Polyolefin composition

Abstract

The present invention relates to a polyolefin composition. The polyolefin composition of the present invention includes a modified polyolefin comprising vinyl silane groups, thereby improving the degree of crosslinking. When manufacturing an encapsulant film using the polyolefin composition of the present invention, an improved degree of crosslinking can be exhibited while maintaining optical and insulating properties.

Description

Technology Field

[0001] The present invention relates to a polyolefin composition. Background Technology

[0003] Polyolefin elastomers (POE) are gaining attention as solar cell encapsulants due to their superior insulation and moisture barrier properties compared to EVA (Ethylene Vinyl Acetate).

[0004] However, in the case of POE encapsulants, the degree of crosslinking is lower compared to EVA, leading to problems such as the occurrence of bubbles and reduced bonding stability during module fabrication. Furthermore, in the case of EVA-POE-EVA 3-layer encapsulants, the market for which has recently been expanding rapidly, problems caused by the low degree of crosslinking, such as bubbles and delamination due to differences in the crosslinking speed and degree of crosslinking between EVA and POE, are emerging more rapidly.

[0005] Therefore, to address the aforementioned problems, attempts are being made to improve module fabrication stability by improving the crosslinking degree of POE encapsulant. Prior art literature

[0007] (Patent Document 0001) JP 2018-145307 A The problem to be solved

[0008] The present invention aims to provide a polyolefin composition with improved crosslinking degree while maintaining optical and insulating properties. means of solving the problem

[0010] 1. The present invention provides a polyolefin composition comprising a modified polyolefin containing vinyl silane groups.

[0011] 2. In the above 1, the modified polyolefin is immersed in acetone at 60°C for 12 hours, washed, and then dissolved in a TCE-d2 solvent. 1A polyolefin composition is provided in which, when analyzed by H NMR (373K), the content of terminal double bonds detected at 5.7 to 6.3 ppm among the peaks originating from the modified portions in the modified polyolefin is 0.001 or more and 1 or less per 1000 total carbons.

[0012] 3. The present invention provides a polyolefin composition according to 1 or 2 above, wherein the vinyl silane group is derived from a silane compound comprising two or more vinyl groups.

[0013] 4. The present invention provides a polyolefin composition in which, in any one of 1 to 3 above, the silane compound is selected from the group consisting of tris(vinyldimethylsiloxy)methylsilane, tris(vinyldimethylsiloxy)phenylsilane, 1,3,5-trivinyl-1,1,3,5,5-pentamethyltrisiloxane, 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane, tetravinylsilane, and 1,3-divinyltetramethyldisiloxane.

[0014] 5. The present invention provides a polyolefin composition in which, in any one of 1 to 4 above, the polyolefin is a copolymer of ethylene and an alpha-olefin comonomer.

[0015] 6. The present invention provides a polyolefin composition in which, in any one of 1 to 5 above, the alpha-olefin comonomer is an alpha-olefin comonomer having 3 to 12 carbon atoms.

[0016] 7. The present invention provides a polyolefin composition in any one of 1 to 6 above, wherein the alpha-olefin comonomer comprises one or more selected from the group consisting of 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-eicocene, norbornene, norvonadiene, ethylidenenorbornene, phenylnorbornene, vinylnorbornene, dicyclopentadiene, 1,4-butadiene, 1,5-pentadiene, 1,6-hexadiene, styrene, alpha-methylstyrene, divinylbenzene, and 3-chloromethylstyrene.

[0017] 8. The present invention provides a composition for a packaging film comprising any one of the polyolefin compositions of 1 to 7 above.

[0018] 9. The present invention provides a packaging film formed from the composition for a packaging film of 8 above.

[0019] 10. The present invention provides a solar cell module comprising the encapsulating film of 9 above. Effects of the invention

[0021] The polyolefin composition of the present invention can exhibit an improved degree of crosslinking by including a modified polyolefin containing vinyl silane groups.

[0022] When manufacturing a packaging film using the polyolefin composition of the present invention as described above, an improved degree of crosslinking can be exhibited while maintaining optical and insulating properties, thereby increasing the stability of module fabrication. Specific details for implementing the invention

[0024] Hereinafter, the present invention will be described in more detail to aid in understanding the invention.

[0026] The present invention provides a polyolefin composition comprising a modified polyolefin containing vinyl silane groups.

[0027] Due to the vinyl silane groups included in the above modified polyolefin, a higher crosslinking reaction can be induced when crosslinking agents, crosslinking aids, etc. are added and reacted for the subsequent manufacture of encapsulating films, etc., thereby exhibiting a significant improvement in the degree of crosslinking.

