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

Abstract

The present invention relates to a composition for a sealing film containing an ethylene / alpha-olefin copolymer, a sealing film, and a solar cell module. When a sealing film is manufactured using the composition for a sealing film according to the present invention, the economic efficiency of the sealing film production process can be improved by shortening the immersion time of the ethylene / alpha-olefin copolymer. Further, the composition for a sealing film manufactured using the present invention exhibits excellent crosslinking degree.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application Nos. 10-2022-0085136 filed on July 11, 2022 and 10-2022-0094551 filed on July 29, 2022, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference in their entirety.

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

Background Art

[0003] As global environmental problems and energy problems are becoming increasingly serious, solar cells are attracting attention as a clean and non-depletable energy generation means. When used outdoors, such as on the roof of a building, solar cells are generally used in the form of modules. However, when manufacturing a solar cell module, in order to obtain a crystalline solar cell module, a protective sheet for a solar cell module (transparent protective member on the front side) / solar cell encapsulant / crystalline solar cell element / solar cell encapsulant / protective sheet for a solar cell module (protective member on the back side) are laminated in this order. On the other hand, in order to obtain a thin-film solar cell module, a thin-film solar cell element / solar cell encapsulant / protective sheet for a solar cell module (protective member on the back side) are laminated in this order.

[0004] As the above-mentioned solar cell encapsulant, generally, an ethylene / vinyl acetate copolymer, an ethylene / alpha-olefin copolymer, etc. are used. In addition, since long-term weather resistance is required for the solar cell encapsulant, a light stabilizer is usually included as an additive. Also, in consideration of the adhesion of the front-side transparent protective member or the back-side protective member typified by glass, a silane coupling agent is usually included in the solar cell encapsulant.

[0005] Specifically, ethylene / vinyl acetate copolymer (EVA) sheets have been widely used because of their excellent transparency, flexibility, adhesiveness, etc. Ethylene-vinyl acetate copolymer (EVA) films are widely used because of their excellent transparency, flexibility, adhesiveness, etc. However, when using an EVA composition as a constituent material of a solar cell encapsulant, there are concerns that components such as acetic acid gas generated by the decomposition of EVA may affect the solar cell element.

[0006] Since the ethylene / alpha-olefin copolymer has no problem of resin hydrolysis, it has been able to solve the problems of lifespan reduction and reliability reduction. However, since the ethylene / alpha-olefin copolymer does not contain a polar group in the resin, conventionally, its miscibility with the polar crosslinking aid contained as a constituent material of the solar cell encapsulant has decreased, and it takes a very long time for impregnation, so there has been a problem with productivity.

[0007] Thus, in a situation where it is necessary to develop a crosslinking aid that can improve the productivity of a solar cell encapsulant containing an ethylene / alpha-olefin copolymer, which is excellent in volume resistivity and can be usefully utilized as a substance requiring high insulation such as a solar cell encapsulant.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] An object of the present invention is to provide a composition for a sealing material film containing a crosslinking aid having excellent miscibility with an ethylene / alpha-olefin copolymer.

Means for Solving the Problems

[0010] In order to solve the above problems, the present invention provides a composition for a sealing material film, a sealing material film, and a solar cell module.

[0011] [1] The present invention provides a composition for a sealing material film, which comprises an ethylene / alpha-olefin copolymer, a crosslinking agent, a crosslinking aid, and a silane coupling agent, and the crosslinking aid contains a compound represented by the following Chemical Formula 1. [Chemical Formula] In Chemical Formula 1, R1 to R6 are each independently an alkyl having 1 to 20 carbon atoms or an alkenyl having 2 to 20 carbon atoms, and here, two or more of R1 to R3 and two or more of R4 to R6 are each independently an alkenyl having 2 to 20 carbon atoms.

[0012] [2] In the present invention according to [1], R1, R3, R4, and R6 are each independently an alkenyl having 2 to 20 carbon atoms, and R2 and R5 are each independently an alkyl having 1 to 20 carbon atoms or an alkenyl having 2 to 20 carbon atoms, and the present invention provides a composition for a sealing material film.

