased, thereby further improving the heat resistance and durability of the final product, such as encapsulated sheets.

[0046] Crosslinking aids can be various crosslinking aids known in the art, and compounds containing at least one unsaturated group, such as allyl or (meth)acryloyloxy, can be used as crosslinking aids.

[0047] Compounds containing an allyl group can be, for example, polyallyl compounds such as triallyl isocyanurate (TAIC), triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate; compounds containing (meth)acryloyloxy groups can be, for example, poly(meth)acryloyloxy compounds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate, but are not limited thereto.

[0048] Based on 100 parts by weight of the composition for encapsulating film, the content of the crosslinking aid can be from 0.01 parts by weight to 0.5 parts by weight, for example, 0.01 parts by weight to 0.3 parts by weight, 0.015 parts by weight to 0.2 parts by weight, or 0.016 parts by weight to 0.16 parts by weight. If the content of the crosslinking aid is less than 0.01 parts by weight, the improvement in heat resistance may not be significant; if the content is greater than 0.5 parts by weight, there may be problems affecting the physical properties of the final product, such as the encapsulated sheet, and production costs may increase.

[0049] Silane coupling agents may be used, for example, one or more selected from N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane (MEMO), but are not limited thereto.

[0050] Based on 100 parts by weight of the composition for encapsulation film, the content of the silane coupling agent can be from 0.1 parts by weight to 0.4 parts by weight. If the amount of silane coupling agent is less than 0.3 parts by weight, the adhesion to the glass during the manufacture of the solar cell module may be poor, water penetration may become easier, and the long-term performance of the module cannot be guaranteed. If the amount is greater than 1 part by weight, the silane coupling agent may undesirably act as a factor increasing YI.

[0051] In addition, the composition used for encapsulating films may further comprise unsaturated silane compounds and aminosilane compounds.

[0052] Unsaturated silane compounds can be grafted onto the main chain of a polymeric unit containing a monomer of the copolymer of the present invention in the presence of a free radical initiator or the like, and are contained in a polymeric form in a silane-modified resin composition or an aminosilane-modified resin composition.

[0053] The unsaturated silane compound may be vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentoxysilane, vinyltriphenoxysilane, or vinyltriacetoxysilane, and in one embodiment, vinyltrimethoxysilane or vinyltriethoxysilane may be used therein, but is not limited thereto.

[0054] Furthermore, aminosilane compounds can act as catalysts to promote hydrolysis reactions in the grafting modification step of ethylene / α-olefin copolymers. This involves converting the alkoxy groups of reactive functional groups, such as vinyltriethoxysilane, into hydroxyl groups to improve the adhesion strength to upper and lower glass substrates or backing sheets made of fluororesin. Simultaneously, aminosilane compounds can directly participate in copolymerization reactions as reactants, and can provide amino-modified resin compositions with amine functional groups.

[0055] Aminosilane compounds are silane compounds containing an amine group, and there is no specific limitation as long as it is a primary or secondary amine. For example, aminosilane compounds can use aminotrialkoxysilanes, aminodialkoxysilanes, etc., and examples can include those selected from 3-aminopropyltrimethoxysilane (APTMS), 3-aminopropyltriethoxysilane (APTES), bis[(3-triethoxysilyl)propyl]amine, bis[(3-trimethoxysilyl)propyl]amine, 3-aminopropylmethyldiethoxysilane, 3-aminopropylmethyldiethoxysilane, N-[3-(trimethoxysilyl)propyl]ethylenediamine (DAS), aminoethylaminopropyltriethoxysilane, aminoethylaminopropylmethyldiethoxysilane, aminoethylaminomethyldiethoxysilane, aminoethylaminomethyltriethoxysilane, aminoethylaminomethyldieth ... The aminosilane compound is selected from one or more of the following: diethyltriaminopropyltrimethoxysilane, diethyltriaminopropyltriethoxysilane, diethyltriaminopropylmethyldimethoxysilane, diethyltriaminomethylmethyldiethoxysilane, (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 compound may be used alone or as a mixture.