[0028] The above modified polyolefin is prepared by immersing the above modified polyolefin in acetone at 60°C for 12 hours, washing it, and then dissolving it in a TCE-d2 solvent. 1 When analyzing H NMR (373K), among the peaks originating from the modified portion in the modified polyolefin, the content of terminal double bonds detected at 5.7 to 6.3 ppm may be 0.001 or more and 1 or less per 1000 total carbons. The detected terminal double bonds may originate from the vinyl silane group.

[0029] When measuring the terminal double bond content detected at 5.7 to 6.3 ppm by NMR analysis of the above modified polyolefin, the content may include some of the terminal double bonds contained in the original polyolefin (i.e., unmodified polyolefin) and terminal double bonds originating from the modified portion. Among the terminal double bonds originating from the unmodified portion within the modified polyolefin, the hydrogen peak of one terminal double bond detected at 5.7 to 6.3 ppm can be calculated through the hydrogen peaks originating from two terminal double bonds detected in a range that does not overlap with the 5.7 to 6.3 ppm range. Accordingly, by analyzing the modified polyolefin with NMR and subtracting the hydrogen peak of one terminal double bond originating from the unmodified portion from the terminal double bond content detected at 5.7 to 6.3 ppm, the content of the terminal double bond originating from the modified portion within the modified polyolefin detected at 5.7 to 6.3 ppm can be determined.

[0030] More specifically, when analyzing the NMR above, the content of terminal double bonds detected at 5.7 to 6.3 ppm among the peaks originating from the modified portion in the modified polyolefin may be 0.001 or more, 0.0015 or more, 0.002 or more, 0.0025 or more, 0.003 or more, 0.0035 or more, 0.004 or more, 0.0045 or more, 0.005 or more per 1000 total carbons, and may also be 1 or less, 0.98 or less, 0.96 or less, 0.94 or less, 0.92 or less, 0.9 or less, 0.88 or less, 0.86 or less, 0.84 or less. By introducing terminal double bonds that play a leading role in the crosslinking reaction into the modified polyolefin, the degree of crosslinking can be improved in subsequent crosslinking reactions using crosslinking agents, crosslinking aids, etc. Accordingly, the polyolefin composition of the present invention can exhibit a significantly improved degree of crosslinking by including a modified polyolefin containing terminal double bonds within the above range.

[0031] The vinyl silane group may be derived from a silane compound. The modified polyolefin may be a conventional polyolefin modified through a chemical reaction with a silane compound (e.g., grafting, polymerization, etc.) to include a vinyl silane group. In this case, the silane compound may include two or more vinyl groups, and by including two or more vinyl groups, one or more unreacted vinyl groups may remain even after the chemical reaction with the polyolefin.

[0032] For example, the modified polyolefin of the present invention may be one in which a silane compound is grafted onto the backbone of the polyolefin. The polyolefin may be a polyolefin that does not contain or polymerize other compounds other than ethylene and alpha-olefin.

[0033] When grafting a silane compound onto the backbone of a polyolefin for the production of the modified polyolefin above, a crosslinking agent may be added together to carry out the reaction. When a crosslinking agent is added, it serves to initiate the reaction in which the silane compound is grafted, thereby enabling the silane compound to be grafted onto the polyolefin backbone more effectively. For example, one or more crosslinking agents selected from the group consisting of organic peroxides, hydroperoxides, and azo compounds may be used. Specifically, 2,5-bis(t-butylperoxy)-2.5-dimethylhexane, t-buphylcumyl 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-hexine, bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, benzoyl peroxide, o-methylbenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, diacyl peroxides; It may be one or more selected from the group consisting of compounds such as t-butylperoxyisobutylate, t-butylperoxyacetate, t-butylperoxy-2-ethylhexyl carbonate (TBEC), t-butylperoxy-2-ethylhexanoate, t-butylperoxyfibarate, t-butylperoxyoctoate, t-butylperoxyisopropyl carbonate, t-butylperoxybenzoate, di-t-butylperoxyphthalate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, and 2,5-dimethyl-2,5-di(benzoylperoxy)-3-hexine. More specifically, it may be 2,5-bis(t-butylperoxy)-2.5-dimethylhexane, and can be manufactured and used or a commercially available product (e.g., Luperox 101) can be purchased and used.

[0034] The above silane compound may contain two or more vinyl groups. By grafting a silane compound containing two or more vinyl groups onto the backbone of a polyolefin, vinyl groups can remain in the modified polyolefin obtained after the silane compound is grafted. Due to these remaining vinyl groups, an effect of improved crosslinking can be obtained when the material is subsequently applied as a packaging film or the like.

[0035] In addition, the silane compound may contain a methyl group. If the silane compound contains a methyl group, the stability of the modified polyolefin may be improved.

[0036] The above silane compound may be selected from the group consisting of, for example, tris(vinyldimethylsiloxy)methylsilane, tris(vinyldimethylsiloxy)phenylsilane, 1,3,5-trivinyl-1,1,3,5,5-pentamethyltrisiloxane, 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane, tetravinylsilane, and 1,3-divinyltetramethyldisiloxane.