[0013] [3] In the present invention according to [1] or [2], R1, R3, R4, and R6 are each independently an alkenyl having 2 to 12 carbon atoms having a double bond at the terminal, and R2 and R5 are each independently an alkyl having 1 to 12 carbon atoms or an alkenyl having 2 to 12 carbon atoms having a double bond at the terminal, and the present invention provides a composition for a sealing material film.

[0014] [4] In the present invention according to any one of [1] to [3], the compound represented by Chemical Formula 1 is hexavinyl disiloxane or tetravinyl dimethyl disiloxane, and the present invention provides a composition for a sealing material film.

[0015] [5] In the present invention according to any one of [1] to [4], the crosslinking aid further contains an allyl group-containing compound, and the present invention provides a composition for a sealing material film.

[0016] [6] In the present invention as described in [5] above, the allyl group-containing compound includes one or more selected from the group consisting of triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate, and provides a composition for a sealing film.

[0017] [7] In the present invention as described in [5] or [6] above, the molar ratio of the compound represented by Chemical Formula 1 and the allyl group-containing compound is 1:0.1 to 1:10, and provides a composition for a sealing film.

[0018] [8] In the present invention as described in any one of [1] to [7] above, the crosslinking aid is 0.01 to 5 parts by weight with respect to 100 parts by weight of the composition for a sealing film, and provides a composition for a sealing film.

[0019] [9] In the present invention as described in any one of [1] to [8] above, the composition for a sealing film further includes 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.

[0020]

[10] The present invention provides a sealing film including the composition for a sealing film according to any one of [1] to [9].

[0021]

[11] The present invention provides a solar cell module including the sealing film according to

[10] .

Advantages of the Invention

[0022] The composition for a sealing film of the present invention contains, as a crosslinking aid, a compound having excellent miscibility with an ethylene / alpha-olefin copolymer, has a fast impregnation rate with respect to the ethylene / alpha-olefin copolymer, and the sealing film produced using the same exhibits excellent volume resistivity and light transmittance, and thus can be widely used in various applications in the field of the electrical and electronic industries.

Embodiments for Carrying Out the Invention

[0023] Hereinafter, in order to facilitate the understanding of the present invention, the present invention will be described in more detail.

[0024] In the description of the present invention and the claims, terms and words used should not be construed as being limited to ordinary or dictionary meanings. The inventors should interpret them in accordance with the meaning and concept consistent with the technical idea of the present invention, in accordance with the principle that they can appropriately define the concept of terms in order to explain their invention in the best way.

[0025] [Composition for encapsulant film] The composition for an encapsulant film of the present invention contains (a) an ethylene / alpha-olefin copolymer, (b) a crosslinking agent, (c) a crosslinking aid, and (d) a silane coupling agent, and the crosslinking aid is characterized by containing a compound represented by Chemical Formula 1.

[0026] [Chem.]

[0027] In Chemical Formula 1 above, R1 to R6 are each independently an alkyl having 1 to 20 carbon atoms or an alkenyl having 2 to 20 carbon atoms, and here, two or more of R1 to R3 and two or more of R4 to R6 are each independently an alkenyl having 2 to 20 carbon atoms.

[0028] Hereinafter, each component will be described in detail.

[0029] (a) Ethylene / alpha-olefin copolymer The composition for a sealing material film of the present invention contains an ethylene / alpha-olefin copolymer. The ethylene / alpha-olefin copolymer is produced by copolymerizing ethylene and an alpha-olefin monomer. Here, 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, examples include 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 it may be one of them alone or a mixture of two or more of them.

[0030] Among them, the alpha-olefin may be 1-butene, 1-hexene or 1-octene, and preferably may be 1-butene, 1-octene or a combination thereof.

[0031] Also, in the ethylene / alpha-olefin copolymer, the content of the alpha-olefin can be appropriately selected within the range that satisfies the above physical property requirements. Specifically, it may be more than 0 and 99 or less mol%, or may be 10 to 50 mol%, but is not limited thereto.