[0056] There are no particular restrictions on the amount of unsaturated silane compounds and / or aminosilane compounds.

[0057] Additionally, if necessary, the composition for encapsulating the film may also contain one or more additives selected from light stabilizers, UV absorbers, and heat stabilizers.

[0058] Depending on the application of the composition, the light stabilizer can capture photothermally induced active species in the resin to prevent photo-oxidation. There are no particular limitations on the type of light stabilizer used; for example, known compounds such as hindered amines and hindered piperidines can be used.

[0059] UV absorbers absorb ultraviolet radiation from sunlight and other sources, converting it into harmless heat energy within the molecules. They also prevent the activation of photothermally induced active species in the resin composition. There are no particular limitations on the specific type of UV absorber used, and for example, one or a mixture of two or more of the following can be used: benzophenone derivatives, benzotriazole derivatives, acrylonitrile derivatives, metal complex derivatives, hindered amine derivatives, and inorganic UV absorbers containing ultrafine titanium dioxide and ultrafine zinc oxide particles.

[0060] In addition, heat stabilizers may include phosphorus-based heat stabilizers such as tris(2,4-di-tert-butylphenyl)phosphite, phosphorous acid, bis[2,4-bis(1,1-dimethylethyl)-6-methylphenyl]ethyl ester, tetra(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4'-diphosphonate, and bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite; and lactone-based heat stabilizers such as the reaction product of 8-hydroxy-5,7-di-tert-butyl-furan-2-one with o-xylene, and one, two, or more of these may be used.

[0061] There are no particular limitations on the amount of light stabilizers, UV absorbers, and heat stabilizers. That is, the amount of additives can be appropriately selected considering the intended use of the resin composition, the shape or density of the additives, etc. Generally, based on the total solids content of 100 parts by weight of the composition for encapsulation, this amount can be appropriately controlled in the range of 0.01 parts by weight to 5 parts by weight.

[0062] In addition to the components described above, the composition for encapsulating films of the present invention may also contain various additives known in the art, depending on the intended use of the resin composition.

[0063] Furthermore, the composition for encapsulating films can be molded into various molded articles by injection molding, extrusion, etc. Specifically, the composition can be used in various optoelectronic devices, for example, as an encapsulating agent for devices used in encapsulating solar cells, and can be used as an industrial material in lamination processes such as heating, but is not limited thereto.

[0064] <Encapsulation film>

[0065] In addition, the present invention provides an encapsulation film comprising a composition for encapsulation film.

[0066] The encapsulating film of the present invention can be manufactured by molding a composition for encapsulation into a film or sheet. The molding method is not particularly limited; for example, the sheet or film can be formed using conventional processes such as T-die processes and extrusion. For example, the encapsulating film can be manufactured using an in-situ process employing an apparatus in which the preparation of a modified resin composition using the composition for encapsulation is combined with a process for forming the film or sheet.

[0067] Considering the support efficiency and breakage probability of devices in optoelectronic devices, as well as the reduction of device weight or processability, the thickness of the encapsulation film can be controlled from about 10 μm to 2,000 μm, or from about 100 μm to 1,250 μm, and can be varied according to its specific application.

[0068] <Solar Cell Module>

[0069] Furthermore, the present invention provides a solar cell module including the aforementioned encapsulation film. In the present invention, the solar cell module may have the following configuration: the gaps between solar cells arranged in series or parallel are filled with the encapsulation film of the present invention, the glass surface is disposed on the side exposed to sunlight, and the back side is protected by a backsheet, but is not limited thereto. Various types and shapes of solar cell modules manufactured using encapsulation films incorporating the techniques described in this invention can be applied.

[0070] Tempered glass can be used on the glass surface to protect solar cells from external impacts and prevent them from breaking, and low-iron tempered glass with low iron content can be used to prevent sunlight reflection and increase sunlight transmittance, but is not limited to these.

[0071] The backsheet is a weather-resistant film that protects the back of the solar cell module from external influences. Examples include, but are not limited to, fluoropolymer sheets, metal plates or films such as aluminum, cycloolefin resin sheets, polycarbonate resin sheets, poly(meth)acrylic acid resin sheets, polyamide resin sheets, polyester resin sheets, laminated composite sheets of weather-resistant films and barrier films.

