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. When the composition for encapsulant film according to the present invention is used to produce an encapsulant film, the immersion time of the ethylene / alpha-olefin copolymer can be shortened, thereby improving the economic efficiency of the encapsulant film production process. In addition, the composition for encapsulant film produced according to the present invention shows an excellent degree of crosslinking.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0059611, filed May 16, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] 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. [Background technology]

[0003] As global environmental problems and energy problems become increasingly serious, solar cells are attracting attention as a means of generating energy without the risk of environmental pollution and 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. When manufacturing a solar cell module, in order to obtain a crystalline solar cell module, the following layers are laminated in this order: front glass / solar cell encapsulant / crystalline solar cell element / solar cell encapsulant / rear glass (or rear protective sheet). As the solar cell encapsulant, ethylene / vinyl acetate copolymer or ethylene / alpha-olefin copolymer, which are excellent in transparency, flexibility, adhesion, etc., are generally used.

[0004] A solar cell module is a package in which solar cell elements such as silicon, gallium-arsenide, and copper-indium-selenium are protected by an upper transparent protective material and a lower substrate protective material, and the solar cell elements and protective materials are fixed with a sealant. In general, the sealant for the solar cell elements in a solar cell module is made by extruding an ethylene / alpha-olefin copolymer containing an organic peroxide or a silane coupling agent into a sheet, and the solar cell module is manufactured by sealing the solar cell elements with the obtained sheet-shaped sealant.

[0005] In the manufacture of the above-mentioned solar cell module, one method for improving productivity is to increase the affinity between various raw materials contained in the composition for the encapsulant film and the ethylene / alpha-olefin copolymer to increase the absorbency. In particular, the crosslinking agent, crosslinking assistant, etc., which are essential for the manufacture of the encapsulant film, are polar substances and therefore have low absorbency for the non-polar ethylene / alpha-olefin copolymer, which is one of the factors that cause a decrease in productivity. [Prior art documents] [Patent documents]

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

[0007] The object of the present invention is to shorten the impregnation time of the ethylene / alpha-olefin copolymer at the initial stage during the production of an encapsulant film by using a crosslinking agent, crosslinking assistant, etc. that have high affinity with the ethylene / alpha-olefin copolymer. [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, a crosslinking agent, a crosslinking aid, and a silane coupling agent, wherein the crosslinking aid comprises a compound represented by the following Chemical Formula 1:

[0010] [ka] In the above Chemical Formula 1, R1 to R6 are each independently an alkyl group having 1 to 10 carbon atoms; X is an aryl group having 6 to 30 carbon atoms or [ka] where L is an alkylene group having 1 to 10 carbon atoms, and R7 is an alkyl group having 1 to 10 carbon atoms.

[0011] (2) The present invention provides a composition for an encapsulant film according to the above (1), wherein in Chemical Formula 1, R1 to R6 are each independently an alkyl group having 1 to 6 carbon atoms.

[0012] (3) The present invention provides a composition for an encapsulant film, wherein the compound represented by Chemical Formula 1 in the above (1) or (2) is selected from the following compounds:

[0013] [ka]

[0014] [ka]

[0015] (4) The present invention provides a composition for a sealant film according to any one of (1) to (3) above, wherein the crosslinking aid is present in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the composition for a sealant film.

[0016] (5) The present invention provides a composition for an encapsulant film according to any one of (1) to (4) above, further comprising an allyl group-containing compound as a crosslinking aid, the allyl group-containing compound comprising at least one selected from the group consisting of triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate.

[0017] (6) The present invention provides the composition for an encapsulant film according to (5), wherein a molar ratio of the compound represented by Chemical Formula 1 to the allyl group-containing compound is 1:0.1 to 1:10.

[0018] (7) The present invention provides a composition for an encapsulant film according to any one of (1) to (6) above, wherein the alpha-olefin includes 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.