[0032] In the present invention, the method and acquisition route for preparing the ethylene / alpha-olefin copolymer are not limited, and an ordinary technician can appropriately select and use them in consideration of the physical properties and purpose of the composition for the sealing material film.

[0033] (b) Crosslinking agent The composition for a sealing material film of the present invention contains a crosslinking agent. In the production step of the silane-modified resin composition, the crosslinking agent can serve as a radical initiator to initiate the reaction in which an unsaturated silane compound grafts onto the resin composition. Further, in the lamination step during the production of an optoelectronic device, by forming crosslinking bonds between the silane-modified resin compositions or between the silane-modified resin composition and the unmodified resin composition, the heat resistance and durability of the final product, for example, the sealing material sheet, can be improved.

[0034] As long as the crosslinking agent is a crosslinkable compound that initiates radical polymerization of vinyl groups or forms crosslinking bonds, various known crosslinking agents in the technical field can be used in various ways. For example, one or more selected from the group consisting of organic peroxides, hydroperoxides, and azo compounds can be used.

[0035] For example, the encapsulant for a solar cell may contain an organic peroxide as a crosslinking agent, and the organic peroxide plays a role in improving the weather resistance of the encapsulant for a solar cell.

[0036] Specifically, one or more selected from the group consisting of dialkyl peroxides such as t-butyl cumyl peroxide, di-t-butyl peroxide, di-cumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 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, t-butyl hydroperoxide; diacyl peroxides such as bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, benzoyl peroxide, o-methylbenzoyl peroxide, 2,4-dichlorobenzoyl peroxide; peroxy esters such as t-butyl peroxyisobutyrate, t-butyl peroxyacetate, t-butyl peroxy-2-ethylhexyl carbonate (TBEC), t-butyl peroxy-2-ethylhexanoate, t-butyl peroxypivalate, t-butyl peroxy octoate, t-butyl peroxyisopropyl carbonate, t-butyl peroxybenzoate, di-t-butyl peroxyphtalate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dimethyl-2,5-di(benzoylperoxy)-3-hexyne; ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide; and azo compounds such as lauryl peroxide, azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile), but not limited thereto.

[0037] The organic peroxide may be an organic peroxide having a 1-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 "1-hour half-life temperature" means the temperature at which the half-life of the crosslinking agent becomes 1 hour. Depending on the 1-hour half-life temperature, the temperature at which the radical initiation reaction occurs efficiently is different. Therefore, when an organic peroxide having a 1-hour half-life temperature in the above range is used as the crosslinking agent, the radical initiation reaction, that is, the crosslinking reaction, can occur effectively at the lamination process temperature for manufacturing the optoelectronic device.

[0038] The crosslinking agent may be contained in an amount of 0.01 part by weight to 2 parts by weight, for example, 0.05 part by weight to 1.5 parts by weight, 0.1 part by weight to 1.5 parts by weight, or 0.5 part by weight to 1.5 parts by weight with respect to 100 parts by weight of the ethylene / alpha-olefin copolymer. When the crosslinking agent is contained within the above range, the effect of improving the heat resistance characteristics is sufficiently exhibited, and the moldability of the encapsulant film is also excellent, and there are no problems in the process and no deterioration in the physical properties of the encapsulant.

[0039] (c) Crosslinking aid The composition for an encapsulant film of the present invention contains a crosslinking aid, where the crosslinking aid includes a compound represented by the following Chemical Formula 1 and an allyl group-containing compound.

[0040] [Chemical formula]

[0041] In Chemical Formula 1 above, R1 to R6 are each independently an alkyl having 1 to 20 carbon atoms or an alkenyl having 2 to 20 carbon atoms, where two or more of R1 to R3 and two or more of R4 to R6 are each independently an alkenyl having 2 to 20 carbon atoms.

[0042] In the chemical formula 1, R1, R3, R4, and R6 may each independently be an alkenyl group having 2 to 12 carbon atoms with a double bond at the terminal, and R2 and R5 may each independently be an alkyl group having 1 to 12 carbon atoms or an alkenyl group having 2 to 12 carbon atoms with a double bond at the terminal.