[0037] In addition, the modified polyolefin is prepared by immersing the modified polyolefin in acetone at 60°C for 12 hours, washing it, and then dissolving it in a TCE-d2 solvent. 1 When analyzing H NMR (373K), the content of methyl groups detected at 0.0 to 0.4 ppm among the peaks originating from the modified portion in the modified polyolefin may be 15 or less per 1000 total carbons.

[0038] In this way, the modified polyolefin may include a methyl silane group, and the detected methyl group may be derived from the methyl silane group.

[0039] If the silane compound chemically reacted to allow the modified polyolefin to include vinyl silane groups contains methyl silane groups, the modified polyolefin may include methyl silane groups.

[0040] More specifically, when analyzing the above NMR, the content of methyl groups detected at 0.0 to 0.4 ppm may be 0 or more, 0.03 or more, 0.05 or more, 0.07 or more, 0.09 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.5 or more, 2 or more, 2.5 or more, 3 or more, and may also be 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, or 11 or fewer. VTMS (vinyltrimethoxysilane), which is commonly used in conventional reaction extrusion, contains methoxy groups and can undergo side reactions such as hydrolysis in the presence of moisture, resulting in poor stability. In contrast, the modified polyolefin contains methyl groups within the above range, thereby preventing such side reactions and improving stability.

[0041] The above polyolefin may be a copolymer of ethylene and an alpha-olefin comonomer. The modified olefin of the present invention may also be modified based on such a polyolefin.

[0042] The above alpha-olefin comonomer may specifically be an alpha-olefin comonomer having 3 to 12 carbon atoms, and more specifically, an alpha-olefin comonomer having 4 to 8 carbon atoms. For example, the above alpha-olefin comonomer may be one or more selected from the group consisting of 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-eicocene, norbornene, norvonadiene, ethylidenenorbornene, phenylnorbornene, vinylnorbornene, dicyclopentadiene, 1,4-butadiene, 1,5-pentadiene, 1,6-hexadiene, styrene, alpha-methylstyrene, divinylbenzene, and 3-chloromethylstyrene, and more specific examples may be 1-butene, 1-octene, or a combination thereof.

[0043] The polyolefin composition of the present invention may comprise only the modified polyolefin, or may comprise an unmodified polyolefin together with the modified polyolefin. The unmodified polyolefin may be a copolymer of the aforementioned ethylene and alpha-olefin comonomers.

[0044] When the polyolefin composition of the present invention includes an unmodified polyolefin together with the modified polyolefin, the modified polyolefin may be included in an amount of 1% or more and 60% or less of the total weight of the polyolefin composition. More specifically, it may be included in an amount of 1% or more, 2% or more, 3% or more, 4% or more, and 5% or more of the total weight, and may also be included in an amount of 60% or less, 59% or less, 58% or less, 57% or less, 56% or less, 55% or less, 54% or less, 53% or less, 52% or less, 51% or less, and 50% or less of the total weight. If the modified polyolefin is included in an amount less than the above range, the effect of improving the degree of crosslinking may be negligible.

[0046] In addition, the present invention provides a composition for a packaging film comprising the aforementioned polyolefin composition.

[0047] The above-described composition for the encapsulation film may further include one or more selected from the group consisting of a crosslinking agent, a crosslinking aid, a silane coupling agent, a light stabilizer, a UV absorber, and a heat stabilizer, in addition to the aforementioned polyolefin composition.

[0048] The above-mentioned crosslinking agent can improve the heat resistance and durability of the encapsulation sheet by helping to form crosslinking bonds.

[0049] The above crosslinking agent may be one or more selected from the group consisting of organic peroxides, hydroperoxides, and azo compounds, for example.

[0050] Specifically, dialkyl peroxides such as t-butylcumyl 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-hexine; hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethyl-2,5-di(hydroperoxy)hexane, t-butyl hydroperoxide; and 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-butylperoxyisobutylate, t-butylperoxyacetate, t-butylperoxy-2-ethylhexyl carbonate (TBEC), t-butylperoxy-2-ethylhexanoate, t-butylperoxyfibarate, t-butylperoxyoctoate, t-butylperoxyisopropyl carbonate, t-butylperoxybenzoate, di-t-butylperoxyphthalate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dimethyl-2,5-di(benzoylperoxy)-3-hexine; One or more selected from the group consisting of ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide, lauryl peroxide, azobis(isobutyronitrile) and azobis(2,4-dimethylvaleronitrile), etc., but are not limited thereto.