[0019] (8) The present invention provides a composition for an encapsulating material film according to any one of the above (1) to (7), wherein the alpha-olefin is contained in an amount of more than 0 and not more than 99 mol % based on the ethylene / alpha-olefin copolymer.

[0020] (9) The present invention provides a composition for an encapsulant film according to any one of the above (1) to (8), further comprising at least one selected from the group consisting of an unsaturated silane compound, an aminosilane compound, a light stabilizer, a UV absorber, and a heat stabilizer.

[0021] (10) The present invention provides an encapsulant film, comprising the composition for an encapsulant film according to any one of (1) to (9) above.

[0022] (11) The present invention provides a solar cell module including the encapsulant film according to (10) above. Effect of the Invention

[0023] When the composition for encapsulant film according to the present invention is used to produce an encapsulant film, the immersion time of the ethylene / alpha-olefin copolymer can be shortened, thereby improving the economic efficiency of the encapsulant film production process. In addition, the composition for encapsulant film produced according to the present invention shows an excellent degree of crosslinking. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The present invention will now be described in more detail to aid in its understanding.

[0025] The terms and words used in the description of the present invention and the claims should not be interpreted in a limited manner to their ordinary or dictionary meanings, but should be interpreted in a manner that is consistent with the technical idea of ​​the present invention, based on the principle that an inventor can appropriately define the concept of a term in order to best describe his / her invention.

[0026] <Composition for sealing film> The composition for an encapsulant film of the present invention comprises (a) an ethylene / alpha-olefin copolymer, (b) a crosslinking agent, (c) a crosslinking aid, and (d) a silane coupling agent, and the crosslinking aid comprises a compound represented by Chemical Formula 1.

[0027] Each component will be described in detail below.

[0028] (a) Ethylene / alpha-olefin copolymer The composition for sealing material 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, and the alpha-olefin, which means a portion derived from the alpha-olefin monomer in the copolymer, is an alpha-olefin having 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 may be one of them alone or a mixture of two or more of them.

[0029] Among them, the alpha olefin may be 1-butene, 1-hexene or 1-octene, preferably 1-butene, 1-hexene or a combination thereof.

[0030] Furthermore, in the ethylene / alpha-olefin copolymer, the content of the alpha-olefin can be appropriately selected within a range that satisfies the above physical property requirements, and specifically, it may be more than 0 and not more than 99 mol%, or 10 to 50 mol%, but is not limited thereto.

[0031] 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 can appropriately select and use the copolymer in consideration of the physical properties and purpose of the composition for the encapsulant film.

[0032] (b) Crosslinking agent The composition for encapsulant film of the present invention contains a crosslinking agent. In the step of preparing a silane-modified resin composition, the crosslinking agent can act as a radical initiator to initiate a reaction in which an unsaturated silane compound is grafted onto the resin composition. In addition, in the lamination step of preparing an optoelectronic device, crosslinking can be formed between the silane-modified resin compositions or between the silane-modified resin composition and a non-modified resin composition, thereby improving the heat resistance and durability of the final product, for example, the encapsulant sheet.

[0033] The crosslinking agent may be any of a variety of crosslinking agents known in the art, so long as the crosslinking agent is a crosslinking compound that initiates radical polymerization of a vinyl group or forms a crosslinked bond. For example, one or more crosslinking agents selected from the group consisting of organic peroxides, hydroperoxides, and azo compounds may be used.

[0034] For example, the solar cell encapsulant may contain an organic peroxide as a crosslinking agent, and the organic peroxide plays a role in improving the weather resistance of the solar cell encapsulant.

[0035] Specifically, dialkyl peroxides such as t-bupyrcumyl peroxide, di-t-butyl peroxide, di-cumyl 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 peroxybenzoate, di-t-butyl peroxyphthalate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, and 2,5-dimethyl-2,5-di(benzoylperoxy)-3-hexyne; ketone peroxides include methyl ethyl ketone peroxide and cyclohexanone peroxide; and azo compounds such as lauryl peroxide, azobisisobutyronitrile, and azobis(2,4-dimethylvaleronitrile). However, the peroxyesters are not limited thereto.