[0043] In addition, the composition for a sealing material film according to an example of the present invention may specifically contain, as the compound of the chemical formula 1, hexavinyl disiloxane represented by the following chemical formula 2 or tetravinyl dimethyl disiloxane represented by the following chemical formula 3.

[0044]

Chemical formula

[0045]

Chemical formula

[0046] Currently widely used allyl group-containing crosslinking agents contain a large number of polar functional groups, while the crosslinking aid used in the present invention consists only of non-polar functional groups such as siloxane. Therefore, the impregnation rate of the ethylene / alpha-olefin copolymer, which is a non-polar substance in the composition for a sealing material film, can be improved.

[0047] Since the crosslinking aid used in the present invention has four or more double bonds, the number of double bonds participating in the crosslinking reaction is sufficiently ensured. If the content of double bonds is less than this, the degree of crosslinking will decrease, and in fact, it will be impossible to use as a sunlight sealing material.

[0048] When the crosslinking aid is included in the composition for a sealing material film, the degree of crosslinking of the composition for a sealing material film by the above-described crosslinking agent can be increased, and thereby, the heat resistance and durability of the final product, for example, the sealing material film, can be further improved.

[0049] In the present invention, the crosslinking aid may further contain an allyl group-containing compound. By using it in admixture with the allyl group-containing compound, the impregnation rate of the ethylene / alpha-olefin copolymer can be maintained at a high level, and the crosslinking degree can be further improved.

[0050] The allyl group-containing compound may contain one or more 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 and the allyl group-containing compound may be 1:0.1 to 1:10, specifically 1:2 to 1:5, and more specifically 1:0.3 to 1:4.

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

[0053] Further, the crosslinking aid may be contained in an amount of 0.01 to 5 parts by weight, specifically 0.05 to 3 parts by weight, or 0.1 to 2 parts by weight, based on 100 parts by weight of the composition for the encapsulant film.

[0054] By including the crosslinking aid within the above range, the crosslinking degree of the composition for the encapsulant film can be maintained at a high level, and the impregnation time of the crosslinking aid of the ethylene / alpha-olefin copolymer can be shortened.

[0055] (d) Silane coupling agent The composition for the encapsulant film of the present invention contains a silane coupling agent, which can play a role in improving the adhesive force between the encapsulant film and the solar cell.

[0056] 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, but are not limited thereto.

[0057] The silane coupling agent may be contained in an amount of 0.1 part by weight to 0.4 part by weight with respect to 100 parts by weight of the composition for the encapsulant film. When the content of the silane coupling agent is within the above range, at the time of manufacturing a solar cell module, it has excellent adhesion to glass and can prevent a decrease in the long-term performance of the module due to penetration of moisture.

[0058] Further, the composition for the 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.

[0059] The unsaturated silane compound may be grafted onto the main chain containing the polymerization unit of the monomer of the copolymer of the present invention in the presence of a radical initiator or the like, and may be contained in a polymerized form in a silane-modified resin composition or an aminosilane-modified resin composition.

[0060] The unsaturated silane compound may be vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentoxysilane, vinyltriphenoxysilane, vinyltriacetoxysilane, etc. As an example, among them, vinyltrimethoxysilane or vinyltriethoxysilane may be used, but is not limited thereto.

[0061] In addition, the amino-silane compound acts as a catalyst for promoting a hydrolysis reaction that converts reactive functional groups, such as alkoxy groups of an unsaturated silane compound grafted onto the main chain of the copolymer, for example, vinyltriethoxysilane, into hydroxy groups in the graft modification step of the ethylene / alpha-olefin copolymer, thereby making it possible to further improve the adhesion strength with the backsheet composed of upper and lower glass substrates or a fluororesin or the like. Further, at the same time, the amino-silane compound can be involved as a reactant in the direct copolymerization reaction, thereby providing a moiety having an amine functional group to the amino-silane modified resin composition.