[0072] Furthermore, as long as the encapsulation film is included, the solar cell module of the present invention can be manufactured by any method known in the art, but is not limited thereto.

[0073] The solar cell module of this invention is manufactured using an encapsulation film with excellent volume resistivity. This encapsulation film prevents leakage current through the movement of electrons within the solar cell module. Therefore, it can largely suppress insulation degradation, leakage current generation, and potential-induced degradation (PID) phenomenon, which causes a rapid decrease in module output.

[0074] Example

[0075] The invention will be explained in more detail below with reference to embodiments. However, the embodiments provided are for illustrative purposes only, and the scope of the invention is not limited thereto.

[0076] [Preparation of transition metal compounds]

[0077] Preparation Example 1

[0078] (1) Preparation of ligand compounds

[0079] <Synthesis of N-tert-butyl-1-(1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophen-3-yl)-1,1-dimethylsilanamine>

[0080] 4.65 g (15.88 mmol) of chloro(1,2-dimethyl-6,7-dihydro-3H-benzo[b]cyclopenta[d]thiophene-3-yl)dimethylsilane was weighed and added to a 100 mL Schulenk flask, and 80 mL of THF was added. tBuNH2 (4 equivalents, 6.68 mL) was added at room temperature, and the reaction was allowed to proceed for 3 days. After the reaction was complete, the THF was removed, and the product was filtered through hexane. The solvent was dried to give 4.50 g (86%) of a yellow liquid.

[0081] 1 H-NMR (in CDCl3, 500MHz): 7.99 (d, 1H), 7.83 (d, 1H), 7.35 (dd, 1H), 7.24 (dd, 1H) , 3.49(s, 1H), 2.37(s, 3H), 2.17(s, 3H), 1.27(s, 9H), 0.19(s, 3H), -0.17(s, 3H).

[0082] (2) Preparation of transition metal compounds

[0083]

[0084] First, the ligand compound (1.06 g, 3.22 mmol / 1.0 equivalent) and 16.0 mL (0.2 M) of MTBE were placed in a 50 mL Schlenk flask and stirred. n-BuLi (2.64 mL, 6.60 mmol / 2.05 equivalent, 2.5 M in THF) was added at -40 °C and the mixture was reacted overnight at room temperature. Then, MeMgBr (2.68 mL, 8.05 mmol / 2.5 equivalent, 3.0 M in diethyl ether) was slowly added dropwise at -40 °C, followed by TiCl4 (2.68 mL, 3.22 mmol / 1.0 equivalent, 1.0 M in toluene), and the mixture was reacted overnight at room temperature. The reaction mixture was then filtered through diatomaceous earth using hexane. After drying the solvent, 1.07 g (82%) of a brown solid was given.

[0085] 1H-NMR (in CDCl3, 500MHz): 7.99 (d, 1H), 7.68 (d, 1H), 7.40 (dd, 1H), 7.30 (dd, 1H), 3.22 (s, 1H) , 2.67(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).

[0086] Preparation Example 2

[0087] (1) Preparation of ligand compounds

[0088] <Synthesis of N-tert-butyl-1-(1,2-dimethyl-3H-benzo[b]cyclopentet[d]thiophen-3-yl)-1,1-(methyl)(2-methylphenyl)silaneamine>

[0089] (i) Preparation of chloro-1-(1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophen-3-yl)-1,1-(methyl)(2-methylphenyl)silane

[0090] 2.0 g (1.0 equivalent, 9.985 mmol) of 1,2-dimethyl-3H-benzo[b]cyclopentyl[d]thiophene and 50 mL of THF were added to a 250 mL Schlenk flask, and 4.2 mL (1.05 equivalent, 10.484 mmol, 2.5 M hexane) of n-BuLi was added dropwise at -30 °C, followed by stirring overnight at room temperature. At -78 °C, the stirred lithium-complex THF solution was transferred to a Schlenk flask containing 2.46 g (1.2 equivalent, 11.982 mmol) of dichloro(o-tolylmethyl)silane and 30 mL of THF, and then stirred overnight at room temperature. After stirring, the solution was dried under vacuum and extracted with 100 mL of hexane.