[0036] The organic peroxide may be an organic peroxide having 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. The "one-hour half-life temperature" means a temperature at which the half-life of the crosslinking agent is one hour. The temperature at which a radical initiation reaction efficiently occurs varies depending on the one-hour half-life temperature. Therefore, when an organic peroxide having a one-hour half-life temperature in the above-mentioned range is used as a crosslinking agent, a radical initiation reaction, i.e., a crosslinking reaction, effectively occurs at a lamination process temperature for manufacturing an optoelectronic device.

[0037] The crosslinking agent may be contained in an amount of 0.01 to 2 parts by weight, for example, 0.05 to 1.5 parts by weight, 0.1 to 1.5 parts by weight, or 0.5 to 1.5 parts by weight, based on 100 parts by weight of the ethylene / alpha-olefin copolymer. When the crosslinking agent is contained in the above range, the effect of improving heat resistance is sufficiently exhibited, while the moldability of the encapsulant film is excellent, and process constraints and deterioration of the physical properties of the encapsulant do not occur.

[0038] (c) Crosslinking aid The composition for an encapsulant film of the present invention contains a crosslinking aid, and the crosslinking aid contains a compound represented by the following Chemical Formula 1.

[0039] [ka] In the above Chemical Formula 1, R1 to R6 are each independently an alkyl group having 1 to 10 carbon atoms; X is an aryl group having 6 to 30 carbon atoms or [ka] where L is an alkylene group having 1 to 10 carbon atoms, and R7 is an alkyl group having 1 to 10 carbon atoms.

[0040] In the above Chemical Formula 1, R1 to R6 may each independently be an alkyl group having 1 to 6 carbon atoms or an alkyl group having 1 to 3 carbon atoms, for example, a methyl group, an ethyl group, or a propyl group.

[0041] In the above formula 1, X is an aryl group having 6 to 30 carbon atoms, an aryl group having 6 to 10 carbon atoms, for example, phenyl; [ka] where L may be an alkylene group having 1 to 10 carbon atoms or an alkylene group having 1 to 6 carbon atoms, such as a propylene group, and R7 may be an alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 3 carbon atoms, such as a methyl group.

[0042] More specifically, the compound represented by Chemical Formula 1 may be selected from the following compounds:

[0043] [ka]

[0044] [ka]

[0045] The crosslinking aid used in the present invention has higher hydrophobicity and a lower liquid phase viscosity than triallyl isocyanurate (TAIC), which has been mainly used in the past, and therefore has excellent compatibility with ethylene / alpha-olefin copolymers, and can improve the impregnation speed of the ethylene / alpha-olefin copolymer in the composition for the encapsulant film.

[0046] In addition, when X contains a double bond capable of crosslinking, the number of crosslinking sites increases, thereby increasing the degree of crosslinking. The siloxane bond (Si-O-Si) of the crosslinking aid is flexible, facilitating the crosslinking reaction, and has a high molecular weight, thereby exhibiting excellent crosslinking properties upon crosslinking.

[0047] By including the crosslinking assistant in the composition for the sealant film, the degree of crosslinking of the composition for the sealant film by the crosslinking agent can be increased, and thus the heat resistance and durability of the final product, for example, the sealant film, can be further improved.

[0048] The crosslinking aid may be present in an amount of 0.01 to 1 part by weight, specifically, 0.05 parts by weight or more, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, 1.0 parts by weight or less, or 0.8 parts by weight or less, relative to 100 parts by weight of the ethylene / alpha-olefin copolymer.

[0049] Within the above range, the crosslinking aid can fully exert the effects of improving the heat resistance and increasing the impregnation speed of the ethylene / alpha-olefin copolymer, and deterioration of the physical properties of the encapsulating material film can be suppressed.

[0050] In the present invention, the composition for the encapsulant film may further contain an allyl group-containing compound as a crosslinking aid, and the allyl group-containing compound includes one or more compounds selected from the group consisting of triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate.