[0062] The amino-silane 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, as the amino-silane compound, aminotrialkoxysilane, amino-dialkoxysilane, etc. may be used. Examples thereof include 3-aminopropyltrimethoxysilane (3-aminopropyltrimethoxysilane; APTMS), 3-aminopropyltriethoxysilane (3-aminopropyltriethoxysilane; APTES), bis[(3-triethoxysilyl)propyl]amine, bis[(3-trimethoxysilyl)propyl]amine, 3-aminopropylmethyldiethoxysilane, 3-aminopropylmethyldimethoxysilane, N-[3-(trimethoxysilyl)propyl]ethylenediamine (N-[3-(Trimethoxysilyl)propyl]ethylenediamine; DAS), aminoethylaminopropyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, aminoethylaminopropylmethyldiethoxysilane, 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. One or more selected from the group consisting of the above are mentioned. The amino-silane compound can be used alone or in combination.

[0063] The light stabilizer can capture the active species that initiate the photo-degradation of the resin and play a role in preventing photo-oxidation according to the application for which the composition is used. The types of light stabilizers that can be used are not particularly limited, and for example, known compounds such as hindered amine-based compounds or hindered piperidine-based compounds can be used.

[0064] The UV absorber can absorb ultraviolet rays from sunlight, etc., convert them into harmless thermal energy within the molecule, and play a role in preventing the active species that initiate photo-degradation in the resin composition from being excited according to the application of the composition. The specific types of UV absorbers that can be used are not particularly limited, and for example, one or a mixture of two or more of inorganic UV absorbers such as benzophenone-based, benzotriazole-based, acrylonitrile-based, metal complex-based, hindered amine-based, ultrafine titanium oxide, ultrafine zinc oxide, etc. can be used.

[0065] Examples of the heat stabilizer also 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 phosphite, tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4'-diyl bisphosphonate, 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 and o-xylene. One or two or more of the above can be used.

[0066] The contents of the light stabilizer, UV absorber, and heat stabilizer are not particularly limited. That is, the content of the additive can be appropriately selected in consideration of the application of the resin composition, the shape and density of the additive, etc., and usually, it can be appropriately adjusted within the range of 0.01 to 5 parts by weight based on 100 parts by weight of the total solid content of the composition for the encapsulant film.

[0067] [Encapsulant Film] The present invention also provides a sealing material film containing the composition for the sealing material film.

[0068] The sealing material film of the present invention can be manufactured by molding the composition for the sealing material film into a film or sheet form. Such a molding method is not particularly limited, and for example, it can be manufactured by sheet-forming or film-forming in a normal process such as a T-die process or extrusion. For example, the production of the sealing material film can be carried out in an in-situ process using an apparatus in which the production of the modified resin composition using the composition for the sealing material film and the film-forming or sheet-forming process are linked to each other.

[0069] The thickness of the sealing material film can be adjusted to about 10 to 2,000 μm or about 100 to 1,250 μm in consideration of the support efficiency and breakage possibility of the elements in the optoelectronic device, weight reduction of the device, workability, etc., and can be changed according to specific applications.

[0070] [Solar cell module] Furthermore, the present invention provides a solar cell module containing the sealing material film. In the present invention, the solar cell module may have a configuration in which the intervals between the solar cell cells arranged in series or parallel are filled with the sealing material film of the present invention, a glass surface is arranged on the surface exposed to sunlight, and the back surface is protected by a backsheet, but it is not limited thereto, and all various types and forms of solar cell modules manufactured to include a sealing material film in the technical field can be applied to the present invention.

[0071] As the glass surface, tempered glass can be used to protect the solar cell from external impacts and prevent breakage, and low iron tempered glass with a low iron content can be used to prevent reflection of sunlight and increase the transmittance of sunlight, but it is not limited thereto.

[0072] The backsheet is a weather-resistant film that protects the back surface of the solar cell module from the outside. Examples include fluorine-based resin sheets, metal plates or foils such as aluminum, cyclic olefin-based resin sheets, polycarbonate-based resin sheets, poly(meth)acrylic-based resin sheets, polyamide-based resin sheets, polyester-based resin sheets, and composite sheets obtained by laminating a weather-resistant film and a barrier film. However, the backsheet is not limited to these.