[0051] The above organic peroxide may be an organic peroxide having a 1-hour half-life temperature of 120 to 135°C, for example, 120 to 130°C, 120 to 125°C, preferably 121°C. The "1-hour half-life temperature" refers to 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 varies, and therefore, when an organic peroxide having a 1-hour half-life temperature within the aforementioned range is used as a crosslinking agent, the radical initiation reaction, i.e., the crosslinking reaction, can proceed effectively at the lamination process temperature for manufacturing optoelectronic devices.

[0052] The above-mentioned crosslinking agent may be included in an amount of 0.01 parts by weight or more and 5 parts by weight or less per 100 parts by weight of the polyolefin composition. Specific examples include being included in an amount of 0.01 parts by weight or more, 0.02 parts by weight or more, 0.04 parts by weight or more, 0.06 parts by weight or more, and 0.08 parts by weight or more, and also being included in an amount of 5 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, and 2 parts by weight or less. If the above-mentioned crosslinking agent is included in an amount of less than 0.01 parts by weight, the effect of improving the degree of crosslinking is negligible, and if it is included in an amount exceeding 5 parts by weight, the moldability of the final product, such as a packaging film or a packaging sheet, decreases, which may cause problems involving process constraints and affect the physical properties of the packaging material.

[0053] In addition, the above-mentioned composition for the encapsulation film may include a crosslinking agent in addition to the crosslinking agent. By including the crosslinking agent in the composition for the encapsulation film, the degree of crosslinking between the film compositions by the aforementioned crosslinking agent can be increased, thereby further improving the degree of crosslinking and stability in the final product.

[0054] The above-mentioned crosslinking agent may be any of the various crosslinking agents known in the art, for example, a compound containing at least one unsaturated group such as an allyl group or a (meth)acryloxy group may be used.

[0055] The above-mentioned compounds containing the allyl group may be exemplified as polyallyl compounds such as trialyl isocyanurate (TAIC), trialyl cyanurate, dialyl phthalate, dialyl fumarate, or dialyl maleate, and the above-mentioned compounds containing the (meth)acryloxy group may be exemplified as poly(meth)acryloxy compounds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, or trimethylolpropane trimethacrylate, but are not particularly limited thereto.

[0056] The above-mentioned crosslinking agent may be included in an amount of 0.1 parts by weight or more and 1 part by weight or less per 100 parts by weight of the polyolefin composition. Specific examples include being included in an amount of 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, and 0.4 parts by weight or more, and also being included in an amount of 1 part by weight or less, 0.9 parts by weight or less, 0.8 parts by weight or less, 0.7 parts by weight or less, and 0.6 parts by weight or less. If the above-mentioned crosslinking agent is included in an amount of less than 0.1 parts by weight, the effect of improving the degree of crosslinking is negligible, and if it is included in an amount exceeding 1 part by weight, problems may arise that affect the physical properties of the final product, such as a packaging film, and the production cost may increase.

[0057] In addition, the above composition for the encapsulant film may further include a silane coupling agent.

[0058] 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 as the silane coupling agent.

[0059] The above silane coupling agent may be included in an amount of 0.1 parts by weight or more and 0.5 parts by weight or less per 100 parts by weight of the polyolefin composition. Specific examples include being included in an amount of 0.1 parts by weight or more, 0.12 parts by weight or more, 0.14 parts by weight or more, 0.16 parts by weight or more, and 0.18 parts by weight or more, and also being included in an amount of 0.5 parts by weight or less, 0.45 parts by weight or less, 0.4 parts by weight or less, 0.3 parts by weight or less, and 0.35 parts by weight or less. If the above silane coupling agent is used in an amount less than 0.1 parts by weight, the adhesion to glass during the fabrication of the solar cell module is poor, making it easy for moisture to penetrate and thus failing to guarantee the long-term performance of the module; if used in an amount exceeding 0.5 parts by weight, it acts as a factor increasing the YI (yellow index) and is therefore undesirable.

[0060] The above light stabilizer can prevent photooxidation by capturing active species that initiate photodegradation of the resin, depending on the application of the above composition. The type of light stabilizer that can be used is not particularly limited, and known compounds such as hindered amine-based compounds or hindered piperidine-based compounds can be used, for example.

[0061] Depending on the use of the composition, the above UV absorber can absorb ultraviolet rays from sunlight, etc., convert them into harmless thermal energy within the molecule, and prevent the active species that initiate photodegradation in the resin composition from being excited. The specific types of UV absorbers that can be used are not particularly limited, and for example, one or more types of inorganic UV absorbers such as benzophenone-based, benzotriazole-based, acrylonitrile-based, metal complex salt-based, hindered amine-based, ultrafine titanium oxide, or ultrafine zinc oxide may be used.

[0062] In addition, examples of the above-mentioned heat stabilizers 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 phosphoric 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 reaction products of 8-hydroxy-5,7-di-tert-butyl-furan-2-one and o-xylene, and one or more of the above may be used.