[0051] Here, the molar ratio of the compound represented by Chemical Formula 1 to the allyl group-containing compound may be 1:0.1 to 1:10, specifically, 1:2 to 1:5, more specifically, 1:0.3 to 1:3, or 1:0.3 to 1:0.8.

[0052] Within the above range, the impregnation time of the ethylene / alpha-olefin copolymer can be shortened while increasing the degree of crosslinking of the composition for the encapsulant film.

[0053] (d) Silane coupling agent The composition for an encapsulant film of the present invention contains a silane coupling agent, which can play a role in improving the adhesive strength between the encapsulant film and the solar cell.

[0054] The silane coupling agent may be, 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), but is not limited thereto.

[0055] The silane coupling agent may be contained in an amount of 0.1 to 0.4 parts by weight based on 100 parts by weight of the composition for encapsulant film. When the content of the silane coupling agent is within the above range, the adhesion to glass is excellent during the production of a solar cell module, and deterioration of the long-term performance of the module due to the penetration of moisture can be prevented.

[0056] The composition for an encapsulant film of the present invention may further contain one or more selected from the group consisting of an unsaturated silane compound, an aminosilane compound, a light stabilizer, a UV absorber, and a heat stabilizer.

[0057] The unsaturated silane compound may be included in the silane-modified resin composition or aminosilane-modified resin composition in a polymerized form by grafting to a main chain containing a polymerized unit of a monomer of the copolymer of the present invention in the presence of a radical initiator or the like.

[0058] The unsaturated silane compound may be vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentoxysilane, vinyltriphenoxysilane, vinyltriacetoxysilane, or the like. As an example, vinyltrimethoxysilane or vinyltriethoxysilane may be used, but is not limited thereto.

[0059] In addition, the aminosilane compound acts as a catalyst to promote a hydrolysis reaction that converts reactive functional groups such as alkoxy groups of an unsaturated silane compound grafted to the main chain of the copolymer, for example, vinyltriethoxysilane, into hydroxyl groups in 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 a moiety having an amine functional group.

[0060] The aminosilane compound is a silane compound containing an amine group, and is not particularly limited as long as it is a primary amine or a secondary amine. For example, aminotrialkoxysilane, aminodialkoxysilane, etc. may be used as the aminosilane compound, and examples thereof include 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, aminoethylaminopropylmethyldieth ... Examples of the aminosilane compound include one or more 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 compound can be used alone or in combination.

[0061] The light stabilizer can capture active species that initiate photodegradation of the resin and prevent photooxidation 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 and hindered piperidine compounds can be used.

[0062] The UV absorbent can absorb ultraviolet rays from sunlight or the like depending on the application of the composition, convert them into harmless heat energy within the molecule, and prevent the excitation of active species that initiate photodegradation in the resin composition. The specific type of UV absorbent that can be used is not particularly limited, and for example, one or a mixture of two or more inorganic UV absorbents such as benzophenone-based, benzotriazole-based, acrylonitrile-based, metal complex salt-based, hindered amine-based, ultrafine titanium oxide, and ultrafine zinc oxide can be used.

[0063] 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.

[0064] The content of the light stabilizer, UV absorber, and heat stabilizer is not particularly limited. That is, the content of the additives can be appropriately selected in consideration of the use of the resin composition, the shape and density of the additives, etc., and can usually be appropriately adjusted within the range of 0.01 parts by weight to 5 parts by weight based on 100 parts by weight of the total solid content of the composition for the encapsulant film.

[0065] <Encapsulant film and solar cell module> The present invention also provides a sealant film comprising the sealant film composition.

[0066] The encapsulant film of the present invention can be produced by forming the composition for encapsulant film into a film or sheet. Such a forming method is not particularly limited, and can be produced by forming into a sheet or film by a normal process such as a T-die process or extrusion. For example, the encapsulant film can be produced in an in situ process using an apparatus in which the production of a modified resin composition using the composition for encapsulant film and the film or sheet process are connected to each other.