[0073] In addition, the solar cell module of the present invention can be manufactured without limitation by a method known in the art, except that it includes the above-mentioned encapsulant film.

[0074] The solar cell module of the present invention is manufactured using an encapsulant film having excellent volume resistivity. The encapsulant film can prevent electrons in the solar cell module from moving 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.

[0075] Example Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are for illustrative purposes only, and the scope of the present invention is not limited thereto.

[0076] Example 1 Tetravinyldimethyldisiloxane (TVDMDS, manufactured by Gelest Inc.) was prepared as a crosslinking aid.

[0077] LUCENE TM LF675, 500 g, manufactured by LG Chem, an ethylene / 1-butene copolymer, was dried overnight using a convection oven at 40°C. The density of the LUCENE TM LF675 measured according to ASTM D1505 was 0.877 g / cm 3It has a melt index (190°C, 2.16 kg) of 14.0 g / 10 min as measured in accordance with ASTM D1238. The temperature of the bowl of a viscometer (manufactured by Thermo Electron (Karsruhe) GmbH, Haake Modular Torque Viscometer) was set at 40°C. After introducing an ethylene / alpha-olefin copolymer into the bowl, using an electric pipette, a crosslinking agent composition [1.00 phr (parts per hundred rubber) of t-butyl 1-(2-ethylhexyl) monoperoxycarbonate (TBEC, manufactured by Sigma-Aldrich) as a crosslinking agent, 0.25 phr of the prepared tetravinyldimethyldisiloxane (TVDMDS) as a crosslinking aid, and 0.20 phr of methacryloxypropyltrimethoxysilane (MEMO, manufactured by Shin-Etsu) as a silane coupling agent] was introduced. While stirring at 40 rpm at 40°C, the change in torque value over time was observed, and impregnation was terminated when the torque value increased rapidly, and the impregnation completion time of the crosslinking agent composition was measured.

[0078] Next, the impregnated sample was press-molded using a micro extruder at a low temperature (under the condition that the extruder barrel temperature was 90 - 100°C) so that it would not be crosslinked at a high temperature to produce a sealing material film in the form of a sheet with an average thickness of 0.5 mm.

[0079] Example 2 A sealing material film was produced in the same manner as in Example 1 except that the amount of tetravinyldimethyldisiloxane (TVDMDS) as a crosslinking aid was changed to 0.50 phr.

[0080] Example 3 A sealing material film was produced in the same manner as in Example 1 except that the amount of tetravinyldimethyldisiloxane (TVDMDS) as a crosslinking aid was changed to 1.00 phr.

[0081] Example 4 A sealing film was produced in the same manner as in Example 1, except that hexavinyl disiloxane (HVDS) was used instead of tetravinyl dimethyl disiloxane (TVDMDS).

[0082] Example 5 A sealing film was produced in the same manner as in Example 1, except that hexavinyl disiloxane (HVDS) was used instead of tetravinyl dimethyl disiloxane (TVDMDS), and the input amount was changed to 0.50 phr.

[0083] Example 6 A sealing film was produced in the same manner as in Example 1, except that hexavinyl disiloxane (HVDS) was used instead of tetravinyl dimethyl disiloxane (TVDMDS), and the input amount was changed to 1.00 phr.

[0084] Example 7 A sealing film was produced in the same manner as in Example 1, except that the input amount of tetravinyl dimethyl disiloxane (TVDMDS) was changed to 0.125 phr, and 0.375 phr of triallyl isocyanurate (TAIC) was further added.

[0085] Example 8 A sealing film was produced in the same manner as in Example 1, except that 0.25 phr of triallyl isocyanurate (TAIC) was further added.

[0086] Example 9 A sealing film was produced in the same manner as in Example 1, except that the input amount of tetravinyl dimethyl disiloxane (TVDMDS) was changed to 0.375 phr, and 0.125 phr of triallyl isocyanurate (TAIC) was further added.