[0091] (ii) Preparation of N-tert-butyl-1-(1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophen-3-yl)-1,1-(methyl)(2-methylphenyl)silaneamine

[0092] 4.0 g (1.0 equivalent, 10.0 mmol) of chloro-1-(1,2-dimethyl-3H-benzo[b]cyclopentyl[d]thiophen-3-yl)-1,1-(methyl)(2-methylphenyl)silane was extracted and stirred in 10 mL of hexane. Then, 4.2 mL (4.0 equivalent, 40.0 mmol) of t-BuNH2 was added at room temperature, followed by stirring overnight at room temperature. After stirring, the mixture was dried under vacuum and extracted with 150 mL of hexane. After drying the solvent, 4.26 g (99%, dr = 1:0.83) of a viscous liquid was obtained.

[0093] 1 H-NMR (in 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).

[0094] (2) Preparation of transition metal compounds

[0095]

[0096] The ligand compound (4.26 g, 10.501 mmol) was placed in 53 mL (0.2 M) of MTBE in a 250 mL round flask and stirred. n-BuLi (8.6 mL, 21.52 mmol, 2.05 equivalents, 2.5 M in hexane) was added at -40 °C and stirred overnight at room temperature.

[0097] Then, MeMgBr (8.8 mL, 26.25 mmol, 2.5 equivalence, 3.0 M in diethyl ether) was slowly added dropwise at -40 °C, followed by TiCl4 (10.50 mL, 10.50 mmol), and the mixture was stirred overnight at room temperature. The reaction mixture was then filtered through hexane. DME (3.3 mL, 31.50 mmol) was added to the filtrate, and the resulting solution was filtered through hexane and concentrated to give 3.42 g (68%, dr = 1:0.68) of a yellow solid.

[0098] 1 H NMR (CDCl3, 500MHz): δ7.83 (d, 1H), 7.80 (d, 1H), 7.74 (d, 1H), 7.71 (d, 1H), 7.6 8(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).

[0099] [Preparation of ethylene / α-olefin copolymers]

[0100] A 1.5 L continuous process reactor was preheated to 150 °C while hexane solvent was injected at a rate of 7 kg / h and 1-butene was injected at a rate of 0.94 kg / h. Triisobutylaluminum compound (0.05 mmol / min), a mixture of compounds from Preparation Example 1 and Preparation Example 2 in a molar ratio of 1:1.5, and dimethylphenylammonium tetra(pentafluorophenyl)borate cocatalyst (1.5 μmol / min) were simultaneously added to the reactor. Then, ethylene (0.87 kg / h) and hydrogen (26 cc / min) were injected into the reactor, and the copolymerization reaction was continuously carried out at a pressure of 89 bar and 136.0 °C for at least 60 minutes to prepare the copolymer. After drying in a vacuum oven for at least 12 hours, compression, and granulation, the physical properties were measured.

[0101] [Manufacturing encapsulating film]

[0102] Example 1

[0103] Polyethylene glycol (Sigma Aldrich Co.) with a number average molecular weight of 3,350 g / mol was added to the ethylene / α-olefin copolymer prepared above, such that the polyethylene glycol was 0.1% by weight based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol, and the extruded blend sample was granulated.

[0104] Then, 500g of granules were placed in a planetary mixer preheated to 40°C, and 0.5 phr of crosslinking aid, 0.2 phr of silane coupling agent and 1.0 phr of organic peroxide were added dropwise. The mixture was then mixed for 1 hour to obtain a composition for encapsulation film.

[0105] Subsequently, an encapsulation film with a thickness of 500±100 μm was manufactured at a T-die temperature of 90°C.

[0106] The number-average molecular weight of polyethylene glycol was determined by measuring it under the following analytical conditions using gel permeation chromatography (GPC).