[0067] The thickness of the encapsulant film can be adjusted to about 10 to 2,000 μm or about 100 to 1,250 μm, taking into consideration the support efficiency and breakage possibility of the elements in the optoelectronic device, the weight reduction and workability of the device, etc., and can be changed depending on the specific application.

[0068] The present invention further provides a solar cell module including the encapsulant film. In the present invention, the solar cell module may have a structure in which the gaps between solar cells arranged in series or parallel are filled with the encapsulant film of the present invention, a glass surface is arranged on the surface exposed to sunlight, and the back surface is protected by a back sheet, but is not limited thereto, and all of the various types and forms of solar cell modules manufactured to include an encapsulant film in the art can be applied to the present invention.

[0069] The glass surface may be made of tempered glass in order to protect the solar cell from external impact and prevent breakage, and may be made of low iron tempered glass having a low iron content in order to prevent reflection of sunlight and increase the transmittance of sunlight, but is not limited thereto.

[0070] The back sheet 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 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.

[0071] In addition, the solar cell module of the present invention can be produced without limitation by any method known in the art, except that it contains the above-mentioned encapsulant film.

[0072] The solar cell module of the present invention is manufactured using an encapsulant film having excellent volume resistivity, and the encapsulant film can prevent electrons in the solar cell module from moving and current from leaking out to the outside. This can significantly suppress the PID (Potential Induced Degradation) phenomenon, in which insulation deteriorates, causing leakage current and a sudden drop in module output. EXAMPLES

[0073] Working Example The present invention will be described in more detail below with reference to examples. However, the following examples are for illustrating the present invention and are not intended to limit the scope of the present invention.

[0074] Example 1 As the ethylene / alpha-olefin copolymer, LF675 (ethylene / 1-butene copolymer, density 0.877 g / cc, MI 14.0) manufactured by LG Chemical was used.

[0075] A planetary mixer manufactured by Thermo Electron (Karlsruhe) GmbH was used for impregnation of the crosslinking agent. 1 phr (parts per hundred rubber) of t-butyl 1-(2-ethylhexyl) monoperoxycarbonate (TBEC), 0.5 phr of a compound represented by the following chemical formula 1-1 (methacryloxypropyl tris(vinyldimethylsiloxy)silane, MPVS), and 0.2 phr of methacryloxypropyl trimethoxysilane (MEMO) were added to 500 g of ethylene / alpha-olefin copolymer, and the torque value was observed over time while stirring at 40 rpm at a temperature of 40°C. When the torque value increased sharply, the impregnation was completed. Before the crosslinking agent was absorbed into the ethylene / alpha-olefin copolymer, it played the role of a lubricant and maintained a low torque value, and when the crosslinking agent was completely absorbed, the torque value increased, so the point at which the torque value increased sharply was set as the impregnation completion time.

[0076] Next, an encapsulant film having an average thickness of 550 μm was produced using a micro extruder at a low temperature (extruder barrel temperature of 100° C. or less) that would not cause high-temperature crosslinking.

[0077] [ka]

[0078] Examples 2 to 6, Comparative Examples 1 to 4 An encapsulant film was produced in the same manner as in Example 1, except for the changes shown in Table 1 below.

[0079] [Table 1]

[0080] [ka]

[0081] [ka]

[0082] [ka]

[0083] [ka]

[0084] [ka]

[0085] [ka]

[0086] Experimental Example 1 The physical properties of the sealing material films of the examples and comparative examples prepared as above were measured by the following methods.

[0087] (1) Impregnation speed (impregnation completion time) As described above, the time when the torque value suddenly increases was determined as the time when the impregnation was completed, and the time from the start of stirring to the completion of the impregnation was measured and shown in Table 2 below.