[0063] The content of the light stabilizer, UV absorber, and / or heat stabilizer is not particularly limited. That is, the content of the additive can be appropriately selected considering the use of the resin composition, the shape or density of the additive, etc., and can typically be appropriately controlled within the range of 0.01 to 5 parts by weight per 100 parts by weight of the total solid content of the encapsulating film composition.

[0065] In addition, the present invention provides a packaging film formed from the aforementioned composition for packaging film.

[0066] The encapsulating film of the present invention can be manufactured by forming the aforementioned composition for encapsulating film into a film or sheet shape. Such a molding method is not particularly limited and can be manufactured by forming a sheet or film using conventional processes such as a T-die process or extrusion. For example, the manufacture of the encapsulating film can be performed as an in-situ process using a device in which the manufacturing of a modified resin composition using the composition for encapsulating film and the film or sheet formation process are interconnected.

[0067] The thickness of the above encapsulating 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 possibility of breakage of the device in the optoelectronic device, as well as the lightness or workability of the device, and can be changed according to the specific application.

[0069] In addition, the present invention provides a solar cell module comprising the above-described encapsulating film. In the present invention, the solar cell module may have a configuration in which solar cells arranged in series or parallel are spaced apart by the encapsulating film of the present invention, a glass surface is disposed on the surface where sunlight strikes, and the back surface is protected by a back sheet, and various types and forms of solar cell modules manufactured including the encapsulating film in the art may all be applied to the present invention.

[0070] The above glass surface may use tempered glass to protect the solar cell from external impact and prevent breakage, and may use low iron tempered glass with a low iron content to prevent reflection of sunlight and increase the transmittance of sunlight.

[0071] The above back sheet is a weather-resistant film that protects the back surface of a solar cell module from the outside, and includes, for example, a fluorine resin sheet, a metal plate or metal foil such as aluminum, a ring-shaped olefin resin sheet, a polycarbonate resin sheet, a poly(meth)acrylic resin sheet, a polyamide resin sheet, a polyester resin sheet, and a composite sheet formed by laminating a weather-resistant film and a barrier film.

[0072] In addition, the solar cell module of the present invention can be manufactured according to methods known in the art without limitation, except for including the aforementioned encapsulating film.

[0073] The solar cell module of the present invention is manufactured using an encapsulation film with minimized creep, and thus hardly any deformation occurs even during long-term use and use in extreme environments (e.g., maintaining durability even under conditions of 85°C temperature and 85% humidity), and delamination is minimized, resulting in excellent durability and significantly suppressing the occurrence of problems such as output degradation.

[0075] Examples

[0076] The present invention will be explained in more detail below through examples. However, the following examples are intended to illustrate the present invention and do not limit the scope of the present invention.

[0078] [Manufacture of Modified Polyolefins]

[0079] Preparation Example 1

[0080] Ethylene / 1-butene copolymer (EBR; density 0.877 g / cm³ 3A modified polyolefin was prepared by mixing 0.1012 moles of tris(vinyldimethylsiloxy)methylsilane and 0.0021 moles of peroxide (Luperox 101) as reagents (silane compounds) with 1 kg of a material having a melt index (190℃, 2.16 kg load) of 14 g / 10 min, and then injecting the mixture at a constant speed through a syringe pump to perform reactive extrusion. At this time, the temperature of the twin-screw extruder used for reactive extrusion was set to 100–220℃, the screw feeder speed to 9.82 rpm, and the extruder screw speed to 200 rpm.

[0082] Preparation Examples 2 to 8

[0083] Modified polyolefins were prepared using the same method as in Preparation Example 1, except that the copolymer type, reagent type and content, and peroxide content were changed as shown in Table 1 below.

[0084] Preparation Example 6 is a copolymer with a density of 0.876 g / cm³ 3 An ethylene / 1-octene copolymer (EOR) with a melt index (190℃, 2.16kg load) of 13 g / 10 min was used.

[0086] copolymer Types of Reagents Reagent content Peroxide content Preparation Example 1 EBR Tris(vinyldimethylsiloxy)methylsilane 0.1012 malls 0.0021mall Preparation Example 2 EBR 0.3373 Mall 0.007mall Preparation Example 3 EBR Tris(vinyldimethylsiloxy)phenylsilane 0.1012 malls 0.0021mall Preparation Example 4 EBR 1,3,5-trivinyl-1,1,3,5,5-pentamethyltrisiloxane 0.1012 malls 0.0021mall Preparation Example 5 EBR 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane 0.1012 malls 0.0021mall Preparation Example 6 EOR 0.1012 malls 0.0021mall Preparation Example 7 EBR Tetravinylsilane 0.1012 malls 0.0021mall Preparation Example 8 EBR 1,3-Divinyltetramethyldisiloxane 0.3373 Mall 0.007mall

[0087] Comparative Manufacturing Example 1

[0088] Ethylene / 1-butene copolymer (EBR; density 0.877 g / cm³ 3A modified polyolefin was prepared by mixing 5.000 parts by weight of vinyltrimethoxysilane (VTMS) and 0.2 parts by weight of peroxide (Luperox 101) as reagents (silane compounds) with respect to 100 parts by weight of a mixture with a melt index (190℃, 2.16kg load) of 14 g / 10min, and then injecting the mixture at a constant speed through a syringe pump to perform reactive extrusion. At this time, the temperature of the twin-screw extruder used for reactive extrusion was set to 100–220℃, the screw feeder speed to 9.82 rpm, and the extruder screw speed to 200 rpm.