[0107] -Column: Ultrahydrogen 250+120

[0108] - Solvent: Phosphate buffer solution at pH 6.35

[0109] - Flow rate: 0.7 ml / min

[0110] - Sample concentration: 100 mg / ml

[0111] -Injection volume: 100μl

[0112] - Column temperature: 35℃

[0113] - Detector: Vicsotek TDA 302

[0114] Data processing: OmniSEC 5.0

[0115] Example 2

[0116] Except for using 0.3% by weight of polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol, the encapsulating film was manufactured by the same method as in Example 1.

[0117] Example 3

[0118] Except for using 0.5% by weight of polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol, the encapsulating film was manufactured by the same method as in Example 1.

[0119] Example 4

[0120] Except for using 0.6% by weight of polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol, the encapsulating film was manufactured by the same method as in Example 1.

[0121] Example 5

[0122] The encapsulation film was manufactured by the same method as in Example 1, except that polyethylene glycol with a number average molecular weight of 6,000 g / mol and 0.5% by weight of polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol.

[0123] Example 6

[0124] The encapsulation film was manufactured by the same method as in Example 1, except that polyethylene glycol with a number average molecular weight of 8,000 g / mol and 0.5% by weight of polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol.

[0125] Example 7

[0126] The encapsulation film was manufactured by the same method as in Example 1, except that polyethylene glycol with a number average molecular weight of 12,000 g / mol and 0.5% by weight of polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol.

[0127] Example 8

[0128] The encapsulation film was manufactured by the same method as in Example 1, except that polyethylene glycol with a number average molecular weight of 20,000 g / mol and 0.5% by weight of polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol.

[0129] Comparative Example 1

[0130] The encapsulation film was manufactured using the same method as in Example 1, except that polyethylene glycol was not mixed in.

[0131] Comparative Example 2

[0132] Except for using 0.04% by weight of polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol, the encapsulating film was manufactured by the same method as in Example 1.

[0133] Comparative Example 3

[0134] Except for using 0.8% by weight of polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol, the encapsulating film was manufactured by the same method as in Example 1.

[0135] Comparative Example 4

[0136] Except for using 1.0% by weight of polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol, the encapsulating film was manufactured by the same method as in Example 1.

[0137] Comparative Example 5

[0138] Except for using 3.0% by weight of polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol, the encapsulating film was manufactured by the same method as in Example 1.

[0139] Comparative Example 6

[0140] Except for using 5.0% by weight of polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol, the encapsulating film was manufactured by the same method as in Example 1.

[0141] Comparative Example 7

[0142] The encapsulation film was manufactured by the same method as in Example 1, except that polyethylene glycol with a number average molecular weight of 400 g / mol and 0.5 wt% polyethylene glycol were used based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol.

[0143] Comparative Example 8

[0144] The encapsulation film was manufactured by the same method as in Example 1, except that polyethylene glycol with a number average molecular weight of 100,000 g / mol and 0.5% by weight of polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol.

[0145] Comparative Example 9

[0146] The encapsulation film was manufactured using the same method as in Example 1, except that an ethylene / vinyl acetate copolymer was used instead of an ethylene / α-olefin copolymer and polyethylene glycol was not mixed in.

[0147] Comparative Example 10

[0148] The encapsulation film was manufactured by the same method as in Example 1, except that an ethylene / vinyl acetate copolymer was used instead of an ethylene / α-olefin copolymer and 0.5% by weight of polyethylene glycol was used based on the total weight of the ethylene / vinyl acetate copolymer and polyethylene glycol.

[0149] Comparative Example 11

[0150] The encapsulation film was manufactured by the same method as in Example 1, except that an ethylene / vinyl acetate copolymer was used instead of an ethylene / α-olefin copolymer and 1.0% by weight of polyethylene glycol was used based on the total weight of the ethylene / vinyl acetate copolymer and polyethylene glycol.