[0088] (2) Degree of crosslinking The degree of crosslinking was evaluated based on the CPIA (China Photovoltaic Industry Association) standard and ASTM D2765. The produced encapsulant film was cut into a size of 10 cm x 10 cm, and then vacuum laminated at 150°C for 20 minutes (5 minutes vacuum / 1 minute pressure / 14 minutes pressure sustained) to obtain a crosslinked sample.

[0089] The crosslinked samples were cut to appropriate sizes, and then weighed in 0.5g portions and placed in 200-mesh iron cages, and dissolved in xylene reflux for 5 hours. The samples were then dried in a vacuum oven, and the weights before and after reflux were compared to determine the degree of crosslinking for each sample.

[0090] (3) MDR torque (M H -M L ,Nm) To evaluate the degree of crosslinking, the MDR torque value of each sample was measured using an Alpha Technologies Production MDR (Moving Die Rheometer).

[0091] Specifically, the 550 μm encapsulant films produced in the above examples and comparative examples were cut into 1 g pieces, and then stacked into 4 pieces to prepare samples weighing 4 g in total. Then, the samples were measured at 150° C. for 20 minutes. H Value and M L The measured M H Value to M L By subtracting the value, the MDR torque (M H -M L ) was calculated, where M H is the maximum vulcanizing torque, and M L is the minimum vulcanizing torque.

[0092] [Table 2]

[0093] As shown in Table 2 above, in the cases of Examples 1 to 6 in which the composition for encapsulant films of the present invention was used, the impregnation speed was fast, so the impregnation completion time was shortened, and the crosslinking degree was also at an excellent level. In contrast, in the case of Comparative Example 1 in which TAIC was used as the crosslinking assistant, the impregnation speed was slow, so the impregnation completion time was significantly longer than in the examples, and in the cases of Comparative Examples 2 to 4 in which a compound not corresponding to Chemical Formula 1 was used as the crosslinking assistant, it was confirmed that the crosslinking degree was reduced.

[0094] In this way, when the composition for an encapsulant film according to the present invention is used, there is an effect of shortening the impregnation time while showing an appropriate level of crosslinking degree.

Claims

1. The composition comprises an ethylene / alpha-olefin copolymer, a crosslinking agent, a crosslinking coagent, and an organic peroxide, The crosslinking assistant agent is a compound represented by the following chemical formula 1. 【Chemistry 1】 In the above Chemical Formula 1, R １ ~R ６ are each independently an alkyl group having 1 to 10 carbon atoms, X is an aryl group having 6 to 30 carbon atoms, or 【Chemistry 2】 where L is an alkylene group having 1 to 10 carbon atoms, R ７ is an alkyl group having 1 to 10 carbon atoms.

2. In the above formula 1, R １ ~R ６ The composition for sealing material films according to claim 1, wherein each of the groups independently represents an alkyl group having 1 to 6 carbon atoms.

3. The composition for a sealing material film according to claim 1 , wherein the compound represented by Chemical Formula 1 is selected from the following compounds: 【Chemistry 3】 【Chemistry 4】

4. The composition for a sealant film according to claim 1, wherein the crosslinking assistant is contained in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the composition for a sealant film.

5. The crosslinking aid further contains an allyl group-containing compound, The composition for a sealing material film according to claim 1 , wherein the allyl group-containing compound comprises at least one selected from the group consisting of triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate.

6. The composition for a sealing material film according to claim 5, wherein a molar ratio of the compound represented by Chemical Formula 1 to the allyl group-containing compound is 1:0.1 to 1:

10.

7. 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. The composition for sealing material film according to claim 1.

8. The composition for sealing material films according to claim 1 , wherein the alpha-olefin is contained in an amount of more than 0 and not more than 99 mol % based on the ethylene / alpha-olefin copolymer.

9. The composition for an encapsulant film according to claim 1 , further comprising at least one selected from the group consisting of an unsaturated silane compound, an aminosilane compound, a light stabilizer, a UV absorber, and a heat stabilizer.

10. A sealant film comprising the composition for sealant films according to any one of claims 1 to 9.

11. A solar cell module comprising the encapsulant film of claim 10.

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