[0087] Example 10 A sealing film was produced in the same manner as in Example 1, except that 0.125 phr of hexavinyl disiloxane (HVDS) was added instead of tetravinyl dimethyl disiloxane (TVDMDS), and 0.375 phr of triallyl isocyanurate (TAIC) was further added.

[0088] Example 11 A sealing film was produced in the same manner as in Example 1, except that 0.25 phr of hexavinyl disiloxane (HVDS) was added instead of tetravinyl dimethyl disiloxane (TVDMDS), and 0.25 phr of triallyl isocyanurate (TAIC) was further added.

[0089] Example 12 A sealing film was produced in the same manner as in Example 1, except that 0.375 phr of hexavinyl disiloxane (HVDS) was added instead of tetravinyl dimethyl disiloxane (TVDMDS), and 0.125 phr of triallyl isocyanurate (TAIC) was further added.

[0090] Comparative Example 1 A sealing film was produced in the same manner as in Example 1, except that triallyl isocyanurate (TAIC) was used instead of tetravinyl dimethyl disiloxane (TVDMDS) as a crosslinking aid, and the amount added was changed to 0.50 phr.

[0091] Comparative Example 2 A sealing film was produced in the same manner as in Example 1, except that 1,3 - divinyltetramethyldisiloxane (DVTMDS) was used instead of tetravinyl dimethyl disiloxane (TVDMDS) as a crosslinking aid, and the amount added was changed to 0.50 phr.

[0092] Table 1 below shows the crosslinking agent compositions used in Examples 1 to 12, and Comparative Examples 1 and 2.

[0093]

Table 1

[0094] Experimental Example 1 A 0.5-mm-thick sealing material film (15 cm × 15 cm) manufactured as described above was placed between two release films (thickness: approximately 100 μm), and laminated and cross-linked using a vacuum laminator at a process temperature of 150°C for a process time of 20 minutes (5 minutes of vacuum / 1 minute of pressurization / 14 minutes of pressure maintenance).

[0095] (1) Impregnation completion time The crosslinking agent impregnation completion times measured in Examples 1 to 12 and Comparative Examples 1 and 2 are shown in Table 2 below.

[0096] (2) Vulcanization characteristics In accordance with ASTM D5289, the vulcanization characteristics were measured using a premier MDR manufactured by Alpha Techbologies. The test was carried out at 150°C for 20 minutes to obtain a torque curve over time. The condition of 150°C at this time corresponds to the lamination temperature, and 20 minutes corresponds to the lamination time. Also, the difference between the maximum torque (MH) and the minimum torque (ML) applied by the MDR during this time was used to relatively compare the vulcanization characteristics between the samples. In addition, T90 (the time when 90% is vulcanized) was measured, and T90 represents the vulcanization rate.

[0097] (3) Degree of crosslinking The cross-linked sheet was cut into a size of 3 × 3 mm using scissors. 2 7 × 10 cm 2The sides and bottom of a 200-mesh wire mesh were sealed with staples. The sheet was placed in the wire mesh, and the weight of the inserted sheet was measured. The amount of the sheet was adjusted to be 0.49 - 0.51 g. After inserting the sheet, the top of the wire mesh was sealed with staples, and the total weight of the sample was measured. A solution prepared by dissolving 10 g of BHT (dibutylhydroxytoluene) in 1,000 g of xylene was poured into a 2L cylindrical reactor, and 3 to 4 of the said samples were put in. The reactor was heated, and reflux was terminated 5 hours after it started to boil. The samples in the reactor were taken out with a metal wire mesh and washed with xylene. They were vacuum dried at 100°C overnight. The weight of the dried samples was measured to calculate the degree of crosslinking. The degree of crosslinking can be determined as the average value of 3 to 4 samples refluxed with xylene.

[0098] Degree of crosslinking (%) = [(weight of the sheet after reflux) / (weight of the sheet before reflux)] × 100

[0099]

Table 2

[0100] As shown in Table 2 above, in the case of Examples 1 - 12 using the composition for the encapsulant film of the present invention, the impregnation rate was fast, the impregnation completion time was shortened, and the degree of crosslinking also showed an excellent level.