[0151] [Table 1]

[0152]

[0153] Experimental Example 1

[0154] Between two release films (thickness: approximately 100 μm), each encapsulating film (15 cm × 15 cm) manufactured in the examples and comparative examples was placed and crosslinked by laminating at a process temperature of 150 °C for 20 minutes in a vacuum laminator.

[0155] (1) Volume resistivity

[0156] Measurements were performed based on ASTM D257. Specifically, the sample was placed in a Keithley 8009 test fixture at a temperature of 23±1°C and a humidity of 50%±3%, and measurements were taken using a connected Keithley 6517 electrometer while a voltage of 1000V was applied for 600 seconds.

[0157] (2) Light transmittance

[0158] Additionally, the transmittance at 550 nm was measured using a Shimadzu UV-3600 spectrophotometer (measurement mode: transmittance, wavelength interval: 1 nm, measurement speed: medium).

[0159] [Table 2]

[0160]

[0161] As shown in Table 2, all encapsulated films manufactured in Examples 1 to 8 exhibited excellent volume resistivity and light transmittance. Conversely, in Comparative Examples 9 to 11, which used ethylene / vinyl acetate copolymer instead of ethylene / α-olefin copolymer, the volume resistivity was significantly lower compared to the examples. Furthermore, it was confirmed that even when polyethylene glycol was used, the use of ethylene / vinyl acetate copolymer did not show an improvement in volume resistivity.

[0162] In addition, Comparative Example 2, which uses an ethylene / α-olefin copolymer with a very low content of polyethylene glycol, also exhibits low volume resistivity.

[0163] Meanwhile, it can be observed that Comparative Example 7, which uses polyethylene glycol with a number average molecular weight of 400 g / mol, exhibits low light transmittance, and Comparative Example 8, which uses polyethylene glycol with a number average molecular weight of 100,000 g / mol (greater than 50,000 g / mol), exhibits even lower volume resistivity.

[0164] Experimental Example 2

[0165] According to ASTM standard D1003, the refractive index (%) of light is measured when light is incident on a 1T (1mm) encapsulating film. Haze is obtained by measuring the transparency of the sample using the formula Td (refracted light) / Tt (transmitted light) × 100 (%).

[0166] [Table 3]

[0167]

[0168] As shown in Table 3, it was confirmed that Comparative Examples 3 to 6, in which excessive amounts of polyethylene glycol were used, and Comparative Examples 7 and 8, in which the number-average molecular weight deviated from 1,000 g / mol to 50,000 g / mol, exhibited high haze and were unsuitable for use in encapsulation films. Through Test Examples 1 and 2, it was confirmed that the composition for encapsulation films obtained by mixing ethylene / α-olefin copolymer and polyethylene glycol with a number-average molecular weight of 1,000 g / mol to 50,000 g / mol, and using 0.05 wt% to 0.7 wt% polyethylene glycol based on the total weight of the ethylene / α-olefin copolymer and polyethylene glycol, exhibited excellent volume resistivity and transmittance as well as low haze, and thus could be usefully used in encapsulation films.

[0169] In addition, if one or more of the number-average molecular weight and content of polyethylene glycol deviate from the range defined in this invention, the desired physical properties of the composition used for encapsulation films may be found to deteriorate.

Claims

1. An encapsulating film comprising an ethylene / α-olefin copolymer and polyethylene glycol, wherein, The polyethylene glycol has a number-average molecular weight of 2,000 g / mol to 20,000 g / mol, and Based on the total weight of the ethylene / α-olefin copolymer and the polyethylene glycol, the content of the polyethylene glycol is from 0.1% by weight to 0.6% by weight.

2. The encapsulating film according to claim 1 further comprises one or more selected from crosslinking agents, crosslinking aids, silane coupling agents, unsaturated silane compounds, aminosilane compounds, light stabilizers, UV absorbers, and heat stabilizers.

3. The encapsulation film according to claim 1, wherein, α-olefins include one or more selected from 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. The encapsulating film according to claim 1, wherein, Based on the ethylene / α-olefin copolymer, the α-olefin is contained in a range of greater than 0 to 99 mol%.

5. A solar cell module comprising an encapsulation film according to any one of claims 1 to 4.

Images