[0090] [Manufacture of Polyolefin Composition and Encapsulation Film]

[0091] Examples 1 to 8

[0092] The modified polyolefins of each of Preparation Examples 1 to 8 were used as polyolefin compositions, and encapsulating films were prepared by the following method.

[0093] The bowl temperature of the Haake Modular Torque Viscometer was set to 40°C. After adding the polyolefin composition to the bowl, 1.0 parts by weight of a crosslinking agent (TBEC), 0.5 parts by weight of a crosslinking co-agent (TAIC), and 0.2 parts by weight of a silane coupling agent (MEMO) were added using an electric pipette, based on 100 parts by weight of the polyolefin composition. The change in torque value over time was observed while stirring at 40 rpm at 40°C, and impregnation was terminated when the torque value increased rapidly. Subsequently, the impregnated sample was press-molded to an average thickness of 0.5 mm at a low temperature (compressor barrel temperature of 90–100°C) to prevent high-temperature crosslinking, thereby producing a sheet-type encapsulating film.

[0095] Examples 9 to 14

[0096] Modified polyolefin of Preparation Examples 3 and 5 and ethylene / 1-butene copolymer (EBR; density 0.877 g / cm³3 A mixture of , melt index (190℃, 2.16kg load) 14 g / 10min) as shown in Table 2 below was used as a polyolefin composition.

[0097] Encapsulating films were prepared in the same manner as Examples 1 to 8 above, except that a mixture as shown in Table 2 below was used as the polyolefin composition.

[0099] Modified polyolefin (weight%) EBR (weight%) Example 9 Preparation Example 3 (5 wt%) 95 wt% Example 10 Preparation Example 3 (30 wt%) 70 wt% Example 11 Preparation Example 3 (50 wt%) 50 wt% Example 12 Preparation Example 5 (5 wt%) 95 wt% Example 13 Preparation Example 5 (30 wt%) 70 wt% Example 14 Preparation Example 5 (50 wt%) 50 wt%

[0100] Comparative Example 1

[0101] Ethylene / 1-butene copolymer (EBR; density 0.877 g / cm³ 3 , melt index (190℃, 2.16kg load) 14 g / 10min) was used as a polyolefin composition.

[0102] Encapsulating films were prepared in the same manner as in Examples 1 to 8 above, except that the polyolefin composition was changed.

[0104] Comparative Example 2

[0105] The modified polyolefin of Comparative Manufacturing Example 1 was used as the polyolefin composition.

[0106] Encapsulating films were prepared in the same manner as in Examples 1 to 8 above, except that the polyolefin composition was changed.

[0108] Experimental Example 1

[0109] The physical properties of the polyolefin compositions of Examples 1 to 14 and Comparative Examples 1 and 2 were evaluated according to the following method and are shown in Table 3.

[0111] 1) Density

[0112] Measured using ASTM D-792.

[0113] 2) Melt Index (MI)

[0114] It was measured according to ASTM D-1238 (condition E, 190℃, 2.16 kg load).

[0115] 3) Melt flow ratio (MFR)

[0116] The ratio of the melt index measured by ASTM D-1238 (condition E, 190°C, 10 kg load) to the melt index measured by ASTM D-1238 (condition E, 190°C, 2.16 kg load) (MI 10 / MI 2.16 It was calculated as ).

[0118] Density (g / cc) MI (dg / min) MFR (dg / min) Example 1 0.8800 7.2 8.9 Example 2 0.8828 2.4 13.0 Example 3 0.8786 10.6 7.7 Example 4 0.8802 9.1 7.9 Example 5 0.8792 3.9 9.8 Example 6 0.8765 4.3 10.1 Example 7 0.8790 9.2 8.1 Example 8 0.8778 4.3 10.9 Example 9 0.8771 13.7 6.8 Example 10 0.8776 13.0 7.0 Example 11 0.8777 12.4 7.4 Example 12 0.8773 13.3 7.0 Example 13 0.8777 11.0 7.7 Example 14 0.8780 9.1 8.5 Comparative Example 1 0.8770 14.0 6.8 Comparative Example 2 0.8828 9.6 8.2

[0119] Experimental Example 2

[0120] NMR was measured for the polyolefin compositions of Examples 1 to 14 and Comparative Examples 1 and 2 according to the following method, and the analysis results are shown in Table 4.