[0101] On the other hand, in the case of Comparative Example 1 using TAIC as a crosslinking aid, the impregnation rate was slow and the impregnation completion time was much longer compared to the examples. In the case of Comparative Example 2 using a compound not corresponding to Chemical Formula 1 as a crosslinking aid, it was confirmed that the degree of crosslinking decreased.

[0102] Experimental Example 2 (1) Volume resistivity The test was conducted at room temperature in accordance with ASTM D257. The prepared sample was placed in a Keithley 8009 Resistivity test fixture, and after applying a voltage of 1,000 V with a 6517B Electrometer / High Resistance meter connected thereto, the volume resistivity was measured.

[0103] (2) Light transmittance Using a Shimadzu UV-3600 spectrophotometer, the light transmittance was measured at 200 nm to 1,000 nm to obtain a light transmittance curve, and then the values at 280 - 380 nm and 380 - 1100 nm were confirmed.

[0104] - Measurement mode: transmittance - Wavelength interval: 1 nm - Measurement speed: medium

[0105] (3) Adhesion strength measurement 40% of the glass substrate area was covered with a sealant film, and the remaining 60% was covered with a polyimide film. Then, a fluorine-based solar backsheet was laminated thereon. Lamination was performed at a temperature of 150 °C for 20 minutes so that the sealant film was adhered to the glass substrate while being crosslinked. The sealant film of the test piece was cut with a width of 1 cm so that the width of the measurement site became 1 cm.

[0106] A UTM sample holder and a 1 kN load cell were attached to a tensile-compression testing machine (LRX Plus Universal Test Machine, manufactured by LLOYD). After fixing the sealant film adhered to the glass substrate and the end of the portion of the glass substrate where the sealant film was not adhered, the tensile adhesion strength was tested at 60 mm / min.

[0107]

Table 3

[0108] As can be confirmed from Table 3 above, when the compositions for the encapsulant films of Examples 1 to 12 were used, it was confirmed that the volume resistivity, light transmittance, and adhesive strength were also realized at excellent levels.

Claims

1. A composition for a sealing film, comprising an ethylene / alpha-olefin copolymer, a crosslinking agent, a crosslinking aid, and a silane coupling agent, wherein the crosslinking aid contains a compound represented by the following Chemical Formula 1. 【Chemical 1】 In Chemical Formula 1, R １ ~R ６ are each independently an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms, where R １ ~R ３ Two or more of and R ４ ~R ６ Two or more of are each independently an alkenyl group having 2 to 20 carbon atoms.

2. The aforementioned R １ , R ３ , R ４ and R ６ are each independently alkenyl having 2 to 20 carbon atoms, and the aforementioned R ２ and R ５ are each independently alkyl having 1 to 20 carbon atoms or alkenyl having 2 to 20 carbon atoms. The composition for a sealing material film according to Claim 1.

3. Said R １ , R ３ , R ４ and R ６ are each independently an alkenyl having 2 to 12 carbon atoms with a double bond at the terminal, Said R ２ and R ５ are each independently an alkyl having 1 to 12 carbon atoms or an alkenyl having 2 to 12 carbon atoms with a double bond at the terminal, and the composition for a sealing material film according to claim 1.

4. The composition for a sealing film according to Claim 1, wherein the compound represented by Chemical Formula 1 is hexavinyl disiloxane or tetravinyl dimethyl disiloxane.

5. The composition for a sealing film according to Claim 1, wherein the crosslinking aid further contains an allyl group-containing compound.

6. The composition for a sealing film according to Claim 5, wherein the allyl group-containing compound contains one or more selected from the group consisting of triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate.

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

10.

8. The composition for a sealing film according to Claim 1, wherein the crosslinking aid is 0.01 to 5 parts by weight based on 100 parts by weight of the composition for a sealing film.

9. The composition for a sealing film according to Claim 1, further comprising 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.

10. A sealing film, comprising the composition for a sealing film according to any one of Claims 1 to 9.

11. A solar cell module, comprising the sealing film according to Claim 10.

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