[0121] The polyolefin composition was pretreated by immersing it in acetone at 60°C for 12 hours, removing the acetone, and washing it four times with clean acetone. The pretreated polyolefin composition was dissolved in TCE-d2 solvent and 1 H NMR (373K) analysis was performed.

[0122] From the above NMR analysis results, the terminal double bond peak detected at 5.7 to 6.3 ppm includes some of the peaks of the terminal double bonds originally contained in the polyolefin prior to modification (i.e., terminal double bonds originating from the unmodified portion). Through the hydrogen peaks originating from two terminal double bonds detected in a range that does not overlap with the 5.7 to 6.3 ppm range among the terminal double bonds originating from the unmodified portion, the hydrogen peak of one terminal double bond detected at 5.7 to 6.3 ppm can be calculated. Therefore, by analyzing the modified polyolefin with NMR and subtracting the hydrogen peak of one terminal double bond originating from the unmodified portion from the terminal double bond content detected at 5.7 to 6.3 ppm, the content of the terminal double bonds originating from the modified portion within the modified polyolefin that is detected at 5.7 to 6.3 ppm can be obtained.

[0123] From the above NMR analysis results, the methyl group peak detected at 0.0 to 0.4 ppm is a characteristic peak of the modified polyolefin, and the number of methyl groups was determined by quantifying the peak in that portion.

[0125] Peak originating from the modified portion within the modified polyolefin Number of terminal double bonds detected at 5.7~6.3 ppm (units / total 1000C) Number of methyl groups detected at 0.0~0.4 ppm (units / total 1000C) Example 1 0.307 3.613 Example 2 0.826 10.787 Example 3 0.095 1.463 Example 4 0.246 3.549 Example 5 0.434 0.983 Example 6 0.347 1.127 Example 7 0.176 0 Example 8 0.255 0.985 Example 9 0.005 0.073 Example 10 0.029 0.439 Example 11 0.048 0.732 Example 12 0.022 0.049 Example 13 0.130 0.295 Example 14 0.217 0.492 Comparative Example 1 - - Comparative Example 2 0 0

[0126] As can be seen from Table 4, although the degree of grafting during the reaction extrusion process varies depending on each reagent and the amount of reagent, it was confirmed that terminal double bonds (detected at 5.7 to 6.3 ppm) were detected in the polyolefin compositions of Examples 1 to 8 of the present invention using silane compounds containing two or more vinyl groups as reagents. In addition, it was confirmed that terminal double bonds (detected at 5.7 to 6.3 ppm) were detected in the polyolefin compositions of Examples 9 to 14 of the present invention, which partially contain modified polyolefins prepared using these silane compounds, even if at values ​​slightly lower than those of Examples 1 to 8.

[0127] In the case of Comparative Example 2, although a modified polyolefin was prepared by grafting a silane compound, the silane compound used itself contains one vinyl group. When preparing the modified polyolefin, the double bond of the vinyl group breaks and bonds to the polyolefin main chain, so it was confirmed that the terminal double bond was not detected at 5.7 to 6.3 ppm among the peaks originating from the modified portion within the modified polyolefin during NMR measurement.

[0129] Experimental Example 3

[0130] After preparing crosslinked sheets using the encapsulating films of Examples 1 to 14 and Comparative Examples 1 and 2 by the method below, the crosslinking properties of the crosslinked sheets were measured according to the method below, and the analysis results are shown in Table 5.

[0131] A 0.5 mm thick encapsulant film (10 cm X 10 cm) was placed between two release films (thickness: about 100 µm), and crosslinked by lamination in a vacuum laminator at a process temperature of 145°C for a process time of 20 minutes (5 minutes vacuum / 1 minute pressurization / 14 minutes pressure maintenance).

[0133] 1) Cultivator

[0134] Cut the above cross-linked sheet 3x3 mm using scissors 2 I cut it to the size of 7X14 cm 2The sides and bottom of a 120-mesh wire mesh were stapled. The sheet was placed into the wire mesh, and the weight of the sheet was measured. The amount of the sheet was set to 0.49 to 0.51 g. After placing the sheet, the top of the wire mesh was stapled, and the total weight of the sample was measured. A solution of 10 g of BHT (dibutylhydroxytoluene) dissolved in 1,000 g of xylene was poured into a 2 L cylinder reactor, and 3 to 4 of the above samples were added. The reactor was heated, and reflux was terminated after 5 hours from the point when it began to boil. The samples were removed from the reactor using a metal strainer and vacuum dried at 140 °C for 24 hours. The weight of the dried samples was measured, and the degree of crosslinking was calculated using the following Equation 1. The degree of crosslinking can be determined as the average value of 3 to 4 samples refluxed in xylene.

[0135] [Mathematical Formula 1]

[0136] Crosslinking (%) = [(Weight of sheet after reflux) / (Weight of sheet before reflux)] x 100

[0138] 2) Light transmittance (%)

[0139] The light transmittance (380 to 1,000 nm) of the above-mentioned crosslinked sheet in the visible light region was measured using a Shimadzu UV-3600 spectrophotometer (measurement mode: transmittance, wavelength interval: 1 nm, measurement speed: medium).

[0141] 3) Volume resistivity (Ω·cm)

[0142] Tests were performed at room temperature based on ASTM D257. The crosslinked sheet was placed in a Keithley 8009 Resistivity test fixture, and after applying a voltage of 1,000 V using a 6517B Electrometer / High Resistance meter connected to it, the volume resistivity was measured.

[0144] Crossed (%) Light transmittance (%) Volume resistivity (Ω·cm) 550 nm Vis Example 1 81.9 93.0 92.5 4.2E+16 Example 2 83.8 92.0 92.1 2.1E+16 Example 3 81.1 92.2 92.3 5.7E+16 Example 4 80.2 92.1 92.4 4.9E+16 Example 5 85.2 92.5 92.7 1.1E+17 Example 6 90.5 92.0 92.2 1.3E+17 Example 7 78.4 92.3 92.5 4.7E+16 Example 8 75.0 92.7 92.5 3.5E+16 Example 9 74.7 92.5 92.4 5.5E+16 Example 10 78.6 92.2 92.1 5.7E+16 Example 11 80.0 92.3 92.5 5.4E+16 Example 12 75.0 92.2 92.3 6.8E+16 Example 13 80.4 92.3 92.1 7.1E+16 Example 14 83.0 92.4 92.5 7.3E+16 Comparative Example 1 73.1 92.0 92.2 6.1E+16 Comparative Example 2 73.8 92.3 92.5 3.0E+16

[0146] As can be seen in Table 5, in the case of Examples 1 to 14 containing terminal double bonds, i.e., vinyl silane groups, within the polyolefin composition, the light transmittance and volume resistivity were similar to or equivalent to those of the comparative example, but it was confirmed that the degree of crosslinking was significantly increased.

[0147] In the case of Comparative Example 2, a slight improvement in the degree of crosslinking was confirmed compared to Comparative Example 1, which used a copolymer that was not modified using a reagent. However, the silane compound used in Comparative Example 2 is a reagent commonly used in the production of graft polyolefins, and since the compound itself contains one vinyl group, an increase in terminal double bonds due to the modified polyolefin in the polyolefin after grafting did not occur, and it was confirmed that it showed a significantly lower degree of crosslinking compared to the present example.

Claims

Claim 1 A modified polyolefin containing vinyl silane groups is included, and the modified polyolefin is immersed in acetone at 60°C for 12 hours and washed, and then dissolved in a TCE-d2 solvent. 1 A polyolefin composition having a content of terminal double bonds detected at 5.7 to 6.3 ppm among the peaks originating from the modified portion within the modified polyolefin when analyzed by H NMR (373K), which is 0.001 or more and 1 or less per 1,000 total carbons. Claim 2 delete Claim 3 A polyolefin composition according to claim 1, wherein the vinyl silane group is derived from a silane compound comprising two or more vinyl groups. Claim 4 A polyolefin composition according to claim 3, wherein the silane compound is selected from the group consisting of tris(vinyldimethylsiloxy)methylsilane, tris(vinyldimethylsiloxy)phenylsilane, 1,3,5-trivinyl-1,1,3,5,5-pentamethyltrisiloxane, 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane, tetravinylsilane, and 1,3-divinyltetramethyldisiloxane. Claim 5 The polyolefin composition of claim 1, wherein the polyolefin is a copolymer of ethylene and an alpha-olefin comonomer. Claim 6 The polyolefin composition of claim 5, wherein the alpha-olefin comonomer is an alpha-olefin comonomer having 3 to 12 carbon atoms. Claim 7 The polyolefin composition of claim 6, wherein the alpha-olefin comonomer comprises one or more selected from the group consisting of 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-eicocene, norbornene, norvonadiene, ethylidenenorbornene, phenylnorbornene, vinylnorbornene, dicyclopentadiene, 1,4-butadiene, 1,5-pentadiene, 1,6-hexadiene, styrene, alpha-methylstyrene, divinylbenzene, and 3-chloromethylstyrene. Claim 8 A composition for a packaging film comprising a polyolefin composition of any one of claims 1, 3 to 7. Claim 9 A packaging film formed from the composition for a packaging film of claim 8. Claim 10 A solar cell module comprising the encapsulating film of claim 9.